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Five Additional Tribes (Aphragmeae, Biscutelleae, Calepineae, Conringieae, and Erysimeae) in the Brassicaceae (Cruciferae)

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Abstract

The tribes Aphragmeae and Conringieae are proposed as new, and the tribes Biscutelleae, Calepineae, and Erysimeae (Brassicaceae; Cruciferae) are re-established. The unigeneric Aphragmeae, Biscutelleae, and Erysimeae include the genera Aphragmus, Biscutella, and Erysimum, respectively. The Conringieae comprises Conringia and Zuvanda, whereas the Calepineae includes Calepina, Goldbachia, and Spirorrhynchus. The prior tribal assignments of these genera, total number of species, and geographic distribution of all five tribes are listed.
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Five Additional Tribes (Aphragmeae, Biscutelleae, Calepineae,
Conringieae, and Erysimeae) in the Brassicaceae (Cruciferae)
Author(s): Dmitry A. German and Ihsan A. Al-Shehbaz
Source: Harvard Papers in Botany, 13(1):165-170. 2008.
Published By: Harvard University Herbaria
DOI: http://dx.doi.org/10.3100/1043-4534(2008)13[165:FATABC]2.0.CO;2
URL: http://www.bioone.org/doi/
full/10.3100/1043-4534%282008%2913%5B165%3AFATABC%5D2.0.CO%3B2
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Extensive molecular studies (for leads, see
Koch et al., 2003; Mitchell-Olds et al., 2005;
Al-Shehbaz et al., 2006; Beilstein et al., 2006;
Bailey et al., 2006; Koch et al., 2007; and
Warwick et al., 2007) were conducted during the
past dozen years on the phylogeny and evolu-
tion of Brassicaceae (Cruciferae). As a result,
tribal classifications of the family based strictly
on morphology, such as the systems of de
Candolle (1821), Prantl (1891), Hayek (1911),
Schulz (1936), and Dorofeyev (2004), as well
as the modifications of Schulz’s system by
Janchen (1942) and Al-Shehbaz (1984), were
shown to be highly artificial. Although the
boundaries of only a few tribes (e.g., Brassiceae
DC., Heliophileae DC.) remained largely unal-
tered, circumscription of almost all of the
remaining tribes needed re-adjustments.
The first attempt to achieve a tribal classifi-
cation of the family based on molecular studies
and re-examination of morphology was made by
Al-Shehbaz et al. (2006). In that study, 25 tribes
(including six new) were recognized. However,
further adjustments at the tribal level, including
placements of several smaller genera not previ-
ously studied or with unresolved positions on
the phylogenetic trees (see Bailey et al., 2006;
Warwick et al., 2007) or super network (Koch
et al., 2007), became immediately evident. As a
result, the tribes Dontostemoneae Al-Shehbaz &
Warwick, and Malcomieae Al-Shehbaz &
Warwick were described as new, and the tribe
Buniadeae DC. was re-established (Al-Shehbaz
and Warwick, 2007).
Based on molecular studies by German et al.
(in prep.), the present paper deals with the tribal
assignments of nine, predominantly Old World,
genera (Aphragmus Andrz. ex DC., Biscutella
L., Calepina Adans., Conringia Heist. ex Fabr.,
Erysimum L., Goldbachia DC., Megadenia
Maxim., Spirorrhynchus Kar. & Kir., and Zuvanda
(Dvořák) R. K. Askerova), either inadequately
studied or with no previous molecular studies.
They are placed in five tribes, of which two
(Aphragmeae and Conringieae) are described as
new, and three (Biscutelleae, Calepineae, and
Erysimeae) are re-established.
FIVE ADDITIONAL TRIBES (APHRAGMEAE, BISCUTELLEAE,
CALEPINEAE, CONRINGIEAE, AND ERYSIMEAE)
IN THE BRASSICACEAE (CRUCIFERAE)
DMITRY A. GERMAN1AND IHSAN A. AL-SHEHBAZ2
Abstract. The tribes Aphragmeae and Conringieae are proposed as new, and the tribes Biscutelleae, Calepineae,
and Erysimeae (Brassicaceae; Cruciferae) are re-established. The unigeneric Aphragmeae, Biscutelleae, and
Erysimeae include the genera Aphragmus, Biscutella, and Erysimum, respectively. The Conringieae comprises
Conringia and Zuvanda, whereas the Calepineae includes Calepina, Goldbachia, and Spirorrhynchus. The prior
tribal assignments of these genera, total number of species, and geographic distribution of all five tribes are listed.
Keywords: Brassicaceae, Cruciferae, tribal classification
We are grateful to GustavoA. Romero-González and Donna Tremonte for their editorial advice and help. We thank Steve
L. O’Kane, Jr. and an anonymous reviewer for their remarks on the manuscript.
1South-Siberian Botanical Garden, Altai State University, 656049, Lenin str. 61, Barnaul, Russia. Email: oreoloma@
rambler.ru.
2Missouri Botanical Garden, 2345 Tower Grove, St. Louis, Missouri 63110, U.S.A. Email: ihsan.al-shehbaz@mobot.org.
Author for correspondence.
Harvard Papers in Botany, Vol. 13, No. 1, 2008, pp. 165–170.
© President and Fellows of Harvard College, 2008.
APHRAGMUS
This genus previously included about four
species (Ebel, 1998), but has recently been
expanded by the discovery of new species and
by its union with the Himalayan Staintoniella H.
Hara and Lignariella Baehni (Al-Shehbaz,
2000, 2002, 2003; Warwick et al., 2006a). As
presently delimited (Warwick et al., 2006b), the
genus includes 11 species, centered primarily in
the Himalayas and adjacent central Asia, with
one species, Aphragmus eschscholtzianus Andrz.
ex DC., distributed in the northern Russian Far
East,northwestern Canada, and Alaska.
Aphragmus was placed in the tribes
Arabideae DC. and Sisymbrieae DC. by Hayek
(1911) and Schulz (1936), respectively. It was
not assigned to a tribe by Al-Shehbaz et al.
(2006) because none of its species were
included in previous molecular studies.
Although Warwick et al. (2006a) clarified the
generic limits of Aphragmus (8 spp.) and
showed that it is unrelated to Braya Sternb. &
Hoppe (tribe Euclidieae DC.), they did not
address its tribal position. Warwick et al.
(2006a) showed that Aphragmus formed a dis-
tinct, well-supported clade separate from the
other tribal groups (Arabideae, Eutremeae, and
Euclideae) included in the analysis. Koch et al.
(2007) included only A. oxycarpus (Hook.f. &
Thomson) Jafri and showed it to form a weakly
supported clade with a species of Heliophila L.
in a basal polytomy of the family-wide tree.
That relationship was not confirmed in the ITS-
based phylogeny (German et al., in prep.), in
which both A. eschscholtzianus and A. involu-
cratus (Bunge) O. E. Schulz formed a well-sup-
ported clade (100% bootstrap [BS]) distinct
from the other existing tribes.
Aphragmus is characterized by an indumen-
tum of minute simple and forked trichomes,
entire or 3–7-lobed leaves, bracteate inflores-
cences, usually eseptate fruits, and often
minutely papillate seeds on long filiform funi-
cles often longer than seeds (except for four
species previously assigned to Lignariella). This
character combination is not found in other gen-
era of the family and, together with its molecu-
lar distinctness (German et al., in prep.), support
the placement of Aphragmus in an independent,
unigeneric tribe, Aphragmeae.
166 HARVARD PAPERS IN BOTANY Vol. 13, No. 1
BISCUTELLA AND MEGADENIA
Biscutella (53 spp.; Warwick et al., 2006b), is
a primarily Mediterranean genus placed by de
Candolle (1821) in the tribe Thlaspideae DC.,
and by Hayek (1911) and Schulz (1936) in the
tribe Lepidieae DC. Such placements were
based primarily on having angustiseptate silicles
characteristic of all three taxa. Molecular phy-
logenetic studies by Beilstein et al. (2006)
included only one species of Biscutella, whose
position was not resolved in the tree and, as a
result, the genus was not assigned to any tribe
by Al-Shehbaz et al. (2006).
The monospecific genus Megadenia includes
M. pygmaea Maxim., a species distributed in S.
Siberia, S. Russian Far East, and C. China (E.
Xizang, S. Gansu, Qinghai, and W. Sichuan).
The first molecular study of the genus by
German et al. (in prep.) demonstrated that it
forms a moderately supported clade (71% BS)
with Biscutella. Both genera have didymous sil-
icles that split at maturity into two one-seeded
mericarps. Although this fruit type has evolved
independently in Lepidium L. (Lepidieae),
Heliophila L. (Heliophileae DC.), Megacarpaea
DC. and Cremolobus DC. (both unassigned to
tribes), Physaria (Physarieae), and Physoptychis
(Alysseae), the clade containing Biscutella and
Megadenia was not related to any of them.
Therefore, Biscutella and Megadenia are
assigned herein in the re-established tribe
Biscutelleae Dumort. Dorofeyev (2004) recently
placed all genera of the family with didymous
fruits in the tribe Cremolobeae. In doing this, he
ignored all the morphological, cytological, paly-
nological, and molecular data that clearly sup-
port the independent origin of didymous fruits
at least five times in the family (Al-Shehbaz et
al., 2006).
CONRINGIA AND ZUVANDA
Conringia, a Eurasian genus of six species
centered primarily in Turkey and adjacent Iran,
was placed by Hayek (1911), Schulz (1923,
1936), and Al-Shehbaz (1985) in the tribe
Brassiceae. Its tribal assignment was based pri-
marily on having in one species, C. planisiliqua
Fisch. & C. A. Mey., subconduplicate cotyle-
dons, a feature characteristic of most members
of the Brassiceae. The tribe was subjected to a
number of phylogenetic studies (see Warwick
and Sauder, 2005, and references therein), but
the placement of Conringia remained unresolved
after its exclusion from the Brassiceae (Lysak et
al., 2005; Al-Shehbaz et al., 2006). Conringia
showed strong alliance (92 to 100% BS) to the
tribe Noccaeeae Al-Shehbaz, Beilstein & E. A.
Kellogg in the ndhF (Beilstein et al., 2006) and
ITS studies (Bailey et al., 2006; German et al.,
in prep.), and similar support (90% BS) in the
trnL-F phylogeny of Koch et al. (2007).
The southwest Asian Zuvanda (3 spp.) was
segregated from Malcolmia W. T. Aiton by
Askerova (1985) based on its lack of branched
trichomes and presence of auriculate leaves.
Malcolmia was placed by de Candolle (1821),
Hayek (1911), and Schulz (1936) in the tribes
Sisymbrieae, Alysseae DC., and Hesperideae
DC., respectively. More recently, Dorofeyev
(2002) transferred all species of Zuvanda and
Conringia perfoliata (C. A. Mey.) N. Busch to
Moricandia DC., but that transfer was not fol-
lowed by Appel and Al-Shehbaz (2003) and Al-
Shehbaz et al. (2006) because Moricandia, like
other members of Brassiceae, has conduplicate
cotyledons (vs. incumbent cotyledons in
Zuvanda). As shown by Lysak et al. (2005) and
Warwick and Sauder (2005), Moricandia is a
member of Brassiceae unrelated to Conringia.
Warwick et al. (2007) demonstrated that
Zuvanda crenulata (DC.) R. K. Askerova, Z.
exacoides (DC.) R. K. Askerova, and
Goldbachia laevigata (M. Bieb.) DC., formed a
separate, but loosely supported (< 50% BS)
clade, unrelated to Malcolmia, and the other 13
tribes included in their study; but they did not
assign the three species to a tribe. Although they
did not include any member of the Brassiceae in
their study, Zuvanda was unrelated to the
Sisymbrieae, a tribe most closely related to the
Brassiceae (Al-Shehbaz et al., 2006). German et
al. (in prep.) showed that Conringia perfoliata
and Z. crenulata formed a clade related to, but
distinct from, the Noccaeeae.
Both Conringia and Zuvanda resemble mem-
bers of the Noccaeeae in being glaucous and
glabrous or with only simple trichomes, and in
having entire or dentate, sessile, mostly amplex-
icaul, cauline leaves. However, they differ by
having terete, latiseptate, or 4-angled (vs. angus-
tiseptate) and linear siliques (vs. oblong, elliptic,
obcordate, obovate, or obdeltoid silicles), many
(vs. few) seeds per fruit, and often decurrent (vs.
entire) stigmas. These significant differences
justify the placement of Conringia and Zuvanda
in a tribe separate from the Noccaeeae and rec-
ognized herein as Conringieae.
2008 GERMAN AND AL-SHEHBAZ, BRASSICACEAE (CRUCIFERAE) 167
CALEPINA,GOLDBACHIA,AND SPIRORRHYNCHUS
Calepina, a monospecific southwest Asian
genus, was placed by de Candolle (1821) in the
tribe Zilleae and by Hayek (1911), Schulz
(1919, 1936), and Al-Shehbaz (1984) in the tribe
Brassiceae because of having slightly condupli-
cate cotyledons with involute margins. Gómez-
Campo (1980) suggested the removal of
Calepina from the Brassiceae, but he later
(Gómez-Campo, 1999) retained it in that tribe.
Recent molecular studies (Lysak et al., 2005;
Warwick and Sauder, 2005) clearly supported
the exclusion of Calepina from the Brassiceae,
a position followed byAl-Shehbaz et al. (2006),
but no tribal placement was suggested.
Goldbachia, a Eurasian genus of six species,
was placed by de Candolle (1821) in the tribe
Anchonieae DC.; by Hayek (1911) in the tribe
Arabideae; and by Schulz (1936) in the tribe
Hesperideae. Recent molecular studies by
Beilstein et al. (2006) revealed a weak relation-
ship between Goldbachia and the tribe
Thlaspideae. Both Goldbachia and Zuvanda
showed no affinity to any of the 13 tribes
included in the analysis (Warwick et al., 2007).
Goldbachia was not assigned to a tribe by
Al-Shehbaz et al. (2006).
The Asian monospecific Spirorrhynchus was
placed by Hayek (1911) in the tribe Arabideae
and by Schulz (1936) in the tribe Euclidieae.
The genus was not included in previous molec-
ular studies, though Al-Shehbaz et al. (2006)
suspected affinity to the tribe Isatideae.
Molecular studies by German et al. (in prep.)
showed that Calepina,Goldbachia, and
Spirorrhynchus formed a clade (58–67% BS)
not closely related to any of the tribes. They are
placed herein in the re-established Calepineae
Horan., a tribe characterized by several charac-
ters given below.
Calepina differs from both Goldbachia and
Spirorrhynchus in having spreading, non-sac-
cate sepals, somewhat zygomorphic petals,
basally non-articulate pedicels, and subcondu-
plicate cotyledons (Appel and Al-Shehbaz,
2003). The three genera, however, resemble
each other in habit, indumentum, cauline leaves,
and fruits (see below).
ERYSIMUM
Erysimum comprises some 223 species
(Warwick et al., in prep.) distributed primarily
in Eurasia, with 8 species native to NorthAfrica
and Macaronesia, and 16 to North America
(authors compilation). Many authors recog-
nized Cheiranthus L. and Erysimum as distinct
genera distinguished by the presence of median
nectaries (vs. their absence), terete or 4-angled
(vs. latiseptate) fruits, and incumbent (vs.
accumbent) cotyledons. These differences were
considered by some to be significant at the tribal
level. Indeed, de Candolle (1821) placed
Erysimum and Cheiranthus in the tribe
Sisymbrieae and Arabideae, respectively,
whereas Hayek (1911) placed Erysimum in the
Arabideae and Cheiranthus in the Alysseae;
Schulz (1936) maintained both genera in the
Hesperideae.
Al-Shehbaz et al. (2006) assigned Erysimum
(including Cheiranthus) to the broadly circum-
scribed tribe Camelineae DC., a position that
was later maintained by Warwick et al. (2007).
The genus Erysimum formed a distinct mono-
phyletic group in several ITS-based studies
(e.g., Heenan et al., 2002; Warwick et al. 2007).
Molecular studies by German et al. (in prep.)
demonstrated that the Camelineae sensu Al-
Shehbaz et al. (2006) is polyphyletic, and
Erysimum (3 spp.) formed a separate, well-
resolved clade from other members of the
Camelineae, that merits the recognition at the
tribal level, herein Erysimeae Dumort. In their
comprehensive ITS phylogeny of the
Brassicaceae, Bailey et al. (2006) also showed
Erysimum to form a well-resolved clade with
100% bootstrap support.
168 HARVARD PAPERS IN BOTANY Vol. 13, No. 1
TAXONOMIC CONSIDERATIONS
Based on the above discussions, the follow-
ing five tribes are recognized. The number of
species in a given genus follows Warwick et al.
(2006b). Listing of the genera under each tribe
is based on molecular studies that are either pub-
lished or in preparation.
Tribe Aphragmeae D. German & Al-Shehbaz,
trib. nov. Type genus: Aphragmus Andrz. ex
DC., Prodr. 1: 209. 1824.
Herbae perennes vel annuae, pilis minutis
simplicibus vel furcatis; folia basalia integra vel
3–7-partita; folia caulina petiolata vel sessilia,
basi cuneata nonauriculata; racemi bracteati;
petala alba, rosea, azurea vel purpurea; ovula
numerosa; fructus siliculae vel siliquae, glabri
vel pubescentes, tereti vel latiseptati; stigma
integra; semina uni- vel biseriata, rarius soli-
taria; cotyledones incumbentes.
Annual or perennial herbs; trichomes minute,
simple or forked; basal leaves entire or
palmately 3–7-lobed; cauline leaves petiolate or
sessile, cuneate, non-auriculate at base; racemes
bracteate; petals white, rose, deep-blue, or pur-
ple; ovules numerous; fruits siliques or silicles,
glabrous or pubescent, terete or latiseptate;
stigma entire; seeds uni- or biseriate, rarely soli-
tary; cotyledons incumbent.
This unigeneric tribe includes 11 species dis-
tributed primarily in the high mountains of cen-
tral Asia and Himalaya, and only Aphragmus
eschscholtzianus grows in the arctic (see above).
The tribe is distinguished from other tribes by a
combination of bracteate racemes, minute tri-
chomes, numerous ovules, entire stigmas, and
incumbent cotyledons.
Tribe Biscutelleae Dumort., Fl. Belg.: 118.
1827. Type genus: Biscutella L., Sp. Pl. 2: 653.
1753.
Annual or perennial herbs; trichomes simple
or absent; basal leaves entire, dentate, or lobed;
cauline leaves sessile, often non-auriculate at
base, sometimes absent; racemes bracteate or
not; petals white or yellow; ovules 2; fruits sili-
cles, didymous, glabrous or pubescent, angus-
tiseptate; stigma entire; seeds flattened;
cotyledons accumbent.
A bigeneric tribe consisting of the primarily
Mediterranean Biscutella (53 spp.) and the
monospecific Megadenia. Schulz (1936) placed
both genera in the tribe Lepidieae subtr.
Iberidineae, but this subtribe included a hetero-
geneous assemblage of genera assigned by Al-
Shehbaz et al. (2006) to at least four tribes. It is
distinguished from other tribes by the didymous,
angustiseptate silicles, 2-ovuled ovaries, entire
stigmas, and accumbent cotyledons.
Tribe Calepineae Horan., Char. Ess. Fam.: 169.
1847. Type genus: Calepina Adans., Fam. 2:
423. 1763.
Annual or biennial herbs; trichomes simple
or absent; basal leaves rosulate or not, dentate or
pinnatifid to pinnatisect; cauline leaves petio-
late or sessile and auriculate to amplexicaul;
racemes bracteate or not; petals white, pink,
purple, or yellowish; ovules 1–3; fruits silicles
or siliques, indehiscent, woody, often glabrous,
terete, or slightly flattened; style short or beak-
like; stigma entire; seeds aseriate; cotyledons
incumbent, rarely subconduplicate.
The tribe consists of eight Asian species, of
which six belong to Goldbachia and one each to
Calepina and Spirorrhynchus. It is distinguished
from other tribes by the indehiscent, woody
fruits, 1–3-ovuled ovaries, simple or no tri-
chomes, and entire stigmas.
Tribe Conringieae D. German & Al-Shehbaz,
trib. nov. Type genus: Conringia Heist. ex Fabr.,
Enum.: 160. 1759.
Herbae annuae vel biennes, pilis simplicibus
vel nullis; folia basalia integra vel dentata; folia
caulina integra vel dentata, sessilia, basi cor-
data, sagittata vel auriculata; racemi
ebracteati; petala alba, lutea, rosea, vel pur-
purea; ovula numerousa; fructus siliquae,
glabri, tereti, latiseptati, vel angulari; stigma
capitata vel conica, biloba, decurrentis, raris-
simi integra; semina uniseriata, cotyledones
incumbentes vel rarissimi subconduplicati.
Annual or biennial herbs; trichomes simple
or absent; basal leaves rosulate or not, entire or
dentate; cauline leaves entire or dentate, sessile,
cordate or sagittate to auriculate at base;
racemes ebracteate; petals white, yellow, rose,
or purple; ovules numerous; fruits siliques,
glabrous, terete, latiseptate, or angled; stigma
capitate or conical, 2-lobed, decurrent, rarely
entire; seeds uniseriate; cotyledons incumbent
or rarely subconduplicate.
The tribe includes Conringia (6 spp.) and
Zuvanda (3 spp.).All species grow in southwest
Asia, but the range of one, C. planisiliqua,
extends into the Himalayas, whereas C. orien-
talis (L.) Dumort. is a naturalized weed outside
its native Eurasian range. The tribe Conringieae
is distinguished from other tribes by being pri-
marily glabrous or with simple trichomes only
and by having sessile, cordate, auriculate or
sagittate cauline leaves, linear fruits, capitate or
conical and decurrent stigmas, and incumbent
or rarely subconduplicate cotyledons.
Tribe Erysimeae Dumort., Fl. Belg. 123. 1827.
Type genus: Erysimum L., Sp. Pl. 2: 660. 1753.
Annual or perennial herbs, sometimes shrubs
or subshrubs; trichomes sessile, malpighiaceous
or stellate; basal leaves rosulate, entire or den-
tate, rarely pinnately lobed; cauline leaves entire
or dentate, petiolate or sessile, non-auriculate or
very rarely auriculate at base; racemes often
ebracteate; petals white, yellow, rose, or purple;
ovules numerous; fruits siliques, often pubes-
cent, terete, latiseptate, or angled; stigma capi-
tate, 2-lobed or subentire; seeds uniseriate or
rarely biseriate; cotyledons incumbent or
accumbent.
This unigeneric tribe consists of 223 species
in Erysimum. It is distinguished from the other
tribes by the predominantly malpighiaceous and
stellate trichomes with unbranched rays, many-
seeded siliques, and predominantly yellow flow-
ers. Both Erysimum and Cheiranthus were
simultaneously published by Linnaeus (Sp. Pl.
2: 660, 661. 1753). Wettstein (1889) was the
first to unite the two genera under Erysimum
and, therefore, this generic name has priority
(McNeill et al., 2006: Article 11.5).
2008 GERMAN AND AL-SHEHBAZ, BRASSICACEAE (CRUCIFERAE) 169
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170 HARVARD PAPERS IN BOTANY Vol. 13, No. 1
... Complex phylogenomic history of mesopolyploid crucifer clades is perhaps illustrated at its best by long unknown and puzzling genome evolution in the small tribe Biscutelleae. Tribe Biscutelleae ($60 species in five genera, see supplementary file 1, Supplementary Material online) was re-established by German and Al-Shehbaz (2008), including Biscutella and Megadenia due to their phylogenetic (German et al. 2009) and morphological affinities. Other three Biscutelleae genera have remained unassigned in several molecular phylogenetic studies, until € Ozüdo gru et al. (2015,2017) expanded Biscutelleae by the inclusion of Heldreichia, Lunaria, and Ricotia. ...
... 6D).DiscussionMultiple Hybridization Events Explain Contentious Phylogenetic Placement of BiscutelleaeThe position of Biscutelleae within the Brassicaceae family tree remained one of the most unsettled phylogenetic issues (e.g., Al-Shehbaz 2012;Nikolov et al. 2019). A sister relationship between Biscutella and Megadenia within an ITS phylogeny was recovered byGerman et al. (2009) and led to the formal re-establishment of Biscutelleae as a bigeneric tribe(German and Al-Shehbaz 2008). Despite expanded taxon sampling in follow-up studies, the tribe was repeatedly retrieved as part of the family's basal polytomy(Couvreur et al. 2010;Warwick et al. 2010;Koch 2012). ...
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Pervasive hybridization and whole genome duplications (WGDs) influenced genome evolution in several eukaryotic lineages. While frequent and recurrent hybridizations may result in reticulate phylogenies, the evolutionary events underlying these reticulations, including detailed structure of the ancestral diploid and polyploid genomes, were only rarely reconstructed. Here, we elucidate the complex genomic history of a monophyletic clade from the mustard family (Brassicaceae), showing contentious relationships to the early-diverging clades of this model plant family. Genome evolution in the crucifer tribe Biscutelleae (c. 60 species, 5 genera) was dominated by pervasive hybridizations and subsequent genome duplications. Diversification of an ancestral diploid genome into several divergent but crossable genomes was followed by hybridizations between these genomes. Whereas a single genus (Megadenia) remained diploid, the four remaining genera originated by allopolyploidy (Biscutella, Lunaria, Ricotia) or autopolyploidy (Heldreichia). The contentious relationships among the Biscutelleae genera, and between the tribe and other early diverged crucifer lineages, are best explained by close genomic relatedness among the recurrently hybridizing ancestral genomes. By using complementary cytogenomics and phylogenomics approaches, we demonstrate that the origin of a monophyletic plant clade can be more complex than a parsimonious assumption of a single WGD spurring post-polyploid cladogenesis. Instead, recurrent hybridization among the same and/or closely related parental genomes may phylogenetically interlink diploid and polyploid genomes despite the incidence of multiple independent WGDs. Our results provide new insights into evolution of early-diverging Brassicaceae lineages and elucidate challenges in resolving the contentious relationships within and between land plant lineages with pervasive hybridization and WGDs.
... In addition to plastid sequences, nuclear ribosomal DNA (nrDNA) cistrons and their internal spacers regions (ITS1-5.8S nrDNA-ITS2, or nrDNA-ITS spacer) have been frequently used as effective markers for Brassicaceae systematics at the tribal level (Bailey et al., 2006;Warwick et al., 2007Warwick et al., , 2010German & Al-Shehbaz, 2008). The full-length nrDNA cistron sequences (18S nrDNA-ITS1-5.8S ...
... The discrepancy of tribes Arabideae and Alysseae may be explained by their polyploid evolutionary history (Hohmann et al., 2015;Mandáková et al., 2020). In addition, the species Conringia planisiliqua assigned to the tribe Conringieae (German & Al-Shehbaz, 2008) was recovered as the sister group of the tribe Isatideae instead of grouping with type species of Conringia Heist. ex Fabr., C. orientalis (L.) Dumort. in nuclear genes analyses (Zhao et al., 2010;Nikolov et al., 2019;Fig. ...
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The Brassicaceae is an economically and scientifically important family distributed globally, including oilseed rape and the model plant, Arabidopsis thaliana . Although growing molecular data have been used in phylogenetic studies, the relationships among major clades and tribes of Brassicaceae are still controversial. Here, we investigated the core Brassicaceae phylogenetics using 222 plastomes and 235 nrDNA cistrons, including 106 plastomes and 112 nrDNA cistrons assembled from newly sequenced genome skimming data of 112 taxa. The sampling covered 73 genera from 61.5% tribes and four unassigned genera and species. Three well‐supported lineages LI, LII, and LIII were revealed in our plastomic analyses, with LI sister to LII + LIII. Besides, the monophyly of the newly delimitated LII was strongly supported by three different partition strategies, concatenated methods under Bayesian and Maximum likelihood analyses. LII comprised 13 tribes, including four tribes previously unassigned to any lineage, i.e., Biscutelleae as the earliest diverging clade, and Cochlearieae as the sister to Megacarpaeeae + Anastaticeae. Within LII, the inter‐tribal relationships were also well‐resolved, except that conflicting position of Orychophragmus was detected among different datasets. In LIII, Shehbazia was resolved as a member of Chorisproreae, but Chorisproreae, Dontostemoneae, and Euclidieae were all resolved as paraphyletic, which was also confirmed by nrDNA analyses. Moreover, the loss of the rps16 gene was detected likely to be a synapomorphy of the tribes Arabideae and Alysseae. Overall, using genome skimming data, we resolved robust phylogenetic relationships of core Brassicaceae and shed new light on the complex evolutionary history of this family. This article is protected by copyright. All rights reserved.
... Зауважимо, що за даними цих досліджень, до триби Calepineae віднесено і рід Goldbachia, зародок якого подібний до такого Calepina тим, що також має різні за формою сім'ядолі. Крім того, на основі цих досліджень від триби Brassiceae відокремлена триба Conrigieae D. German et Al-Shehbaz., до якої віднесено Conringia та кілька інших родів [22]. Місце у системі родини таких родів, як Lunaria та Subularia (також мають специфічні за формою сім'ядолі), за результатами аналогічних досліджень визначити ще не вдалося [39]. ...
... Early molecular phylogenetic studies by Warwick and Sauder (2005) indicated that Conringia fell outside the Brassiceae, and based on a review of the literature and unpublished findings by one of us (D.A.G.), German & Al-Shehbaz (2008) proposed the tribe Conringieae to include Conringia and Zuvanda (Dvořák 1972: 271) Askerova (1985: 522). Shortly thereafter, Khosravi et al. (2009), German et al. (2009), Couvreur et al. (2010, and Warwick et al. (2010) firmly established the remote relationships between the Brassiceae and Conringieae. ...
Article
Iljinskaea is described as a new monospecific genus based on a critical evaluation of morphology and in light of the extensive molecular phylogenetic data. The new combination I. planisiliqua is proposed, and the distinguishing characters separating the new genus from Conringia are discussed. The new tribal assignment of Iljinskaea in the Isatideae is discussed and compared with the previous placement in the Conringieae.
... However, only 25 tribes were recognized then. Combined results of following molecular studies on relevant genera (Yue et al., 2008(Yue et al., , 2009German and Al-Shehbaz, 2008a;German et al., 2009;Koch et al., 2010;Alexander et al., 2010;Jordon-Thaden et al., 2010;Warwick et al., 2011;Heenan et al., 2012) and tribes (Koch et al., 2007;Beilstein et al., 2008;Warwick et al., 2007Warwick et al., , 2008Warwick et al., , 2009German and Al-Shehbaz, 2008b;German et al., 2011;Bailey et al., 2007) with critical evaluations on morphologic characters, Al-Shehbaz (2012) refined this phylogeny based tribal classification and recognized 49 tribes. With the reinstatement of Malcolmieae (Al-Shehbaz et al., 2014) and newly established Shehbazieae (German and Friesen, 2014) and Hillielleae (Chen et al., 2016), the current tribe number of Brassicaceae adds up to 52. ...
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Euclidieae, a morphologically diverse tribe in the family Brassicaceae (Cruciferae), consists of 29 genera and more than 150 species distributed mainly in Asia. Prior phylogenetic analyses on Euclidieae are inadequate. In this study, sequence data from the plastid genome and nuclear ribosomal DNA of 72 species in 27 genera of Euclidieae were used to infer the inter- and intra-generic relationships within. The well-resolved and strongly supported plastome phylogenies revealed that Euclidieae could be divided into five clades. Both Cymatocarpus and Neotorularia are polyphyletic in nuclear and plastome phylogenies. Besides, the conflicts of systematic positions of three species of Braya and two species of Solms-laubachia s.l. indicated that hybridization and or introgression might have happened during the evolutionary history of the tribe. Results from divergence-time analyses suggested an early Miocene origin of Euclidieae, and it probably originated from the Central Asia, Pamir Plateau and West Himalaya. In addition, multiple ndh genes loss and pseudogenization were detected in eight species based on comparative genomic study.
... Зауважимо, що за даними цих досліджень, до триби Calepineae віднесено і рід Goldbachia, зародок якого подібний до такого Calepina тим, що також має різні за формою сім'ядолі. Крім того, на основі цих досліджень від триби Brassiceae відокремлена триба Conrigieae D. German et Al-Shehbaz., до якої віднесено Conringia та кілька інших родів [22]. Місце у системі родини таких родів, як Lunaria та Subularia (також мають специфічні за формою сім'ядолі), за результатами аналогічних досліджень визначити ще не вдалося [39]. ...
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The structure of the embryo of 226 species of Brassicaceae in the flora of Ukraine was studied. The embryos are attributed to three types and 11 subtypes. The direct embryos with equal cotyledons of Leavenworthia species are considered as the third type. Subtypes are allocated on the basis of the distinction between the embryos in the form of cotyledons. Incumbent embryos are very diverse in their form of cotyledon, which can be plane, conduplicate, sulcate, heterosulcate, spiral, biplicate, involute, and sectional. In accumbent ones they are often plane, and only in some species can be foliaceous or convex. Diagnostic, phylogenetic and evolutionary value of the embryo features as well as the factors causing development of the obliquely incumbent embryo are discussed.
... Formerly treated as a member of tribe Alysseae (Hayek 1911;Janchen 1942;Melchior 1964), the position of Lunaria remained unresolved with initial molecular data (Beilstein et al. 2010;Warwick et al. 2010;Al-Shehbaz 2012), but recent molecular studies have assigned Lunaria to the tribe Biscutelleae (Huang et al. 2015;€ Oz€ udo gru et al. 2015). The tribe Biscutelleae in a narrow circumscription only contains the genera Biscutella and Megadenia (German & Al-Shehbaz 2008). Both are characterised by angustiseptate siliquae (i.e. ...
Article
The generally held opinion that the seeds of Lunaria remain at the replum after detachment of the two valves and then the wind causes a shaking or rattling of the replum with its diaphragm, thus launching the seeds was challenged by the first author. In a sparse forest in the Swabian Alb, he noticed flying valves of Lunaria rediviva to which the narrow-winged flat seeds are attached. Investigations by SEM and histology have shown that the valves secrete a glue just at those sites where the seeds rest on the valves before the dying of the valvar tissues. Further analysis has shown (proof by periodic acid-Schiff reaction) that the glue consists of polysaccharides. After detachment and dispersal of the valves, the adhesive strength continuously decreases. This is the first report for a sticky valve exudate in the Brassicaceae. Owing to the adhesion of the Lunaria seeds to their valves for some time, the 1st order diaspore is a mericarp in a broad sense and can be interpreted as an adaptation to long-distance dispersal by stronger winds. In this context, the “flying carpets” of Lunaria are more effective and transport more than one seed. Molecular studies assigned Lunaria to the tribe Biscutelleae that now contains the angustiseptate genera Biscutella and Megadenia as well as the latiseptate genera Lunaria and Ricotia. The valves in Ricotia can easily be detached (studied in herbarium material and in a living plant), but, in contrast to Lunaria, the ripe seeds remain at the replum and its diaphragm, respectively. This article is protected by copyright. All rights reserved.
Article
Karyotypic changes in chromosome number and structure are drivers in the divergent evolution of diverse plant species and lineages. This study aimed to reveal the origins of the unique karyotype (2n = 12) and phylogenetic relationships of the genus Megadenia (Brassicaceae). A high‐quality chromosome‐scale genome was assembled for Megadenia pygmaea using Nanopore long reads and high‐throughput chromosome conformation capture (Hi‐C). The assembled genome is 215.2 Mb and is anchored on six pseudochromosomes. We annotated a total of 25,607 high‐confidence protein‐coding genes and corroborated the phylogenetic affinity of Megadenia with the Brassicaceae expanded lineage II, containing numerous agricultural crops. We dated the divergence of Megadenia from its closest relatives to 27.04 (19.11–36.60) million years ago. A reconstruction of the chromosomal composition of the species was performed based on the de novo assembled genome and comparative chromosome painting analysis. The karyotype structure of M. pygmaea is very similar to the previously inferred proto‐Calepineae karyotype (PCK; n = 7) of the lineage II. However, an end‐to‐end translocation between two ancestral chromosomes reduced the chromosome number from n = 7 to n = 6 in Megadenia. Our reference genome provides fundamental information for karyotypic evolution and evolutionary study of this genus.
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Background The family Brassicaceae encompasses diverse species, many of which have high scientific and economic importance. Early diversifications and phylogenetic relationships between major lineages or clades remain unclear. Here we re-investigate Brassicaceae phylogeny with complete plastomes from 51 species representing all four lineages or 5 of 6 major clades (A, B, C, E and F) as identified in earlier studies. ResultsBayesian and maximum likelihood phylogenetic analyses using a partitioned supermatrix of 77 protein coding genes resulted in nearly identical tree topologies exemplified by highly supported relationships between clades. All four lineages were well identified and interrelationships between them were resolved. The previously defined Clade C was found to be paraphyletic (the genus Megadenia formed a separate lineage), while the remaining clades were monophyletic. Clade E (lineage III) was sister to clades B + C rather than to all core Brassicaceae (clades A + B + C or lineages I + II), as suggested by a previous transcriptome study. Molecular dating based on plastome phylogeny supported the origin of major lineages or clades between late Oligocene and early Miocene, and the following radiative diversification across the family took place within a short timescale. In addition, gene losses in the plastomes occurred multiple times during the evolutionary diversification of the family. Conclusions Plastome phylogeny illustrates the early diversification of cruciferous species. This phylogeny will facilitate our further understanding of evolution and adaptation of numerous species in the model family Brassicaceae.
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Sequence data from the nuclear ITS region of 1.18 species (152 accessions) were used to test the monophyletic status and interrelationships of four related tribes in the Brassicaceae: Anchonieae, Chorisporeae, Euclidieae, and Hesperideae. Both maximum parsimony and maximum likelihood analyses support the recognition of the tribes Hesperideae (unigeneric, Hesperis L.) and Chorisporeae (3 genera, including Chorispora R. Br. ex DC, Diptychocarpus Trautv., and Parrya R. Br.), whereas the Anchonieae and the Euclidieae each separate into two distinct and distant clades (designated here as Anchonieae I and II and Euclidieae I and II). The data also support the exclusion of eight genera from the latter four tribes, with appropriate tribal assignment given in parentheses: Aubrieta Adans. (Arabideae), Blennodia R. Br. (Camelineae), Erysimum L. (Camelineae), Goldbachia DC. (unresolved), Hesperidanthus (B. L. Rob.) Rydb. (Schizopetaleae), Notothlaspi Hook. f. (unresolved), Pseudocamelina (Boiss.) N. Busch (Thlaspideae), and Zuvanda (Dvorák) Askerova (unresolved). The genus Malcolmia R. Br. (ca. 35 species) was paraphyletic and divided into three tribal clades, providing support for the separate genera Malcolmia, Strigosella Boiss., and Zuvanda. The genera Anchonium DC., Desideria Pamp., Eremobium Boiss., Erysimum, Iskandera N. Busch, Matthiola R. Br., Morettia DC., Neotorularia Hedge & J. Léonard, Rhammatophyllum O. E. Schulz, Sisymbriopsis Botsch. & Tzvelev, Sterigmostemum M. Bieb., and Tetracme Bunge each fell within a single tribal clade but were not monophyletic.
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Aphragmus bouffordii from Tibet is described and illustrated, and its relationship to the other members of the genus are discussed. A synopsis and key to all seven species of Aphragmus is presented. As delimited by Al-Shehbaz (2000), Aphragmus Andrzejowski ex de Candolle was expanded to include Staintoniella H. Hara and consisted of five species. Since then, Al-Shehbaz (2002) added a new species, A. ladakiana Al-Shehbaz, from India and with the description of A. bouffordii Al-Shehbaz below, the genus now consists of seven species. Except for A. eschscholtzianus Andrzejowski ex de Candolle, which is restricted to Alaska and Canada (Schulz, 1924; Rollins, 1993), the remaining species of the genus grow in Asia, with the highest concentration in the Himalayas (Al-Shehbaz, 2000). The present paper describes the new species Aphragmus bouffordii, provides a brief synop-sis of all seven species of the genus, and pre-sents an updated key to the species.
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The present review summarizes results from the past decade on the systematics, population genetics, and evolutionary biology of the mustard family, Brassicaceae (Cruciferae). The research of various authors is discussed and presented in the context of ongoing and accumulating studies. The review is useful in view of the immensely increasing work on Arabidopsis thaliana, the model species of plant molecular biology, and on important crop plants such as species of Brassica. Traditional and molecular-based phylogenies are critically discussed, new generic alignments are proposed, and groups in need of molecular studies are identified. Unfortunately, knowledge obtained from molecular genetics and development of A. thaliana is only very slowly creeping into the systematics of Brassicaceae. Future directions of research should move beyond assessing generic relationships or limits, and should also address character development and evolution, the molecular basis of various homoplastic characters, the nature of the genome, and many other new challenges that are emerging from detailed molecular studies of A. thaliana.
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Nuclear ribosomal DNA ITS sequence data were used to assess the relationships of Cheesemania, Ischnocarpus, and Pachycladon to each other and to other genera in the Brassicaceae. Phylogenetic analyses are congruent with other studies that infer the Pachycladon complex (including Pachycladon, Cheesemania, and Ischnocarpus) is monophyletic. The complex occurs within an Arabidopsoid clade that includes Arabidopsis and the recently recognised segregate genera Beringia, Crucihimalaya, Olimarabidopsis, and Pseudoarabidopsis, and the Arabis segregates Boechera and Turritis. The Pachycladon complex is sister to Beringia and Crucihimalaya, and forms a distinct New Zealand lineage. Molecular clock estimates suggest the Pachycladon complex diverged from its nearest relatives between 1.0 and 3.5 million years ago. The close relationship of Cheesemania, Ischnocarpus, and Pachycladon is reflected in low (