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Estudo sobre a reprodução sexuada e caracterização de cultivares de Castanea sativa Mill
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In this work, we established the phenology in four Castanea sativa chestnut Portuguese cultivars (Amarelal, Longal 5, Verdeal and Martainha 2). The unisexual and androgenic flower differentiation was determined: June of the previous vegetative cycle and May of the vegetative cycle, respectively.
The more relevant morphological aspect of the inflorescence was the presence of hermaphroditic flowers in all the studied cultivars. We could determine that only the terminal zone of the style corresponds to the stigmatic region. For the first time, it was referred the presence of the secretory cells, which layered the aperture of the stigma, at full receptivity. This secretion is important in the process of pollen adhesion and germination. Histochemical characterisation of the secretion revealed the presence of polysaccharides and lipids. A new model for hermaphroditic flowers with anthers and stigma location was described.
The receptivity period of each stigma is restricted to a few days (about 2 days), corresponding to the presence of the mucilaginous secretion. The receptivity is not synchronised, only one style at a time becomes receptive. If it is successfully pollinated, the other styles of that flower will arrest the final development. If not, the next becomes receptive and so on. The pollen tubes inside the style reach the ovule after 10 to 12 days. During this period, the final steps of ovule development occur. Only a few pollen tubes reach the ovary, and only one ovule seems to be fertilised and develop a normal seed.
Best results for in vitro pollen germination were obtained with a modified F-medium (0.01% H3BO3, 0.04% MgSO4 7H2O, 0.1% Ca (NO3)2 3 H2O, 0.025% K2PO4, and 0.025% KCl) at pH 7.0 and 20% of sucrose.
Patterns of phenotypic and phenetic variability in six Portuguese cultivars of chestnut (Castanea sativa Mill.) were evaluated cultivares (Amarelal, Longal 5, Longal 6, Verdeal, Martainha 1 and Martainha 2). Morphological characterisation was based on the quantification of seventeen quantitative traits, for a five years period. Variance analysis showed significant differences among cultivars, and cultivar year, for all the traits studied, and tree within cultivar, showed also some significant differences, for some of the morphological variables. A significant correlation was obtained between length of the leaf blade and the percentage of unisexual and androgynic inflorescence with the effective thermal index, accumulated rainfall from April to October and from July to October, or the accumulated temperature below seven during the dormant period. Principal Component and cluster analyses were performed to group the cultivars, according to their similarity coefficients, one group formed by Verdeal, Martainha 1 and Martainha 2 and the other by Amarelal, Longal 5 and Longal 6.
For molecular characterisation, 125 RAPD polymorphic markers were amplified using 28 primers. Three groups were formed: Amarelal/Longal 5, Verdeal/Martainha 1 and Longal 6/Martainha 2. Martainha 1 and Martainha 2 (81,6% of similarity) and Longal 5 and Longal 6 (83,6% of similarity) might be different cultivars. Martainha 1 and Verdeal (97,7% of similarity) have probably the same identity.
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... However, this pattern is not mimicked by CsaPI, as there is expression of this gene in female flowers, in late developmental stages, which does not occur in Q. suber. Reports of hermaphroditism in C. sativa female flowers [26,[36][37][38][39][40] suggest that the rudimentary stamens are sterile [27,36]. A pollen germination assay might be required to assess the fertility of these rudimentary stamens in the presently studied 'Judia' cultivar. ...
The sweet chestnut tree (Castanea sativa Mill.) is one of the most significant Mediterranean tree species, being an important natural resource for the wood and fruit industries. It is a monoecious species, presenting unisexual male catkins and bisexual catkins, with the latter having distinct male and female flowers. Despite the importance of the sweet chestnut tree, little is known regarding the molecular mechanisms involved in the determination of sexual organ identity. Thus, the study of how the different flowers of C. sativa develop is fundamental to understand the reproductive success of this species and the impact of flower phenology on its productivity. In this study, a C. sativa de novo transcriptome was assembled and the homologous genes to those of the ABCDE model for floral organ identity were identified. Expression analysis showed that the C. sativa B- and C-class genes are differentially expressed in the male flowers and female flowers. Yeast two-hybrid analysis also suggested that changes in the canonical ABCDE protein–protein interactions may underlie the mechanisms necessary to the development of separate male and female flowers, as reported for the monoecious Fagaceae Quercus suber. The results here depicted constitute a step towards the understanding of the molecular mechanisms involved in unisexual flower development in C. sativa, also suggesting that the ABCDE model for flower organ identity may be molecularly conserved in the predominantly monoecious Fagaceae family.
... Other genetic analyses with isoenzymes were performed by Bonnefoi ( 1984 ) , Malvotti and Fineschi ( 1987 ) , Fineschi et al. ( 1990a, b ) , Huang et al. ( 1994a ) , and . RAPD markers were studied by Valdiviesso ( 1999 ) , RAPD and ISSR by Goulao et al. ( 2001 ) , and nuSSRs by Costa et al. ( 2008 ) . The Portuguese cultivars showed great genetic variability, with multiple genotypes obtained per cultivar indicating their polyclonal origin . ...
Chestnut (Castanea) is a tree genus distributed throughout the northern
Hemisphere in natural stands, orchards, and coppices. As a multipurpose
tree, chestnut is used to produce timber, nuts, tannins, and other related
products. Interspecific hybridization was first done in 1894 in the USA, in
the 1910s in Japan, and in the 1920s in Europe. In the USA, blight resistant
Chinese (C. mollissima) and Japanese (C. crenata) species have been used
since 1930 as the pollen parents in a backcrossing program with American
chestnuts (C. dentata) as the recurrent parent, in order to produced blight
resistant timber chestnuts. In Europe, Japanese chestnut trees were
introduced because of their resistance to ink disease (caused by Phytophthora
spp.). A clonal collection of hybrids of Japanese chestnut crossed with
European chestnut (C. sativa) is used to produce nuts and timber, and for
rootstocks for local cultivars. The pellicle of the Japanese chestnut cultivars
is not easily removed, but this has been overcome with the newly released
Japanese chestnut hybrid ‘Porotan’, with the easy-peel pellicle trait controlled
by a single recessive gene (P/p) from native Japanese chestnuts. After more
than 100 years of chestnut hybridisation, new technologies and the recently
reported genome sequence will allow us to face new threats and to maintain
the rich genetic and cultural heritage of chestnut.
... En Portugal se realizaron estudios de variabilidad genética de cultivares de castaño con isoenzimas (Pereira-Lorenzo et al. 1999), con RAPDs (Valdiviesso, 1999(Valdiviesso, y 2000 y RAPDs e ISSRs (Goulao et al., 2001). ...
The genus Castanea, chestnuts and chinkapins, belongs to the family Fagaceae, which includes other important timber producing genera such as Quercus and Fagus. The genus Castanea is divided into three geographically delimited sections with at least seven consistently recognized interfertile species: 4 species in Asia (C. mollissima, C. henryi, C. seguinii, and C. crenata), two or more species in North America (C. dentata, C. ozarkensis, and C. pumila) and one in Europe and Turkey (C. sativa). The two most important diseases of chestnut are ink disease (Phytophthora) and chestnut blight (Cryphonectria). Resistance to these is the major objective for rootstock breeding in Europe and scion breeding in North America. In both cases, the source of resistance was Asian species. European breeding programs developed resistant hybrid rootstocks, which are propagated by stooling, cuttings, or in vitro culture. A major pest of chestnut is the gall wasp Dryocosmus kuriphilus whose control is based on the spread of parasitoids but also on the selection of resistant cultivars. For nut production, the most important breeding objectives include the following: good horticultural traits, product quality, suitability to storage and processing, and ease of peeling. For timber, important characters include wood quality, rapid growth, and nonchecking of wood (ring-shake). Molecular maps have been developed, which has expanded the genetic knowledge of the chestnut. An efficient genetic transformation protocol for C. sativa through the coculture of somatic embryos with different strains of Agrobacterium tumefaciens has been described. © Springer Science+Business Media, LLC 2012. All rights reserved.
. This study presents the first results obtained in controlled pollinations, performed for
the production of hybrid populations involving resistant (Castanea crenata Sieb. & Zucc and
Castanea mollissima Blume) and susceptible (Castanea sativa Mill) genotypes to ink and blight
diseases thus enabling the mapping of genes resistant to fungal diseases. The cultivars selection
(the feminine parent) was targeted on the individuals with the greatest economic interest, while
the choice of the masculine parents (C. crenata and C mollissima), on the diseases resistance. For
the total of 68 isolations in 4 cultivars, about 408 flowers were pollinated. The total production
of hybrid seeds was of 21 fruits. These seeds were then germinated, resulting in 11 plants. DNA
was extracted both from the parents, as well as their progeny and nuclear microsatellites were
applied. The inheritance of the loci, for the different microsatellites, involving parents and
progenies, was then analysed.
This study deals with the occurrence and relative abundance of four different types of abortive ovules in three species of Quercus. It was found that, contrary to previous literature, fertilization does not always occur in the abortive ovules. The most common type of abortive ovule is the one in which a normal embryo sac develops, yet fertilization does not occur. The absence of embryo sacs and the occurrence of empty embryo sacs account for abortion in other ovules. All types of abortive ovules can occur in the same ovary. It is proposed that all of the ovules that develop a normal embryo sac are potential seeds, but the first one to be fertilized suppresses the normal development of the others.
Brewbaker, James L., and Beyoung H. Kwack. (U. Hawaii, Honolulu.) The essential role of calcium ion in pollen germination and pollen tube growth. Amer. Jour. Bot. 50(9): 859–865. Illus. 1963.—A pollen population effect occurs whenever pollen grains are grown in vitro. Small pollen populations germinate and grow poorly if at all, under conditions which support excellent growth of large pollen populations. The pollen population effect is overcome completely by a growth factor obtained in water extracts of many plant tissues. This factor is shown to be the calcium ion, and its action confirmed in 86 species representing 39 plant families. Other ions (K⁺, Mg⁺⁺, Na⁺) serve in supporting roles to the uptake or binding of calcium. The high requirement of calcium (300–5000 ppm, as Ca (NO3)2·4H2O, for optimum growth) and low calcium content of most pollen may conspire to give calcium a governing role in the growth of pollen tubes both in vitro and in situ. It is suspected that ramifications of this role extend to the self-incompatibilities of plants and to the curious types of arrested tube growth distinguishing, for example, the orchids. A culture medium which proved its merit in a wide variety of pollen growth studies included, in distilled water, 10% sucrose, 100 ppm H3BO3, 300 ppm Ca (NO3)2·4H2O, 200 ppm MgSO4·7H2O and 100 ppm KNO3.
This chapter discusses the stratification of angiosperm pollen grain walls. Pores and slits form conspicuous features of the pollen wall. Shortly before final maturation of the pollen grains, surface coatings of various kinds are acquired, derived from secretory or breakdown products of the tapetum. The most striking characteristic of the material of the exine is its remarkable resistance to degradation by both physico-chemical and biological agencies. The spore environment is an important factor in controlling the orientation and disposition of various exine features. The observations of early exine ontogeny in many species have revealed constant relationships between the locations of spores, colpi, and other aspects of exine pattern with the axis of the young spore of the tetrad. The pattern-generating processes within the spore, while necessarily reflecting the capacities of the genome so far as detail is concerned, are dependent upon cellular interactions for their initiation and early orientation.
