Julie Hofer

• PhD
• PostDoc Position at John Innes Centre

Pea, Pisum sativum, is an excellent model system through which Gregor Mendel established the foundational principles of inheritance. Surprisingly, till today, the molecular nature of the genetic differences underlying the seven pairs of contrasting traits that Mendel studied in detail remains partially understood. Here, we present a genomic and phe...

The afila (af) mutation causes the replacement of leaflets by a branched mass of tendrils in the compound leaves of pea – Pisum sativum L. This mutation was first described in 1953, and several reports of spontaneous af mutations and induced mutants with a similar phenotype exist. Despite widespread introgression into breeding material, the nature...

Pea, Pisum sativum, is an excellent model system through which Gregor Mendel established the foundational principles of inheritance. Surprisingly, till today, the molecular nature of the genetic differences underlying the seven pairs of contrasting traits that Mendel studied in detail remains partially understood. Here, we present a genomic and phe...

In common with other plant species, the garden pea (Pisum sativum) produces the auxin indole-3-acetic acid (IAA) from tryptophan via a single intermediate, indole-3-pyruvic acid (IPyA). IPyA is converted to IAA by PsYUC1, also known as Crispoid (Crd). Here, we extend our understanding of the developmental processes affected by the Crd gene by exami...

Genomic resources are becoming available for Pisum but to link these to phenotypic diversity requires well marked populations segregating for relevant traits. Here we describe two such resources. Two recombinant inbred populations, derived from wide crosses in Pisum are described. One high resolution mapping population involves cv Caméor, for which...

The afila ( af ) mutation of Pisum sativum L. (pea) is characterised by leaves that are composed of a basal pair of stipules, a petiole and a branched mass of tendrils. These are bipinnate leaves in which the leaflet primordia are replaced by midrib-like, or terminal tendril, primordia. The phenotype was first reported as a spontaneous mutation in...

The seed-containing pod is the defining structure of plants in the legume family, yet pods exhibit a wide range of morphological variation. Within a species pod characters are likely to be correlated with reproductive strategy, and within cultivated forms will correspond to aspects of yield determination and/or end use. Here variation in pod size,...

A controversy arose over Mendel’s pea crossing experiments after the statistician R.A. Fisher proposed how these may have been performed and criticised Mendel’s interpretation of his data. Here we re-examine Mendel’s experiments and investigate Fisher’s statistical criticisms of bias. We describe pea varieties available in Mendel’s time and show th...

Pea ( Pisum sativum ) is one of relatively few genetically amenable plant species with compound leaves. Pea leaves have a variety of specialized organs: leaflets, tendrils, pulvini and stipules, which enable the identification of mutations that transform or affect distinct parts of the leaf. Characterization of these mutations offers insights into...

Land plants lose vast quantities of water to the atmosphere during photosynthetic gas exchange. In angiosperms a complex network of veins irrigates the leaf, and it is widely held that the density and placement of these veins determines maximum leaf hydraulic capacity and thus maximum photosynthetic rate. This theory is largely based on interspecif...

The legume family is astonishingly diverse; inventiveness in the form of novel organs, modified organs and additional meristems, is rife. Evolutionary changes can be inferred from the phylogenetic pattern of this diversity, but a full understanding of the origin of these 'hopeful monsters' of meristematic potential requires clear phylogenetic recon...

During their symbiotic interaction with rhizobia, legume plants develop symbiosis-specific organs on their roots, called nodules, that house nitrogen-fixing bacteria. The molecular mechanisms governing the identity and maintenance of these organs are unknown. Using Medicago truncatula nodule root (noot) mutants and pea (Pisum sativum) cochleata (co...

Plants exhibit various kinds of movements that have fascinated scientists and the public for centuries. Physiological studies in plants with the so-called motor organ or pulvinus suggest that cells at opposite sides of the pulvinus mediate leaf or leaflet movements by swelling and shrinking. How motor organ identity is determined is unknown. Using...

The inheritance of flower color in pea (Pisum sativum) has been studied for more than a century, but many of the genes corresponding to these classical loci remain unidentified. Anthocyanins are the main flower pigments in pea. These are generated via the flavonoid biosynthetic pathway, which has been studied in detail and is well conserved among h...

Mendel's paper 'Versuche über Pflanzen-Hybriden' is the best known in a series of studies published in the late 18th and 19th centuries that built our understanding of the mechanism of inheritance. Mendel investigated the segregation of seven gene characters of pea (Pisum sativum), of which four have been identified. Here, we review what is known a...

Pea (Pisum sativum L.) has a compound leaf like many other legume species. The ‘semi-leafless’ pea (afaf TLTL), with all leaflets transformed into tendrils, is considered one of the most important achievements in pea breeding, due to a significantly enhanced standing ability and equally efficient dry matter production in comparison to normal-leafed...

Sequence divergence of the bHLH gene in germplasm and exotic pea lines. (A) Sequence of exotic pea lines. For JI 4 and 9 exotic white flowered pea lines; JI 232, JI 616, JI 817, JI 1497, JI 1512, JI 1782, JI 1987, JI 2647 and JI 3003 the G to A mutation is highlighted and marked with *. Three independent individuals of the white flowered JI 1987 (n...

Synteny between the pea genetic map and M. truncatula genome sequence. PEAPCF1 [GU176398] and CD72 [Y11207] flank the A locus in the pea genetic map. In the M. truncatula genome, BACs with the best BLAST matches to these pea genes are indicated by arrows along with BAC contigs and the genetic markers that were used to assemble the physical map. BAC...

Alignment of the predicted amino acid sequence of the N-terminal region of bHLH proteins. (0.04 MB DOC)

Sequence alignment of the A gene. (A) Alignment of genomic DNA of pea bHLH genes from colored flowered A line PI 269818 BAC 112D23 [GU132941] and white flowered a cultivar Caméor BAC 452H2 [GU132942]. The sequence shown for the exons is that of PI 269818 as this is known to be a functional allele. Exons 1–7 are marked and nucleotide differences bet...

Annotated sequence of the A2 gene from JI2822 and showing differences in various lines. The sequence from nt 160 to nt 217 (bold italic) is a direct duplication, only one copy of which is found in the PI 198074 allele. From nucleotide 530 to 644 (bold italic) is also deleted in the PI 198074 allele. Note the GCACA sequence is repeated at either end...

A) Primers used in the identification and characterization of the bHLH gene from pea (Ps) [GU132941] and M. truncatula (Mt) [GU132940]. (B) Primers used in the identification and characterization of the WD40 gene from pea. (0.11 MB DOC)

Complementation of white pea petals by particle bombardment. Particle bombardment of petals of Greenfeast (PI 250447 that carries the G to A splice donor mutation) with [left to right], over-expression cassettes for PhAN1 (AN1), reproduced from Figure 3 for comparison, and PhAN2. All experiments included an over-expression cassette of green fluores...

The genetic regulation of flower color has been widely studied, notably as a character used by Mendel and his predecessors in the study of inheritance in pea. We used the genome sequence of model legumes, together with their known synteny to the pea genome to identify candidate genes for the A and A2 loci in pea. We then used a combination of genet...

Tendrils are contact-sensitive, filamentous organs that permit climbing plants to tether to their taller neighbors. Tendrilled legume species are grown as field crops, where the tendrils contribute to the physical support of the crop prior to harvest. The homeotic tendril-less (tl) mutation in garden pea (Pisum sativum), identified almost a century...

The genomes of several legume species contain two Phantastica-like genes. Previous studies on leaf development have found that Phantastica confers leaf blade adaxial identity in plant species with simple leaves and leaflet adaxial identity in pea (Pisum sativum L.), a legume with compound leaves. Previous characterisation of the phantastica mutant...

New tools, such as ordered mutant libraries, microarrays and sequence based comparative maps, are available for genetic and genomic studies of legumes that are being used to shed light on seed production, the objective of most arable farming. The new information and understanding brought by these tools are revealing the biological processes that un...

Pinnate compound leaves have laminae called leaflets distributed at intervals along an axis, the rachis, whereas simple leaves have a single lamina. In simple- and compound-leaved species, the PHANTASTICA (PHAN) gene is required for lamina formation. Antirrhinum majus mutants lacking a functional gene develop abaxialized, bladeless adult leaves. Tr...

Morphology in many animals is preordained during embryonic development and remains unchanged by environment. In contrast, vast differences in phenotype can occur in plants of identical genotype in different environments. Being sessile organisms, plants must rely on morphological and physiological plasticity to cope with a variable environment. The...

SQUAMOSA and APETALA1 are floral meristem identity genes from snapdragon (Antirrhinum majus) and Arabidopsis, respectively. Here, we characterize the floral meristem identity mutation proliferating inflorescence meristem (pim) from pea (Pisum sativum) and show that it corresponds to a defect in the PEAM4 gene, a homolog of SQUAMOSA and APETALA1. Th...

The Arabidopsis genome sequence has given us an inventory of the genes needed to specify a flowering plant. Plants are highly diverse in appearance and the mechanisms whereby this diversity has arisen need explanation. A fundamental question is to what extent diversity arises from remodelling of gene function or relocation of gene pathways, rather...

The partial-shoot theory of the leaf was a controversial hypothesis revived by Arber and supported by her morphological and anatomical studies. This theory highlighted the parallels between leaves and shoots and contrasted with an alternative view that leaves, with their limited growth potential, are completely distinct from shoots. Pea morphologic...

Differences in knotted1-like (knox) gene expression may account for some of the diversity of leaf forms seen in nature. Class 1 knox genes are expressed in the compound leaf primordia of tomato but not in the simple leaf primordia of a range of species examined so far. In order to test the hypothesis that all compound leaves differ from simple leav...

Isolation and characterization of two severe alleles at the Stamina pistilloida (Stp) locus reveals that Stp is involved in a wide range of developmental processes in the garden pea. The most severe allele, stp-4, results in flowers consisting almost entirely of sepals and carpels. Production of ectopic secondary flowers in stp-4 plants suggests th...

The compound leaf primordium of pea represents a marginal blastozone that initiates organ primordia, in an acropetal manner, from its growing distal region. The UNIFOLIATA (UNI) gene is important in marginal blastozone maintenance because loss or reduction of its function results in uni mutant leaves of reduced complexity. In this study, we show th...

On Apr 29, 2005 this sequence version replaced gi:9972156.

Shoot-like compound leaves are ancient and predate the evolutionary origin of whorled flowers. By studying leaves of this type it may be possible to gain further insight into similar fundamental processes in plant development. Here, we describe the pea compound leaf from the viewpoint that considers it as a determinate lateral shoot. By integrating...

On Aug 22, 2000 this sequence version replaced gi:3462611.

A cytogenetic analysis of inbred lines that have been used to generate genetic maps of pea is presented. Mitotic karyotyping of the inbred lines and meiotic studies of their F 1 hybrids have been used to test the prediction that structural differences exist between the parental lines. The results are not compatible with the previously published mol...

The vegetative phenotype of the pea mutant unifoliata (uni) is a simplification of the wild-type compound leaf to a single leaflet. Mutant uni plants are also self-sterile and the flowers resemble known floral meristem and organ identity mutants. In Antirrhinum and Arabidopsis, mutations in the floral meristem identity gene FLORICAULA/LEAFY (FLO/LF...

On Aug 22, 2000 this sequence version replaced gi:2306982.

The C2H2 TFIIIA/Krüppel class of zinc finger proteins are an important group of regulatory nucleic acid binding factors and have been extensively studied in humans, Drosophila and yeast. We have employed 3' RACE PCR, using a highly degenerate oligonucleotide primer, for the facile isolation of a C2H2 zinc finger protein cDNA (Pszf1) from pea petals...

We have investigated the relationship between viral DNA replication and virion sense gene expression in wheat dwarf virus (WDV), a member of the geminivirus group, by testing a series of deletion mutants in transfected Triticum monococcum (einkorn) protoplasts. Mutants contained a transcription fusion of the chloramphenicol acetyltransferase coding...