Publications by authors named "Mike Ambrose"

Control of organ size and shape by cell proliferation and cell expansion is a fundamental process during plant development, but the molecular mechanisms that set the final size and shape of determinate organs in plants remain unclear, especially in legumes. In this study, we characterized several mutants including bigger organs (bio) and elephant-ear-like leaf 1 (ele1) in pea that displayed similar phenotypes, with enlarged leaves and symmetrical lateral and ventral petals. Genetic analysis showed that BIO interacted with the specific regulators SYMMETRICAL PETAL1 (SYP1) and SYP5 to control floral organ internal asymmetry in pea.

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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 the development and evolution of novel leaf traits.

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One of the traits studied by Mendel in pea ( L.) was the wrinkled-seeded phenotype, and the molecular basis for a mutation underlying this phenotype was discovered in the 1990s. Although the starch-branching enzyme gene mutation identified at the genetic locus is most likely to be that in seeds available to Mendel in the mid-1800s, it has remained an open question as to whether or not additional natural mutations in this gene exist within germplasm collections.

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Transcriptome profiles derived from the site of human disease have led to the identification of genes that contribute to pathogenesis, yet the complex mixture of cell types in these lesions has been an obstacle for defining specific mechanisms. Leprosy provides an outstanding model to study host defense and pathogenesis in a human infectious disease, given its clinical spectrum, which interrelates with the host immunologic and pathologic responses. Here, we investigated gene expression profiles derived from skin lesions for each clinical subtype of leprosy, analyzing gene coexpression modules by cell-type deconvolution.

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Article Synopsis
  • The Def locus in pea seeds influences the abscission between the funicle and seed coat, requiring cell wall remodeling for this process.
  • Researchers investigated changes in pectic polysaccharides in wild type and def mutant pea seeds using immunolabeling techniques to identify factors behind abscission.
  • Results showed specific changes in pectic components during abscission, highlighting that de-methyl esterification may contribute to the remodeling necessary for seed separation, as seen in the different patterns of labeling in dominant and recessive lines.
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In Papilionoideae legume, Lotus japonicus, the development of dorsal-ventral (DV) asymmetric flowers is mainly controlled by two TB1/CYCLOIDEA/PCF (TCP) genes, SQUARED STANDARD (SQU) and KEELED WINGS IN LOTUS (KEW), which determine dorsal and lateral identities, respectively. However, the molecular basis of how these two highly homologous genes orchestrate their diverse functions remains unclear. Here, we analyzed their expression levels, and investigated the transcriptional activities of SQU and KEW.

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Vavilovia formosa (Stev.) Fed. is a scientifically valuable common ancestor of the plant tribe Fabeae and also important in breeding and agronomy studies of the cultivated Fabeae, but it is close to extinction.

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Background: The eukaryotic translation initiation factor 4E was shown to be involved in resistance against several potyviruses in plants, including pea. We combined our knowledge of pea germplasm diversity with that of the eIF4E gene to identify novel genetic diversity.

Methodology/principal Findings: Germplasm of 2803 pea accessions was screened for eIF4E intron 3 length polymorphism, resulting in the detection of four eIF4E(A-B-C-S) variants, whose distribution was geographically structured.

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A fast neutron (FN)-mutagenised population was generated in Pisum sativum L. (pea) to enable the identification and isolation of genes underlying traits and processes. Studies of several phenotypic traits have clearly demonstrated the utility of the resource by associating gene deletions with phenotype followed by functional tests exploiting additional mutant sources, from both induced and natural variant germplasm.

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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 (coch) mutants, which are characterized by the abnormal development of roots from the nodule, we identified the NOOT and COCH genes as being necessary for the robust maintenance of nodule identity throughout the nodule developmental program.

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During organ development, many key regulators have been identified in plant genomes, which play a conserved role among plant species to control the organ identities and/or determine the organ size and shape. It is intriguing whether these key regulators can acquire diverse function and be integrated into different molecular pathways among different species, giving rise to the immense diversity of organ forms in nature. In this study, we have characterized and cloned LATHYROIDES (LATH), a classical locus in pea, whose mutation displays pleiotropic alteration of lateral growth of organs and predominant effects on tendril and dorsal petal development.

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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 higher plants.

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Article Synopsis
  • The study focused on the def mutant pea, which has a unique trait of non-abscission of seeds from the funicule, and investigated the relationship between seed development, growth patterns, and the inheritance of the def allele.
  • Findings showed that as pods mature, pod length and seed fresh weight increase, impacting the abscission event, but seed positioning within the pod did not affect this trait.
  • The inheritance of the Def locus was significant, revealing a monogenic trait controlled by a homozygous recessive def allele, leading to differences in the seed coat structure compared to wild-type peas.
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Previous study has shown that during zygomorphic development in garden pea (Pisum sativum L.), the organ internal (IN) asymmetry of lateral and ventral petals was regulated by a genetic locus, SYMMETRIC PETAL 1 (SYP1), while the dorsoventral (DV) asymmetry was determined by two CYC-like TCP genes or the PsCYC genes, KEELED WINGS (K) and LOBED STANDARD 1 (LST1). In this study, two novel loci, ELEPHANT EAR-LIKE LEAF 1 (ELE1) and ELE2 were characterized.

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Background: In pea seeds (Pisum sativum L.), the Def locus defines an abscission event where the seed separates from the funicle through the intervening hilum region at maturity. A spontaneous mutation at this locus results in the seed failing to abscise from the funicle as occurs in wild type peas.

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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 ago, transforms tendrils into leaflets.

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Floral zygomorphy (flowers with bilateral symmetry) has multiple origins and typically manifests two kinds of asymmetries, dorsoventral (DV) and organ internal (IN) asymmetries in floral and organ planes, respectively, revealing the underlying key regulators in plant genomes that generate and superimpose various mechanisms to build up complexity and different floral forms during plant development. In this study, we investigate the loci affecting these asymmetries during the development of floral zygomorphy in pea (Pisum sativum L.).

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Sequence diversity of 39 dispersed gene loci was analyzed in 48 diverse individuals representative of the genus Pisum. The different genes show large variation in diversity parameters, suggesting widely differing levels of selection and a high overall diversity level for the species. The data set yields a genetic diversity tree whose deep branches, involving wild samples, are preserved in a tree derived from a polymorphic retrotransposon insertions in an identical sample set.

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The genetic structure and evolutionary history of the genus Pisum were studied exploiting our germplasm collection to compare the contribution of different mechanisms to the generation of diversity. We used sequence-specific amplification polymorphism (SSAP) markers to assess insertion site polymorphism generated by a representative of each of the two major groups of LTR-containing retrotransposons, PDR1 (Ty1/copia-like) and Cyclops (Ty3/gypsy-like), together with Pis1, a member of the En/Spm transposon superfamily. The analysis of extended sets of the four main Pisum species, P.

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