Functional Plant Biology
Volume 40 Number 12 2013
The timing of flowering has major effects on crop productivity and plant adaptation. Here we review FT genes which encode important floral activators and discuss recent work in the model legume Medicago highlighting the importance of an FT ortholog FTa1 in flowering. Our work and others shows that while FT orthologs promote flowering in many plants, there appears to be considerable diversity in the upstream pathways that regulate these genes.
FP13123Overexpression of miR160 affects root growth and nitrogen-fixing nodule number in Medicago truncatula
The phytohormone auxin plays fundamental roles in plant development, including the formation of symbiotic nitrogen-fixing nodules in legumes. This study shows that (i) microRNA160 represses the expression of five transcription factors of the auxin response factor family in Medicago truncatula; and (ii) that its overexpression in the root affects both root growth and nodule number. The miR160/ARF regulatory loop may thus be involved in auxin-dependent regulation of nodule organogenesis.
The majority of legume crops suffer from low level of crop productivity especially in developing countries due to their exposure to several stresses. Therefore, it is important to identify candidate genes and molecular mechanisms associated with resistance to these stresses. This article provides a critical appraisal on recent advances and potential of functional genomics for crop improvement in legume crops.
VIGS (virus-induced gene silencing) technology is a powerful technology for determining the function of unknown genes in species recalcitrant to stable genetic transformation. Here we provide an overview of the VIGS systems available for legumes, and present their successful applications in functional genomics studies. We also discuss the limitations and future challenges of VIGS technology in legumes.
The gravitropic response of peanut gynophore plays an essential role in peanut pod development and, thus, plays an important role in pod yield. Transcriptome analysis was conducted using a high-density peanut microarray to identify candidate genes and pathways related to peanut gynophore gravitropism, leading to an enhanced understanding of this process.
FP13147Exploiting a fast neutron mutant genetic resource in Pisum sativum (pea) for functional genomics
Deletion mutants can be used in both forward and reverse genetic screens to discover genes controlling the biology of important plant and seed traits. Here we describe the use of mutants in pea in providing a route to gene isolation and the identification of mutations in genes with non-obvious phenotypes such as those altering seed composition or quality. This mutant resource broadens further the tools available for gene discovery in pea.
Aphids are sap-sucking insects that cause significant yield losses in agriculture. This review focuses on the progress made in understanding plant defense responses against aphid infestation particularly in legumes. Over the last decade, increased research efforts have been made to understand how aphids manipulate the plant to establish a successful feeding site. Progress in this area is described.
FP13063Understanding the molecular defence responses of host during chickpea–Fusarium interplay: where do we stand?
Comparative functional genomic studies involving chickpea and wilt disease causing fungus, Fusarium oxysporum are conducted to enrich present understanding of Fusarium–legume interplay. This report describes the differential pattern of molecular responses associated with wilt disease in susceptible and resistant chickpea. Molecular information deciphered from the present case study is expected to promote the development of legume crop protection strategies.
Root-knot nematodes are parasites that infect a number of crops and cause significant economic losses. The use of resistant cultivars is a promising practice to reduce the use of nematicides, which are toxic to environment. Although peanut is susceptible to the nematode Meloidogyne arenaria, resistance is observed in its wild relative, Arachis stenosperma. We investigated the molecular mechanisms of this resistance, and identified 16 A. stenosperma genes potentially involved in plant defence, thus, provided additional resources for peanut breeding.
The current genomic-centered era brings a belief that drought tolerance genes will soon be unraveled, although molecular genetics research on drought often overlooks water. Deciphering the molecular basis of water stress adaptation should focus on traits affecting plant water budget. Here we survey these traits, their interactions among them and with the environment, and provide a framework using crop simulation modeling to guide their use in crop improvement.
FP13116Evaluation of five peanut (Arachis hypogaea) genotypes to identify drought responsive mechanisms utilising candidate-gene approach
Drought can significantly reduce peanut yield and increase the likelihood of aflatoxin contamination. Selections of drought tolerant peanuts have been difficult because of strong environment × and genotype interactions. The goal of this research was to identify potential molecular mechanism(s) utilising peanut genotypes with contrasting drought responses through a candidate-gene approach. The identification of drought regulated genes, determination of their specific gene-expression patterns, and the association with the levels of drought tolerance will provide a basis for drought tolerant plant selection in peanut breeding programs.
FP13082Heat-stress-induced reproductive failures in chickpea (Cicer arietinum) are associated with impaired sucrose metabolism in leaves and anthers
Heat stress induces reproductive failures in various crops, the underlying biochemical mechanisms are not known. The present work demonstrates that heat stress impairs sucrose metabolism in male reproductive organs of chickpea to impair their functioning. Selecting genotypes having superior sucrose metabolism in male components under heat stress would improve heat tolerance in this crop.
FP13088Variation in carbon isotope discrimination and its relationship with harvest index in the reference collection of chickpea germplasm
The variation in carbon isotope discrimination (Δ13C), an integrator of plant behaviour indicating drought tolerance, was studied using a reference collection of chickpea germplasm. High Δ13C was associated with early maturity, moderate shoot biomass production, high seed yield and high harvest index (HI). There were indications that Δ13C’s association with grain yield was indirectly through final shoot biomass and HI.