Introduction: The cowpea weevil, Fab., is the most economically important storage pest of cowpeas, causing up to 100 percent grain losses within six months of storage. To sustainably resist weevil damage, the cowpea cultivar IT86D-1010 was genetically modified via -mediated transformation to produce event CSI-32, which expresses the kidney bean alpha-amylase inhibitor 1 (αAI-1) protein exclusively in the seed, providing suppression of weevil development.
View Article and Find Full Text PDFTwo homoeologous QTLs for number of spikelets per spike (SPS) were mapped on chromosomes 7AL and 7BL using two wheat MAGIC populations. Sets of lines contrasting for the QTL on 7AL were developed which allowed for the validation and fine mapping of the 7AL QTL and for the identification of a previously described candidate gene, WHEAT ORTHOLOG OF APO1 (WAPO1). Using transgenic overexpression in both a low and a high SPS line, we provide a functional validation for the role of this gene in determining SPS also in hexaploid wheat.
View Article and Find Full Text PDFIn the Australian wheat belts, short episodes of high temperatures or hot spells during grain filling are becoming increasingly common and have an enormous impact on yield and quality, bringing multi-billion losses annually. This problem will become recurrent under the climate change scenario that forecast increasing extreme temperatures, but so far, no systematic analysis of the resistance to hot spells has yet been performed in a diverse genetic background. We developed a protocol to study the effects of heat on three important traits: grain size, grain dormancy and the presence of Late Maturity α-Amylase (LMA), and we validated it by analysing the phenotypes of 28 genetically diverse wheat landraces and exploring the potential variability existing in the responses to hot spells.
View Article and Find Full Text PDFWe consider several economic uncertainty indicators for the US and UK before and during the COVID-19 pandemic: implied stock market volatility, newspaper-based policy uncertainty, Twitter chatter about economic uncertainty, subjective uncertainty about business growth, forecaster disagreement about future GDP growth, and a model-based measure of macro uncertainty. Four results emerge. First, all indicators show huge uncertainty jumps in reaction to the pandemic and its economic fallout.
View Article and Find Full Text PDFThe number of rachis nodes (spikelets) on a wheat spike is a component of grain yield that correlates with flowering time. The genetic basis regulating flowering in cereals is well understood, but there are reports that flowering time can be modified at a high frequency by selective breeding, suggesting that it may be regulated by both epigenetic and genetic mechanisms. We investigated the role of DNA methylation in regulating spikelet number and flowering time by treating a semi-spring wheat with the demethylating agent, Zebularine.
View Article and Find Full Text PDFPre-harvest sprouting (PHS) is an important cause of quality loss in many cereal crops and is particularly prevalent and damaging in wheat. Resistance to PHS is therefore a valuable target trait in many breeding programs. The locus on wheat chromosome arm 4AL has been consistently shown to account for a significant proportion of natural variation to PHS in diverse mapping populations.
View Article and Find Full Text PDFHydration at low temperatures, commonly referred to as cold stratification, is widely used for releasing dormancy and triggering germination in a wide range of species including wheat. However, the molecular mechanism that underlies its effect on germination has largely remained unknown. Our previous studies showed that methyl-jasmonate, a derivative of jasmonic acid (JA), promotes dormancy release in wheat.
View Article and Find Full Text PDFEpigenetic regulatory states can persist through mitosis and meiosis, but the connection between chromatin structure and DNA replication remains unclear. Arabidopsis INCURVATA2 (ICU2) encodes the catalytic subunit of DNA polymerase α, and null alleles of ICU2 have an embryo-lethal phenotype. Analysis of icu2-1, a hypomorphic allele of ICU2, demonstrated that ICU2 functions in chromatin-mediated cellular memory; icu2-1 strongly impairs ICU2 function in the maintenance of repressive epigenetic marks but does not seem to affect ICU2 polymerase activity.
View Article and Find Full Text PDFBackground: Next-generation sequencing technologies provide new opportunities to identify the genetic components responsible for trait variation. However, in species with large polyploid genomes, such as bread wheat, the ability to rapidly identify genes underlying quantitative trait loci (QTL) remains non-trivial. To overcome this, we introduce a novel pipeline that analyses, by RNA-sequencing, multiple near-isogenic lines segregating for a targeted QTL.
View Article and Find Full Text PDFIt is well known that abscisic acid (ABA) plays a central role in the regulation of seed dormancy and that transcriptional regulation of genes encoding ABA biosynthetic and degradation enzymes is responsible for determining ABA content. However, little is known about the upstream signaling pathways impinging on transcription to ultimately regulate ABA content or how environmental signals (e.g.
View Article and Find Full Text PDFThioredoxin (Trx) reduces disulfide bonds and play numerous important functions in plants. In cereal seeds, cytosolic h-type Trx facilitates the release of energy reserves during the germination process and is recycled by NADPH-dependent Trx reductase. This review presents a summary of the research conducted during the last 10 years to elucidate the structure and function of the barley seed Trx system at the molecular level combined with proteomic approaches to identify target proteins.
View Article and Find Full Text PDFAbscisic acid (ABA) plays a central role in seed dormancy and transcriptional regulation of genes coding for ABA biosynthetic and degradation enzymes is responsible for control of ABA content. However, little is known about signalling both before and after ABA regulation, in particular, how environmental signals are perceived and transduced. We are interested in these processes in cereal grains, particularly in relation to the development of strategies for controlling pre-harvest sprouting in barley and wheat.
View Article and Find Full Text PDFLate maturity α-amylase (LMA) is a genetic defect that is commonly found in bread wheat (Triticum aestivum) cultivars and can result in commercially unacceptably high levels of α-amylase in harvest-ripe grain in the absence of rain or preharvest sprouting. This defect represents a serious problem for wheat farmers, and apart from the circumstantial evidence that gibberellins are somehow involved in the expression of LMA, the mechanisms or genes underlying LMA are unknown. In this work, we use a doubled haploid population segregating for constitutive LMA to physiologically analyze the appearance of LMA during grain development and to profile the transcriptomic and hormonal changes associated with this phenomenon.
View Article and Find Full Text PDFWe isolated Arabidopsis thaliana mutants with incurved vegetative leaves. Positional cloning of incurvata8 (icu8), icu9 and icu15 has identified them as new loss-of-function alleles of the HYPONASTIC LEAVES1 (HYL1), ARGONAUTE1 (AGO1) and HUA ENHANCER1 (HEN1) genes, respectively, which encode known components of the microRNA pathway. The morphological and histological characterization of these mutants and of dicer-like1-9 indicates that small RNAs participate in the proximal-distal and adaxial-abaxial patterning of leaves, as well as in stomatal number establishment.
View Article and Find Full Text PDF• Lack of grain dormancy in cereal crops such as barley and wheat is a common problem affecting farming areas around the world, causing losses in yield and quality because of preharvest sprouting. Control of seed or grain dormancy has been investigated extensively using various approaches in different species, including Arabidopsis and cereals. However, the use of a monocot model plant such as Brachypodium distachyon presents opportunities for the discovery of new genes related to grain dormancy that are not present in modern commercial crops.
View Article and Find Full Text PDFMutants in the rice PLASTOCHRON 3 and maize VIVIPAROUS 8 genes have been shown to have reduced dormancy and ABA levels. In this study we used several mutants in the orthologous gene ALTERED MERISTEM PROGRAM 1 (AMP1) to determine its role in seed dormancy in Arabidopsis. Here we report that there are accession-specific effects of mutations in AMP1.
View Article and Find Full Text PDFSeed dormancy is a very important trait that maximizes the survival of seed in nature, the control of which can have important repercussions on the yield of many crop species. We have used gene expression profiling to identify genes that are involved in dormancy regulation in Arabidopsis thaliana. RNA was isolated from imbibed dormant (D) and after-ripened (AR) ecotype C24 seeds, and then screened by quantitative RT-PCR (qRT-PCR) for differentially expressed transcription factors (TFs) and other regulatory genes.
View Article and Find Full Text PDFThe decay of seed dormancy during after-ripening is not well understood, but elucidation of the mechanisms involved may be important for developing strategies for modifying dormancy in crop species and, for example, addressing the problem of preharvest sprouting in cereals. We have studied the germination characteristics of barley (Hordeum vulgare 'Betzes') embryos, including a description of anatomical changes in the coleorhiza and the enclosed seminal roots. The changes that occur correlate with abscisic acid (ABA) contents of embryo tissues.
View Article and Find Full Text PDFSeveral plant hormones, including auxin, brassinosteroids and gibberellins, are required for skotomorphogenesis, which is the etiolated growth that seedlings undergo in the absence of light. To examine the growth of abscisic acid (ABA)-deficient mutants in the dark, we analysed several aba1 loss-of-function alleles, which are deficient in zeaxanthin epoxidase. The aba1 mutants displayed a partially de-etiolated phenotype, including reduced hypocotyl growth, cotyledon expansion and the development of true leaves, during late skotomorphogenic growth.
View Article and Find Full Text PDFCell type-specific gene expression patterns are maintained by the stable inheritance of transcriptional states through mitosis, requiring the action of multiprotein complexes that remodel chromatin structure. Genetic and molecular interactions between chromatin remodeling factors and components of the DNA replication machinery have been identified in Schizosaccharomyces pombe, indicating that some epigenetic marks are replicated simultaneously to DNA with the participation of the DNA replication complexes. This model of epigenetic inheritance might be extended to the plant kingdom, as we report here with the positional cloning and characterization of INCURVATA2 (ICU2), which encodes the putative catalytic subunit of the DNA polymerase alpha of Arabidopsis thaliana.
View Article and Find Full Text PDFThe responsiveness of plants to osmotic stress is critically mediated by the increase in abscisic acid (ABA) levels. Osmotic stress induces the biosynthesis of ABA, whose increased levels subsequently exert a positive feedback on its own biosynthetic pathway. As only qualitative or semi-quantitative analyses were performed to test the inducibility of ABA biosynthetic genes in Arabidopsis thaliana, we used quantitative reverse transcriptase-polymerase chain reaction to re-examine the induction of the ABA1, ABA2, ABA3, NCED3 and AAO3 genes by NaCl and ABA.
View Article and Find Full Text PDFMuch of the literature on the phytohormone abscisic acid (ABA) describes it as a mediator in triggering plant responses to environmental stimuli, as well as a growth inhibitor. ABA-deficient mutants, however, display a stunted phenotype even under well-watered conditions and high relative humidity, which suggests that growth promotion may also be one of the roles of endogenous ABA. Zeaxanthin epoxidase, the product of the ABA1 gene of Arabidopsis thaliana, catalyses the epoxidation of zeaxanthin to antheraxanthin and violaxanthin, generating the epoxycarotenoid precursor of the ABA biosynthetic pathway.
View Article and Find Full Text PDFMutants able to germinate and perform early growth in medium containing a high NaCl concentration were identified during the course of two independent screenings and named salt resistant (sre) and salobreño (sañ). The sre and sañ mutants also were able to germinate in high-osmoticum medium, indicating that they are osmotolerant in a germination assay. Complementation analyses revealed that sre1-1, sre1-2, sañ3-1, and sañ3-2 were alleles of the abscisic acid (ABA) biosynthesis ABA2 gene.
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