Project description:Drought represents a major constraint on maize production worldwide. Understanding the genetic basis for natural variation in drought tolerance of maize may facilitate efforts to improve this trait in cultivated germplasm. Here, using a genome-wide association study, we show that a miniature inverted-repeat transposable element (MITE) inserted in the promoter of a NAC gene (ZmNAC111) is significantly associated with natural variation in maize drought tolerance. For maize RNA-seq analysis, pooled tissues from three, eight-day-old maize seedlings were collected from transgenic and wild-type plants, prior to or after 2-hour dehydration, to conduct the RNA-seq analysis.
Project description:Salt stress is one major abiotic stress limiting maize grain yield throughout the world.To better understand maize salt tolerance molecular mechanism, comparative proteomic analysis was conducted on seedling roots of salt-tolerant genotype Jing724 and salt-sensitive genotype D9H under NaCl. Jing724 exhibited significantly higher germination rate and growth parameters (weight/length) than did D9H under salt treatment.We identified 565 differentially regulated proteins (DRP) usingiTRAQ and 89 were specific to Jing724 while 424 were specific to D9H. In salt stressed Jing724, pentose phosphate pathway, glutathione metabolism and nitrogen metabolism were enriched. By pathway enrichment and protein-protein interaction analyses, key DRPs such as glucose-6-phosphate 1-dehydrogenase, NADPH producing dehydrogenase, glutamate synthase and glutamine synthasewere identified.Additionally, salt responsive proteins of Jing724 were indicated to facilitate energy management, maintenance of redox homeostasis, reducing ammonia toxicity, osmotic homeostasis regulation, stress defense, stress adaptation, biotic cross-tolerance and gene transcription regulation. Quantification of multiple metabolic or enzymatic changes including SOD activity, MDA content, relative electrolyte leakage and Proline content were consistent with their predicted changes based on functions of DRPs. DRP analysis was correlated with the mRNA transcripts abundance variation of eight representative DRPs. These results contribute to elucidating molecular networks of salt tolerance.
Project description:<p>Cold stress negatively affects maize (<em>Zea mays</em> L.) growth, development and yield. Metabolic adjustments contribute to the adaptation of maize under cold stress. We show here that the transcription factor INDUCER OF CBF EXPRESSION 1 (ZmICE1) plays a prominent role in reprogramming amino acid metabolome and <em>COLD-RESPONSIVE</em> (<em>COR</em>) genes during cold stress in maize. Derivatives of amino acids glutamate/asparagine (Glu/Asn) induce a burst of mitochondrial reactive oxygen species, which suppress the cold-mediated induction of <em>DEHYDRATION RESPONSE ELEMENT-BINDING PROTEIN 1</em> (<em>ZmDREB1</em>) genes and impair cold tolerance. ZmICE1 blocks this negative regulation of cold tolerance by directly repressing the expression of the key Glu/Asn biosynthesis genes, <em>ASPARAGINE SYNTHETASEs</em>. Moreover, ZmICE1 directly regulates the expression of <em>DREB1s</em>. Natural variation at the <em>ZmICE1</em> promoter determines the binding affinity of the transcriptional activator ZmMYB39, a positive regulator of cold tolerance in maize, resulting in different degrees of <em>ZmICE1</em> transcription and cold tolerance across inbred lines. This study thus unravels a mechanism of cold tolerance in maize and provides potential targets for engineering cold-tolerant varieties.</p>
Project description:Gene transcription is an essential step of gene function and transcriptome variation is of agronomical, ecological and evolutionary importance. To explore global expression patterns and dissect the underlying genetic mechanisms are important scientific inquires which are still largely unknown, especially between a segregating population and the parents. In our study, we used RNA-Seq to profile the shoot apex transcriptome variation (including protein coding genes and non-coding genes) in maize IBM RIL population, to map eQTLs underlying the transcriptome variations and to utilize eQTLs to clone genes involved in maize shoot apices development. We revealed that: Much of the variation (the population mean, the coefficient of variation) of gene expression levels in RILs is reflective of differences present among the parents; These transcriptome variations could be explained by 30,774 eQTLs with 96 trans-eQTL hotspots; In many cases, the genes commonly regulated by a trans-eQTL hotspot are enriched for a specific function or act in the same genetic pathway; Structural variation within and near genes contributs to cis-regulatory variation. All of these results indicate Mendelian factors play as major contributors to the transcriptome variation. Meanwhile, non-Mendelian regulations were also observed as paramutation-like expression pattern for 145 genes, of which 88% genes were predicted to be potential targets of miRNAs or ta-siRNAs, and as unexpected presence/absence expression patterns for 210 genes. These genes with unexpected presence/absence expression patterns in the RILs likely include examples of functional genes as well as transposed gene fragments that may contribute to regulatory variation of their ancestral syntenic genes.
Project description:To investigate the role of melatonin in salt tolerance of maize, we determine the seed germinated rate of maize under CK, NaCl and NaCl+melatonin. We then performed miRNA profiling analysis using data obtained from miRNA-seq of the seeds of three different treatments.
Project description:To investigate the role of melatonin in salt tolerance of maize, we determine the seed germinated rate of maize under CK, NaCl and NaCl+melatonin. We then performed gene expression profiling analysis using data obtained from RNA-seq of the seeds of three different treatments.