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: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:Opaque2 (O2) is a transcription factor that plays important roles during maize endosperm development. Mutation of the O2 gene improves the nutritional value of maize seeds, but also confers pleiotropic effects that result in reduced agronomic quality. To reveal the transcriptional regulatory framework of O2, we determined O2 DNA binding targets using chromatin immunoprecipitation coupled to high-throughput sequencing (ChIP-Seq). ChIP-Seq analysis detected 1,686 O2 DNA binding sites distributed over 1,143 genes. We identified 4 new O2 binding motifs; among them, TGACGTGG appears to be the most conserved and strongest. We confirmed that, except for the 16 kD and 18 kD zeins, O2 directly regulates expression of all other zeins. O2 directly regulates two transcription factors, genes linked to carbon and amino acid metabolism and abiotic stress resistance. Examination of 15 days after pollination(DAP) wild type maize endosperm with O2 specific antibody and IgG serves as control.
Project description:High-throughput sequencing of genomic regions isolated using FAIRE (Formaldehyde-assisted isolation of regulatory elements) from two maize lines of contrasting cold-sensitivity, S68911 (tolerant) and B73 (sensitive) grown in cold and control conditions. Three growth stages were examined: coleoptile (VE), seedling with the tip of the second leaf visible (called here “VE/V1 stage”), first leaf fully developed (V1, ligular region present). Results suggest both efficient metabolism and active defense mechanisms as a basis of S68911 maize cold-tolerance.
Project description:Opaque2 (O2) is a transcription factor that plays important roles during maize endosperm development. Mutation of the O2 gene improves the nutritional value of maize seeds, but also confers pleiotropic effects that result in reduced agronomic quality. To reveal the transcriptional regulatory framework of O2, we determined O2 DNA binding targets using chromatin immunoprecipitation coupled to high-throughput sequencing (ChIP-Seq). ChIP-Seq analysis detected 1,686 O2 DNA binding sites distributed over 1,143 genes. We identified 4 new O2 binding motifs; among them, TGACGTGG appears to be the most conserved and strongest. We confirmed that, except for the 16 kD and 18 kD zeins, O2 directly regulates expression of all other zeins. O2 directly regulates two transcription factors, genes linked to carbon and amino acid metabolism and abiotic stress resistance.
Project description:Cold tolerance of crop plants influences survival and productivity under low-temperature conditions. Elucidation of molecular mechanisms underlying low temperature tolerance could be helpful in breeding. In this study, based on transcriptome and metabolomic analysis, we successfully identified a number of candidate genes and metabolites involved in key biological pathways during cold stress response. During cold stress, a total of 22335 differentially expressed genes were detected in each group (093Cvs120C, 093Tvs120T, 093Cvs093T, 120Cvs120T), of which 12978 were up-regulated and 9357 were down-regulated. A total of 18,166 metabolites were detected and 7,670 metabolites were annotated, among which 654 were secondary metabolites with significant differences. Under cold stress, the petC gene in both common bean cultivars was down-regulated, which led to the decrease of photosynthetic efficiency. Transcriptome and metabolome results under cold stress showed that the synthesis pathways of various unsaturated fatty acids including alpha-linolenic acid were significantly up-regulated and their contents were enriched. In addition, leukotriene-A4 hydrolase in the catabolic pathway of 120 arachidonic acid was inhibited under cold stress. Furthermore, the content of arachidonic acid was increased. A variety of amino acids in both 093 and 120 were enriched under cold stress, which was beneficial to the resistance of bean to osmotic stress caused by cold stress. However, in addition to a few amino acids that were enriched together, 093 was mainly positively charged and 120 was negatively charged among the amino acids that were enriched differently. This is an interesting phenomenon that needs to be further studied. In addition, under cold stress, we found that genes in multiple metabolic pathways, including ABA, GA, JA and other hormone metabolism pathways, were differentially expressed in 093 and 120.
Project description:Cold stress is one of the major abiotic stress factors affecting rice growth and development, leading to great yield loss in the context of global climate change. Exploring superior natural variants that confer cold resistance and the underlying molecular mechanism is the major strategy to breed cold tolerant rice varieties. Here, we identified natural variations of a SIMILAR to RCD ONE (SRO) gene OsSRO1c that confers cold tolerance in rice at both seedling and booting stages. OsSRO1c interacts with transcription factor OsDREB2B and promotes its transcriptional activity by concentrating OsDREB2B into biomolecular condensates in the nucleus. The OsSRO1c-OsDREB2B complex directly sense cold stress through dynamic phase transitions in vivo and in vitro and regulate key cold response gene COLD1. Introgression of an elite haplotype of OsSRO1c into a cold susceptible indica rice can significantly increase its cold resistance ability. Thus, our work revealed a novel cold stress sensing module and provided a promising gene resource for breeding cold tolerant rice varieties.