Project description:Chilling is a major stress to plants of subtropical and tropical origins including maize. To reveal molecular mechanisms underlying chilling tolerance and chilling survival, we investigated maize transcriptome responses to chilling stress in differentiated leaves and roots as well as in crowns with meristem activity for survival. Chilling stress on maize shoots and roots is found to each contribute to seedling lethality in maize. Comparison of maize lines with different chilling tolerance capacity reveals that chilling survival in maize is highly associated with upregulation in leaves and crowns of abscisic acid response pathway, transcriptional regulators and cold response as well as downregulation of heat response in crowns. Comparison of chilling treatment on whole and part of the plants reveals that response to distal-chilling is very distinct from, and sometimes opposite to, response to local- or whole-plant chilling in both leaves and roots, suggesting a communication between shoots and roots in environmental perception. In sum, this study details chilling responses in leaves, roots and crowns and reveals potential chilling survival mechanism in maize, which lays ground for further understanding survival and tolerance mechanisms under low but non-freezing temperatures in tropical and subtropical plants.
Project description:Purpose: The goal of this analysis is that to reveal the different expression pattern in chilling-tolerant and chilling susceptible lines under chilling stress.Chilling is a major stress to plants of subtropical and tropical origins including maize. To reveal molecular mechanisms underlying chilling tolerance and chilling survival, we investigated maize transcriptome responses to chilling stress in differentiated leaves and roots as well as in crowns with meristem activity for survival. Chilling stress on maize shoots and roots is found to each contribute to seedling lethality in maize. Comparison of maize lines with different chilling tolerance capacity reveals that chilling survival in maize is highly associated with upregulation in leaves and crowns of abscisic acid response pathway, transcriptional regulators and metal ion transporters as well as downregulation of heat response in crowns. Comparison of chilling treatment on whole and part of the plants reveals that response to distal-chilling is very distinct from, and sometimes opposite to, response to local- or whole-plant chilling in both leaves and roots, suggesting a communication between shoots and roots in environmental perception. In sum, this study details chilling responses in leaves, roots and crowns and reveals potential chilling survival mechanism in maize, which lays ground for further understanding survival and tolerance mechanisms under low but non-freezing temperatures in tropical and subtropical plants.
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:<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:Improvement of chilling tolerance is a key strategy to face potential menace from abnormal temperature in rice production, which depends on the signaling network triggered by receptors. However, little is known about the QTL genes encoding membrane complexes for sensing cold. Here, Chilling-tolerance in Gengdao/japonica rice 1 (COG1) was isolated from a chromosome segment substitution line containing a QTL (qCS11-jap) for chilling sensitivity. The major gene COG1 was found to confer chilling tolerance in japonica rice. In natural rice populations, only the haplogroup1 encoded a functional COG1. Evolutionary analysis showed that COG1 originated from Chinese O. Rufipogon and was fixed in japonica rice during domestication. COG1, a membrane-localized LRR-RLP, targeted and activated the kinase OsSERL2 in a cold-induced manner, promoting chilling tolerance. Furthermore, the cold signal transmitted by COG1-OsSERL2 activates OsMAPK3 in the cytoplasm. Our findings reveal a cold-sensing complex, which mediates signaling network for the chilling defense in rice.
Project description:To understand the molecular mechanisms underlying chilling tolerance in rice, transcriptomic deep sequencing was performed to reveal the differentially expressed genes between chilling tolerance chromosome substitution line (CSL), DC90 and its chilling-sensitive recurrent parent 9311 under early chilling stress events. Our results revealed a set of DEGs with higher basal expression in DC90 by comparison with 9311. They were functionally enriched in GO terms, such as, response to stress, response to stimulus, and response to abiotic stimulus, suggesting their positive role in intrinsic chilling tolerance. Common up-regulated and down-regulated DEGs were enriched in 26 and 34 GO terms, including response to stimulus, response to stress, and response to abiotic stimulus, respectively. Furthermore, comparative transcriptomic analysis between DC90 and 9311 in response to early chilling stress revealed 502 DEGs specifically identified in DC90. Most of gene loci were located beyond introgressed regions, implying that the introgression led to reprogramming of transcriptome in response to early chilling stress. CARMO platform analysis of these DEGs presented a complex regulatory network, including phytohormone signaling, photosynthesis pathway, that coordinately involved in chilling tolerance response of DC90. Here, the unveiled molecular regulatory network shed light on deep understanding the mechanisms of rice chilling tolerance. As well, chilling tolerant-QTLs and co-localized DEGs in introgressed fragments, will be focused for further functional investigation of the molecular mechanisms of early chilling stress response in rice.
Project description:Most crops are from tropical origin and, consequently, chilling sensitive. However, some tropical plants, are able to augment their chilling tolerance in response to suboptimal growth temperatures. Yet, the molecular and physiological mechanisms underlying this response still remain unclear. Here, we demonstrate that tomato plants can develop a chilling acclimation response and document the comprehensive transcriptomic and metabolic adjustments leading to the increase in chilling tolerance.