Graduate Program in Biotechnology, University of Taquari Valley - Univates, Lajeado, Brazil.
Graduate Program in Cellular and Molecular Biology, Federal University of Rio Grande do Sul, Porto Alegre, Brazil.
J Plant Physiol. 2020 Dec;255:153307. doi: 10.1016/j.jplph.2020.153307. Epub 2020 Oct 14.
Rice (Oryza sativa L.) ssp. indica is the most cultivated species in the South of Brazil. However, these plants face low temperature stress from September to November, which is the period of early sowing, affecting plant development during the initial stages of growth, and reducing rice productivity. This study aimed to characterize the root response to low temperature stress during the early vegetative stage of two rice genotypes contrasting in their cold tolerance (CT, cold-tolerant; and CS, cold-sensitive). Root dry weight and length, as well as the number of root hairs, were higher in CT than CS when exposed to cold treatment. Histochemical analyses indicated that roots of CS genotype present higher levels of lipid peroxidation and HO accumulation, along with lower levels of plasma membrane integrity than CT under low temperature stress. RNAseq analyses revealed that the contrasting genotypes present completely different molecular responses to cold stress. The number of over-represented functional categories was lower in CT than CS under cold condition, suggesting that CS genotype is more impacted by low temperature stress than CT. Several genes might contribute to rice cold tolerance, including the ones related with cell wall remodeling, cytoskeleton and growth, signaling, antioxidant system, lipid metabolism, and stress response. On the other hand, high expression of the genes SRC2 (defense), root architecture associated 1 (growth), ACC oxidase, ethylene-responsive transcription factor, and cytokinin-O-glucosyltransferase 2 (hormone-related) seems to be related with cold sensibility. Since these two genotypes have a similar genetic background (sister lines), the differentially expressed genes found here can be considered candidate genes for cold tolerance and could be used in future biotechnological approaches aiming to increase rice tolerance to low temperature.
水稻（Oryza sativa L.）亚种印度型是巴西南部种植最多的品种。然而，这些植物在 9 月至 11 月的早期播种期会面临低温胁迫，这会影响生长初期的植物发育，并降低水稻的产量。本研究旨在描述两个水稻基因型（CT，耐寒；CS，感冷）在早期营养生长阶段对低温胁迫的根系响应特征。在冷处理下，CT 的根干重和根长以及根毛数量均高于 CS。组织化学分析表明，低温胁迫下 CS 基因型的根中脂质过氧化和 HO 积累水平较高，而质膜完整性水平较低。RNAseq 分析表明，不同基因型对低温胁迫的分子响应完全不同。在低温条件下，CT 的过表达功能类别数量低于 CS，这表明 CS 基因型比 CT 更易受到低温胁迫的影响。一些基因可能有助于水稻的耐寒性，包括与细胞壁重塑、细胞骨架和生长、信号转导、抗氧化系统、脂质代谢和应激反应相关的基因。另一方面，SRC2（防御）、与根构型相关的 1（生长）、ACC 氧化酶、乙烯响应转录因子和细胞分裂素-O-葡糖苷转移酶 2（激素相关）的高表达似乎与耐寒性有关。由于这两个基因型具有相似的遗传背景（姊妹系），因此这里发现的差异表达基因可以被认为是耐寒性的候选基因，并可用于未来旨在提高水稻对低温耐受性的生物技术方法。
