National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, 430070, China.
Department of Biology, Wilkes University, Wilkes-Barre, PA, 18766, USA.
Plant J. 2019 May;98(4):697-713. doi: 10.1111/tpj.14267. Epub 2019 Mar 5.
Drought is a major abiotic stress that threatens global food security. Circular RNAs (circRNAs) are endogenous RNAs. How these molecules influence plant stress responses remains elusive. Here, a large-scale circRNA profiling identified 2174 and 1354 high-confidence circRNAs in maize and Arabidopsis, respectively, and most were differentially expressed in response to drought. A substantial number of drought-associated circRNA-hosting genes were involved in conserved or species-specific pathways in drought responses. Comparative analysis revealed that circRNA biogenesis was more complex in maize than in Arabidopsis. In most cases, maize circRNAs were negatively correlated with sRNA accumulation. In 368 maize inbred lines, the circRNA-hosting genes were enriched for single nucleotide polymorphisms (SNPs) associated with circRNA expression and drought tolerance, implying either important roles of circRNAs in maize drought responses or their potential use as biomarkers for breeding drought-tolerant maize. Additionally, the expression levels of circRNAs derived from drought-responsible genes encoding calcium-dependent protein kinase and cytokinin oxidase/dehydrogenase were significantly associated with drought tolerance of maize seedlings. Specifically, Arabidopsis plants overexpressing circGORK (Guard cell outward-rectifying K -channel) were hypersensitive to abscisic acid, but insensitive to drought, suggesting a positive role of circGORK in drought tolerance. We report the transcriptomic profiling and transgenic studies of circRNAs in plant drought responses, and provide evidence highlighting the universal molecular mechanisms involved in plant drought tolerance.
干旱是一种主要的非生物胁迫，威胁着全球粮食安全。环状 RNA（circRNA）是内源性 RNA。这些分子如何影响植物的应激反应仍然难以捉摸。在这里，大规模的 circRNA 分析分别在玉米和拟南芥中鉴定出 2174 和 1354 个高可信度的 circRNA，并且大多数在响应干旱时表现出差异表达。大量与干旱相关的 circRNA 宿主基因参与了干旱反应中的保守或特定于物种的途径。比较分析表明，circRNA 的生物发生在玉米中比在拟南芥中更为复杂。在大多数情况下，玉米 circRNA 与 sRNA 的积累呈负相关。在 368 个玉米自交系中，circRNA 宿主基因富集了与 circRNA 表达和耐旱性相关的单核苷酸多态性（SNP），这表明 circRNA 在玉米干旱反应中具有重要作用，或者它们可能作为耐旱玉米育种的生物标志物。此外，来自编码钙依赖性蛋白激酶和细胞分裂素氧化酶/脱氢酶的干旱响应基因的 circRNA 的表达水平与玉米幼苗的耐旱性显著相关。具体而言，过表达 circGORK（Guard cell outward-rectifying K -channel）的拟南芥植物对脱落酸敏感，但对干旱不敏感，这表明 circGORK 在耐旱性中起积极作用。我们报告了植物干旱响应中 circRNA 的转录组分析和转基因研究，并提供了证据，突出了植物耐旱性所涉及的普遍分子机制。
