Cereal Crops Research Institute, Henan Academy of Agricultural Sciences/Henan Provincial Key Laboratory of Maize Biology/Henan International Joint Laboratory on Maize Precision Production, Zhengzhou, China.
The Key Laboratory of Genetics and Germplasm Innovation of Tropical Special Forest Trees and Ornamental Plants (Ministry of Education), College of Forestry, Hainan University, Haikou, China.
Physiol Plant. 2022 Nov;174(6):e13818. doi: 10.1111/ppl.13818.
Heterosis, known as one of the most successful strategies for increasing grain yield and abiotic/biotic stress tolerance, has been widely exploited in maize breeding. However, the underlying molecular processes are still to be elucidated. The maize hybrid "Zhengdan538" shows high tolerance to drought stress. The transcriptomes of the seedling leaves of its parents, "ZhengA88" and "ZhengT22" and their reciprocal F hybrid under well-watered and water deficit conditions, were analyzed by RNA sequencing (RNA-Seq). Transcriptome profiling of the reciprocal hybrid revealed 2994-4692 differentially expressed genes (DEGs) under well-watered and water-deficit conditions, which were identified by comparing with their parents. The reciprocal hybrid was more closely related to the parental line "ZhengT22" than to the parental line "ZhengA88" in terms of gene expression patterns under water-deficit condition. Furthermore, genes showed expression level dominance (ELD), especially the high-parental ELD (Class 3 and 5), accounted for the largest proportion of DEGs between the reciprocal F hybrid and their parental lines under water deficit. These ELD genes mainly participated in photosynthesis, energy biosynthesis, and metabolism processes. The results indicated that ELD genes played important roles in hybrid tolerance to water deficit. Moreover, a set of important drought-responsive transcription factors were found to be encoded by the identified ELD genes and are thought to function in improving drought tolerance in maize hybrid plants. Our results provide a better understanding of the molecular mechanism of drought tolerance in hybrid maize.
杂种优势是提高作物产量和抗逆性的最成功策略之一，已被广泛应用于玉米育种。然而，其潜在的分子机制仍不清楚。玉米杂交种“郑单 538”对干旱胁迫具有较高的耐受性。本研究通过 RNA 测序（RNA-Seq）分析了其亲本“郑 A88”和“郑 T22”及其正反交 F1 杂种幼苗叶片在充分供水和水分亏缺条件下的转录组。与亲本相比，正反交杂种在充分供水和水分亏缺条件下共鉴定到 2994-4692 个差异表达基因（DEGs）。在水分亏缺条件下，正反交杂种的基因表达模式与亲本“郑 T22”更为相似，而与亲本“郑 A88”差异较大。此外，基因表现出表达水平优势（ELD），特别是高亲本 ELD（第 3 类和第 5 类），在水分亏缺条件下，正反交杂种与亲本间差异表达基因中占比最大。这些 ELD 基因主要参与光合作用、能量生物合成和代谢过程。结果表明，ELD 基因在杂种对水分亏缺的耐受性中发挥重要作用。此外，还发现了一组重要的干旱响应转录因子，这些转录因子由鉴定出的 ELD 基因编码，被认为在提高玉米杂种植物的耐旱性方面发挥作用。本研究结果为深入了解杂交玉米耐旱的分子机制提供了依据。
