Zhao Xiaoqiang, Zhong Yuan, Zhou Wenqi
Gansu Provincial Key Lab of Aridland Crop Science, Gansu Agricultural University, Lanzhou 730070, China.
Gansu Provincial Key Lab of Aridland Crop Science, Gansu Agricultural University, Lanzhou 730070, China.
Genomics. 2021 Nov;113(6):3565-3581. doi: 10.1016/j.ygeno.2021.08.020. Epub 2021 Aug 26.
Deep-seeding is an important way to improve maize drought resistance, mesocotyl elongation can significantly enhance its seedling germination. To improve our understanding of transcription-mediated maize mesocotyl elongation under deep-seeding stress. RNA-sequencing was used to identify differentially expressed genes (DEGs) in both deep-seeding tolerant W64A and intolerant K12 mesocotyls following culture for 10 days after 2.0 mg·L 24-epibrassinolide (EBR) induced stress at the depths of 3 and 20 cm. Phenotypically, the mesocotyl length of both maize significantly increased under 20 cm stress and in the presence of EBR. Microstructure observations revealed that the mesocotyls underwent programmed cell death under deep-seeding stress, which was alleviated by EBR. This was found to be regulated by multiple DEGs encoding cysteine protease/senescence-specific cysteine protease, aspartic protease family protein, phospholipase D, etc. and transcription factors (TFs; MYB, NAC). Additionally, some DEGs associated with cell wall components, i.e., cellulose synthase/cellulose synthase like protein (CESA/CSL), fasciclin-like arabinogalactan (APG), leucine-rich repeat protein (LRR) and lignin biosynthesis enzymes including phenylalanine ammonia-lyase, S-adenosyl-L-methionine-dependent methyltransferases, 4-coumarate-CoA ligase, cinnamoyl CoA reductase, cinnamyl alcohol dehydrogenase, catalase, peroxiredoxin/peroxidase were found to control cell wall sclerosis. Moreover, in auxin, ethylene, brassinosteriod, cytokinin, zeatin, abscisic acid, gibberellin, jasmonic acid, and salicylic acid signaling transduction pathways, the corresponding DEGs were activated/inhibited by TFs (ARF, BZR1/2, B-ARR, A-ARR, MYC2, ABF, TGA) and synthesis of phytohormones-related metabolites. These findings provide information on the molecular mechanisms controlling maize deep-seeding tolerance and will aid in the breeding of deep-seeding maize varieties.
深播是提高玉米抗旱性的重要途径，中胚轴伸长可显著提高其种子萌发率。为了增进我们对深播胁迫下转录介导的玉米中胚轴伸长的理解，我们利用RNA测序来鉴定在2.0 mg·L 24-表油菜素内酯（EBR）诱导胁迫后，于3厘米和20厘米深度培养10天的深播耐受性W64A和不耐受性K12中胚轴中的差异表达基因（DEG）。从表型上看，在20厘米胁迫下以及存在EBR的情况下，两种玉米的中胚轴长度均显著增加。微观结构观察表明，中胚轴在深播胁迫下经历了程序性细胞死亡，而EBR可缓解这种情况。研究发现，这受多个编码半胱氨酸蛋白酶/衰老特异性半胱氨酸蛋白酶、天冬氨酸蛋白酶家族蛋白磷脂酶D等的DEG以及转录因子（TF；MYB、NAC）调控。此外，还发现一些与细胞壁成分相关的DEG，即纤维素合酶/类纤维素合酶（CESA/CSL）、类 Fasciclin 阿拉伯半乳聚糖（APG）、富含亮氨酸重复蛋白（LRR）以及包括苯丙氨酸解氨酶、S-腺苷-L-甲硫氨酸依赖性甲基转移酶、4-香豆酸-CoA连接酶、肉桂酰辅酶A还原酶、肉桂醇脱氢酶、过氧化氢酶、过氧化物酶/过氧化物酶等木质素生物合成酶控制细胞壁硬化。此外，在生长素、乙烯、油菜素甾醇、细胞分裂素、玉米素、脱落酸、赤霉素、茉莉酸和水杨酸信号转导途径中，相应的DEG被转录因子（ARF、BZR1/2、B-ARR、A-ARR、MYC2、ABF、TGA）激活/抑制以及植物激素相关代谢物的合成。这些发现提供了有关控制玉米深播耐受性的分子机制的信息，并将有助于深播玉米品种的育种。
