Wang Xiaohui, Wang Min, Yan Gui, Yang Huiyi, Wei Guangwei, Shen Tinghai, Wan Zehua, Zheng Wei, Fang Sheng, Wu Ziming
Key Laboratory of Crop Physiology, Ecology, and Genetic Breeding, Ministry of Education/College of Agronomy, Jiangxi Agricultural University, Nanchang, China.
Institute of Garden Science and Technology, Nanchang City Gardening Service Center, Nanchang, China.
Front Plant Sci. 2023 Feb 21;14:1117507. doi: 10.3389/fpls.2023.1117507. eCollection 2023.
Sesame production is severely affected by unexpected drought stress during flowering stage. However, little is known about dynamic drought-responsive mechanisms during anthesis in sesame, and no particular attention was given to black sesame, the most common ingredient in East Asia traditional medicine. Herein, we investigated drought-responsive mechanisms of two contrasting black sesame cultivars (Jinhuangma, JHM, and Poyanghei, PYH) during anthesis. Compared to PYH, JHM plants showed higher tolerance to drought stress through the maintenance of biological membrane properties, high induction of osmoprotectants' biosynthesis and accumulation, and significant enhancement of the activities of antioxidant enzymes. For instance, the drought stress induced a significant increase in the content of soluble protein (SP), soluble sugar (SS), proline (PRO), glutathione (GSH), as well as the activities of superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) in leaves and roots of JHM plants compared to PYH plants. RNA sequencing followed by differentially expressed genes (DEGs) analysis revealed that more genes were significantly induced under drought in JHM than in PYH plants. Functional enrichment analyses disclosed that several pathways related to drought stress tolerance, such as photosynthesis, amino acids and fatty acid metabolisms, peroxisome, ascorbate and aldarate metabolism, plant hormone signal transduction, biosynthesis of secondary metabolites, and glutathione metabolism, were highly stimulated in JHM than in PYH plants. Thirty-one (31) key highly induced DEGs, including transcription factors and glutathione reductase and ethylene biosynthetic genes, were identified as potential candidate genes for improving black sesame drought stress tolerance. Our findings show that a strong antioxidant system, biosynthesis and accumulation of osmoprotectants, TFs (mainly ERFs and NACs), and phytohormones are essential for black sesame drought tolerance. Moreover, they provide resources for functional genomic studies toward molecular breeding of drought-tolerant black sesame varieties.
芝麻生产在开花期受到意外干旱胁迫的严重影响。然而，关于芝麻花期动态干旱响应机制知之甚少，并且东亚传统医学中最常见的成分黑芝麻也未受到特别关注。在此，我们研究了两个对比鲜明的黑芝麻品种（金黄麻，JHM，和鄱阳黑，PYH）在花期的干旱响应机制。与PYH相比，JHM植株通过维持生物膜特性、高诱导渗透保护剂的生物合成和积累以及显著增强抗氧化酶的活性，表现出对干旱胁迫更高的耐受性。例如，与PYH植株相比，干旱胁迫导致JHM植株叶片和根系中可溶性蛋白（SP）、可溶性糖（SS）、脯氨酸（PRO）、谷胱甘肽（GSH）的含量以及超氧化物歧化酶（SOD）、过氧化氢酶（CAT）和过氧化物酶（POD）的活性显著增加。RNA测序结合差异表达基因（DEG）分析表明，干旱条件下JHM中显著诱导的基因比PYH中更多。功能富集分析表明，与干旱胁迫耐受性相关的几个途径，如光合作用、氨基酸和脂肪酸代谢、过氧化物酶体、抗坏血酸和醛糖代谢、植物激素信号转导、次生代谢物生物合成和谷胱甘肽代谢，在JHM中比在PYH中受到更高的刺激。31个关键的高度诱导DEG，包括转录因子、谷胱甘肽还原酶和乙烯生物合成基因，被鉴定为提高黑芝麻干旱胁迫耐受性的潜在候选基因。我们的研究结果表明，强大的抗氧化系统、渗透保护剂（主要是ERFs和NACs）的生物合成和积累以及植物激素对黑芝麻耐旱性至关重要。此外，它们为耐旱黑芝麻品种分子育种的功能基因组学研究提供了资源。
