背景:干旱被认为是制约苹果生产和苹果产业发展的主要环境因素。砧木在提高苹果植株耐旱性方面发挥着重要作用。生理学研究表明,\'ZC9-3\'是一种很强的抗旱砧木,而“吉珍2”是一种弱抗旱砧木。然而,这两个苹果砧木品种对干旱胁迫的代谢产物尚未被表征,它们响应干旱胁迫的分子机制尚不清楚。
结果:在这项研究中,探索了“Jizhen-2”(干旱敏感性)和“ZC9-3”(抗旱)苹果砧木抗旱性差异的生理和分子机制。在干旱胁迫下,叶片的相对含水量在\'ZC9-3\'中保持在比\'Jizhen-2\'更高的水平,和光合作用,抗氧化剂,“ZC9-3”的渗透调节能力强于“吉珍2”。代谢组分析显示,在干旱胁迫下,\'Jizhen-2\'和\'ZC9-3\'中总共有95和156种差异积累的代谢产物,分别。两个品种中上调的代谢产物主要是氨基酸及其衍生物。转录组分析表明,在整个干旱处理中,\'ZC9-3\'比'吉珍-2\'中的差异表达基因和转录因子更多。代谢组学和转录组学分析表明,氨基酸生物合成途径在介导苹果砧木抗旱性中起关键作用。共有13种代谢物,包括L-α-氨基己二酸,L-高丝氨酸,L-苏氨酸,L-异亮氨酸,L-缬氨酸,L-亮氨酸,(2S)-2-异丙基苹果酸,邻氨基苯甲酸酯,L-色氨酸,L-苯丙氨酸,L-酪氨酸,L-谷氨酸,和L-脯氨酸,在ZC9-3和吉珍-2的抗旱性差异中起重要作用。此外,13个编码O-乙酰丝氨酸-(硫醇)裂解酶的基因,S-腺苷甲硫氨酸合成酶,酮醇-酸异型还原酶,二羟基酸脱水酶,异丙基苹果酸异构酶,支链氨基转移酶,丙酮酸激酶,3-脱氢奎宁酸脱水酶/莽草酸5-脱氢酶,N-乙酰谷氨酸-5-P-还原酶,和吡咯啉-5-羧酸合成酶正调节\'ZC9-3\'对干旱胁迫的响应。
结论:这项研究增强了我们对苹果砧木对干旱胁迫的生理响应的理解,新陈代谢,和转录水平,并提供了关键的见解,将有助于抗旱苹果砧木品种的培育。尤其是,它确定了苹果砧木抗旱性的关键代谢产物和基因。
BACKGROUND: Drought is considered the main environmental factor restricting apple production and thus the development of the apple industry. Rootstocks play an important role in enhancing the drought tolerance of apple plants. Studies of the physiology have demonstrated that \'ZC9-3\' is a strong drought-resistant rootstock, whereas \'Jizhen-2\' is a weak drought-resistant rootstock. However, the metabolites in these two apple rootstock varieties that respond to drought stress have not yet been characterized, and the molecular mechanisms underlying their responses to drought stress remain unclear.
RESULTS: In this study, the physiological and molecular mechanisms underlying differences in the drought resistance of \'Jizhen-2\' (drought-sensitive) and \'ZC9-3\' (drought-resistant) apple rootstocks were explored. Under drought stress, the relative water content of the leaves was maintained at higher levels in \'ZC9-3\' than in \'Jizhen-2\', and the photosynthetic, antioxidant, and osmoregulatory capacities of \'ZC9-3\' were stronger than those of \'Jizhen-2\'. Metabolome analysis revealed a total of 95 and 156 differentially accumulated metabolites in \'Jizhen-2\' and \'ZC9-3\' under drought stress, respectively. The up-regulated metabolites in the two cultivars were mainly amino acids and derivatives. Transcriptome analysis revealed that there were more differentially expressed genes and transcription factors in \'ZC9-3\' than in \'Jizhen-2\' throughout the drought treatment. Metabolomic and transcriptomic analysis revealed that amino acid biosynthesis pathways play key roles in mediating drought resistance in apple rootstocks. A total of 13 metabolites, including L-α-aminoadipate, L-homoserine, L-threonine, L-isoleucine, L-valine, L-leucine, (2S)-2-isopropylmalate, anthranilate, L-tryptophan, L-phenylalanine, L-tyrosine, L-glutamate, and L-proline, play an important role in the difference in drought resistance between \'ZC9-3\' and \'Jizhen-2\'. In addition, 13 genes encoding O-acetylserine-(thiol)-lyase, S-adenosylmethionine synthetase, ketol-acid isomeroreductase, dihydroxyacid dehydratase, isopropylmalate isomerase, branched-chain aminotransferase, pyruvate kinase, 3-dehydroquinate dehydratase/shikimate 5-dehydrogenase, N-acetylglutamate-5-P-reductase, and pyrroline-5-carboxylate synthetase positively regulate the response of \'ZC9-3\' to drought stress.
CONCLUSIONS: This study enhances our understanding of the response of apple rootstocks to drought stress at the physiological, metabolic, and transcriptional levels and provides key insights that will aid the cultivation of drought-resistant apple rootstock cultivars. Especially, it identifies key metabolites and genes underlying the drought resistance of apple rootstocks.