School of Agricultural Engineering and Food Science, Shandong University of Technology, Zibo, 255049 Shandong, P. R. China.
J Agric Food Chem. 2020 May 20;68(20):5529-5538. doi: 10.1021/acs.jafc.9b08069. Epub 2020 May 6.
Methyl jasmonate (MeJA), a natural phytohormone, played a critical role not only in plant growth but also in plant defense response to biotic and abiotic stresses. MYC2, a basic helix-loop-helix transcription factor, is a master regulator in MeJA signaling pathway. In the present work, mutants were generated by the clustered regularly interspaced short palindromic repeats and associated Cas9 protein (CRISPR/Cas9) system to investigate the role of in tomato plant growth and fruit disease resistance induced by exogenous MeJA. The results showed that mutants possessed a higher number of flowers and a lower fruit setting rate in comparison with wild-type plants. In addition, the fruit shape of s mutant was prolate, while the control fruits were oblate. Knockout of significantly decreased the activities of disease defensive and antioxidant enzymes, as well as the expression levels of pathogen-related (PR) genes ( and ) and the key genes related to jasmonic acid (JA) biosynthesis and signaling pathway including (), (), , and (), and consequently aggravated the disease symptoms. By contrast, the disease symptoms were largely reduced in MeJA-treated fruit that possessed higher activities of these enzymes and expression levels of genes. However, the induction effects of MeJA on fruit disease resistance and these enzymes' activities and genes' expressions were significantly attenuated by knockout of . Therefore, the results indicated that played positive regulatory roles not only in the growth of tomato plants but also in MeJA-induced disease resistance and the antioxidant process in tomato fruits.
茉莉酸甲酯（MeJA）作为一种天然植物激素，不仅在植物生长中起着关键作用，而且在植物对生物和非生物胁迫的防御反应中也起着关键作用。MYC2 是一种基本的螺旋-环-螺旋转录因子，是 MeJA 信号通路中的主要调节因子。在本工作中，通过成簇规律间隔短回文重复序列和相关 Cas9 蛋白（CRISPR/Cas9）系统生成 突变体，以研究 在外源 MeJA 诱导的番茄植物生长和果实抗病性中的作用。结果表明，与野生型植物相比，突变体具有更多的花和更低的结实率。此外，s 突变体的果实形状为长圆形，而对照果实为扁圆形。 基因的敲除显著降低了防御和抗氧化酶的活性，以及与抗病性相关的基因（和）和与茉莉酸（JA）生物合成和信号通路相关的关键基因（包括 ()、()、()、()和())的表达水平，从而加重了病害症状。相比之下，在具有更高这些酶活性和基因表达水平的 MeJA 处理的果实中，病害症状在很大程度上得到了缓解。然而，MeJA 对果实抗病性和这些酶活性及基因表达的诱导作用，均因 基因的敲除而显著减弱。因此，结果表明 基因不仅在番茄植株的生长中起正向调控作用，而且在 MeJA 诱导的抗病性和番茄果实的抗氧化过程中也起正向调控作用。
