Cai Zilin, Guo Hao, Shen Shijing, Yu Qilu, Wang Jinbin, Zhu Engao, Zhang Pinghua, Song Lili, Zhang Yanjun, Zhang Kewei
Zhejiang Provincial Key Laboratory of Biotechnology on Specialty Economic Plants, College of Chemistry and Life Sciences, Institute of Plant Stress Adaptation and Genetic Enhancement, Zhejiang Normal University, Jinhua, 321004, Zhejiang, People's Republic of China.
State Key Laboratory of Subtropical Silviculture, Sino-Australia Plant Cell Wall Research Centre, School of Forestry and Biotechnology, Zhejiang A&F University, Lin'an, Hangzhou, 311300, Zhejiang, People's Republic of China.
Plant Methods. 2022 Jun 28;18(1):89. doi: 10.1186/s13007-022-00922-x.
Salicylic acid (SA) is one of the plant hormones, which plays crucial roles in signaling transduction in plant growth, disease resistance, and leaf senescence. Arabidopsis (Arabidopsis thaliana) SA 3-hydroxylase (S3H) and 5-hydroxylase (S5H) are key enzymes which maintain SA homeostasis by catalyzing SA to 2,3-dihydroxybenzoic acid (DHBA) and 2,5-DHBA, respectively.
SA deficient transgenic Arabidopsis lines were generated by introducing two binary vectors S5Hpro::EGFP-S3H and 35Spro::EGFP-S3H respectively, in which the expression of S3H is under the control of the S5H promoter or CaMV 35S promoter. Compared with the constitutive expression of S3H gene under the control of 35S promoter, the S3H gene under the native S5H promoter is activated by endogenous SA and results in a dynamic control of SA catabolism in a feedback mode. The SA accumulation, growth, leaf senescence, and pathogen resistance of the S5Hpro::GFP-S3H transgenic plants were investigated in parallel with NahG transgenic plants. The SA levels in the S5Hpro::EGFP-S3H transgenic plants were similar to or slightly lower than those of NahG transgenic Arabidopsis and resulted in SA deficient phenotypes. The low-SA trait of the S5Hpro::EGFP-S3H transgenic lines was inherited stably in the later generations.
Compared with NahG transgenic lines producing by-product catechol, S5Hpro::EGFP-S3H transgenic lines reduce SA levels by converting SA to a native product 2,3-DHBA for catabolism. Together, we provide new SA-deficient germplasms for the investigations of SA signaling in plant development, leaf senescence, and disease resistance.
水杨酸（SA）是一种植物激素，在植物生长、抗病性和叶片衰老的信号转导中起关键作用。拟南芥（Arabidopsis thaliana）SA 3-羟化酶（S3H）和5-羟化酶（S5H）是关键酶，分别通过将SA催化为2,3-二羟基苯甲酸（DHBA）和2,5-DHBA来维持SA稳态。
通过分别导入两个双元载体S5Hpro::EGFP-S3H和35Spro::EGFP-S3H来产生SA缺陷型转基因拟南芥株系，其中S3H的表达受S5H启动子或CaMV 35S启动子的控制。与35S启动子控制下S3H基因的组成型表达相比，天然S5H启动子控制下的S3H基因被内源性SA激活，并以反馈模式对SA分解代谢进行动态控制。对S5Hpro::GFP-S3H转基因植物的SA积累、生长、叶片衰老和抗病性与NahG转基因植物进行了平行研究。S5Hpro::EGFP-S3H转基因植物中的SA水平与NahG转基因拟南芥相似或略低，并导致SA缺陷表型。S5Hpro::EGFP-S3H转基因株系的低SA性状在后代中稳定遗传。
与产生副产物儿茶酚的NahG转基因株系相比，S5Hpro::EGFP-S3H转基因株系通过将SA转化为天然产物2,3-DHBA进行分解代谢来降低SA水平。总之，我们为研究SA在植物发育、叶片衰老和抗病性中的信号传导提供了新的SA缺陷种质。
