Overexpressing broccoli tryptophan biosynthetic genes BoTSB1 and BoTSB2 promotes biosynthesis of IAA and indole glucosinolates
Overexpressing broccoli tryptophan biosynthetic genes BoTSB1 and BoTSB2 promotes biosynthesis of IAA and indole glucosinolates
复制标题
过度表达西兰花色氨酸生物合成基因 BoTSB1 和 BoTSB2 可促进 IAA 和吲哚芥子油苷的生物合成。
DOI：
10.1111/ppl.12933
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发表时间：
2020-01-01
影响因子：
6.4
通讯作者：
Li, Jing
中科院分区：
文献类型：
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作者：
Li, Rui;Jiang, Jia;Li, Jing
色氨酸是一种人类不能产生的氨基酸，必须主要从植物中获得。在拟南芥中，色氨酸合成酶β亚单位(TSB)基因被发现催化色氨酸的生物合成。在这里，我们报道了甘蓝(青花菜)中两个TSB基因的分离和鉴定，命名为BoTSB1和BoTSB2。在拟南芥中过表达BoTSB1或BoTSB2导致较高的色氨酸含量，并导致莲座叶中吲哚-3-乙酸(IAA)和吲哚硫代葡萄糖苷的积累。因此，转基因植株表现出一系列高生长素表型，包括长的下胚轴、大的植株和大量的侧根。用实时荧光定量聚合酶链式反应检测了BoTSB1和BoTSB2基因在青花菜中的空间表达，并在拟南芥中表达了受这两个基因启动子控制的β-葡萄糖醛酸酶报告基因(GUS)。BoTSB1在新梢和花序的维管组织中大量表达。与BoTSB1相比，BoTSB2在地上部的表达水平很低，而在根中的表达水平较高。我们进一步研究了这两个基因对几种激素和胁迫处理的表达反应。这两个基因都被茉莉酸甲酯(MeJA)、水杨酸(SA)、赤霉酸(GA)、Flg22(细菌鞭毛蛋白产生的保守的22个氨基酸)、伤害、低温和氯化钠诱导，并被IAA抑制。我们的研究加深了对花椰菜和拟南芥中色氨酸生物合成及其调控的理解。此外，我们提供的证据表明，TSB基因有可能成为培育高生物量和高营养植物的良好工具。
Tryptophan is one of the amino acids that cannot be produced in humans and has to be acquired primarily from plants. In Arabidopsis thaliana (Arabidopsis), the tryptophan synthase beta subunit (TSB) genes have been found to catalyze the biosynthesis of tryptophan. Here, we report the isolation and characterization of two TSB genes from Brassica oleracea (broccoli), designated BoTSB1 and BoTSB2. Overexpressing BoTSB1 or BoTSB2 in Arabidopsis resulted in higher tryptophan content and the accumulation of indole-3-acetic acid (IAA) and indole glucosinolates in rosette leaves. Therefore, the transgenic plants showed a series of high auxin phenotypes, including long hypocotyls, large plants and a high number of lateral roots. The spatial expression of BoTSB1 and BoTSB2 was detected by quantitative real-time PCR in broccoli and by expressing the β-glucuronidase reporter gene (GUS) controlled by the promoters of the two genes in Arabidopsis. BoTSB1 was abundantly expressed in vascular tissue of shoots and inflorescences. Compared to BoTSB1, BoTSB2 was expressed at a very low level in shoots but at a higher level in roots. We further investigated the expression response of the two genes to several hormone and stress treatments. Both genes were induced by methyl jasmonate (MeJA), salicylic acid (SA), gibberellic acid (GA), Flg22 (a conserved 22-amino acid peptide derived from bacterial flagellin), wounding, low temperature and NaCl and were repressed by IAA. Our study enhances the understanding of tryptophan biosynthesis and its regulation in broccoli and Arabidopsis. In addition, we provide evidence that TSB genes can potentially be a good tool to breed plants with high biomass and high nutrition.