Kolachevskaya Oksana O, Sergeeva Lidiya I, Floková Kristyna, Getman Irina A, Lomin Sergey N, Alekseeva Valeriya V, Rukavtsova Elena B, Buryanov Yaroslav I, Romanov Georgy A
Laboratory of Signaling Systems, Institute of Plant Physiology RAS, Moscow, 127276, Russia.
Laboratory of Plant Physiology, Wageningen University, 6708 PB, Wageningen, The Netherlands.
Plant Cell Rep. 2017 Mar;36(3):419-435. doi: 10.1007/s00299-016-2091-y. Epub 2016 Dec 20.
Ectopic auxin overproduction in transgenic potato leads to enhanced productivity accompanied with concerted and occasional changes in hormonal status, and causing altered response of transformants to exogenous auxin or cytokinin. Previously, we generated potato transformants expressing Agrobacterium-derived auxin synthesis gene tms1 driven by tuber-specific patatin gene promoter (B33-promoter). Here, we studied the endogenous hormonal status and the response to exogenous phytohormones in tms1 transformants cultured in vitro. Adding indole-3-acetic acid (IAA) or kinetin to culture medium affected differently tuberization of tms1-transformed and control plants, depending also on sucrose content in the medium. Exogenous phytohormones ceased to stimulate the tuber initiation in transformants at high (5-8%) sucrose concentration, while in control plants the stimulation was observed in all experimental settings. Furthermore, exogenous auxin partly inhibited the tuber initiation, and exogenous cytokinin reduced the average tuber weight in most transformants at high sucrose content. The elevated auxin level in tubers of the transformants was accompanied with a decrease in content of cytokinin bases and their ribosides in tubers and most shoots. No concerted changes in contents of abscisic, jasmonic, salicylic acids and gibberellins in tubers were detected. The data on hormonal status indicated that the enhanced productivity of tms1 transformants was due to auxin and not mediated by other phytohormones. In addition, exogenous cytokinin was shown to upregulate the expression of genes encoding orthologs of auxin receptors. Overall, the results showed that tms1 expression and local increase in IAA level in transformants affect both the balance of endogenous cytokinins and the dynamics of tuberization in response to exogenous hormones (auxin, cytokinin), the latter reaction depending also on the carbohydrate supply. We introduce a basic model for the hormonal network controlling tuberization.
转基因马铃薯中异位生长素过量产生导致生产力提高，同时激素状态发生协同和偶尔的变化，并使转化体对外源生长素或细胞分裂素的反应发生改变。此前，我们构建了由块茎特异性Patatin基因启动子（B33启动子）驱动的表达农杆菌来源的生长素合成基因tms1的马铃薯转化体。在此，我们研究了体外培养的tms1转化体的内源激素状态以及对外源植物激素的反应。向培养基中添加吲哚-3-乙酸（IAA）或激动素对tms1转化植株和对照植株块茎形成的影响不同，这也取决于培养基中的蔗糖含量。在高蔗糖浓度（5-8%）下，外源植物激素不再刺激转化体的块茎起始，而在对照植株中，在所有实验条件下均观察到刺激作用。此外，外源生长素部分抑制块茎起始，外源细胞分裂素在高蔗糖含量下降低了大多数转化体的平均块茎重量。转化体块茎中生长素水平升高伴随着块茎和大多数茎中细胞分裂素碱基及其核糖苷含量的降低。未检测到块茎中脱落酸、茉莉酸、水杨酸和赤霉素含量的协同变化。激素状态数据表明，tms1转化体生产力的提高是由于生长素，而非由其他植物激素介导。此外，外源细胞分裂素被证明可上调编码生长素受体直系同源物的基因表达。总体而言，结果表明tms1的表达以及转化体中IAA水平的局部升高影响内源细胞分裂素的平衡以及对外源激素（生长素、细胞分裂素）的块茎形成动态，后一种反应也取决于碳水化合物供应。我们引入了一个控制块茎形成的激素网络基本模型。
