Ibragimova N N, Mokshina N E
Kazan Institute of Biochemistry and Biophysics of Kazan Scientific Center of the Russian Academy of Sciences, Kazan, Russia.
Vavilovskii Zhurnal Genet Selektsii. 2024 Feb;28(1):33-43. doi: 10.18699/VJGB-24-05.
Gravitropism is an adaptive reaction of plants associated with the ability of various plant organs to be located and to grow in a certain direction relative to the gravity vector, while usually the asymmetric distribution of the phytohormone auxin is a necessary condition for the gravitropical bending of plant organs. Earlier, we described significant morphological changes in phloem fibers with a thickened cell wall located on different sides of the stem in the area of the gravitropic curvature. The present study is the first work devoted to the identification of genes encoding auxin transporters in cells at different stages of development and during gravity response. In this study, the flax genes encoding the AUX1/LAX, PIN-FORMED, PIN-LIKES, and ABCB auxin transporters were identified. A comparative analysis of the expression of these genes in flax phloem fibers at different stages of development revealed increased expression of some of these genes at the stage of intrusive growth (LusLAX2 (A, B), LuxPIN1-D, LusPILS7 (C, D)), at the early stage of tertiary cell wall formation (LusAUX1 (A, D), LusABCB1 (A, B), LusABCB15-A, LusPIN1 (A, B), LusPIN4-A, and LusPIN5-A), and at the late stage of tertiary cell wall development (LusLAX3 (A, B)). It was shown that in the course of gravitropism, the expression of many genes, including those responsible for the influx of auxin in cells (LusAUX1-D), in the studied families increased. Differential expression of auxin transporter genes was revealed during gravity response in fibers located on different sides of the stem (upper (PUL) and lower (OPP)). The difference was observed due to the expression of genes, the products of which are responsible for auxin intracellular transport (LusPILS3, LusPILS7-A) and its efflux (LusABCB15-B, LusABCB19-B). It was noted that the increased expression of PIN genes and ABCB genes was more typical of fibers on the opposite side. The results obtained allow us to make an assumption about the presence of differential auxin content in the fibers of different sides of gravistimulated flax plants, which may be determined by an uneven outflow of auxin. This study gives an idea of auxin carriers in flax and lays the foundation for further studies of their functions in the development of phloem fiber and in gravity response.
向重力性是植物的一种适应性反应，与各种植物器官相对于重力矢量定位并沿特定方向生长的能力相关，而植物激素生长素的不对称分布通常是植物器官向重力性弯曲的必要条件。此前，我们描述了在向重力性弯曲区域茎的不同侧面上，具有增厚细胞壁的韧皮部纤维发生的显著形态变化。本研究是首次致力于鉴定在不同发育阶段以及重力响应过程中细胞内生长素转运蛋白编码基因的工作。在本研究中，鉴定出了亚麻中编码AUX1/LAX、PIN-FORMED、PIN-LIKES和ABCB生长素转运蛋白的基因。对这些基因在亚麻韧皮部纤维不同发育阶段的表达进行比较分析发现，其中一些基因在侵入性生长阶段（LusLAX2 (A, B)、LuxPIN1-D、LusPILS7 (C, D)）、三生细胞壁形成早期（LusAUX1 (A, D)、LusABCB1 (A, B)、LusABCB15-A、LusPIN1 (A, B)、LusPIN4-A和LusPIN5-A）以及三生细胞壁发育后期（LusLAX3 (A, B)）表达增加。结果表明，在向重力性过程中，包括负责生长素流入细胞的基因（LusAUX1-D）在内的许多研究家族中的基因表达增加。在茎不同侧面（上部（PUL）和下部（OPP））的纤维重力响应过程中，揭示了生长素转运蛋白基因的差异表达。观察到这种差异是由于基因表达所致，其产物负责生长素的细胞内运输（LusPILS3、LusPILS7-A）及其外排（LusABCB15-B、LusABCB19-B）。值得注意的是，PIN基因和ABCB基因表达增加在相对一侧的纤维中更为典型。所获得的结果使我们能够假设，在重力刺激的亚麻植物不同侧面的纤维中存在生长素含量差异，这可能由生长素的不均匀流出所决定。本研究揭示了亚麻中的生长素载体情况，并为进一步研究其在韧皮部纤维发育和重力响应中的功能奠定了基础。
