Gorshkova Tatyana, Gorshkov Oleg, Mokshina Natalia
Kazan Institute of Biochemistry and Biophysics, FRC Kazan Scientific Center of RAS, Lobachevsky Str., 2/31, 420111, Kazan, Russia.
Plant Mol Biol. 2025 Apr 26;115(3):61. doi: 10.1007/s11103-025-01588-4.
Plants have developed two major strategies to adjust their position in response to gravity: differential cell growth on opposing sides of elongating regions and complex processes in non-elongating stem parts, such as the development of reaction wood. Gravistimulation of flax plants induces gravitropic curvature in non-elongating stem parts, largely associated with modifications in phloem and xylem fibers. To gain insight into the key "triggers" and "forward players" that induce negative gravitropic reactions, transcriptome profiling of phloem fibers and xylem tissues from the pulling and opposite stem sides was conducted 1 and 8 h after gravistimulation. The first observed reaction was the activation of processes associated with RNA synthesis and protein folding in both tissues and stem sides, followed by the activation of kinases and transferases. Transcriptomic data revealed rapid and substantial shifts in chloroplast metabolism across all analyzed tissues, including the temporal activation of the branched-chain amino acid pathway, adjustments to light-harvesting complexes, and jasmonic acid biosynthesis. Notably, auxin transporter genes were activated only in the xylem, while other auxin-related genes showed minimal upregulation 1 h after stem inclination in any analyzed sample. Asymmetric changes between stem sides included the sharp activation of ethylene-related genes in the phloem fibers of the opposite stem side, as well as tertiary cell wall deposition in both the phloem and xylem fibers of the pulling stem side during the later stages of the graviresponse. These results provide valuable insights into the mechanisms underlying plant response to gravity.
在伸长区域相对两侧的细胞差异生长,以及在非伸长茎部的复杂过程,如反应木的形成。对亚麻植株进行重力刺激会在非伸长茎部诱导向重力性弯曲,这在很大程度上与韧皮部和木质部纤维的变化有关。为了深入了解诱导负向重力反应的关键“触发因素”和“推进因素”,在重力刺激后1小时和8小时,对茎部受拉一侧和相对一侧的韧皮部纤维和木质部组织进行了转录组分析。首先观察到的反应是,在两个组织和茎部两侧,与RNA合成和蛋白质折叠相关的过程被激活,随后激酶和转移酶被激活。转录组数据显示,在所有分析的组织中,叶绿体代谢都发生了快速而显著的变化,包括支链氨基酸途径的瞬时激活、对光捕获复合体的调整以及茉莉酸的生物合成。值得注意的是,生长素转运蛋白基因仅在木质部中被激活,而在任何分析样本中,其他生长素相关基因在茎倾斜1小时后上调幅度极小。茎两侧的不对称变化包括,相对茎侧韧皮部纤维中乙烯相关基因的急剧激活,以及在重力反应后期,受拉茎侧韧皮部和木质部纤维中三生细胞壁的沉积。这些结果为植物对重力反应的潜在机制提供了有价值的见解。