Present address: Institute for Experimental Medicine, Christian-Albrechts University Kiel, Niemannsweg 11, 24105, Kiel, Germany.
Department Biochemistry of Plant Interactions, Leibniz Institute of Plant Biochemistry, Weinberg 3, 06122, Halle (Saale), Germany.
BMC Biol. 2023 Nov 9;21(1):249. doi: 10.1186/s12915-023-01739-3.
Shifts in dynamic equilibria of the abundance of cellular molecules in plant-pathogen interactions need further exploration. We induced PTI in optimally growing Arabidopsis thaliana seedlings for 16 h, returning them to growth conditions for another 16 h.
Turn-over and abundance of 99 flg22 responding proteins were measured chronologically using a stable heavy nitrogen isotope partial labeling strategy and targeted liquid chromatography coupled to mass spectrometry (PRM LC-MS). These experiments were complemented by measurements of mRNA and phytohormone levels.
Changes in synthesis and degradation rate constants (K and K) regulated tryptophane and glucosinolate, IAA transport, and photosynthesis-associated protein (PAP) homeostasis in growth/PTI transitions independently of mRNA levels. K values increased after elicitation while protein and mRNA levels became uncorrelated. mRNA returned to pre-elicitation levels, yet protein abundance remained at PTI levels even 16 h after media exchange, indicating protein levels were robust and unresponsive to transition back to growth. The abundance of 23 PAPs including FERREDOXIN-NADP( +)-OXIDOREDUCTASE (FNR1) decreased 16 h after PAMP exposure, their depletion was nearly abolished in the myc234 mutant. FNR1 K increased as mRNA levels decreased early in PTI, its K decreased in prolonged PTI. FNR1 K was lower in myc234, mRNA levels decreased as in wild type.
Protein K and K values change in response to flg22 exposure and constitute an additional layer of protein abundance regulation in growth defense transitions next to changes in mRNA levels. Our results suggest photosystem remodeling in PTI to direct electron flow away from the photosynthetic carbon reaction towards ROS production as an active defense mechanism controlled post-transcriptionally and by MYC2 and homologs. Target proteins accumulated later and PAP and auxin/IAA depletion was repressed in myc234 indicating a positive effect of the transcription factors in the establishment of PTI.
在植物-病原体相互作用中，细胞分子丰度的动态平衡变化需要进一步探索。我们用稳定的重氮同位素部分标记策略和靶向液相色谱-质谱联用（PRM LC-MS）方法，在最佳生长的拟南芥幼苗中诱导 PTI 16 小时，然后让它们回到生长条件下再培养 16 小时。
使用稳定的重氮同位素部分标记策略和靶向液相色谱-质谱联用（PRM LC-MS）方法，按时间顺序测量 99 种 flg22 应答蛋白的周转率和丰度。这些实验还补充了 mRNA 和植物激素水平的测量。
在生长/PTI 转变过程中，K 和 K 值的变化（K 和 K 值分别代表合成和降解的速率常数）独立于 mRNA 水平，调节色氨酸和硫代葡萄糖苷、IAA 转运和与光合作用相关的蛋白（PAP）的动态平衡。在激发后 K 值增加，而蛋白质和 mRNA 水平变得不相关。mRNA 恢复到激发前的水平，但即使在介质交换 16 小时后，蛋白质丰度仍保持在 PTI 水平，表明蛋白质水平稳健且对向生长的转变无反应。在 PAMP 暴露 16 小时后，包括 FERREDOXIN-NADP(+) - OXIDOREDUCTASE (FNR1) 在内的 23 种 PAP 的丰度下降，其在 myc234 突变体中的耗竭几乎被消除。在 PTI 早期，FNR1 的 K 值随着 mRNA 水平的降低而增加，在持续的 PTI 中，其 K 值降低。在 myc234 中，FNR1 的 K 值较低，mRNA 水平下降如在野生型中一样。
蛋白质 K 和 K 值随 flg22 的暴露而变化，构成了生长防御转变中除了 mRNA 水平变化之外的另一个蛋白质丰度调节层。我们的结果表明，在 PTI 中，光系统的重塑将电子流从光合碳反应中转移出来，朝向 ROS 产生，作为一种受转录后调控和 MYC2 及其同源物控制的主动防御机制。靶蛋白积累较晚，PAP 和 auxin/IAA 耗竭在 myc234 中受到抑制，表明转录因子在 PTI 的建立中具有积极作用。
