Protein kinases in plant responses to drought, salt, and cold stress

Abstract

Protein kinases are major players in various signal transduction pathways. Understanding the molecular mechanisms behind plant responses to biotic and abiotic stresses has become critical for developing and breeding climate-resilient crops. In this review, we summarize recent progress on understanding plant drought, salt, and cold stress responses, with a focus on signal perception and transduction by different protein kinases, especially sucrose non-fermenting1 (SNF1)-related protein kinases (SnRKs), mitogen-activated protein kinase (MAPK) cascades, calcium-dependent protein kinases (CDPKs/CPKs), and receptor-like kinases (RLKs). We also discuss future challenges in these research fields.

Regulation of Plant Responses to Salt Stress

“…They also act as signaling molecules to induce ABA accumulation, affect related gene expression, and regulate plant growth under salt stress [ 48 ]. Protein kinases act as a convergence point of rapid osmoregulation and salt stress signaling [ 49 ]. In response to osmotic treatments, the mRNA levels of histidine kinases, MAPKKK, MAPKK, and MAPK are increased, leading to increased osmolyte synthesis and accumulation [ 50 , 51 ].…”

Cryogenian glacial habitats as a plant terrestrialisation cradle – the origin of the anydrophytes and Zygnematophyceae split

“…Many studies of Embryophyta as well as algal Streptophyta indicate a tight coupling between the adaptation to high irradiation, as well as cold stress and drought stress (e.g. De Vries et al 2017;Chen et al, 2021a). These three stresses result in the major energetic cellular imbalance and ROS production, and are best studied in model plants, especially Arabidopsis (e.g.…”

“…Intimate connection between drought and cold/freeze stresses is well documented in CBF/DREB transcription factors (C-repeat binding factor/ dehydration responsive element binding factor) in both stresses, and it is clear their evolution was boosted in Streptohytes and especially in lineage going to Embryophytes (Jiao et al, 2020;Rensing 2020 ). Activation of DREB TFs is positively regulated by ICE1 (Inducer of CBF expression 1) transcriptional regulator which is a direct target of OST1 kinase (Zhu 2016;Chen et al, 2021a). SNF1-related protein kinases2 (SnRK2) protein kinase family member Open Stomata1 (OST1), which was originally identified for its role in stomatal closure (Mustilli et al, 2002), is the central regulator of cold-signalling pathway -and not only in the Arabidopsis via activation of DREB TFs (Lamers et al, 2020;Chen et al 2021a).…”

“…Activation of DREB TFs is positively regulated by ICE1 (Inducer of CBF expression 1) transcriptional regulator which is a direct target of OST1 kinase (Zhu 2016;Chen et al, 2021a). SNF1-related protein kinases2 (SnRK2) protein kinase family member Open Stomata1 (OST1), which was originally identified for its role in stomatal closure (Mustilli et al, 2002), is the central regulator of cold-signalling pathway -and not only in the Arabidopsis via activation of DREB TFs (Lamers et al, 2020;Chen et al 2021a). Already the CKIN2 (A) family of chlorophytic Chlamydomonas reinhardtii is closely related to the land plant SnRK2, and contains a conserved SnRK2 box and ABA box (but without relation to ABA-dependent signalling which evolved later in Streptohytes -Embryophytes) after the kinase domains (Komatsu et al, 2020).…”

Designed breeding for adaptation of crops to environmental abiotic stresses

“…。在干旱期间，植物通过增加根系的吸水能力、关闭气孔 减少水分的流失、调节组织内的渗透势等来维持生理水分的平衡 [4] 。在细胞水平上，干 旱信号促进了脯氨酸和海藻糖等应激保护代谢物的产生，触发抗氧化系统以维持氧化还 A c c e p t e d https://engine.scichina.com/doi/10.1360/SSV-2021-0162 原反应的稳态，防止急性细胞损伤和维持膜的完整性。除此之外，也会触发特定的信号 响应，比如脱落酸(abscisic acid, ABA) 、油菜素内酯(brassinosteroids, BR) 、乙烯 (ethylene)等植物激素途径 [5] 。比如干旱胁迫促进脱落酸的积累，通过激酶活性调节作 用靶向包括离子通道和转录因子在内的底物蛋白，将信号进行级联传递来应答干旱胁迫 [6] 。 植物能够通过调控根部形态和蒸腾效率提高抗旱性，比如水稻中的编码生长素应答 DRO1 [7] 、拟南芥和水稻的类受体蛋白激酶 ERECTA(ER) [8] ，以及水稻、小麦、玉米 中具有抗旱调控作用的转录因子家族，包括 DREB、ERF、WRKY、ZFP、MYB 基因家 族成员等。 目前陆续从不同作物中克隆到大量关于提高植物抗旱性的基因， 如 OsNAC5、 OsNAC9、OsNAC10 在水稻中过量表达显著提高抗旱能力，有助于增加水稻在干旱胁迫 下的总产量 [4] ；此外 OsbZIP 家族成员也发挥着关键作用，如以 OsbZIP46 为核心的干旱 应答精细调控网络，同样能够赋予水稻更强的耐旱性 [9] ；以及 ERF 家族的成员 OsERF4a 和 DREB 的成员 OsDREB2B，超表达株系均能够增强水稻在干旱胁迫环境中的耐受能 力 [10] ，这些调控因子的深度挖掘为水稻抗旱遗传改良提供新思路。小麦是重要的粮食资 源，超量表达 TaERF1、TaERF3 均能提高小麦对干旱胁迫的耐受性；TaZFP34 通过改变 根的形态建成，增强根伸长的能力，提高小麦抗旱性 [11] 。研究发现小麦中类受体蛋白激 酶 TaER1 和 TaER2 正调控叶片大小，进而会增强水分利用效率、提高生物量积累和单 株产量 [11] 。除此之外，研究发现三种胞质甘油醛-3-磷酸脱氢酶(TaGAPC2/5/6)通过活 性氧清除和气孔运动，正向调控小麦对干旱胁迫的响应 [12] 。水分是维持植物生长发育所 必需的，玉米在开花过程需要充足的水分以确保正常的受精和结实，干旱胁迫会导致玉 米单产持续下降。研究表明 NAC 基因 ZmNAC111 启动子中的转座子插入影响玉米对干 旱敏感性 [13] 。此外，玉米中 NAC 转录因子 NUT1 参与调控次级细胞壁的生物合成和分 解，控制木质部细胞壁厚度和强度，从而影响玉米的干旱和高温响应 [14] [22][23][24][25][26][27][28][29][30][31][32] 。最近的一项研究发现，SOS2 同家族蛋白 CIPK8 的功能与 SOS2 的功能类似，介 导拟南芥的盐稳态 [33] 。 除了 SOS3/SCaBP8 外， GRIK (Geminivirus Rep Interaction Kinase) 1 和 GRIK2 蛋白也可以磷酸化并激活 SOS2 的活性，以提高植物的耐盐性 [34] 。PA 激活 的 MPK6 可以磷酸化和激活 SOS1 [35] 。盐胁迫缓解后，BIN2 磷酸化并抑制 SOS2，从而 平衡胁迫响应和植物生长 [36] 。正常条件下，蛋白激酶 PKS5 磷酸化 SOS2，GI 及 14-3-3 [37][38][39][40] [45] 。参与表观修饰作用的 AGO 蛋白也参与调控水稻耐盐性。近 期研究发现，过表达水稻 AGO2 可增加谷粒大小和耐盐性，通过直接调控嘌呤转运活性 的通透酶 BG3 启动子区 H3K4me3 和 H3K27me3 修饰水平促进其表达， 控制细胞分裂素 的分布模式，进而影响水稻响应逆境和谷粒的发育…”