Keshishian Erika A, Cliver Brannan R, McLaughlin William F, Hallmark H Tucker, Plačková Lenka, Goertzen Leslie R, Novák Ondřej, Cobine Paul A, Leisner Courtney P, Rashotte Aaron M
Department of Biological Sciences, Auburn University, Auburn, AL, 36849, USA.
Laboratory of Growth Regulators, Faculty of Science, Palacký University & Institute of Experimental Botany, The Czech Academy of Sciences, CZ-783 71, Olomouc, Czech Republic.
Plant J. 2022 May;110(4):1097-1110. doi: 10.1111/tpj.15726. Epub 2022 Mar 28.
Cytokinin has strong connections to development and a growing role in the abiotic stress response. Here we show that CYTOKININ RESPONSE FACTOR 2 (CRF2) is additionally involved in the salt (NaCl) stress response. CRF2 promoter-GUS expression indicates CRF2 involvement in the response to salt stress as well as the previously known cytokinin response. Interestingly, CRF2 mutant seedlings are quite similar to the wild type (WT) under non-stressed conditions yet have many distinct changes in response to salt stress. Cytokinin levels measured by liquid chromatography-tandem mass spectrometry (LC-MS/MS) that increased in the WT after salt stress are decreased in crf2, potentially from CRF2 regulation of cytokinin biosynthesis genes. Ion content measured by inductively coupled plasma optical emission spectrometry (ICP-OES) was increased in the WT for Na, K, Mn, Ca and Mg after salt stress, whereas the corresponding Ca and Mg increases are lacking in crf2. Many genes examined by RNA-seq analysis were altered transcriptionally by salt stress in both the WT and crf2, yet interestingly approximately one-third of salt-modified crf2 transcripts (2655) showed unique regulation. Different transcript profiles for salt stress in crf2 compared with the WT background was further supported through an examination of co-expressed genes by weighted gene correlation network analysis (WGCMA) and principal component analysis (PCA). Additionally, Gene Ontology (GO) enrichment terms found from salt-treated transcripts revealed most photosynthesis-related terms as only being affected in crf2, leading to an examination of chlorophyll levels and the efficiency of photosystem II (via the ratio of variable fluorescence to maximum fluorescence, F /F ) as well as physiology after salt treatment. Salt stress-treated crf2 plants had both reduced chlorophyll levels and lower F /F values compared with the WT, suggesting that CRF2 plays a role in the modulation of salt stress responses linked to photosynthesis.
细胞分裂素与植物发育密切相关，并且在非生物胁迫响应中发挥着越来越重要的作用。在此，我们表明细胞分裂素响应因子2（CRF2）还参与了盐（NaCl）胁迫响应。CRF2启动子-GUS表达表明CRF2参与了对盐胁迫的响应以及先前已知的细胞分裂素响应。有趣的是，CRF2突变体幼苗在非胁迫条件下与野生型（WT）非常相似，但在盐胁迫下有许多明显的变化。通过液相色谱-串联质谱（LC-MS/MS）测量的细胞分裂素水平在盐胁迫后在WT中升高，而在crf2中降低，这可能是由于CRF2对细胞分裂素生物合成基因的调控。通过电感耦合等离子体发射光谱法（ICP-OES）测量的离子含量在盐胁迫后WT中的Na、K、Mn、Ca和Mg增加，而crf2中相应的Ca和Mg增加缺乏。通过RNA-seq分析检测的许多基因在WT和crf2中都因盐胁迫而发生转录改变，但有趣的是，约三分之一的盐修饰crf2转录本（2655个）表现出独特的调控。通过加权基因共表达网络分析（WGCMA）和主成分分析（PCA）对共表达基因的检查进一步支持了crf2与WT背景下盐胁迫的不同转录谱。此外，从盐处理转录本中发现的基因本体（GO）富集术语显示，大多数与光合作用相关的术语仅在crf2中受到影响，从而导致对叶绿素水平和光系统II效率（通过可变荧光与最大荧光的比率，Fv/Fm）以及盐处理后的生理学进行检查。与WT相比，盐胁迫处理的crf2植物的叶绿素水平降低且Fv/Fm值较低，这表明CRF2在与光合作用相关的盐胁迫响应调节中发挥作用。
