Characteristics of TaFTSH6 Gene and Expression Analysis under Dry and Heat Stress in Wheat

Li Yuan ^1,2　Jiang Huijun ¹　Liu Jun ²　Liu Yunguo ¹　Hu Xiaojun ^1*

1 College of Life Science, Linyi University, Linyi, 276000; 2 College of Life Science and Technology, University, Xinjiang Urumqi City, 830046

* Corresponding author, huxiaojun19812003@126.com

Abstract　In order to study the characteristics and functions of wheat FTSH genes, TaFTSH6 was cloned from wheat "bobwhite". Phylogenetic tree analysis showed that the amino acid sequence was very similar to FTSH6 sequence of other species. SMART analysis showed that TaFTSH6 had a conserved N-terminal transmembrane domain, ATP binding sites and hydrophilic Zn²⁺ metalloproteinase domain. The gene was located on chr7D chromosome of wheat, named as TaFTSH6-7D. Cis-elements analysis of TaFTSH6 promoter sequence showed that there are several drought responses sites CAACTG and a heat stress response site GACnnCTCnnGAA in the promoter, as well as many cis-elements related to hormone signal transduction. Quantitative expression analysis of TaFTSH6 gene in wheat seedlings under drought and heat stress showed that both drought and heat stress could increase the expression level of TaFTSH6 gene in root and leaf tissues, which indicated that TaFTSH6 is induced by drought and heat stress. Further study on the function of TaFTSH6 gene in wheat will partly support theoretical guidance to wheat breeding for drought and heat stress tolerance.

Keywords　Wheat, TaFTSH6, Dry stress, Heat stress

FTSH (filamentation temperature-sensitive H)是一种胞质膜蛋白内肽酶，属于AAA (ATPase associated with diverse cellular activities)蛋白酶家族(Ogura and Wilkinson, 2001)。该家族具有N端跨膜结构域、ATP和Zn²⁺结合位点，以环状同型六聚体的形式与调节因子HflK或HflC低聚物形成复合物，依赖ATP降解短寿命蛋白质和错误组装的膜蛋白，从而调节生物的正常生长发育(Kihara et al., 1997; Kihara and Ito, 1998; Ito and Akiyama, 2005)。FTSH是许多生物生长必需的，该家族基因表达量降低或者基因突变都会导致枯草芽孢杆菌(Bacillus subtilis)和大肠杆菌(Escherichia coli)严重的生长缺陷，甚至致死(Deuerling et al., 1997; Jayasekera et al., 2000)。FTSH基因最初由4个不同的研究小组在大肠杆菌中筛选不同表型时分别独立发现的(Schumann, 1999)，至今已在枯草芽孢杆菌(Deuerling et al., 1995)、乳酸乳球菌(Lactococcus lactis) (Duwat et al., 1995)、拟南芥(Arabidopsis thaliana) (Lindahl et al., 1996)、烟草(Nicotiana tabacum) (Seo et al., 2000)、苜蓿(Medicago sativa) (Ivashuta et al., 2002)、野生西瓜(Citrullus lanatus) (Akashi et al., 2004)、蓝细菌(Synechocystis sp) (Kamata et al., 2005)、番茄(Solanum lycopersicum) (Sun et al., 2006a)、玉米(Zea mays) (Andjelkovic and Thompson 2006)、菠菜(Spinacia oleracea) (Yoshioka et al., 2006)、荠菜(Brassica juncea) (Knight et al., 2006)、马铃薯(Solanum tuberosum) (范敏等, 2007)、复活草(Xerophyta viscose) (Ingle et al., 2007)、水稻(Oryza sativa) (Zhang and Sun, 2009)、大豆(Glycine max) (Yin et al., 2011)、植物乳杆菌(Lactobacillus plantarum) (Bove et al., 2012)、花生(Arachis hypogaea) (郑春花等, 2016, 江苏农业科学, 44(12): 74-77)、西瓜噬酸菌(Acidovorax citrulli) (季苇芹等, 2019)等多种生物中发现和研究。

FTSH参与生物对多种逆境胁迫的响应。热胁迫或光胁迫增加蓝细菌细胞中FTSH基因的表达量(Kamata et al., 2005)，缺乏FTSH蛋白酶的植物乳杆菌突变体对热和盐浓度升高表现出显著的敏感性，而FTSH过表达则导致其耐热性和耐盐性增加(Bove et al., 2012)，西瓜噬酸菌FTSH基因缺失突变体在热、高盐等逆境胁迫条件下的生长能力均显著减弱(季苇芹等, 2019)。在植物中也发现FTSH参与抵御冷胁迫、热胁迫、干旱胁迫、盐胁迫等逆境胁迫反应，逆境胁迫能够增加FTSH基因的表达量。例如，冷胁迫导致苜蓿MsFTSH基因表达量增加(Ivashuta et al., 2002)；热胁迫导致拟南芥AtFTSH11 (Chen et al., 2006)、番茄LeFTSH6 (Sun et al., 2006b)基因表达量增加；干旱胁迫使马铃薯SoFTSH4-like基因在叶片和根系里的表达量明显增加(范敏等, 2007)；盐胁迫使9个花生FTSH基因表达量上调，其中包括一个FTSH6-like基因(郑春花等, 2016)。FTSH基因能提高植物对逆境胁迫的耐受性，拟南芥中过表达AtFTSH11有助于对热胁迫的整体耐受性(Chen et al., 2006)；FTSHi5可抑制衰老相关基因的表达，维持细胞氧化还原平衡(Wang et al., 2018b; Havé et al., 2018)。但目前未见FTSH基因在小麦中的研究报道。

小麦是世界上重要的粮食作物，在全球的不同产区，小麦整个生育期经常遭受干旱胁迫和热胁迫，产量和质量受到严重的影响，因此，提高小麦的抗旱性和抗热性对小麦的高产稳产和优质供应具有重要意义。为了研究小麦FTSH基因的特征和功能，本研究以小麦“Bobwhite”为材料，克隆了一个小麦TaFTSH家族基因TaFTSH6，并对其进行生物信息学分析、干旱胁迫和热胁迫下的表达量变化分析，以期为小麦耐旱性、耐热性提供理论基础，为小麦耐干热性育种提供新的思路。

1结果与分析

1.1 TaFTSH6基因克隆及氨基酸序列的进化树分析

以小麦叶片cDNA为模板，用TaFTSH6F和TaFTSH6R进行PCR扩增，扩增产物用1%琼脂糖凝胶电泳检测，可见大于2 000 bp的基因片段(图1)，与预期一致。将目的片段回收纯化并与pMD19-T载体连接，转化大肠杆菌(E.coil) DH5α感受态细胞，转化产物经过菌落PCR筛选阳性克隆、提取质粒并送至华大基因测序。该序列具有2 049 bp的ORF，编码683个氨基酸。用基因序列在小麦基因库URGI上进行比对，发现该基因位于chr7D染色体上，因此，命名为TaFTSH6-7D。

对不同物种的FTSH氨基酸序列进行进化树分析，TaFTSH6序列与其他物种的FTSH6相似度高，FTSH6序列在单子叶植物中和双子叶植物种也表现出明显的差异(图2)。TaFTSH6-7D与其二倍体祖先节节麦(Aegilops auschii)的同源性最高，达到99%，与TaFTSH6-7A与TaFTSH6-7B略有差异，与大麦、二穗短柄草、水稻、高粱、玉米等亲缘关系较近，与其他物种的FTSH6亲缘关系远。

1.2 TaFTSH6蛋白结构分析

对小麦TaFTSH6蛋白序列与水稻、大麦和玉米的TaFTSH6蛋白序列进行比对分析，发现FTSH6序列高度保守，具有典型的FTSH家族特点，特别是在90~670 aa之间。在164~182处表现出保守的跨膜N端结构域。在260~268、315~320和360~366处有典型的ATP结合位点，在260~268处为WalkerA保守结构域GXXGXGK (S/T)，315~320处为保守的WalkerB结构域VFIDE，在ATP结合位点后还有典型的LLRXGRX精氨酸指环结构(375~381处) (图3)。

注: HvFSTH6, OsFSTH6和ZmFSTH6分别为大麦, 水稻和玉米的FTSH6蛋白的氨基酸序列, Accession号分别为KAE8798980.1, XP_01-
5641788.1和ACG28886.1

Note: HvFSTH6, OsFSTH6 and ZmFSTH6 are amino acid sequences of FTSH6 protein of barley, rice and maize, and the 
access numbers are KAE8798980.1, and XP_015641788.1 and ACG28886.1 respectively

1.3 TaFTSH6启动子序列顺式作用元件分析

对TaFTSH6-7D基因编码区起始密码子上游2 kb左右区域内的启动子序列进行分析，结果显示，在ATG上游56 bp、339 bp、1 101 bp和1 833 bp处发现CAACTG干旱响应位点，在ATG上游234 bp处发现GACnnCTCnnGAA热激转录因子结合位点。除此之外，在TaFTSH6-7D基因启动子区域存在许多与生长发育相关顺式作用调控元件、激素信号传导途径相关的顺式作用调控元件及非生物逆境胁迫响应相关的顺式作用调控元件(表1)。

1.4 TaFTSH6-7D在干旱和热胁迫条件下的表达量增加

为了研究TaFTSH6-7D基因对干旱和热胁迫的响应情况，用RT-PCR方法分析在干旱和热环境处理下，苗期小麦叶片和根组织中TaFTSH6基因表达状况。结果显示：在干旱胁迫下，小麦叶片和根组织TaFTSH6-7D基因的表达量均呈现升高的变化趋势，特别是在处理12 h后，TaFTSH6-7D基因的表达量在叶组织和根组织中分别呈现显著或极显著增高；在热胁迫下，小麦叶片和根组织TaFTSH6-7D基因的表达量也呈现升高的变化趋势，在处理6 h、2 d (6 h/d)和3 d (6h/d)，TaFTSH6-7D基因的表达量在叶组织显著增高，在根组织中极显著增高(图4)。以上结果说明TaFTSH6-7D基因受干旱和热胁迫的诱导。

2讨论

植物在整个生活史中面临多种非生物和生物胁迫，蛋白质的体内降解是植物响应环境胁迫并协调生长发育和胁迫响应之间的关系的重要方式之一(Chen et al., 2020)。生物体通过降解寿命期满蛋白质、错误组装的膜蛋白，调节生物的正常生长发育和对环境的响应(Wang et al., 2018a)。生物体内降解蛋白质的方式主要有不依赖ATP的溶酶体途径和依赖ATP的泛素蛋白酶体降解途径，近年来的研究还发现了胱天蛋白酶(caspase)途径、线粒体的La蛋白酶途径、高尔基体内Kex2水解酶途径和细胞膜表面的水解酶途径等(Ling et al., 2019)。FTSH蛋白酶降解蛋白质依赖于ATP提供能量，在大肠杆菌中，FTSH以环状同型六聚体的形式与调节因子Hf1KC低聚物形成复合物，其活性受磷酸化修饰(Kato and Sakamoto, 2019)，降解短寿命蛋白质和错误组装蛋白(Nishimura et al., 2016)。其特殊之处在于它是膜锚定的，可在逆境胁迫条件下降解错误蛋白并维持膜的稳定性(Kato and Sakamoto, 2018)，是细胞膜表面的水解酶类。因此，FTSH蛋白酶家族具有一个N端跨膜结构域和一个延伸到基质中的C端区域。C端区域包含ATPase和蛋白酶域，ATPase结构域发挥去折叠酶的功能，通过一个狭窄的孔将底物转移到蛋白酶域降解室中。本研究发现，不同物种的FTSH6蛋白序列在N端的跨膜域、C端的ATP结合位点以及精氨酸指环处都高度保守。

目前，对FTSH蛋白酶的作用机理还知之甚少。FTSH蛋白酶能将完整的膜蛋白从膜中抽出并降解(Kato and Sakamoto, 2018)。拟南芥有12个FTSH编码基因。其中9种位于蛋白质以叶绿体的类囊体膜上，3种定位于线粒体膜上。FTSH参与了叶绿体早期发育过程中类囊体膜的形成，烟草中的FTSH突变在叶片发育的后期表现出类囊体膜的崩塌(Kato et al., 2012)，另外，FTSH还参与光系统II修复周期中D1蛋白和光合电子传递途径中几种蛋白质复合物的降解及组装过程，缺乏FTSH的拟南芥突变体中光损伤D1蛋白累积，ROS (Reactive oxygen species)信号得不到有效传递，对强光胁迫表现出更高的敏感性(Zaltsman et al., 2005; Dogra et al., 2017; Wang et al., 2018a)。然而，FTSH的蛋白酶活性的调节方式，FTSH及其复合体识别受损蛋白的模式，FTSH的具体功能和发挥作用的方式还需要深入的研究。

FTSH被报道参与植物对干旱和热胁迫的响应。干旱条件下，复活草(Ingle et al., 2007)、起源于非洲沙漠的野生西瓜(Akashi et al., 2004)、玉米(Andjelkovic and Thompson, 2006)、荠菜(Knight et al., 2006)、马铃薯(范敏等, 2007)等植物体内均发现有FTSH基因表达量的增加或FTSH蛋白的大量合成。水稻根系中FTSH基因表达量的增加可增强耐旱性(Zhang and Sun, 2009)。热胁迫可导致番茄LeFTSH6基因表达量增加(Sun et al., 2006a; 2006b)。拟南芥的FTSH11蛋白酶过表达有助于植物对热的整体耐受性(Chen et al., 2006)。在小麦中研究发现，热胁迫下耐热小麦品种FTSH2表达量显著高于热敏品种(Wang et al., 2015)。本论文研究发现，在小麦苗期，PEG模拟干旱或者36℃热处理条件下TaFTSH6-7D基因的表达量均会显著升高，与其它植物中的报道一致。本论文研究结果说明TaFTSH6-7D基因受干旱和热胁迫的诱导，对TaFTSH6基因功能及调控模式的后续研究将为改良小麦耐干热分子育种提供了一定理论基础。

3材料与方法

3.1植物材料及处理

在光照培养箱中，将小麦(Triticum aestivum L.)品种Bobwhite种子置培养基中4℃培养5 d、12℃培养5 d 25℃培养2 d后转移到1/2MS培养液中在25℃ (16 h)/20℃ (8 h) (昼/夜)、相对湿度75%条件下培养至三叶期，对幼苗进行模拟干旱(15% PEG, 6 h, 12 h, 24 h和48 h)、热(36℃, 3 h, 6 h, 2 d (6 h/d)和3 d (6 h/d))胁迫处理，并以正常生长幼苗对照。样品液氮冷冻，-80℃保存。

3.2 RNA提取及cDNA合成

参照Trizol法从小麦的叶和根中提取总RNA，保证提取RNA的植株为幼苗，并且生长状态良好。RNA样品去除DNA后参照Tiangen公司的一步法逆转录试剂盒说明合成cDNA，-20℃保存。

3.3引物设计与PCR扩增

本实验所用引物(表2)。用TaFTSH6F和TaFTSH6R进行基因克隆，PCR反应程序为：94℃预变性5 min，94℃变性45 S，60℃左右退火45 S，72℃延伸120 S，前5个循环，每个循环退火温度比前一个降低1℃，降低为55℃后30个循环，72℃延伸10 min，12℃保温。荧光定量PCR采用ABI Stepone plus定量PCR仪器，操作参照SYBR Green PCR Master Mix (Applied Biosystems)试剂盒说明书，为了保证引物特异性，3’-端引物设计在非翻译序列，引物特异性在Wheat Gene Index database (http://blast.jcvi.org/euk-blast/index.cgi?project=tae1)网站核对，熔解曲线呈现单峰，持家基因TaRP15在干旱和热胁迫条件下表达量没有变化。实验设置3个重复。

3.4生物信息学分析

在URGI (https://urgi.versailles.inra.fr/blaST/?dbgroup=wheat_all&program=blaSTn)上根据小麦已知序列进行TaFTSH6基因物理位置定位，根据所得定位在(http://202.194.139.32/)中获取cDNA序列。在Softberry的FGENESH HMM based Gene Structure prediction中进行TaFTSH6基因内含子外显子分析。通过NCBI网站上的BLASTX (http://www.ncbi. nlm.nih.gov/)搜索其他物种的FTSH6序列。在MEGA10.0中运用ClustalW方法进行多序列比对分析，然后采用邻接法(neighbor-joining method) (bootstrap=1000)构建系统进化树。在(http://www.cbs.dtu.dk/services/TMHMM-2.0/)上进行跨膜结构域分析。在(http://bioinformatics.psb.ugent.be/webtools/plantcare/html)中进行启动子分析，通过对启动子顺式作用元件的分析。

作者贡献

李媛是本研究的执行人，完成数据分析，论文初稿的写作；蒋慧君参与实验设计和试验结果分析；刘军和刘云国是项目的构思者，胡晓君指导实验设计、数据分析、论文写作与修改。全体作者都阅读并同意最终文本。

致谢

本研究由山东省重点研发公益类项目(No.2017NC210010)和国家重点研发项目(No.2017YFD0301003)共同资助。

参考文献

Akashi K., Nishimura N., Ishida Y., and Yokota A., 2004, Potent hydroxyl radical-scavenging activity of drought-induced type-2 metallothionein in wild watermelon, Biochem. Biophy. Res. Commun., 323(1): 72-78

Andjelkovic V., and Thompson R., 2006, Changes in gene expression in maize kernel in response to water and salt stress, Plant Cell Reports, 25(1): 71-79

Bove P., Capozzi V., Garofalo C., Rieu A., Spano G., and Fiocco D., 2012, Inactivation of the FTSH gene of Lactobacillus plantarum WCFS1: effects on growth, stress tolerance, cell surface properties and biofilm formation, Microbiol. Res., 167(4): 187-193

Chen J., Burke J.J., Velten J., and Xin Z., 2006, FTSH11 protease plays a critical role in Arabidopsis thermotolerance, Plant J. Cell Mol. Biol., 48(1): 73-84

Chen Q., Yu F., and Xie Q., 2020, Insights into endoplasmic reticulum-associated degradation in plants, New Phytol., 226(2): 345-350

Deuerling E., Paeslack B., and Schumann W., 1995, The FTSH gene of Bacillus subtilis is transiently induced after osmotic and temperature up shock, J. Bacteriol., 177(14): 4105-4112

Deuerling E., Mogk A., Richter C., Purucker M., and Schumann W., 1997, The FTSH gene of Bacillus subtilis is involved in major cellular processes such as sporulation, stress adaptation and secretion, Mol. Microbiol., 23(5): 921-933

Dogra V., Duan J., Lee K.P., Lv S., Liu R., and Kim C., 2017, FTSH2-dependent proteolysis of EXECUTER1 is essential in mediating singlet oxygen-triggered retrograde signaling in Arabidopsis thaliana, Front. Plant Sci., 8: 1145

Duwat P., Ehrlich S.D., and Gruss A., 1995, The recA gene of Lactococcus lactis: Characterization and involvement in oxidative and thermal stress, Mol.Microbiol., 17(6): 1121-1131

Fan M., Jin L.P., Huang S.W., Xie K.Y., Liu Q.C., and Qun D.Y., 2007, Cloning and expression of a full-length cDNA of SoFTSH gene in potato under drought stress, Zuowu Xuebao (Acta Agronomica Sinica), 33(11): 1748-1754 (范敏, 金黎平, 黄三文, 谢开云, 刘庆昌, 屈冬玉, 2007, 马铃薯SoFTSH基因全长cDNA克隆与在干旱条件下表达研究, 作物学报, 33(11): 1748-1754)

Havé M., Balliau T., Cottyn-Boitte B., Dérond E., Cueff G., Soulay F., Lornac A., Reichman P., Dissmeyer N., Avice J.C., Gallois P., Rajjou L., Zivy M., and Masclaux-Daubresse C., 2018 , Increases in activity of proteasome and papain-like cysteine protease in Arabidopsis autophagy mutants: Back-up compensatory effect or cell-death promoting effect? J. Exp. Botany, 69(6): 1369-1385

Ingle R.A., Schmidt U.G., Farrant J.M., Thomson J.A., and Mundree S.G., 2007, Proteomic analysis of leaf proteins during dehydration of the resurrection plant Xerophyta viscose, Plant Cell Environment, 30(4): 435-446

Ito K., and Akiyama Y., 2005, Cellular functions, mechanism of action, and regulation of FTSH protease, Ann. Rev. Microbiol., 59(1): 211-231

Ivashuta S., Imai R., Uchiyama K., Gau M., and Shimamoto Y., 2002, Changes in chloroplast FTSH-like gene during cold acclimation in alfalfa (Medicago sativa), J. Plant Physiol., 159(1): 85-90

Jayasekera M.M., Foltin S.K., Olson E.R., and Holler T.P., 2000, Escherichia coli requires the protease activity of FTSH for growth, Arch. Biochem. Biophy., 380(1): 103-107

Ji W.Q., Yan J.P., Bai X., Qiao P., Li Z.P., Yang Y.W., Guan W., and Zhao T.C., 2019, Functional analysis of the gene FTSH in Acidovorax citrulli, Zhiwu Binli Xuebao (Plant Pathology), 49(4): 488-499 (季苇芹, 闫建培, 白雪, 乔培, 李智鹏, 杨玉文, 关巍, 赵廷昌, 2019, 西瓜噬酸菌FTSH基因功能分析, 植物病理学报, 49(4): 488-499)

Kato Y., Kouso T., and Sakamoto W., 2012, Variegated tobacco leaves generated by chloroplast FTSH suppression: Implication of FTSH function in the maintenance of thylakoid membranes, Plant Cell Physiol., 53: 391-404

Kato Y., and Sakamoto W., 2018, FTSH Protease in the thylakoid membrane: physiological functions and the regulation of protease activity, Front. Plant Sci., 9: 855

Kato Y., and Sakamoto W., 2019, Phosphorylation of the chloroplastic metalloprotease FTSH in Arabidopsis characterized by Phos-Tag SDS-PAGE, Front. Plant Sci., 10: 1080

Kamata T., Hiramoto H., Morita N., Shen J.R., Mann N.H., and Yamamoto Y., 2005, Quality control of Photosystem II: An FTSH protease plays an essential role in the turnover of the reaction center D1 protein in Synechocystis PCC 6803 under heat stress as well as light stress conditions, Photochem. Photobiol. Sci., 4(12): 983-990

Kihara A., Akiyama Y., and Ito K., 1997, Host regulation of lysogenic decision in bacteriophage lambda: Transmembrane modulation of FTSH (HflB), the cII degrading protease, by HflKC (HflA), Proc. Natl. Acad. Sci. USA, 94: 5544-5549

Kihara A., and Ito K., 1998, Translocation, folding, and stability of the HflKC complex with signal anchor topogenic sequences, J. Biol. Chem., 273(45): 29770-29775

Knight C.A., Vogel H., Kroymann J., Shumate A., and Mitchell-Olds T., 2006, Expression profiling and local adaptation of Boechera holboellii populations for water use efficiency across a naturally occurring water stress gradient, Mol. Ecol., 15(5): 1229-1237

Lindahl M., Tabak S., Cseke L., Pichersky E., Andersson B., and Adam Z., 1996, Identification, characterization, and molecular cloning of a homologue of the bacterial FTSH protease in chloroplasts of higher plants, J. Biol. Chem., 271(46): 29329-29334

Ling Q.H., Broad W., Trösch R., Töpel M., Sert T.D., Lymperopoulos P., Baldwin A., and Jarvis R.P., 2019, Ubiquitin-dependent chloroplast-associated protein degradation in plants, Science, 363(6429): eaav4467

Nishimura K., Kato Y., and Sakamoto W., 2016, Chloroplast Proteases: Updates on proteolysis within and across suborganellar compartments, Plant Physiol., 171(4): 2280-2293

Ogura T., and Wilkinson A.J., 2001, AAA+ superfamily ATPases: Common structure--diverse function, Genes to Cells, 6(7): 575-597

Schumann W., 1999, FTSH—a single-chain charonin? FEMS Microbiol. Rev., 23(1): 1-11

Seo S., Okamoto M., Iwai T., Iwano M., Fukui K., Isogai A., Nakajima N., and Ohashi Y., 2000, Reduced levels of chloroplast FTSH protein in tobacco mosaic virus-infected tobacco leaves accelerate the hypersensitive reaction, Plant Cell, 12(6): 917-932

Sun A.Q., Yi S.Y., Yang J.Y., Zhao C.M., and Liu J., 2006a, Identification and characterization of a heat-inducible FTSH gene from tomato (Lycopersicon esculentum Mill.), Plant Sci., 170: 551-562

Sun A.Q., Yang J.Y., Yi S.Y., Zhao C.M., and Liu J., 2006b, Cloning and molecular characteristic of the metalloprotease gene LeFTSH6 from tomato, J. Plant Physiol. Mol. Biol., 32(1): 64-72

Wang Q.L., Chen J.H., He N.Y., and Guo F.Q., 2018a, Metabolic reprogramming in chloroplasts under heat stress in plants, Int. J. Mol. Sci., 19(3): 849

Wang T., Li S.H., Chen D., Xi Y., Xu X.Z., Ye N.H., Zhang J.H., Peng X.X., and Zhu G.H., 2018b, Impairment of FTSHi5 function affects cellular redox balance and photorespiratory metabolism in Arabidopsis, Plant Cell Physiol., 59(12): 2526-2535

Wang X., Dinler B.S., Vignjevic M., Jacobsen S., and Wollenweber B., 2015, Physiological and proteome studies of responses to heat stress during grain filling in contrasting wheat cultivars, Plant Science, 230: 33-50

Yoshioka M., Uchida S., Mori H., Komayama K., Ohira S., Morita N., Nakanishi T., and Yamamoto Y., 2006, Quality control of photosystem II, leavage of reaction center D1 protein in spinach thylakoids by FtsH protease under moderate heat stress, J. Biol. Chem., 281(31): 21660-21669

Yin Z.T., Meng F.F., Song H.N., Wang X.L., Chao M.N., Zhang G.Z., Xu X.M., Deng D.X., and Yu D.Y., 2011, GmFTSH9 expression correlates with in vivo photosystem II function: chlorophyll a fluorescence transient analysis and eQTL mapping in soybean, Planta, 234(4): 815-827

Zaltsman A., Feder A., and Adam Z., 2005, Developmental and light effects on the accumulation of FTSH protease in Arabidopsis chloroplasts-implications for thylakoid formation and photosystem II maintenance, Plant J., 42: 609-617

Zhang J.D., and Sun A.Q., 2009, Genome-wide comparative analysis of the metalloprotease FTSH gene families between Arabidopsis thaliana and rice, China J. Biotechnol., 25(9): 1402-1408

Zheng C.H., Kong X.Y., Sui J.M., Shu C., and Zhao C.M., 2016, Identification, classification and salt stress expression analysis of metalloproteinase FTSH family in peanut (Arachis hypogaea L.), Jiangsu Nongye Kexue (Journal of Jiangsu Agricultural Sciences), 44(12): 74-77 (郑春花, 孔祥远, 隋炯明, 束晨, 赵春梅, 2016, 花生金属蛋白酶家族基因FTSH的鉴定、分类和盐胁迫表达分析, 江苏农业科学, 44(12): 74-77)