Lignin synthesized byCmCAD2andCmCAD3in oriental melon (Cucumis meloL.) seedlings contributes to drought tolerance

文献类型： 外文期刊

第一作者： Liu, Wei

作者： Liu, Wei;Jiang, Yun;Wang, Chenghui;Zhao, Lili;Xing, Qiaojuan;Li, Meng;Lv, Tinghui;Qi, Hongyan;Wang, Chenghui;Zhao, Lili;Jin, Yazhong

作者机构：

关键词： Casparian strip; Cinnamyl alcohol dehydrogenase; Drought; Lignin; Oriental melon

期刊名称：PLANT MOLECULAR BIOLOGY （ 影响因子：4.076； 五年影响因子：4.89 ）

ISSN： 0167-4412

年卷期： 2020 年 103 卷 6 期

页码：

收录情况： SCI

摘要： Key message CmCAD2andCmCAD3function more positively thanCmCAD1in oriental melon for lignin synthesis which is important to ensure internal water status and thus for drought tolerance. Well-lignification may be the guarantee of efficient axial water transport and barrier of lateral water flow in oriental melon tolerating drought stress, however remains to be verified. As an important enzyme in monolignol synthesis pathway, five cinnamyl alcohol dehydrogenase (CAD) genes were generally induced in melon seedlings by drought. Here we further revealed the roles ofCmCAD1,2, and3in lignin synthesis and for drought tolerance. Results found that overexpressingCmCAD2or3strongly recovered CAD activities, lignin synthesis and composition in Arabidopsiscadc cadd, whose lignin synthesis is disrupted, whileCmCAD1functioned modestly. In melon seedlings, silencedCmCAD2and3individually or collectively decreased CAD activities and lignin depositions drastically, resulting in dwarfed phenotypes. Reduced lignin, mainly composed by guaiacyl units catalyzed by CmCAD3, is mainly due to the limited lignification in tracheary elements and development of Casparion strip. While CmCAD1 and 2 exhibited catalysis top-coumaraldehyde and sinapaldehyde, respectively. Compared withCmCAD1, drought treatments revealed higher sensitivity ofCmCAD2and/or3silenced melon seedlings, accompanying with lower relative water contents, water potentials and relatively higher total soluble sugar contents. Slightly up-regulated expressions of aquaporin genes together with limited lignification might imply higher lateral water loss in stems of silenced lines. In Arabidopsis,CmCAD2and3transgenic lines enhancedcadc cadddrought tolerance through recovering lignin synthesis and root development, accompanying with decreased electrolyte leakage ratios and increased RWCs, thus improved survival rates. Briefly, lignin synthesized byCmCAD2and3functions importantly for drought tolerance in melon.

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