OsWR2-RNAi对水稻角质层生物合成和耐旱性的影响

Influence of OsWR2-RNAi on Rice Cuticle Biosynthesis and Drought Resistance

植物的角质层在干旱胁迫下对降低植物的非气孔性失水起重要作用。对水稻蜡质相关转录因子基因OsWR2过表达研究发现,OsWR2对水稻表皮蜡质和角质的含量和组分构成以及非气孔性失水均有影响,推测OsWR2是植物角质层代谢途径中重要的调控基因。本研究通过构建OsWR2-RNAi载体并转入水稻获得抑制OsWR2表达的突变转基因植株,发现OsWR2-RNAi水稻叶片角质层组成和含量明显变化,其蜡质组分中醛类、醇类和烷烃类的减少导致表皮蜡质晶体的积累和表皮蜡质总量减少14.8%,角质单体中C16:0ω-OH、C18:1ω-OH脂肪酸和di-OH脂肪酸等角质组分含量的显著降低导致OsWR2-RNAi水稻叶片中角质单体总量减少36.2%。幼苗干旱处理前后,OsWR2-RNAi植株自由脯氨酸含量与野生型相比变化不大,但其表皮通透性、水分散失率和MAD含量显著增加,幼苗耐旱性降低。本研究结果进一步证实OSWR2对水稻蜡质和角质生物合成及对非气孔性失水的调控作用,有望为水稻耐旱性状的改良提供重要基因资源。

Plant cuticle plays an important role on decreasing plant non-stomatal water loss under drought stress.Overexpression of wax related transcription factor gene OsWR2 in rice can increase total cuticular wax and cutin amounts,affect cuticular wax and cutin monomer composition,and alter cuticular wax crystallization patterns and cuticle membrane ultrastructure,implying important roles of OsWR2 in rice cuticle biosynthesis and non-stomatal water loss regulation.In this report,we constructed OsWR2 RNA inhibition vector（OsWR2-RNAi）,and transformed it into rice callus to obtain OsWR2 knockout rice mutants using Agrobacterium-mediated transforming method.OsWR2-RNAi transgenic rice exhibited reduced total cuticular wax amounts by 14.8% mainly due to the decrease of aldehydes,alkanes and alcohols,and lessened full cutin monomer level by 36.2% due primarily to the decrease of C16：0 ω-OH,C18：1 ω-OH,and di-OH fatty acid components.OsWR2-RNAi transgenic rice also showed enriched leaf chlorophyll leaching,water loss rates and MDA contents,whereas reduced tolerance to water deficit.All these physiologic and biochemical index to support the previous hypothesis of OsWR2 acting as a transcriptional regulator of both cuticle biosynthetic pathways and non-stomatal water loss,providing evidence of OsWR2 exerting direct influence over rice dehydration,and a potential application resource in genetic improvement of crop drought tolerance.