过表达马铃薯气孔密度调节因子StEPF1增强拟南芥抗旱性

Overexpressing Potato Stomatal Density Regulator StEPF1 Enhances Arabidopsis Drought Tolerance

表皮模式因子1(epidermal patterning factor 1,EPF1)是气孔发育的负调控因子,对于植物生长发育和环境胁迫响应至关重要。为了明确马铃薯EPF1在气孔发育过程中的功能,本研究从‘大西洋’(Atlantic)马铃薯品种中克隆得到气孔密度表皮模式因子St EPF1,并对该基因的表达特性及功能进行分析。亚细胞定位显示StEPF1主要定位于细胞间隙并且它在顶端未展开叶中表达最多。StEPF1基因表达量在一天中呈现周期性变化,长日照条件下(16/8 h,光照/黑暗),在授时因子为20 h时表达量达到最高。聚乙二醇(PEG)模拟干旱胁迫、脱落酸(ABA)和NaCl胁迫处理后,其表达水平均呈现出持续降低的趋势。功能鉴定表明,过量表达StEPF1基因的拟南芥(E1)植株相对于野生型(WT)植株的气孔密度显著降低,E1植株的光合速率也随之降低。此外,与野生型相比(WT),E1植株离体叶片的水分散失速率和H2O2含量也显著降低。干旱胁迫下,E1株系的光合速率、气孔导度和瞬时水分利用效率(iWUE)都显著高于野生型拟南芥。综上结果可知,表皮模式因子St EPF1在调控植物气孔密度和抗旱性上具有重要作用,本研究结果为后期通过调节StEPF1基因的表达,培育抗旱节水型马铃薯株系提供理论基础。

Epidermal patterning factor 1(EPF1)is a negative regulator of stomatal development,and is essential for plant growth,development,and environmental stre ss responses.To define the function of potato EPF1 during stomatal development,we cloned and functionally characterized the stomatal density regulator StEPF1 from potato(cv.Atlantic).Subcellular localization showed StEPF1 is predominantly intercellular space localized and has the highest expression level in the apical unexpanded leaves.Interestingly,StEPF1 gene expression is rhythmically expressed with a peak around Zeitgeber time(ZT)20 h under long-day(16/8 h,light/dark)conditions,and were markedly down-regulated in response to polyethylene glycol(PEG),abscisic acid(ABA)and sodium chloride(NaCl).Functional identification showed that the stomatal density of Arabidopsis(E1)plants with overexpression of StEPF1 gene was significantly lower than that of wild-type(WT)plants,and lead to minished photosynthetic rate.Moreover,StEPF1 overexpression(E1)lines showed less water loss and hydrogen peroxide(H2 O2)accumulation in detached leaves compared with wild-type(WT)plants.Under drought stress,E1 lines maintained higher photosynthetic rates,stomatal conductance,and instantaneous water use efficiency(iWUE)than WT Arabidopsis plants.Taken together,the results showed that the epidermal model factor StEPF1 plays an important role in regulating stomatal density and plant drought resistance.These results provide fundamental basis for the development of drought-tolerant and water-saving potato lines by manipulating the StEPF1 gene in the future.