StvacINV1负调控马铃薯的耐旱性

StvacINV1 negatively regulates drought tolerance in potato

植物液泡酸性转化酶不可逆的催化蔗糖转化为葡萄糖和果糖,在植物的生长和发育及其逆境适应中扮演重要的角色。马铃薯液泡转化酶基因StvacINV1参与调控薯块的糖化,但其是否参与对干旱胁迫的调控尚不清楚。本研究以马铃薯品种‘Atlantic’和‘Russet Burbank’的StvacINV1 RNA干扰表达的转基因株系及其野生型为材料,采用停止浇水进行自然干旱处理,研究StvacINV1对马铃薯植株耐旱性的调控机制。结果表明干旱胁迫引起马铃薯叶片StvacINV1的表达量及其液泡酸性转化酶活性显著降低;与野生型相比,干旱胁迫下StvacINV1干扰效率高的转基因株系植株不易失水萎蔫、离体叶片的失水率低,MDA含量低且叶片的相对水分含量高,由此表明StvacINV1干扰效率高的转基因株系的耐旱性高于野生型,即StvacINV1负调控马铃薯的耐旱性;进一步的分析表明,干旱胁迫下StvacINV1干扰效率高的转基因株系的气孔开度和气孔导度显著低于野生型,水分利用率显著高于野生型,因此推测StvacINV1可能通过介导气孔的关闭来调节马铃薯植株的耐旱性;干旱胁迫下StvacINV1干扰株系的蔗糖含量显著高于野生型,且外源高浓度蔗糖处理可诱导气孔的关闭,因此推测StvacINV1可能通过其底物蔗糖参与调控气孔的关闭;外源ABA诱导的气孔关闭过程中,StvacINV1干扰株系比野生型更敏感。综上所述,干旱胁迫下StvacINV1通过介导气孔的关闭负调控马铃薯植株的耐旱性,StvacINV1可能通过其所催化的底物蔗糖参与调控气孔的关闭,StvacINV1也参与ABA介导的气孔关闭。本研究为选育既耐糖化(块茎)又耐干旱的马铃薯品种提供理论依据。

Plant vacuolar acid invertase catalyses irreversible hydrolysis of sucrose into glucose and fructose,which plays a vital role in plant growth,development,and abiotic stress adaption.The vacuolar acid invertase gene StvacINV1 in potato(Solanum tuberosum L.)are involved in regulating cold-induced sweetening in tubers,however the physiological role of StvacINV1 during adaptation to drought stress conditions is not yet fully understood.To investigate the mechanism of StvacINV1 regulating drought toleration under natural drought stress(water was withheld),this experiment was conducted with potato cultivars‘Atlantic’,‘Russet Burbank’,and their StvacINV1-RNAi transgenic lines.The results showed that drought stress strongly reduced mRNA abundance of StvacINV1 and vacuolar acid invertase activity in the leaves of the wild-type plants and StvacINV1-RNAi transgenic lines.Compared with the wild type,the transgenic lines with high interference efficiency of StvacINV1-RNAi were less prone to slower wilting,lower water loss,lower MDA content,and higher relative water content in leaves under drought stress,which indicated that the transgenic strains with high interference efficiency of StvacINV1 had higher drought tolerance than wild type.StvaclNV1 regulated negatively drought tolerance of potao.Further analysis showed that under drought stress,stomatal aperture and stomatal conductance in highly interfered StvacINV1-RNAi transgenic lines were significantly lower than wild type,whereas water use efficiency was significantly higher,which demonstrated StvacINV1 might regulate the drought tolerance of potato plants by stomatal movement.Sucrose content in highly interfered StvacINV1-RNAi transgenic lines was significantly higher than wild type under drought stress,meanwhile the exogenous high concentration sucrose treatment can induce stomatal closure,which led us to speculate that StvacINV1 was involved in regulating stomatal closure through its catalytic substrate sucrose.Compared with wild type,StvacINV1-RNAi transgenic lines were more sensitive during ABA-induced stomatal closure.In conclusion,StvacINV1 negatively regulated the drought tolerance by stomatal closure in potato plants,and StvacINV1 may be involved in regulating stomatal closure through its catalytic substrate sucrose,and StvacINV1 was involved in ABA-induced stomatal closure.This study provides a theoretical basis for breeding potato varieties resistant to both sweetening(tubers)and drought stress.