【作者】 胡伟； 刘玉； 王珊珊； 周治国；

【Author】 Hu Wei;Liu Yu;Wang Shanshan;Zhou Zhiguo;College of Agriculture,Nanjing Agricultural University;

【机构】 南京农业大学农学院；

【摘要】 干旱胁迫显著抑制棉花的生殖活动,导致棉花产量降低。已有研究表明,干旱胁迫能显著降低雄性生殖器官活性,但对雌性生殖器官活性影响的研究还未开展。因此,为了探索干旱对棉花雌性生殖器官活性的影响,以豫早棉9110为材料,在温室中开展干旱盆栽实验。结果表明:花粉管生长前期,雌蕊淀粉含量与花粉管生长速率密切相关,而受旱植株雌蕊的淀粉含量在此阶段比对照低31.6%。受旱植株雌蕊中淀粉含量降低,一方面与光合同化物的运输受阻有关,因为干旱胁迫显著下调雌蕊中蔗糖转运基因GhSUT-1表达量;另一方面与淀粉生物合成受阻有关,因为干旱显著降低雌蕊中腺苷二磷酸葡萄糖焦磷酸化酶和可溶性淀粉合酶活性。此外,受旱植株雌蕊蔗糖含量在花粉管生长前期和快速伸长期都显著高于对照,因为受旱植株雌蕊中蔗糖合成酶和酸性转化酶活性、蔗糖合酶基因(GhSusA、GhSusB、GhSusD)、酸性转化酶基因(GhINV1、GhINV2)表达量显著降低,限制了蔗糖向己糖转化。此外,花粉管快速伸长期,受旱植株雌蕊中α-淀粉酶活性显著降低,导致淀粉向己糖的水解受抑制。最终,受旱植株雌蕊中葡萄糖和果糖含量在花粉管快速伸长期较低。作为呼吸作用的底物—葡萄糖含量降低,抑制丙酮酸产生,进一步导致AT P在受旱植株雌蕊中生成受阻,最终能量不足抑制花粉管伸长。这些结果说明,干旱破坏了雌蕊中碳水化合物平衡,减少花柱中花粉管生长所需的碳和能量供应,引起生殖失败。更多还原

【Abstract】 It has been reported that drought stress(DS) reduces cotton yield by negatively affecting reproductive activities.Some studies have investigated the effects of DS on pollen physiology and biochemistry,but studies exploring the impact of drought on pistil biochemistry and its relationship with pollen tube growth rates in vivo are scarce.In order to investigate these objectives,a greenhouse study was conducted and a drought sensitive cotton cultivar,Yuzaomian 9110,was grown under optimum water condition until flowering.Then,the plants were separated into two groups and two water treatments were imposed,1) control,where plants were irrigated with optimum quantity of water and,2) DS treatment,where plants were irrigated with 50% of the optimum quantity of water.Results indicated that stored starch content at the early stage of pollen tube growth(12:00 h) was 31.6% lower in drought-stressed pistils than control pistils,and it was highly correlated with pollen tube growth rate.The decline in starch accumulation of drought-stressed pistils could be attributed to the impeded export of photosynthetic carbon assimilates,since the expression of GhSUT-1 was significantly down-regulated under DS.Moreover,decreased ADP-glucose pyrophosphorylase and soluble starch synthase activities also resulted in curtailing starch accumulation in drought stressed pistils.Furthermore,pistil sucrose concentration was significantly higher in drought stressed plants relative to control plants at 12:00 and 18:00 h(during the rapid growth period),which was due to lower activities of sucrose synthase and acid invertase,and the down-regulated expressions of sucrose synthase genes,GhSusA,GhSusB and GhSusD,and acid invertase genes,GhINV1 and GhINV2,in drought-stressed pistils,limiting as a result the hydrolysis of sucrose into hexose.Moreover,drought-stressed pistils sampled at 18:00 h had lower α-amylase activity compared with control pistils,resulting in decreased starch hydrolysis,which,in conjunction with the decreased decomposition of sucrose,led to lower glucose and fructose contents in drought-stressed pistils at 18:00 h.Finally,lower pyruvate level in drought-stressed pistils could not produce enough acetyl-CoA in the tricarboxylic acid cycle to yield sufficient ATP for pollen tube growth.We conclude that DS disrupts the carbohydrate balance of pistil,reducing as a consequence carbon and energy supply for pollen tube elongation in the style,and ultimately resulting in significant reproductive failure.更多还原