【作者】 刘玉；

【导师】 周治国；

【作者基本信息】 南京农业大学 ， 农业硕士（专业学位）， 2019， 硕士

【摘要】 花铃期是棉花对土壤水分变化最敏感时期,此时期缺水会严重影响棉花产量和品质。花铃期干旱影响铃重进而降低产量,而铃重与受精率密切相关。选用干旱敏感型品种豫早棉9110和耐干旱品种德夏棉1号,于2017-2018年在南京农业大学卫岗校区(32°02’N,118°50’E)采用盆栽方法进行花铃期棉花干旱试验,在棉花初花期设置土壤相对含水量分别为(75±5)%(CK)和(45±5)%(干旱)两个水平,研究干旱胁迫对棉花花粉活力及其相关的碳水化合物代谢、抗氧化代谢及铃重的影响,以揭示花铃期干旱胁迫影响棉花花粉育性的生理机制。主要研究结果如下:1.花铃期干旱胁迫对棉花花粉育性和铃重的影响干旱胁迫显著降低了两品种花粉活力、体外萌发率及柱头萌发率,在干旱下德夏棉1号的花粉活力高于豫早棉9110。干旱导致两品种不孕籽率增高,降低单铃棉籽数,最终导致铃重显著降低。干旱处理下,与豫早棉9110相比,德夏棉1号具有较高的花粉活力,所以其不孕籽率低,具有较高的单铃棉籽数,最终维持较稳定的铃重。2.花铃期干旱胁迫对花药生理代谢的影响干旱胁迫下,两品种叶片的碳同化能力降低。干旱胁迫还导致蔗糖转移酶基因GhSUT-1表达下调,影响了同化物从叶片向花药中的转运能力,最终花药中同化物累积降低,导致腺嘌呤核苷三磷酸含量降低,花药中能量供应减少。在花药生理代谢中表现为,干旱通过降低蔗糖合成酶和酸性转化酶活性,使得蔗糖水解速率降低,降低了花药中己糖的供应。干旱导致了葡萄糖焦磷酸化酶(AGPase)活性的降低,限制了UDP-葡萄糖的生成,尽管颗粒淀粉合成酶活性升高,底物的不足限制了淀粉的合成,最终导致两品种花药中淀粉含量显著降低。在干旱处理下,与豫早棉9110相比,德夏棉1号花药中蔗糖合成酶基因SuSC和蔗糖酶基因INV1较高的表达水平,使其花药中蔗糖合成酶和酸性转化酶活性变化较小,保证了花药中蔗糖的分解速率。干旱下,德夏棉1号花药中AGPase活性显著高于豫早棉9110,保证了淀粉的合成速率,最终使其干旱胁迫的花药中拥有较高的淀粉含量。干旱胁迫降低了两品种花药中超氧化物歧化酶(SOD)、过氧化物酶、过氧化氢酶、抗坏血酸过氧化物酶(APX)活性,使得花药中过氧化氢(H2O2)和丙二醛(MDA)含量升高。与豫早棉9110相比,干旱处理下,德夏棉1号花药含有较高的SOD和APX活性,这导致其花药中活性氧清除能力优于豫早棉9110,最终其花药中的MDA和H2O2含量较低。这也是干旱胁迫下,德夏棉1号花粉活力更强的原因之一。更多还原

【Abstract】 Cotton during the flowering and boll stage is the most sensitive to water stress.Water shortage during this period will seriously impact cotton yield and fiber quality.Drought during this period can significantly reduce boll weight,resulting in yield loss.The fertilization rate of cotton is positively correlated with boll weight.A pot experiment was carried out in greenhouses with a drought-sensitive variety Yuzaomian 9110 and a drought-resistant variety Dexiamian 1 in Nanjing Agricultural University campus(32°02’N and 118°50’E)in 2017-2018.Two water regimes:a well-watered treatment with soil relative water content of 75±5%(CK),and a drought stress tredatment with soil relative water content of 45±5%,donated as CK and drought,were imposed at the beginning of flowering stage.The effects of soil drought during flowering and boll-forming stage on pollen fertility,related carbohydrate metabolism and antioxidant metabolism in pistil and boll weight were investigated to reveal the physiological mechanism of drought stress during flowering and boll period affecting cotton pollen fertility.The main results are as follows:1.Drought effects on boll weight and pollen fertilityDrought stress significantly reduced the pollen viability,in vitro pollen germination rate and in vivo pollen germination rate of the two cultivars.Drought stress also increased the infertility seed rate and reduced the number of fertilized seeds,which ultimately reduced boll weight.Under drought treatment,compared with Yuzaomian 9110,the higher pollen vitality of Dexiamian 1 resulted in higher number of fertilized seeds and lower seed abortion rate,which eventually led to higher boll weight.2.Drought effects on physiological metabolism on antherUnder drought stress,the carbon assimilation ability of the leaves decreased.Drought stress also down-regulated the GhSUT-1 expression,which affected the carbohydrate transport ability to the anthers,affecting energy supply in the anthers,so reduced ATP content in the anthers was measured under drought stress.Drought stress reduced the sucrose hydrolysis into hexose in anthers by reducing the activity of sucrose synthetase and acid invertase.Drought stress led to a decrease in ADP-glucose py-rophosphorylase polypetide(AGPase)activity,which limited the production of UDP-glucose.Despite the activity of Granule-bound starch synthase increased,the lack of substrate inhibited the synthesis of starch,which ultimately led to a significant decrease in anther starch of the two varieties.Under drought treatment,the higher expression of SuSC and INV1 genes in the anthers of Dexiamian 1 than Yuzaomian 9110 resulted in less changed acrivities of SuSy and acid invertase,which ensured the rate of hydrolysis of sucrose into hexose.Moreover,under drought stress,the AGPase activity in the anther was significantly higher for Dexiamian 1 than Yuzaomian 9110,which also provided sufficient reaction substrate for GBSSase and SSSase to ensure the starch synhesis.Eventually,droughted anther of Dexiamian 1 had a higher starch content than that of Yuzaomian 9110.Drought stress reduced the activities of superoxide dismutase(SOD),peroxidase,catalase and antioxidant catalase(APX)in the anthers of the two varieties,and increased the content of hydrogen peroxide(H2O2)and malonaldehyde(MDA)in the anthers.Compared with Yuzaomian 9110,Dexiamian 1 had higher SOD and APX activities in anthetrs,which resulted in higher active oxygen scavenging ability of anthers,and smaller damage of active oxygen to anther cells in Dexiamian 1 than Yuzaomian 9110.Eventually resulted in less MDA and H2O2 in the anthers.This was one of the reasons for stronger pollen fertility in Dexiamian 1 than Yuzaomian 9110.更多还原