Regulatory Mechanism of the Photosynthetic Pathway in Dwarfed Upland Cotton (Gossypium hirsutum L.)

[Objective] Here, we examined the mechanism of the photosynthetic pathway in dwarfed upland cotton (Gossypium hirsutum L.). [Methods] The upland cotton dwarf line LA-1 and the near-isogenic line LH-1 were used as research materials. We screened for dwarf-related differentially expressed genes at protein and mRNA levels by applying the isobaric tags for relative and absolute quantitation method in combination with LC-MS/MS quantitative proteomic technology and quantitative reverse-polymerase chain reaction. The difference in the photosynthetic abilities between the two materials were detected using physiological and biochemical methods. [Results] An analysis on the differential expression of proteins encoded by photosynthetic system elements revealed that PsbO, PsaE, PsaH, PetF-1 and PetF-2 were down-regulated, while PetC and delta were up-regulated in LA-1. The expression trends of the mRNA levels were the same as at the protein levels, except for those of the delta gene. The net photosynthetic rate, stomatal conductance and transpiration rate in LA-1 were lower than those LH-1, but the intercellular CO₂ concentration was not significantly different after budding. This indicated that the non-stomatal factor led to a decreased net photosynthetic rate in LA-1. Chlorophyll fluorescence detection revealed that the actual photosynthetic efficiency and potential photochemical activity of photosystem II in LA-1 were significantly decreased, while non-photochemical quenching was significantly increased. [Conclusion] The dwarfism of LA-1 is related to the photosynthetic pathway, and the results lay a foundation for exploring key dwarf-related genes and the molecular basis for dwarfism in upland cotton.     

棉花抗坏血酸过氧化物酶基因GhAPX的克隆及耐冷性初步鉴定

抗坏血酸过氧化物酶(ascorbate peroxidase,APX)是活性氧H2O2的清除剂,对抵抗植物逆境发挥着重要的作用。为了探究棉花APX基因的耐冷功能,本实验应用RT-PCR和RACE技术从苗期耐冷型棉花品种‘新陆早25号’叶片中克隆得到一个APX基因GhAPX,并对转基因烟草的主要抗氧化酶活性和快速荧光参数进行了分析。结果表明,该基因c DNA全长1763 bp,开放阅读框1137 bp,编码379个氨基酸。Blastx比对表明该基因与已克隆的棉花气孔APX相似性最高,达99%。进化分析表明该基因与刚毛怪柳关系较近,与拟南芥(AtAPX)和小麦(TaAPX)关系较远。蛋白质结构分析显示该基因属于植物过氧化物酶基因家族,亚细胞定位结果显示该蛋白位于叶绿体中。实验成功构建了植物表达载体PZP35S-GhAPX。转基因研究发现,转GhAPX基因会提高烟草的POD和CAT活性。在4℃冷害条件下,转基因烟草的POD和CAT活性及Fv/Fm和pI均大于野生(对照)株,且下降幅度和速度均小于野生植株,而SOD活性在转基因和野生植株间差异不大,初步推测GhAPX基因可以提高棉花幼苗的低温冷害抵抗力。本研究为揭示GhAPX基因的功能及其与棉花耐冷性的关系提供了理论参考。     

Effects of Foliar Nitrogen Applications on the Absorption of Nitrate Nitrogen by Cotton Roots

[Objective] The purpose of this study was to explore the effects of foliar nitrogen application on nitrate nitrogen uptake and cotton growth. [Method] The experiment was carried out using the ¹⁵N isotopic tracer technique in a greenhouse hydroponic culture experiment. Four foliar treatments were applied; ammonium nitrogen, nitrate nitrogen, amide nitrogen treatments (all with the same concentration of nitrogen applied), and a water control treatment. [Result] Compared to the water control treatment, the nitrogen contents of the cotton shoots and the whole plant were significantly higher in plants with foliar nitrogen treatments 6 d after application. The nitrogen accumulation in the shoots, roots, and total plants was higher with the ammonium nitrogen treatment, but there was no significant difference among treatments. The isotopic tracer results showed that ¹⁵N accumulation in the shoot and root was 0.794 mg·plant^－1 and 0.318 mg·plant^－1 with the ammonium nitrogen treatment, respectively. These values were higher than the ¹⁵N accumulation with the water control treatment and the amide nitrogen treatment and significantly higher than the nitrate treatment. After foliar application, the plant accumulation of nitrogen via root uptake was approximately 11.35 mg with the ammonium nitrogen treatment. Compared with the water control treatment, the nitrogen uptake efficiency increased by 28.0% with the ammonium nitrogen treatment and reduced by 9.5% and 20.5% with the amide nitrogentreatment and the nitrate treatment, respectively. The proportion of nitrogen from root uptake was about 7:3 between the shoots and the roots with each treatment, indicating that the form of foliar-applied nitrogen did not affect the distribution of nitrate nitrogen via root uptake. [Conclusion] Foliar application of ammonium nitrogen could, therefore, promote nitrate nitrogen uptake by cotton seedling roots.     

脱落酸和热激处理对棉花苗期生长的影响

采用人工气候箱研究了棉花(Gossypium hirsutum L.)种子热激萌动(42℃)2 h、ABA(10-5mol/L)浸种6 h、二叶期用ABA叶面喷施和根部灌施对棉苗抵御高温干旱逆境能力的影响。结果表明,与对照相比,各处理对棉苗生长具有一定的抑制作用,其中对苗高和茎粗的抑制作用较大;但在遭遇高温干旱条件时,各处理苗高增长速度较慢,但生物质量增加速度较快。说明一定程度的逆境锻炼有助于棉苗获得一定抵御逆境的能力。     

基于异速生长关系的棉籽油分含量模拟模型

基于不同熟性棉花品种的异地分期播种和施氮量试验,分析棉籽油分含量与棉籽生物量间的异速关系,综合品种特性、主要气象条件,以棉籽生物量为驱动,建立基于异速生长关系的棉籽油分含量模拟模型。利用不同生态点品种、播期和施氮量的田间试验资料的检验结果表明:安阳、淮安和徐州试点模拟值与实测值的RMSE分别为2.2%、2.9%和2.4%。说明依据棉籽油分含量与生物量间的异速生长关系预测棉籽油分含量切实可行,模型预测性好,广适性较强。     

高品质陆地棉铃-叶系统干物质质量的发育遗传研究

 应用加性-显性发育遗传模型及条件与非条件的统计分析方法,对6个高品质陆地棉品种（系）及其30个F₁组合的伏桃与对位果枝叶的干物质质量进行了研究。非条件方差分析表明,果枝叶质量在棉铃体积增大期主要受加性效应控制,内部充实期主要受显性效应控制;铃壳质量在不同发育时期均以加性效应为主;铃重在前中期主要受显性效应控制,后期以加性效应为主。条件遗传分析表明,影响果枝叶质量的净遗传效应在铃龄38 d至45 d达到高峰;控制铃壳质量的基因表达分别在铃龄17 d至24 d和铃龄38 d至45 d出现两个高峰;影响铃重性状的基因分别在铃龄17 d至24 d和铃龄31 d至38 d出现两个表达活跃的高峰,此后基因的表达量急剧下降。遗传相关分析表明不同发育时期的铃壳质量均与最终铃重成极显著的加性正相关。     

陆地棉三个WRKY基因的克隆及表达分析

WRKY转录因子可调控下游抗逆基因的表达,进而在植物生长发育以及对外界环境的反应中起着重要的调控作用,目前对棉花WRKY家族基因的研究比较少。本研究利用电子克隆的方法,从陆地棉品种山农圣杂3号中克隆得到了3个具有完整开放阅读框的棉花WRKY基因,聚类分析表明它们同属于WRKY家族中的第Ⅱ类。利用RT-PCR结果表明:250mmol/LNaCl盐胁迫和20%PEG6000干旱胁迫下同时诱导GhWRKY4的基因表达,GhWRKY5仅受干旱胁迫下的诱导,而GhWRKY6对这两种逆境胁迫都没有变化。     

棉花无菌苗培养条件的探讨

以棉花(Gossypium hirsutum L.)种子为试验材料,对无菌苗培养前种子消毒和接种的最佳条件进行了研究。结果表明,棉花种子消毒的最佳条件为1.0 g/L升汞消毒5 min或50.0 g/L次氯酸钠消毒15min,无菌水冲洗5～6次,无菌水浸泡24 h,倒掉瓶中的无菌水后换上新的无菌水继续浸泡至种子露白约3～4 mm,手捏种子的子叶端挤掉种皮,胚根端接触培养基的方式接种至MS基本培养基。     

对一个新发现的棉纤维突变体的鉴定及特性分析

在农杆菌介导的转基因组织培养再生后代中发现了一个无绒有絮的纤维发育突变体,通过自交选择T₃代获得其纯合体,命名为CM突变体。尽管CM突变体从转基因后代中发现,但和转基因插入位点无关,推测是在组织培养过程中产生的点突变所致。通过与陆地棉遗传标准系TM-1,海岛棉军海1号,以及新乡小吉无绒有絮(XinFLM),新乡小吉无绒无絮(XinWX),徐州142无绒无絮(XZ142WX),显性光子N1N1,隐性光子n2n2、SL-7-1、MD17及T586等一系列纤维发育突变体分别配制F₂组合进行突变基因的遗传及等位性分析,结果表明CM突变体与纤维发育正常的TM-1和军海1号杂交,F₁表型均为无绒有絮,F₂表现无绒有絮和有绒有絮3∶1分离,说明该突变体与纤维发育正常材料相比,在短绒发育方面存在一个位点的差异,该突变性状由单显性基因控制。等位性测验及分子定位均表明, 控制该突变体短绒的基因与控制N1N1显性光子的N1基因等位。扫描电镜进一步证明该基因突变会造成纤维起始突起延迟。与N1N1突变体相比,CM突变体的衣分比N1N1显著高,而百粒重比N1N1极显著低。推测CM突变体中的突变基因与显性N1基因为复等位基因。