干旱及复水条件下转基因甘薯抗氧化防御系统特性

以转铜锌超氧化物歧化酶（Cu/Zn SOD）和抗坏血酸过氧化物酶（APX）基因甘薯(TS)及未转基因甘薯(NT)为实验材料,研究在旱后复水条件下转基因甘薯及未转基因甘薯抗氧化防御系统变化。结果显示,连续36h胁迫条件下,TS和NT的SOD活性都先降低后升高,但TS的SOD活性始终高于NT。胁迫至24h时,TS的SOD活性约为NT的1.2倍,复水后二者SOD活性都下降。持续胁迫时,TS的APX活性先升高后降低,NT与之相反,复水后TS和NT的APX活性都是先升高后降低,复水12h,TS的APX活性是NT1.5倍。在水分胁迫条件下,TS抗氧化物质AsA、CAR增长速度较快,复水后,TS中的AsA含量仍显著高于NT水分胁迫条件下TS的膜质受伤害程度要轻于NT,胁迫24h,复水12h,NT的MDA含量均约为TS的1.2倍。实验结果表明,同时转入SOD、APX抗氧化基因后,在胁迫及复水条件下转基因甘薯的抗氧化系统可以更好的对植株体进行保护及修复。     

玉米叶片气孔特征及气体交换过程对气候变暖的响应

气孔是植物叶片表面控制大气与植物间气体交换的孔状结构,对于生态系统碳、水循环过程的调节起着非常重要的作用。本文利用典型农田生态系统实验增温平台,研究了未来气候变暖对玉米叶片的气孔特征(包括气孔频度、气孔开口大小和形状以及气孔分布格局)和气体交换过程的影响。结果表明:(1)尽管增温并没有改变气孔密度(P0.05),但却由于表皮细胞数目的减少导致气孔指数显著增加12%(P0.05);(2)增温使气孔开口的长度显著减小18%(P0.01),宽度增加26%(P0.01),面积和周长分别增加31%(P0.01)和13%(P0.05);(3)实验增温还使单个气孔之间最近邻域的平均距离显著增加,表明气孔在玉米叶片上的分布变得更加均匀;(4)增温导致玉米叶片的净光合反应速率(Pn)、气孔导度(Gs)和蒸腾速率(Tr)分别增加52%(P0.05)、163%(P0.001)和81%(P0.05);与此相反,玉米叶片的暗呼吸速率(Rd)却显著降低24%(P0.01)。增温没有对细胞间CO2浓度(Ci)和水分利用效率(WUE)产生显著的影响(P0.05)。本研究结果表明,未来全球气候变暖可能通过改变玉米叶片的气孔频度、气孔开口大小和形状及其在叶片上的空间分布格局来改变其气体交换过程。     

高温条件下超级稻对灌水处理的响应及原因分析

(1 湖南省长沙农业气象试验站 湖南 长沙 410125; 2 湖南省水稻研究所 湖南 长沙 410125; 3湖南省气象科学研究所 湖南 长沙 410007)     

灌浆斯冬小麦对干旱胁迫的某些生理生化响应

灌浆期冬小麦在干旱胁迫下,叶片中Ｐｒｏ含量增加,抗旱性弱的品种升市幅度大于抗旱性强的品种;可溶性蛋白质和可溶性糖下降,抗旱性强的品种下降幅度小于抗旱弱的品种。     

高温条件下CO_2对黄瓜SOD、POD和CAT活性及其基因表达的影响

为了探索高温条件下,CO_2对保护酶SOD、POD和CAT活性及其基因相对表达量的影响,以温室嫁接黄瓜为材料,研究高温条件下,CO_2处理后黄瓜叶片中SOD、POD和CAT活性及其基因相对表达量的变化趋势。结果显示,高温条件下,CO_2处理增加了黄瓜叶片SOD、POD和CAT的活性。与常温处理相比,高温结合CO_2处理黄瓜的SOD、POD和CAT活性分别在处理42,28,21 d时差异最大,分别增加了19.1%,50.4%和45.0%。利用Real-time PCR分析SOD、POD和CAT基因相对表达量,结果显示,高温条件下,CO_2处理增加了黄瓜叶片的SOD、POD和CAT基因的相对表达量。高温结合CO_2处理中黄瓜的SOD、POD和CAT基因相对表达量分别在处理28,28,21 d时达到最大值,比常温处理增加了60.7%,70.3%和44.9%。结果表明,高温结合CO_2处理增加了温室黄瓜SOD、POD和CAT的活性及其基因的表达水平。     

棉花对水分胁迫及复水的生理生态响应

水分胁迫是田间条件下存在最广泛的一种作物生长逆境,了解作物对该逆境的响应,是对作物进行合理调控、实现农业节水的前提.过去研究大多集中在胁迫期间的作物响应,而对胁迫后复水作物在生理、形态上的响应认识有限.本文通过在棉花苗期和蕾期实施不同程度的水分胁迫处理,研究水分胁迫及复水对棉花生长发育和生理特性的影响,为作物优化用水方式提供理论依据.     

旱地条件下冬小麦产量和农艺性状对养分投入的响应

以9个旱地冬小麦品种为材料,通过田间试验研究其产量及主要农学性状与养分投入水平的关系。与不施肥对照相比,在低、高水平养分投入条件下小麦籽粒产量分别提高20%和40%,生物量提高17%和35%,单位面积穗数增加11%和25%,穗粒数增加8%和10%。高产品种的生物量、单位面积穗数、穗粒数及其随养分投入增加而提高的幅度显著高于低产品种。千粒重不受养分投入水平的影响。旱地条件下,不同小麦品种的产量、生物量、单位面积穗数和穗粒数均随养分投入水平的提高而显著提高,并且存在品种间差异。高生物量、高单位面积穗数和穗粒数是旱地高产品种的重要特征,它们对养分投入的敏感响应是高产品种养分投入提高后产量提高的主要原因。     

玉米花期干旱及复水对植株补偿生长及产量的影响

研究了花期干旱对盆栽玉米生长发育、生理特性和产量的影响及复水后植株的补偿生长。花期干旱使雌穗生长发育不良，产量下降，复水后被干旱所延迟的雌穗发育可以部分恢复，存在关明显的补偿生长。复水后产量的补偿表现为百粒重的增加，但这种补偿不足以弥补由于穗粒数的减少而导致的产量下降。随胁迫时间延长及胁迫强度的增加，叶片气孔阻力迅速增加，复水后气孔阻力迅速减少，胁迫强度愈大，恢复速率愈快、蒸腾速率与气孔阻力基本上     

持续干旱胁迫及复水对橡胶树渗透调节能力的影响

干旱胁迫是影响植物生长发育的重要因子。为了研究橡胶树的抗旱能力及其抗旱机制,以橡胶树为供试材料,通过盆栽试验,在温室条件下研究自然干旱胁迫和复水处理对橡胶树叶片渗透调节物质及细胞膜透性的影响。结果表明：随着干旱胁迫时间的延长,相对电导率、游离脯氨酸含量、可溶性糖含量及可溶性蛋白含量都呈现上升的趋势;复水处理后,相对电导率与可溶性蛋白含量均能恢复至对照水平;游离脯氨酸含量与可溶性糖含量呈下降趋势,但高于对照水平。综合各指标变化情况,说明橡胶树有着较强的抗旱和恢复能力。     

水分和CO2浓度对冬小麦气孔特征、气体交换参数和生物量的影响

利用可精准控制CO₂浓度([CO₂])的大型人工气候室, 研究了水分亏缺和[CO₂]升高对冬小麦气孔特征、气体交换参数及生物量的影响。结果表明, 水分亏缺导致冬小麦气孔开度减小和气孔空间分布的规则程度降低, 提高[CO₂]能够减缓水分亏缺时气孔开度和气孔分布规则程度的下降幅度。与充分灌溉相比, 不同水分亏缺条件下冬小麦的净光合速率、气孔导度和蒸腾速率均显著降低(P<0.05), [CO₂]仅可缓解轻度亏水对气体交换过程的影响, 该缓解能力随水分亏缺程度的加剧而降低。水分亏缺降低冬小麦生物量, 但[CO₂]升高对水分亏缺时生物量产生的影响不显著(P>0.05)。水分亏缺条件下, 冬小麦通过调整气孔开度和气孔空间分布格局改变叶片的气体交换效率, [CO₂]升高对冬小麦产生的“施肥效应”受土壤水分条件的限制。     

Independent and combined effects of high temperature and drought stress around anthesis on wheat

High temperature and drought stress are projected to reduce crop yields and threaten food security. While effects of heat and drought on crop growth and yield have been studied separately, little is known about the combined effect of these stressors. We studied detrimental effects of high temperature, drought stress and combined heat and drought stress around anthesis on yield and its components for three wheat cultivars originating from Germany and Iran. We found that effects of combined heat and drought on the studied physiological and yield traits were considerably stronger than those of the individual stress factors alone, but the magnitude of the effects varied for specific growth‐ and yield‐related traits. Single grain weight was reduced under drought stress by 13%–27% and under combined heat and drought stress by 43%–83% but not by heat stress alone. Heat stress significantly decreased grain number by 14%–28%, grain yield by 16%–25% and straw yield by 15%–25%. Cultivar responses were similar for heat but different for drought and combined heat and drought treatments. We conclude that heat stress as imposed in this study is less detrimental than the effects of those other studied stresses on growth and yield traits.     

CO2浓度对大豆叶片气孔特征和气体交换参数的影响

利用可精准控制CO₂浓度的大型气候箱设置7个CO₂浓度处理(400、600、800、1000、1200、1400和1600 μmol mol ^-1), 对大豆进行CO₂浓度富集的室内培养试验。结果表明, CO₂浓度升高显著减小大豆叶片近轴面的气孔密度和远/近轴面的气孔面积指数。当CO₂浓度为400 μmol mol ^-1时, 远轴面气孔分布最规则, 提高CO₂浓度导致远轴面气孔的不规则分布; 与远轴面相反, CO₂浓度升高导致近轴面气孔的空间分布更加规则, 即在较高CO₂浓度处理下的Lhat(d)最小值均低于对照组。不同叶面(远/近轴面)气孔特征对大气CO₂浓度变化的响应存在明显差异, 但大豆可以通过调整气孔形态特征和气孔空间分布格局进一步改变叶片的气体交换参数。研究结果有助于从气孔特征响应的角度深入理解CO₂浓度对大豆叶片气体交换过程产生的影响。     

Water-use efficiency, leaf area and leaf gas exchange of cowpeas under mid-season drought

Ten cowpea (Vigna unguiculata L. “Walp.”) genotypes were grown in a growth chamber under well-watered conditions up to early flowering and were then either subjected to water deficit or were continually well-watered. Water deficit was induced by withholding irrigation until the soil water potential was −75 kPa, which was then maintained for 10 days. Variation in water use efficiency (WUE), leaf area, specific leaf area (SLA), leaf area ratio (LAR) and leaf gas exchange (i.e. assimilation, transpiration, stomata conductance and internal CO₂ concentration) in response to water deficit were investigated. Water deficit treatment reduced mean water use by 21%. This caused between 11 and more than 40% reduction of biomass across the genotypes. Reductions in biomass were due to decline in leaf gas exchange and leaf area during water deficit. Water deficit improved the WUE of two genotypes (IFH 27-8 and Lobia) by approximately 20%, but caused moderate to huge reductions in most genotypes. High relative water content (RWC) of leaves was maintained in some of the genotypes by stomata closure and a reduction of leaf area. Drought avoidance by maintaining high leaf water content was negatively associated with leaf area as well as SLA. High assimilation rate under water deficit was associated with high RWC. Decline in assimilation rate were due mainly to stomata closure, however, some evidence of non-stomatal regulation were also found. WUE and instantaneous water use efficiency (IWUE, a molar ratio of assimilation to transpiration) were not directly associated, but IWUE and leaf internal CO₂ concentration (c_i) were negatively related while c_i was also moderately related with SLA. Overall, significant genotypic variations in leaf gas exchange parameters were found, which can give some indications of superiority when comparing cowpea genotypes for agronomic fitness under drought. The lack of relationship between WUE and IWUE was due to the instantaneous measurement of leaf gas exchange, which can be corrected by calculations to reflect the entire season.     

Comparison of osmotic adjustment,leaf proline concentration,canopy temperature and root depth for yield of juncea canola under terminal drought

Two glasshouse and two field experiments were conducted in 2013 and 2014 to compare the relative importance of four physiological traits: osmotic adjustment (OA), leaf proline concentration, canopy temperature depression (CTD) and root depth on drought performance of canola quality B. juncea (juncea canola). Glasshouse experiments were conducted at The University of Melbourne, Parkville, and field experiments were conducted at Horsham, Victoria. The experiments used juncea canola hybrids and their parental lines and were laid out in a randomised complete block design with three replications. The glasshouse experiments consisted of two treatments, well watered and water deficit from first open flower to maturity, whereas the field experiments were sown at a site that received 266 mm annual rainfall in 2014. In the glasshouse, canopy temperature depression was the only trait to show a positive and consistent association with drought performance of juncea canola. Cooler canopy temperature was also associated with improved yield in field experiments. Root depth was positively correlated with CTD in 2014 in glasshouse, whereas no correlation of root depth with OA and leaf proline was observed. The results indicated that CTD was the only reliable trait among those tested to screen juncea canola for drought tolerance. Root depth of juncea canola hybrids was a constitutive trait and probably was a result of hybrid vigour.     

大豆叶片响应CO2浓度升高、干旱及其交互作用的转录组分析

气候变暖及大气CO₂浓度升高成为全球共识,由此增加极端天气气候事件(干旱)发生的频率和强度并对大豆生产带来不确定性。本研究通过大豆表型和叶片转录组测序(RNA-seq)分析,阐释CO₂浓度升高、干旱及其交互条件对大豆基因表达影响,明确CO₂浓度升高影响大豆耐旱性的调控途径,并在两个不同遗传背景品种中验证,从分子水平为未来气候变化背景下大豆抗旱育种提供理论参考。表型结果表明, CO₂浓度升高促进了大豆的生长并缓解干旱胁迫的负面效应。叶片转录组测序分析共筛选到89个CO₂响应基因, KEGG分类显示这些基因主要参与抗氧化物质(萜类、黄酮类等)代谢,同时特异性差异表达基因功能主要集中在细胞组分和生长发育方面。干旱条件下筛选的1006个差异表达(16倍)基因主要参与各类氨基酸(脯氨酸、色氨酸等)代谢途径,绝大多数蛋白质合成与转运相关基因上调,表明干旱胁迫下大豆叶片内物质合成交换过程加强。交互条件下筛选出的8566个差异表达基因主要参与碳水化合物代谢,光合作用-天线蛋白途径的相关基因几乎...     

Effect of the transgenerational exposure to elevated CO2 on low temperature tolerance of winter wheat: Chloroplast ultrastructure and carbohydrate metabolism

The transgenerational effect of elevated atmospheric CO₂ concentration (e[CO₂]) on low temperature response in wheat is still little investigated, through the interaction of e[CO₂], and low-temperature stress has been reported in a single generation. Here, the low temperature-induced modifications of chloroplast ultrastructure and carbohydrate metabolism in wheat after four generations continuously grown under ambient CO₂ concentration (a[CO₂]) and e[CO₂] (2014–2018) were investigated. The results indicated that the transgenerational exposure to e[CO₂] increased the number of grana lamellae and the amounts of osmiophilic lipid droplets, attenuating the negative effect of low temperature on chloroplast ultrastructure. The transgenerational e[CO₂] enhanced the activities of antioxidant enzymes (i.e. SOD, POD and CAT) and concentrations of osmotic substances (i.e. proline and soluble sugar), which alleviated the low temperature-induced oxidative damage to the chloroplast ultrastructure. In addition, transgenerational exposure of wheat to e[CO₂] increased activities of vacInv and cwInv, while decreased fructokinase activity, which affected the sucrose metabolism in wheat leaf. These findings elucidated that transgenerational exposure to e[CO₂] could improve low temperature tolerance of winter wheat, which provide novel insights to the response of wheat to future climate change.     

Elevated CO2 modulates the effects of drought and heat stress on plant water relations and grain yield in wheat

To investigate the interactive effects of drought, heat and elevated atmospheric CO₂ concentration ([CO₂]) on plant water relations and grain yield in wheat, two wheat cultivars with different drought tolerance (Gladius and Paragon) were grown under ambient and elevated [CO₂], and were exposed to post‐anthesis drought and heat stress. The stomatal conductance, plant water relation parameters, abscisic acid concentration in leaf and spike, and grain yield components were examined. Both stress treatments and elevated [CO₂] reduced the stomatal conductance, which resulted in lower leaf relative water content and leaf water potential. Drought induced a significant increase in leaf and spike abscisic acid concentrations, while elevated [CO₂] showed no effect. At maturity, post‐anthesis drought and heat stress significantly decreased the grain yield by 21.3%–65.2%, while elevated [CO₂] increased the grain yield by 20.8% in wheat, which was due to the changes of grain number per spike and thousand grain weight. This study suggested that the responses of plant water status and grain yield to extreme climatic events (heat and drought) can be influenced by the atmospheric CO₂ concentration.     

氮素对高大气CO2浓度下小麦叶片光合功能的影响

为探讨高大气CO₂浓度下植物光合作用适应现象的光合能量转化和分配的氮素响应及其对C₃植物光合功能的影响,本试验对盆栽小麦进行2个大气CO₂浓度和2个氮水平的组合处理,通过测定小麦光合气体交换参数、叶绿素荧光参数和叶绿素含量等指标,研究施氮对高大气CO₂浓度下小麦叶片光合功能的影响。结果表明,大气CO₂浓度升高后,低氮处理小麦叶片光合速率发生明显的适应性下调,光合速率(P_n)、气孔导度(G_s)、蒸腾速率(T_r)下降;但高氮叶片则无明显的光合作用适应现象发生。高大气CO₂浓度下低氮叶片光化学速率、PSII线性电子传递速率(J_F)、光合电子流的光化学传递速率(J_C)、Rubisco羧化速率(V_C)和TPU下降,并随生育时期推进其下降趋势更为明显,但高氮叶片的上述参数无显著变化;小麦叶片J_C/J_F、V_C/J_C和V₀ /V_C随氮素水平和大气CO₂浓度的变化无显著变化,表明施氮能提高光合机构对光合能量的传递速率,但对光合能量的分配方向无明显影响。施氮提高小麦叶片氮素和叶绿素含量,并且使高大气CO₂浓度下光合氮素利用效率(NUE)明显增加。大气CO₂浓度升高后,施氮增强光合机构的光合能量运转速率,同化力提高,无明显的光合作用适应现象;由于氮素水平与大气CO₂浓度对小麦叶片的光合能量利用存在明显的交互作用,而且高大气CO₂浓度下施氮使得小麦叶片NUE增加、正常大气CO₂浓度下降低,证明高大气CO₂浓度下施氮对光合作用具有直接的影响。     

Sorghum bicolor prioritizes the recovery of its photosynthetic activity when re-watered after severe drought stress,while manages to preserve it under elevated CO2 and drought

Understanding plant response and resilience to drought under a high CO₂ environment will be crucial to ensure crop production in the future. Sorghum bicolor is a C₄ plant that resists drought better than other crops, which could make it a good alternative to be grown under future climatic conditions. Here, we analyse the physiological response of sorghum under 350 ppm CO₂ (aCO₂) or 700 ppm CO₂ (eCO₂) with drought (D) or without drought (WW) for 9, 13 and 16 days; as well as its resilience under long (R1: 9D + 7R) or short (R2: 13D + 3R) recovery treatments. Sorghum showed elevated rates of gs under aCO₂ and WW, which resulted in a significant decrease in Ψ_w, gs, E, Φ_PSII, F_v’/F_m′ when exposed to drought. Consequently, A was greatly decreased. When re-watered, both re-watering treatments prioritized A recovery by restoring photosynthetic machinery under aCO₂, whereas under eCO₂ plants required little recovery since plant were hardly affected by drought. However, sorghum growth rate for aboveground organs did not reach control values, indicating a slower long-term recovery. Overall, these results provide information about the resilience of sorghum and its utility as a suitable candidate for the drought episodes of the future.