【作者】 戴飞；

【导师】 张国平；

【作者基本信息】 浙江大学 ， 作物学， 2009， 博士

【摘要】 低温是一种全球普遍发生、影响农作物生产的环境胁迫。作为世界上第四大谷类作物,大麦种植分布十分广泛。在冬大麦种植区,冬季极端低温一般并不导致苗期遭受严重冻害,而春季时常发生的低温寒潮常造成减产。防御这种灾害性天气,提高大麦生殖生长期低温耐性是最根本且有效的途径。本研究旨在探讨大麦耐低温种质资源筛选技术,并试图明确大麦营养生长期和生殖生长期低温耐性机制的差异,为大麦育种提供理论依据和种质筛选技术方法。主要研究结果如下:大麦等越冬作物耐低温的一个重要农艺特性是冷驯化。以苗期低温敏感性不同的两个大麦品种为材料,探讨了冷驯化和光强对大麦非致死冻害处理后恢复过程中叶片H₂O₂积累和ROS清除系统的影响,并利用叶绿素荧光技术研究恢复过程中光合器官功能的变化。结果表明:在冻害损伤发生后的恢复过程中测定叶绿素荧光参数可以直接了解植物体的生活力指标,从而明确低温和光照强度这两个重要的环境因子对相关指标的影响。冷驯化可能并不直接增强大麦的抗冻性,但它可显著提高大麦冻害损伤后的恢复能力,并显著增强冷驯化植株对过剩光能和光抑制的应对能力。细胞膜是植物受低温损伤的初始位点,且根系的稳定性在植物体抵御低温胁迫及其恢复生长过程中起着重要的作用。为检测大麦根系离子流对低温胁迫的反应,本研究在国内首次采用澳大利亚塔斯马尼亚大学Newman等研制的MIFE（Microelectrode Ion Flux Estimation）技术,比较了低温胁迫下3个大麦品种的H⁺离子流和K⁺离子流动力学,并研究不同温度胁迫对根系K⁺离子吸收能力的影响。结果表明,利用MIFE技术进行离子流的测定,可以及时准确地监测到大麦根系离子流受低温胁迫而引起的细微变化,可为大麦低温胁迫生理研究和种质筛选提供一种潜在的方法。同时证明低温处理显著抑制大麦根系K⁺的吸收,且在本实验的非致死低温胁迫后经过短暂的恢复,大麦根系K⁺的吸收能力即可得到显著的恢复。光温变化显著影响植物光合器官的功能,从而抑制大麦生长和产量形成。本研究采用抽穗期低温耐性有一定差异的2个大麦品种,利用人工气候室进行低温肋、迫处理,分析低温胁迫后恢复过程中的光合作用相关参数,旨在明确大麦生殖生长期低温耐性的基因型差异及其生理机制。结果表明,在大麦抽穗期利用实验室（人工气候室）处理可以有效模拟自然低温条件,可作为大麦生殖生长期耐低温种质材料的鉴定方法之一。同时,本研究首次尝试利用离体穗培养的方法在大麦生殖生长期进行低温处理,通过研究低温对大麦离体穗的旗叶光合器官的影响,证明该方法可用于大麦生殖生长期耐低温种质的筛选,可克服因生育期差异而造成的大田筛选困难,也可减少整株植物体移栽需要的大量人力物力。同时,本研究采用这一方法对一个大麦DH群体进行了生殖生长期低温耐性相关基因的QTL分析,在3H染色体上检测到一个与低温耐性有关的QTL位点。更多还原

【Abstract】 Low temperature is a major environmental stress for cereal crops worldwide, reducing yield potential and grain quality of barley in sensitive reproductive stages. Barley （Hordeum vulgare L.） is a major world crop ranked the fourth in planting areas among cereal crops. In general, extreme low temperature in winter does not cause considerable damage to barley seedlings in the winter-barley growing areas. However, frost or low temperature frequently occurring in spring affects barley grain production significantly, because the plants at reproductive stage are quite sensitive to low temperature. Developing of frost-tolerant barley in reproductive stages is one of basic and effective approaches to fignt against the low temperature during spring. This study is going to developing potential methods of screening barley germplasm with low temperature tolerance. Meanwhile a comprehensive study was undertaken to compare the difference in low temperature tolerance between vegetative and reproductive stage of barley plants.One of the most important agronomic traits in barley is freezing tolerance, which can be enhanced by cold acclimation. In order to clarify the mechanisms of alleviating injury by cold acclimation in vegetative stage, two winter barley cultivars with different cold tolerance in vegetative stage were used to study the effect of irradiance on leaf H₂O₂ accumulation and ROS scavenging systems after removal of unlethal freezing stress. Moreover, the functions of photosynthetic apparatus in leaves were measured by chlorophyll fluorescence during recovery. The results indicated that some chlorophyll fluorescence parameters during recovery from freezing treatment might be used as the indicators in identification and evaluation of cold tolerance in barley. The functions of photosynthetic apparatus were affected by irradiance after freezing stress. It can be concluded that cold acclimation may not directly enhance cold tolerance of barley plants, but it increased recovery ability from freezing injury, and the ability to cope with excess energy and photoinhibition was much improved in cold-acclimated plants.The primary sites of chilling action appear to be plant membranes, and the membrane stability in root plays a central role in cold stress tolerance and recovery from cold injury. MIFE technique, developed by Newman in University of Tasmania, Australia, was employed to determine the effect of low temperature stress on ion flux from barley roots. Root H⁺ and K⁺ flux of three barley cultivars were measured and the effect of low temperature on K⁺ uptake by barley roots was studied. As a effective, non-invasive, and laboratory-based technique, MIFE technique can detect minimum fluctuation of ion flux caused by low temperature stress in barley roots. The possibility of using MIFE technique as a potential screening tool in identification and screening of barley genotypes with high frost tolerance was tested. The results showed the potential value of the technique. Meanwhile, it was proved that the ability of K⁺ uptake by barley roots was significantly inhibited by low temperature stress, and it can be reversed dramatically after removal of un-lethal low temperature.The functions of photosynthetic apparatus were affected by irradiance and temperature. In order to clarify the variation of genotypes and mechanisms of frost tolerance at reproductive stage of barley, two winter barley cultivars with different frost tolerance at reproductive stage were used in this study. Photosynthetic apparatus were measured during recovery stage after low temperature stress. The results showed that growth chamber could be used to simulate low temperature stress at reproductive stage of barley, and to evaluate frost tolerance of barley genotypes. Moreover, In vitro culture method was employed to investigate the photosynthetic apparatus responses of detached flag leaves to low temperature stress. The evaluation of the differences among barley genotypes in their responses to low temperature occurring at reproductive stage is limited by uncertainty in a course of weather and different growth rate. The results indicated that In vitro culture may provide an effective method of screening and evaluating barley germplasm in low temperature tolerance at reproductive stage. Meanwhile, In vitro culture method was used to evaluate frost tolerance of a double haploid population, and the analysis of QTLs controlling frost tolerance was conducted. A QTL relevant to frost tolerance was located on chromosome 3H.更多还原