粳稻超优1号背景回交导入系的耐热性筛选与评价

全球气候变暖不可避免地影响水稻的生产。本研究以粳稻品种超优1号为轮回亲本与9个来自不同国家的供体品种杂交培育的BC₂F₄回交导入群体为材料, 通过开花期高温胁迫, 共初筛到124个耐高温单株; 以粳稻为供体的回交导入群体出现耐热个体的频率高于籼稻供体的导入群体, 表明粳稻资源中同样存在耐热有利基因。经对初筛后代的耐热性重复鉴定和在正常条件下的性状评价, 发现有80个株系的结实率显著高于轮回亲本, 耐热性选择效率为64.5%, 这些耐热导入系的产量及其相关性状在高温胁迫和正常条件下均出现广幅分离, 从中鉴定出耐热性和产量性状均显著好于轮回亲本的8个优良导入系。在3个耐热导入系的聚合F₂群体中, 筛选出耐热个体的平均结实率在80%以上, 极显著高于轮回亲本和最高聚合亲本, 从中获得106株耐热性极显著好于聚合亲本的单株, 显示出较理想的耐热性聚合效果。通过对耐热导入系和轮回亲本在正常和高温胁迫条件下的产量以及相关性状的表型比较分析, 有助于提高对水稻耐热性状筛选中的供体选择、选择效率和筛选方法等一些重要问题的认识。本研究获得的高产耐热聚合系, 将为水稻耐热有利基因发掘和耐热性标记辅助选择聚合育种提供宝贵材料。     

SSR分子标记在小麦遗传育种中应用与研究进展

综述简单重复序列标记(SSR)的特点及优点,重点介绍了SSR分子标记在小麦遗传育种中的应用,即利用SSR分子标记技术基因标记与定位、遗传图谱构建、外源染色体鉴定与标记、种质资源鉴定和遗传多样性研究、辅助育种的研究进展。     

黑麦染色体特异分子标记的开发及应用研究进展

黑麦(Secale cereale L.)为小麦(Triticum aeistvum L.)三级基因源,是小麦改良育种中重要的遗传资源。分子标记作为鉴定外源遗传物质的有效手段,在小麦×黑麦杂交及黑麦、小黑麦品种培育中被广泛应用。本研究对黑麦特异性分子标记的开发,以及分子标记在黑麦遗传图谱构建、遗传多样性分析、优异基因发掘鉴定等方面的应用进行了综述,旨在为黑麦特异分子标记在小麦×黑麦分子辅助育种中的应用提供依据,为高效利用黑麦优异资源提供基础。     

籼稻开花期耐热性鉴定与QTL定位分析

高温热害是水稻生产的重要制约因素之一。本研究利用籼稻恢复系蜀恢527为轮回亲本,以来自不同来源的6个籼稻品种为供体亲本构建了131个BC2F3:4选择导入系群体,在正常大田和温室大棚高温胁迫条件下进行连续两年(2011年和2012年)的耐热性鉴定,并结合基因型分析进行产量相关性状和耐热性QTL定位。耐热表型分析结果表明,尽管轮回亲本和供体本身不具备很强的耐热性,但绝大多数导入系后代出现了耐热性的超亲分离。本研究通过分子标记基因型和表型分析的单向方差分析进行产量相关性状(每穗总粒数,结实率,千粒重,单株产量)和耐热性(热胁迫指数)QTL发掘,共定位的到39个产量相关性状QTL,贡献率为7.3%~39.7%和12个耐热性QTL,贡献率为14.7%~30.2%。12个耐热性QTL中,有9个也在产量相关性状中检测到。40例QTL有利等位基因来自供体亲本,61.5%的QTL能在不同群体或环境中被重复检测到。产量性状和耐热性QTL在染色体上大多成簇分布,每个簇往往同时影响几个性状(多效性)。其中,第2染色体上RM341(Bin2.8)对每穗总粒数、千粒重和单株产量影响较大;第7染色体RM051(Bin7.1)则是主要控制结实率、单株产量和耐热指数等性状。第10染色体RM258(Bin10.5)则是主要控制每穗总粒数和耐热指数等性状。研究结果将为水稻耐热性改良及其分子标记辅助育种提供有益信息。     

兰花热胁迫响应机制及耐热性研究进展

兰花是世界著名的花卉资源,具有极高的经济价值,是全世界重要的花卉贸易产品之一,也是中国重要的观赏花卉。近年来,随着全球气候变暖,高温已成为影响农作物产量和品质的主要环境因素之一,严重制约了兰花产业的发展。因此,兰花热胁迫响应机制及耐热性的研究是兰花产业应对全球气候变暖的重要内容。本研究系统地陈述了高温胁迫对兰花生长发育、生理代谢的影响、兰花热胁迫响应分子机制、耐热评价及提高耐热性途径等方面的研究进展,并对未来研究方向进行了探讨,以期为进一步研究兰花的耐热机制和耐热育种提供基础依据。     

小麦耐热性鉴定和热处理对品质的影响

为鉴定育成小麦品种的耐热性,同时也为小麦耐热育种提供种质资源,用千粒重热感指数和产量热感指数法鉴定河北、山西和山东省13个推广品种的耐热性。结果表明,晋麦47、石优20、泰山5366和金禾9123耐热性好;石麦22和石4185的产量在正常和热处理环境中差异不大,耐热性较好;衡136的产量和千粒重在正常环境下较高,但在热处理下产量和千粒重较低,耐热性较差。尧麦16的湿面筋、蛋白质、吸水率和延展性的差异极显著。石麦19、邢麦6、沧麦028、石麦22和金禾9123的湿面筋和蛋白质差异显著。     

分子标记辅助选育小麦抗白粉病、优质高分子量麦谷蛋白亚基聚合体

现代小麦育种的目标是选育丰产、综合抗逆性好的优质小麦新品种,将分子标记技术与传统育种方法相结合可以大大提高育种效率.本研究利用与小麦抗白粉病基因Pm21紧密连锁的共显性PCR标记、以及优质高分子量麦谷蛋白亚基1Dx5 1Dy10特异的PCR标记对以小麦品种安农94212、安农92484为优质亲本和以抗白粉病小麦簇毛麦易位系为抗病亲本的杂交高代材料进行标记位点的检测,结合田间抗病性鉴定结果,筛选、培育出聚合有Pm21和1Dx5 1Dy10的抗白粉病小麦聚合体,为小麦抗病、优质育种提供了具有重要利用价值的中间材料.     

作物耐热性研究进展

随着“温室效应”的不断加剧,短期异常高温发生频繁,高温已成为制约农业生产的重要非生物胁迫之一。在综述高温对作物生理生态、产量和品质形成的影响,作物耐热性分子遗传等关键问题的基础上,对作物耐热性研究领域提出了筛选优良耐热种质资源、加强作物耐热生理生化及遗传机理研究、加强作物高温热害预警机制和缓解高温胁迫技术研究等建议,以期为作物耐热性研究提供理论依据。     

水稻抽穗扬花期耐热性的QTL分析

培育高产稳产、对环境钝感的优质杂交稻新组合已成为当前水稻育种的重要目标;近年高温造成水稻结实率显著下降而导致产量的严重损失,水稻耐热性的改良也日益迫切。本研究用一个籼粳交重组自交系群体构建遗传连锁图谱,图谱拟合157个SSR标记位点,覆盖水稻基因组2352．62cM,标记间平均遗传距离14．89cM。以常温和高温结实率的差值作为耐热指数,采用复合区间作图法,对水稻抽穗扬花期的耐热性进行了QTL分析,在第2、3、5连锁群上检测到3个新的耐热QTL。贡献率为：6．59％、10．72％和10．7％,联合贡献率为28．01％。     

小麦光合作用与耐热性的关系初探

不同小麦品种对高温的反应存在差异。在田间选择４个耐热性不同的品种，于籽粒灌浆期测定植株旗叶在高温条件下的光合作用变化，结果分析表明耐热品种农大９３和农大９６比热敏感品种丰抗１３和京４１１具有较高的光合能力，并讨论了光合作用对小麦耐热性的重要性     

Genetic loci linking improved heat tolerance in wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.) to lower leaf and spike temperatures under controlled conditions

Heat stress adversely affects wheat production in many regions of the world and is particularly detrimental during reproductive development. The objective of this study was to identify novel quantitative trait loci (QTL) associated with improved heat tolerance in wheat (Triticum aestivum L.) and to confirm previous QTL results. To accomplish this, a recombinant inbred line (RIL) population was subjected to a three-day 38°C daytime heat stress treatment during early grain-filling. At maturity, a heat susceptibility index (HSI) was calculated from the reduction of three main spike yield components; kernel number, total kernel weight, and single kernel weight. The HSI, as well as temperature depression (TD) of the main spike and main flag leaf during heat stress were used as phenotypic measures of heat tolerance. QTL analysis identified 14 QTL for HSI, with individual QTL explaining from 4.5 to 19.3% of the phenotypic variance. Seven of these QTL co-localized for both TD and HSI. At all seven loci, the allele for a cooler flag leaf or spike temperature (up to 0.81°C) was associated with greater heat tolerance, indicated by a lower HSI. In a comparison to previous QTL results in a RIL population utilizing the same source of heat tolerance, seven genome regions for heat tolerance were consistently detected across populations. The genetic effect of combining three of these QTL, located on chromosomes 1B, 5A, and 6D, demonstrate the potential benefit of selecting for multiple heat tolerance alleles simultaneously. The genome regions identified in this study serve as potential target regions for fine-mapping and development of molecular markers for more rapid development of heat tolerant germplasm.     

Mapping quantitative trait loci associated with grain filling duration and grain number under terminal heat stress in bread wheat (Triticum aestivum L.)

Terminal heat stress has the potential negative impact on wheat production across the world, especially in South Asia. Under the threat of terminal heat stress, wheat genotypes with stay green trait would suffer from high temperature stress during their long grain filling duration (GFD). The genotypes with short GFD would be advantageous. To identify quantitative trait loci (QTL) for heat tolerance, a RIL population of K 7903 (heat tolerant) and RAJ 4014 (heat sensitive) wheat genotypes was investigated under timely and late‐sown conditions. Heat susceptibility index of GFD, yield components and traits under late‐sown condition were used as phenotypic data for QTL identification. Stable QTLs associated with these traits were identified on chromosomes 1B, 2B, 3B, 5A and 6B. The LOD value ranged from 2.9 to 5.0 and the corresponding phenotyping variation explained ranged from 12.0–22%. QTL for heat susceptibility index for the grain filling duration were colocalized with QTL for productive tillers under late sown and GFD under late‐sown condition on chromosomes 1B and 5A, respectively. These genomic regions could be exploited for molecular wheat breeding programmes targeting heat tolerance.     

Effect of Heat Stress on Grain Starch Content in Diploid, Tetraploid and Hexaploid Wheat Species

Heat stress during grain development adversely affects the starch content of grain in wheat, which results in poor grain quality and yield. Identification of the sources of heat tolerance for grain starch content in wheat species is an important step towards breeding for heat‐tolerant wheat. In this study, 32 wild and cultivated genotypes belonging to diploid (probable donors of B, A and D genomes), tetraploid (BBAA and AAGG genomes) and hexaploid (BBAADD genome) wheat species were evaluated for heat stress tolerance in the field at the Indian Agricultural Research Institute (IARI), New Delhi, India (77°12′ E; 28°40′ N; 228.6 m m.s.l) on two dates, 18 November (normal sowing) and 15 January (heat stress), during 1995–96. The crop sown in January experienced mean maximum temperatures of 31.0–39.3 °C during grain development, which are considered to represent heat stress for wheat grain development. Hexaploids had the highest grain starch content and the lowest heat susceptibility index, followed by tetraploid and diploid species. The heat susceptibility index (S) for grain starch correlated significantly and positively with that of grain weight (Y = 1.259X ? 0.29, R² = 0.8902, P < 0.001) across wheat species, while the actual grain growth duration or the ‘S’ of grain growth duration did not correlate significantly with that of grain weight. Hence, a high mean grain growth rate under heat stress is a better trait for heat tolerance than long grain growth duration. Wide genetic variability for heat tolerance in grain starch content was observed among the wheat species. Hence, the grain weight and quality under heat stress can be improved by using the variability available among wheat species.     

小麦耐热性研究

对８个小麦品种开花后的耐热性研究结果表明，耐热性在小麦品种间存在着较大的遗传差异，耐热性的高低与品种叶片的叶绿素含量、丙二醛含量、冠层温度显著相关，它直接影响到品种开花后的同化物积累量；叶片细胞膜热稳定性和冠层温度可以作为小麦抗热性育种的选择指标。     

Evaluation of drought and heat tolerance in wheat based on seedling traits and molecular analysis

Polyethylene glycol and cell membrane stability (CMS) assay were used to evaluate drought and heat tolerance, respectively, among 14 wheat lines based on seedling traits and molecular analysis. Significant variation was evidenced for all the investigated seedling traits. Different levels of heritability and genetic advance were found among the tested traits, indicating whether the trait is controlled by additive or non-additive gene action. Drought caused a significant reduction in root and shoot lengths. However, root/shoot ratio under drought stress was increased. Root length showed a highly significant negative correlation with drought susceptibility index (DSI) under drought conditions. Cluster analysis based on seedling traits separated lines mainly by DSI and CMS. Some lines showed drought and heat tolerance by exhibiting a low DSI with high CMS. Sequence-related amplified polymorphism (SRAP) generated a total of 135 bands, with a level of polymorphism ranging from 30 to 86% among the tested lines. SRAP showed its efficiency in discriminating wheat genotypes by gathering all high-DSIlines in one sub-cluster and generating 10 and 3 unique and specific bands for high-DSI-lines and low-DSI-lines, respectively. These bands could be used for further work as SRAP markers associated with drought tolerance in wheat.     

冬小麦品种生育后期的耐热性评价

冬小麦品种生育后期耐热性遗传差异的表现受环境影响较大。通过1997～2000年间在北京对群体气-冠温差、灌浆特性、热感指数等三种耐热性评价方法有效性的比较研究，认为热感指数反映品种对后期热胁迫的敏感程度，利用千粒重热感指数可鉴定出后期耐热性较好的基因型。气-冠温差法快速、简便、准确，但叶片持绿期长的品种气-冠温差一般较大，可结合对灌浆速率的评价来筛选生育期适中的耐热基因型。在3年的试验中，小麦品种鲁936098表现耐热性强，千粒重稳定。     

QTL associated with heat susceptibility index in wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.) under short-term reproductive stage heat stress

Heat stress adversely affects wheat production in many regions of the world and is particularly detrimental during reproductive development and grain-filling. The objective of this study was to identify quantitative trait loci (QTL) associated with heat susceptibility index (HSI) of yield components in response to a short-term heat shock during early grain-filling in wheat. The HSI was used as an indicator of yield stability and a proxy for heat tolerance. A recombinant inbred line (RIL) population derived from the heat tolerant cultivar ‘Halberd’ and heat sensitive cultivar ‘Cutter’ was evaluated for heat tolerance over 2 years in a controlled environment. The RILs and parental lines were grown in the greenhouse and at 10 days after pollination (DAP) half the plants for each RIL received a three-day heat stress treatment at 38°C/18°C day/night, while half were kept at control conditions of 20°C/18°C day/night. At maturity, the main spike was harvested and used to determine yield components. A significant treatment effect was observed for most yield components and a HSI was calculated for individual components and used for QTL mapping. QTL analysis identified 15 and 12 QTL associated with HSI in 2005 and 2006, respectively. Five QTL regions were detected in both years, including QTL on chromosomes 1A, 2A, 2B, and 3B. These same regions were commonly associated with QTL for flag leaf length, width, and visual wax content, but not with days to flowering. Pleiotropic trade-offs between the maintenance of kernel number versus increasing single kernel weight under heat stress were present at some QTL regions. The results of this study validate the use of the main spike for detection of QTL for heat tolerance and identify genomic regions associated with improved heat tolerance that can be targeted for future studies.     

A strategy of ideotype development for heat-tolerant wheat

Heat stress significantly limits yield in many wheat-growing areas globally including north-western NSW. While various traits linked to high-temperature tolerance have been identified, the combination of traits that optimize the heat tolerance of wheat has not been established in most environments. A total of 554 genotypes were evaluated in the field at different times of sowing in north-western NSW for three consecutive years to develop a heat-tolerant wheat ideotype for this environment. The later sown experiments were exposed to higher temperatures at the critical reproductive and grain-filling stages of development. The impact of high temperature was greatest at anthesis, and eventual grain yield was reduced by between 4% and 7% with every 1°C rise in average maximum temperature above the optimum of 25°C. High temperature reduced yield, plant height, grain weight and days to anthesis and maturity, and increased the percentage of screenings and grain protein content. Genotypes that produced higher yield under heat stress had shorter days to flowering and maturity, higher NDVI during grain filling, greater chlorophyll content at the milk stage of grain fill, taller plants, greater grain weight and number, and lower screenings compared with the benchmark cultivar Suntop. The genotype closest to the predicted heat-tolerant wheat ideotype identified from trait ranges had 79.6% similarity.     

Application of natural plant extracts improves the tolerance against combined terminal heat and drought stresses in bread wheat

Drought and heat are among the main abiotic stresses causing severe damage to the cereal productivity when occur at reproductive stages. In this study, ten wheat cultivars were screened for combined heat and drought tolerance imposed at booting, heading, anthesis and post‐anthesis stages, and role of the foliage applied plant extracts was evaluated in improving the performance of differentially responding wheat cultivars under terminal heat and drought stresses. During both years, wheat crop was raised under ambient temperature and 70% water holding capacity (WHC) till leaf boot stage. The plant extracts (3% each) of sorghum, brassica, sunflower and moringa were foliage applied at booting, anthesis and post‐anthesis stage; and after one week of application of these plant extracts, combined heat and drought was imposed at each respective stage. Heat and drought stresses were imposed at each respective stage by placing pots in glass canopies with temperature of 4 ± 2°C above than the ambient temperature in combination with drought stress (35% WHC) until maturity. Combination of drought and heat stresses significantly reduced the performance of tested wheat cultivars; however, stress at the booting and heading stages was more damaging than the anthesis and post‐anthesis stages. Cultivars Mairaj‐2008 and Chakwal‐50 remained green with extended duration for grain filling, resulting in the maintenance of number of grains per spike and 100‐grain weight under stress conditions and thus had better grain yield and water‐use efficiency. However, in cultivars Fsd‐2008, and Shafaq‐2006, the combined imposition of drought and heat accelerated the grain filling rate with decrease in grain filling duration, grain weight and grain yield. Foliar application of all the plant extracts improved the wheat performance under terminal heat and drought stress; however, brassica extract was the most effective. This improvement in grain yield, water‐use efficiency and transpiration efficiency due to foliage applied plant extracts, under terminal heat and drought stress, was owing to better stay‐green character and accumulation of more soluble phenolics, which imparted stress tolerance as indicated by relatively stable grain weight and grain number. In crux, growing of stay‐green wheat cultivars with better grain filling and foliage application of plant extracts may help improving the performance of bread wheat under combined heat and drought stresses.     

Exogenous application of allelopathic water extracts helps improving tolerance against terminal heat and drought stresses in bread wheat (Triticum aestivum L. Em. Thell.)

The allelopathic water extracts (AWEs) may help improve the tolerance of crop plants against abiotic stresses owing to the presence of the secondary metabolites (i.e., allelochemicals). We conducted four independent experiments to evaluate the influence of exogenous application of AWEs (applied through seed priming or foliage spray) in improving the terminal heat and drought tolerance in bread wheat. In all the experiments, two wheat cultivars, viz. Mairaj‐2008 (drought and heat tolerant) and Faisalabad‐2008 (drought and heat sensitive), were raised in pots. Both wheat cultivars were raised under ambient conditions in the wire house till leaf boot stage (booting) by maintaining the pots at 75% water‐holding capacity (WHC). Then, managed drought and heat stresses were imposed by maintaining the pots at 35% WHC, or shifting the pots inside the glass canopies (at 75% WHC), at booting, anthesis and the grain filling stages. Drought stress reduced the grain yield of wheat by 39%–49%. Foliar application of AWEs improved the grain yield of wheat by 26%–31%, while seed priming with AWEs improved the grain yield by 18%–26%, respectively, than drought stress. Terminal heat stress reduced the grain yield of wheat by 38%. Seed priming with AWEs improved the grain yield by 21%–27%; while foliar application of AWEs improved the grain yield by 25%–29% than the heat stress treatment. In conclusion, the exogenous application of AWEs improved the stay green, accumulation of proline, soluble phenolics and glycine betaine, which helped to stabilize the biological membranes and improved the tolerance against terminal drought and heat stresses.