作物耐热性的评价

对作物耐热性进行评价,是耐热性机制研究和耐热性品种选育的基础.在综述了作物耐热性评价的基础、评价方法以及评价指标的基础上,展望了作物耐热性评价的研究方向.     

植物耐热性及热激信号转导机制研究进展

随着温室效应的加剧,全球气候变暖已经成为现代农业生产体系所面临的严峻挑战．高温灾害性气候是影响作物产量的一种主要的非生物胁迫．因此,对于农作物生产而言,研究植物耐热信号转导机制不仅有重要的科学意义,而且有现实的紧迫性．最近几年,在阐明植物耐热信号转导机制的研究方面取得了很多重要的进展,这些进展涵盖植物高温胁迫的感受机制、热激转录因子和热激蛋白的表达调控、热激转录因子结合蛋白参与耐热性调控的分子机制等几个主要的方面．热胁迫影响细胞膜系统、RNA、蛋白质的稳定性,同时改变酶的活性和细胞骨架系统．当热胁迫来临时,植物的转录组会发生显著变化,所涉及的基因大约占基因组的2％．这些高温胁迫响应基因构成了热激响应网络,是植物抵御热胁迫的第一道防线．植物的耐热性分为基础耐热性和获得性耐热性．基础耐热性是植物固有的耐热性．获得性耐热性是温和的热驯化诱导的耐热性．获得性耐热性状的形成反映了植物在自然生长环境下适应高温胁迫的生理机制．     

茄子苗期耐热性的模糊综合评判

确定客观、合理的耐热性评价指标,评价不同品种蔬菜的耐热性强弱,对其耐热性机制的研究及耐热性品种的选育具有重要的意义。以不同耐热性的茄子品种为材料,测定苗期耐热性相关的生理生化指标,采用层次分析法(AHP)确定各耐热性指标的权数,通过模糊数学原理对茄子的耐热性进行综合评价分析。结果表明:热害指数、恢复指数、MDA含量、SOD活性、POD活性对耐热性影响较大,其权重依次为:0.2500、0.2500、0.1092、0.1092、0.1092。综合评价结果为茄子品种友谊一号耐热性最强,F-762茄子耐热性居中,古田紫长茄耐热性最弱,与田间自然高温鉴定结果一致,表明此方法对茄子苗期耐热性进行综合评价有较好的适用性,可用于大批量品种的耐热性鉴定。     

作物种质资源品质性状鉴定评价现状与展望

作物种质资源品质性状鉴定评价是作物种质资源研究的重要方面,是深入挖掘、广泛利用作物种质资源的基础。本文对近年来作物种质资源品质性状鉴定评价情况进行了回顾,总结了鉴定评价工作取得的主要进展:完成了近20万份的作物种质资源(约占保存总数的50%)主要营养品质性状的初步鉴定评价;作物种质资源品质鉴定评价内容涉及面广、鉴定的品质性状变异性大、多样性丰富;提高了作物种质资源品质性状鉴定评价标准化程度。此外还介绍了国际上有关品质性状鉴定的发展趋势,并对未来国内作物种质资源品质性状鉴定评价提出了意见和建议。     

作物种质资源调查收集的理论基础与方法

作物种质资源调查与收集是作物种质资源保护、基础研究、鉴定评价和创新利用的基础。调查获得的地理分布、生态类型、特征特性等可为作物起源进化和保护生物学研究提供信息支撑,收集到的作物种质资源的多样性对是否能够发掘出具有重要利用价值的资源具有决定性作用。本文简要回顾了作物种质资源调查收集历史,从物种分布不平衡性、作物起源中心与种质资源分布、人类文明对作物起源与品种演化的影响等3个方面阐述了作物种质资源调查收集相关的理论基础,详细介绍了作物种质资源调查收集的方法,提出了未来作物种质资源调查收集的发展趋势。     

小麦耐热性鉴定方法及热胁迫应答机理研究进展

小麦是全球最重要的粮食作物之一,高温特别是开花期和灌浆期的高温胁迫严重影响小麦的产量和品质。本文从直接鉴定法和间接鉴定法两个方面提出了小麦耐热性的评价指标;分析了在高温胁迫下温度信号的感知和传递以及植物对高温的响应机理;从传统育种方法和基因工程策略两个方向综述了小麦耐热性培育的研究进展。最后总结了提高小麦耐热性的措施及存在的问题,并提出了今后小麦耐热性研究展望。     

作物种质资源学理论框架与发展战略

作物种质资源是保障全球粮食安全和绿色发展的基础资源,是农业科技原始创新与现代种业发展的物质基础。作物种质资源学是以栽培植物起源中心理论、遗传变异的同源系列定律和作物及其种质资源与人文环境及社会发展的协同演变学说为基础,依托遗传多样性、遗传完整性、遗传特异性与遗传累积性技术体系,研究作物及其野生近缘植物多样性与利用的科学,涵盖作物种质资源调查、保护、评价、研究、创新与共享服务的理论、技术、管理及其体系。本文构建了作物种质资源学理论框架,对基本概念和特征特性进行了界定,并提出了作物种质资源学的发展战略。     

黄瓜发芽期耐热性评价及全基因组关联分析

高温会降低作物种子活力,减慢或完全抑制发芽,是制约黄瓜生产的重要非生物胁迫之一。本研究以96份黄瓜核心种质为试材,在42℃下进行发芽试验,利用相对发芽率、相对发芽势、相对发芽指数和相对胚根长度计算出的综合评价值,对核心种质发芽期耐热性进行鉴定评价;并利用重测序数据,对核心种质发芽期的耐热性进行全基因组关联分析。通过鉴定,筛选出了2份耐热性极强的材料CG109和CG110,综合评价值均大于0.9。通过全基因组关联分析,检测到5个与相对发芽率关联的位点,分别是GGP4.1、GGP4.2、GGP5.1、GGP5.2和GGR6.1;2个与相对发芽势关联的位点,分别是GGV4.1和GGV5.1;2个与相对发芽指数关联的位点,分别是GGI4.1和GGI5.1;2个与相对胚根长度关联的位点,分别是GRL6.1和GRL7.1。在以上位点中,GGI4.1、GGV4.1和GGP4.1均位于Chr.4的同一区间;GGI5.1、GGV5.1和GGP5.2均位于Chr.5的同一区间。这2个区段的关联位点利用相对发芽率、相对发芽指数和相对发芽势3个指标均可检测到,由此推测该区域存在与发芽期耐热性相关的基因。     

山茶属主要物种耐热性研究

以山茶属17个组130个物种为材料,通过相对电导率、丙二醛含量及超氧阴离子产生速率等生理指标测定及SPSS统计分析对其耐热性进行了研究.结果表明:持续1周36~38℃的高温胁迫能够有效区分不同山茶物种的耐热性;生理生化相关指标测定结果的系统聚类与主成分分析能够对不同山茶物种的耐热性进行有效评价.耐热性较强的有5个组,即离生雄蕊茶组、秃茶组、毛蕊茶组、茶组和连蕊茶组;耐热性最差为古茶组;部分组与组内物种的耐热性不完全一致,同组内不同物种的耐热性可能具较大差异.     

196份葡萄属(Vitis L.)种质资源耐热性评价

以国家果树种质郑州葡萄圃保存的196份代表性葡萄属种质为试材,利用叶绿素荧光参数法对其耐热性进行了鉴定评价。结果表明:196份葡萄属植物的耐热性叶绿素荧光参数Fv/Fm数值在0.0792~0.6836之间,品种间抗性存在差异,耐热性服从正态分布,表现为多基因控制的数量性状。利用有序样品最优分割聚类法,将其耐热性分为弱、中、强3种类型,叶绿素荧光参数分级阈值分别对应≤0.3、(0.3,0.5]、0.5,利用该分级标准筛选出了腺枝葡萄双溪03、刺葡萄梅岭山1301、菱叶葡萄0945和和田绿葡萄等48份耐热性强的葡萄种质,起源于我国的野生葡萄耐热性整体上高于其他类群或品种。研究结果对于利用抗性亲本选育耐热葡萄新品种和葡萄抗热机理研究具有参考意义。     

Heat tolerance as a function of membrane lipid remodeling in the major US oilseed crops (soybean and peanut)

With a steadily increasing population, the demand for crops to feed the world population and satisfy the energy needs is also increasing. The diminishing land resources and changing environmental conditions, specifically global warming, have further exacerbated these problems. Developing heat-tolerant crops that maintain yield under stress is one way to keep pace with future demands. Heat stress tolerance is a complex trait; hence it is vital to identify major contributors to heat stress tolerance and develop molecular markers to breed for them. The present communication reviews the recent progress made in this direction in oilseed crops soybean and peanuts, where heat-induced membrane lipid unsaturation was identified as an indicator of heat tolerance and the heat-induced changes in the expression pattern of the fatty acid desaturase gene as a marker to select for this trait. The further efforts underway and the future research needed in this direction are discussed.

     

Protective mechanisms of heat tolerance in crop plants

High temperature (HT) has become a global concern because it severely affects the growth and production of crops. Heat stress causes an abrupt increase in the expression of stress-associated proteins which provide tolerance by stimulating the defense response in plants. Heat-shock proteins (Hsps) and antioxidant enzymes are important in encountering heat stress in plants. The heat-shock response is characterized by repression of normal cellular protein synthesis and induction of Hsp synthesis. Under HT stress, upregulation of various enzymatic and nonenzymatic antioxidants, maintenance of cell membrane stability, production of various compatible solutes and hormonal changes occurs. Reactive oxygen species involving several pathways such as water–water cycle, Halliwell–Asada, glutathione peroxidase, Haber–Weiss and Fenton reactions helps in protecting plants against toxic radicals which otherwise could cause damage to lipophilic protein. Genetic approaches to elucidate and map genes or quantitative trait loci conferring thermotolerance will facilitate marker-assisted breeding for heat tolerance and also pave the way for characterizing genetic factors which could be useful for engineering plants with improved heat tolerance. This review discusses the protective mechanism of heat stress responses encompassing different pathways that provide tolerance during HT stress.     

Quantitative trait loci mapping of heat tolerance in broccoli (<Emphasis Type="Italic">Brassica oleracea</Emphasis> var. <Emphasis Type="Italic">italica</Emphasis>) using genotyping-by-sequencing

Key message

Five quantitative trait loci and one epistatic interaction were associated with heat tolerance in a doubled haploid population of broccoli evaluated in three summer field trials.

Abstract

Predicted rising global temperatures due to climate change have generated a demand for crops that are resistant to yield and quality losses from heat stress. Broccoli (Brassica oleracea var. italica) is a cool weather crop with high temperatures during production decreasing both head quality and yield. Breeding for heat tolerance in broccoli has potential to both expand viable production areas and extend the growing season but breeding efficiency is constrained by limited genetic information. A doubled haploid (DH) broccoli population segregating for heat tolerance was evaluated for head quality in three summer fields in Charleston, SC, USA. Multiple quantitative trait loci (QTL) mapping of 1,423 single nucleotide polymorphisms developed through genotyping-by-sequencing identified five QTL and one positive epistatic interaction that explained 62.1% of variation in heat tolerance. The QTL identified here can be used to develop markers for marker-assisted selection and to increase our understanding of the molecular mechanisms underlying plant response to heat stress.