应用主基因-多基因混合模型研究昆明小白谷孕穗期耐冷性的遗传

以耐寒的昆明小白谷与农艺性状好但不耐寒的十和田杂交并以十和田为轮回亲本回交培育的耐寒的近等基因系(NIL)不同单株(BC4F6)与轮回亲本杂交再自交的4个F2代群体,2003年在海拔为2150m用冷泉水(18℃～19℃)灌溉的阿子营乡种植,利用主基因-多基因混合遗传模型分析了4个F2代群体的耐冷基因效应,结果表明4个组合中耐冷基因是受一对主效基因控制,其主效基因的遗传率为59.10%～81.04%.     

水稻丽粳2号近等基因系杂种后代耐冷性遗传研究

在昆明低温冷害条件下,以十和田×(十和田和丽粳2号BC4F5)配制的杂种BC5F1、BC5F2、BC5F3和BC5F4及亲本为材料,用主基因-多基因混合遗传模型对丽粳2号作耐冷基因供体培育出的近等基因系进行孕穗期耐冷性遗传研究。结果表明:(1)杂种BC5F2、BC5F3和BC5F4分离群体在同一世代每穗实粒数与总粒数、结实率呈极显著的正相关;(2)以结实率为耐冷性鉴定指标,近等基因系孕穗期耐冷性受2对主基因和多基因共同控制,其主效基因的遗传率为90.97%,微效基因遗传率为3.83%,主基因和微效基因都存在加性-显性-上位性效应。     

黄瓜的冷害及耐冷性

随着蔬菜反季节栽培面积的不断扩大,如何提高黄瓜(Cucumis sativus L.)耐冷性已成为选育新品种的研究重点。系统地综述近几年黄瓜耐冷性的鉴定、获得途径、冷害机理以及遗传和分子遗传学等方面的研究,以促进对黄瓜冷害机制的研究, 加速耐冷品种的培育。耐冷性鉴定时要从耐冷指数、低温发芽能力、MDA (丙二醛)含量和电解质渗漏率等几个方面综合鉴定。耐冷性的获得途径主要有冷驯化、激素处理、热激处理和培育耐低温品种,最重要的途径是耐冷品种选育。黄瓜冷害机理包括细胞膜的流动性降低及透性增加,光合作用被抑制,根系吸收减弱,可溶性糖含量减少,淀粉粒积累增加,微管的稳定性受到破坏等。黄瓜低温发芽能力由非加性基因决定,而幼苗时期主要由加性基因控制。黄瓜 耐冷的分子遗传学研究进展缓慢,目前已克隆出在低温锻炼中特异表达的功能未知的基因CCR18。今后还应研究黄瓜低温胁迫时的信号转导系统,以进一步揭示黄瓜的冷害机理;利用野生资源的抗逆性状,拓宽栽培黄瓜的遗传基础,选育适于保护地栽培的耐低温品种。     

黄瓜的冷害及耐冷性

随着蔬菜反季节栽培面积的不断扩大,如何提高黄瓜(Cucumis sativus L.)耐冷性已成为选育新品种的研究重点.系统地综述近几年黄瓜耐冷性的鉴定、获得途径、冷害机理以及遗传和分子遗传学等方面的研究,以促进对黄瓜冷害机制的研究,加速耐冷品种的培育.耐冷性鉴定时要从耐冷指数、低温发芽能力、MDA(丙二醛)含量和电解质渗漏率等几个方面综合鉴定.耐冷性的获得途径主要有冷驯化、激素处理、热激处理和培育耐低温品种,最重要的途径是耐冷品种选育.黄瓜冷害机理包括细胞膜的流动性降低及透性增加,光合作用被抑制,根系吸收减弱,可溶性糖含量减少,淀粉粒积累增加,微管的稳定性受到破坏等.黄瓜低温发芽能力由非加性基因决定,而幼苗时期主要由加性基因控制.黄瓜耐冷的分子遗传学研究进展缓慢,目前已克隆出在低温锻炼中特异表达的功能未知的基因CCRl8.今后还应研究黄瓜低温胁迫时的信号转导系统,以进一步揭示黄瓜的冷害机理;利用野生资源的抗逆性状,拓宽栽培黄瓜的遗传基础,选育适于保护地栽培的耐低温品种.     

水稻RIL群体芽期耐冷性基因的分子标记定位

水稻芽期冷害是我国长江中下游的早稻种植区和东北、西北稻区及云贵高原的一季稻区水稻生产中的重要限制因子之一。研究中利用纸卷法测定1个水稻重组自交系群体对10℃低温的芽期耐冷性,结合1张高密度分子遗传图谱,进行QTL定位分析。检测到控制水稻芽期耐冷性的4个QTL,分别位于1、3、7和11号染色体上。其中,位于11号染色体上的QTL qSCT-11的效应最大,在10℃低温处理13d时,对性状的贡献率达26％～30％,被检测到的LOD值也高达16～19,其加性效应值为正,增效等位基因存在于亲本Lemont中,RM202为与QTL qSCT-11紧密连锁的SSR标记。该主效QTL的增效基因,可作为分子标记辅助选择的操作对象用于水稻芽期耐冷性的遗传改良。     

水稻耐冷相关基因克隆研究进展

全球约有一半的人口以稻米为主食,然而,大多数栽培水稻品种(尤其是籼稻品种)的耐冷性不强,易受冷害(冰点以上低温危害)。采用分子育种方法培育耐冷水稻新品种是提高水稻耐冷性、减轻冷害的措施之一,对水稻耐冷相关基因进行定位与克隆是水稻耐冷分子育种的重要环节。介绍了以东乡野生稻为研究对象的耐冷相关基因定位以及以栽培稻为研究对象的OsDREB1A与OSISAP1等耐冷相关基因的克隆,并指出了今后该领域研究的重点。     

水稻RIL群体苗期耐冷性QTL分析

水稻苗期冷害是影响早春季节和高纬度地区水稻成苗和秧苗生长的重要限制因素之一。为了鉴定控制水稻苗期耐冷性的QTL,研究采用了1个水稻“粳籼交”重组自交系(RIL)群体,结合1张高密度分子遗传图谱,对3叶期幼苗经过10℃冷处理3d、恢复培养2d和4d时的秧苗存活率进行复合区间作图。亲本Lemont和特青的苗期耐冷性具有极显著差异,Lemont的苗期耐冷性很强,而特青对低温敏感。在重组自交系群体中,苗期耐冷性表现为连续变异,在两个方向上均出现大量超亲分离。共检测到5个水稻苗期耐冷性QTL,分别位于水稻1、3、8和11号染色体上,单个QTL对性状的贡献率为7％～21％。其中,4个QTL的增效基因来源于亲本Lemont,另1个QTL的增效基因来源于亲本特青。2个主效QTL(qSCT-3和qSCT-8)分别位于3号染色体标记区间RM282-RM156和8号染色体标记区间RM230—RM264,对性状的贡献率达到或接近20％,被检测到的LOD值显著较高,其增效基因均来自于耐冷性亲本Lemont。研究结果进一步揭示了水稻苗期耐冷性QTL具有丰富的位点多样性,表明耐冷性普遍较强的粳稻是发掘苗期耐冷性优异基因的主要稻种资源。     

广西水稻地方品种耐冷性鉴定及相关分析

对419份广西水稻地方品种初级核心种质进行芽期、苗期的耐冷性鉴定及相关分析,结果表明:广西水稻地方品种芽期、苗期耐冷性主要集中在7级和9级,总体耐冷性较弱。芽期、苗期极强耐冷种质(1级)分别为24份和27份,占参试总数的5.73%和6.44%,其中10份种质芽期和苗期均表现极强耐冷(1级)。芽期、苗期耐冷性呈极显著正相关(r=0.66)。粳稻芽期、苗期耐冷性均显著高于籼稻;粘糯稻之间耐冷性差异是由籼粳稻类型的耐冷差异引起的;来自高寒山区稻作区的品种芽期和苗期平均耐冷表现最强。利用34个SSR标记与芽期、苗期耐冷性进行Pearson相关分析,在第7和第9染色体上,各鉴定出1个同时与芽期和苗期耐冷性相关联的位点。本研究为水稻芽期、苗期耐冷育种提供新的抗源材料,并为水稻耐冷基因定位及机理研究奠定基础。     

基于单片段代换系的水稻芽期耐冷QTL定位和聚合北大核心CSCD

芽期耐冷性是华南双季稻地区水稻育种的一个重要目标。虽然水稻芽期耐冷QTL的标记定位已取得了一定的进展,但是这些QTL/基因尚未在水稻育种中得到有效的应用。定位稳定表达的芽期耐冷QTL,开展QTL聚合育种是水稻芽期耐冷性育种取得突破的关键。在本研究中,利用以粳稻IR65598-112-2为供体,籼稻华粳籼74为受体构建的单片段代换系(SSSL)开展芽期耐冷QTL定位,并进行聚合育种。通过评价SSSL与受体华粳籼74的芽期耐冷性差异,定位了2个稳定的芽期耐冷QTLs(qCTBB-3和qCTBB-12)。试验表明,分别携带有耐冷QTL qCTBB-3和qCTBB-12的SSSL在冷处理后都比华粳籼74表现出更高的幼苗成活率。通过代换作图,发现在qCTBB-3区间存在2个紧密连锁的耐冷QTLs(qCTBB-3a和qCTBB-3b)。利用本研究携带qCTBB-3a/qCTBB-3b的单片段代换系和前期研究鉴定出的芽期耐冷QTL qCTBB-6的单片段代换系为亲本进行杂交,通过分子标记辅助选择,获得了2份含有这3个QTL的聚合系。耐冷性评价表明,来源于两个供体/亲本的QTL不存在显著的上位性效应,聚合系的芽期耐冷性较亲本显著增强。可见,通过聚合芽期耐冷QTLs qCTBB-3a/qCTBB-3b和qCTBB-6能显著提高水稻芽期的耐冷性,获得的QTL及三耐冷QTL聚合系为水稻芽期耐冷性分子育种提供了优良的基因资源和亲本材料。     

广适性光温敏不育系Y58S幼穗分化期耐冷性表现及生理机制

为了阐明水稻光温敏不育系幼穗分化期耐冷的形态生理机制,以耐冷不育系Y58S和4个生产上常用光温敏不育系为试验材料,研究了低温胁迫(17.5℃,10 d)下结实率、穗部形态、株高、光合特性以及抗氧化物酶系统等的变化。结果表明,低温胁迫下Y58S的幼穗分化期耐冷性在5个不育系中最强,与敏感的C815S和株1S相比,Y58S表现为株高和穗长降低幅度较小,保持较高结实率;光合作用受低温影响不显著,SPAD值、光合速率等光合指标无显著变化;SOD、POD活性降低幅度较小,MDA含量、相对电导率增幅较小。     

Fine mapping a QTL qCTB7 for cold tolerance at the booting stage on rice chromosome 7 using a near-isogenic line

Low temperature at the booting stage is a serious abiotic stress in rice, and cold tolerance is a complex trait controlled by many quantitative trait loci (QTL). A QTL for cold tolerance at the booting stage in cold-tolerant near-isogenic rice line ZL1929-4 was analyzed. A total of 647 simple sequence repeat (SSR) markers distributed across 12 chromosomes were used to survey for polymorphisms between ZL1929-4 and the cold-sensitive japonica cultivar Towada, and nine were polymorphic. Single marker analysis revealed that markers on chromosome 7 were associated with cold tolerance. By interval mapping using an F₂ population from ZL1929-4 × Towada, a QTL for cold tolerance was detected on the long arm of chromosome 7. The QTL explained 9 and 21% of the phenotypic variances in the F₂ and F₃ generations, respectively. Recombinant plants were screened for two flanking markers, RM182 and RM1132, in an F₂ population with 2,810 plants. Two-step substitution mapping suggested that the QTL was located in a 92-kb interval between markers RI02905 and RM21862. This interval was present in BAC clone AP003804. We designated the QTL as qCTB7 (quantitative trait locus for cold tolerance at the booting stage on chromosome 7), and identified 12 putative candidate genes.     

QTLs of cold tolerance-related traits at the booting stage for NIL-RILs in rice revealed by SSR

QTLs for cold tolerance-related traits at the booting stage using balanced population for 1525 recombinant inbred lines of near-isogenic lines (viz.NIL-RILs for BC5F3 and BC₅F₄ and BC₅F₅) over 3 years and two locations by backcrossing the strongly cold-tolerant landrace (Kunmingxiaobaigu) and a cold-sensitive cultivar (Towada) was analyzed. In this study, 676 microsatellite markers were employed to identify QTLs conferring cold tolerance at booting stage. Single marker analysis revealed that 12 markers associated with cold tolerance on chromosome 1, 4 and 5. Using a LOD significance threshold of 3.0,compositive interval mapping based on a mixed linear model revealed eight QTLs for 10 cold tolerance-related traits on chromosomes 1, 4, and 5. They were tentatively designatedqCTB-1-1, qCTB-4-1, qCTB-4-2, qCTB-4-3, qCTB-4-4, qCTB-4-5, qCTB-4-6, andqCTB-5-1. The marker intervals of them were narrowed to 0.3-6.8 cM. Genetic distances between the peaks of the QTL and nearest markers varied from 0 to 0.04 cM. We were noticed in some traits associated cold tolerance, such asqCTB-1-1 for 5 traits (plant height, panicle exsertion, spike length, blighted grains per spike and spikelet fertility),qCTB-4-1 for 8 traits (plant height, node length under spike, leaf length, leaf width, spike length, full grains per spike, total grains per spike and spikelet fertility),qCTB-4-2 for 3 traits (spike length, full grains per spike and spikelet fertility),qCTB-5-1 for 5 traits (plant height, panicle exsertion, blighted grains per spike, full grains per spike and spikelet fertility). The variance explained by a single QTL ranged from 0.80 to 16.80%. Three QTLs (qCTB-1-1, qCTB-4-1, qCTB-4-2) were detected in two or more trials. Our study sets a foundation for cloning cold-tolerance genes and provides opportunities to understand the mechanism of cold tolerance at the booting stage.     

中国粳稻地方品种孕穗期耐冷性评价及聚类分析

用原产于中国18个省的329份粳稻地方品种为材料,分析了自然低温和冷水胁迫下不同省份粳稻地方品种孕穗期耐冷性及主要农艺性状表型差异和聚类特点。结果表明,在自然低温和冷水胁迫下各省份粳稻地方品种的孕穗期耐冷性状及主要农艺性状有明显的差异。在自然低温和冷水胁迫下,天津、四川和台湾品种的结实率及冷水反应指数均较高,表现较强的孕穗期耐冷性和迟钝的冷水反应。云南品种在自然低温下表现为较强的孕穗期耐冷性（结实率）,而在冷水胁迫下播种至抽穗天数和株高的冷水反应指数较高,表现为迟钝的冷水反应。从总体趋势上看,自然低温和冷水胁迫下,除个别省份外,纬度相对较高的北方省份品种的孕穗期耐冷性（结实率）强于纬度相对较低的南方省份品种。此外,在自然低温和冷水胁迫下,各省粳稻地方品种的聚类结果总体上与各省品种的地理位置及其耐冷性有密切的联系,而在冷水胁迫下品种的聚类结果与品种地理位置的关系比自然低温下更为密切。     

Water stress mediated root trait dynamics and identification of microsatellite markers associated with root traits in rice ( Oryza sativa L.)

To identify microsatellite markers associated with root traits for drought tolerance in rice (Oryza sativa L.) a study was conducted at Department of Plant Physiology, College of Agriculture, Trivandrum, Kerala Agricultural University. A set of thirty-five rice genotypes were exposed to water stress and evaluated for physio-morphological components as indices of water stress tolerance. Observations were made on leaf rolling score and root traits, especially the root length, root dry weight, root volume and root shoot ratio at booting stage. As of the data obtained, ten tolerant and ten susceptible varieties were selected for bulk line analysis to identify the DNA markers linked with target gene conferring drought tolerance. Out of 150 SSR primers screened, RM474 showed polymorphism between the tolerant and susceptible bulks. Individual genotypes of the bulks also showed the same product size of the respective tolerant and susceptible bulks.     

低温胁迫下粳稻选育品种耐冷性状的鉴定评价

选取来源于中国11个省份和其他9个国家的347份粳稻选育品种作为试验材料,分析了自然低温和冷水胁迫下,不同来源粳稻选育品种孕穗期的耐冷性及主要农艺性状的表型差异和聚类特点。研究表明,在自然低温和冷水胁迫下各省份或国家粳稻选育品种主要农艺性状及其冷水反应指数有明显的差异。在自然低温和冷水胁迫下,云南和日本品种的孕穗期结实率及其冷水反应指数均较高,表现出较强的孕穗期耐冷性。从总体趋势上看,在自然低温下,除个别省份外,我国纬度相对较高的北方省份品种的孕穗期耐冷性强于纬度相对较低的南方省份品种;而在冷水胁迫下,品种的耐冷性与其来源地的关系并不密切,没有呈现出一定的规律性。此外,聚类结果表明,不同省份或国家粳稻选育品种的聚类结果与其品种的地理来源均有一定的相关性,而与自然条件相比,冷水胁迫下粳稻选育品种的聚类结果与其品种的地理来源的相关性更为密切。     

Physical mapping and putative candidate gene identification of a quantitative trait locus <Emphasis Type="Italic">Ctb1</Emphasis> for cold tolerance at the booting stage of rice

Norin-PL8 is a cold-tolerant variety of rice (Oryza sativa L.) that was developed by introgressing chromosomal segments from a cold-tolerant tropical japonica variety, Silewah, into a template japonica variety, Hokkai241. We previously identified two closely linked quantitative trait loci, Ctb1 and Ctb2, for cold tolerance at the booting stage of Norin-PL8 in the long arm of chromosome 4. We report here the physical mapping of Ctb1 and the identification of the candidate genes. A total of 2,008 segregating individuals were screened for recombination in the Ctb1 region by a PCR-based screening, and a series of near-isogenic lines (NILs) were developed from progenies of recombinants. A comparison of the degrees of cold tolerance of the NILs indicated that Ctb1 is located in the 56-kb region covered by a bacterial artificial chromosome clone, OSJNBa0058 K23, that had been sequenced by the International Rice Genome Sequence Project. We found seven open reading frames (ORFs) in the 56-kb region. Two ORFs encoded receptor-like protein kinases that are possibly involved in signal transduction pathways. Proteins that may be associated with a ubiquitin-proteasome pathway were encoded by three ORFs, two of which encoded F-box proteins and one of which encoded a protein with a BAG domain. The other two ORFs encoded a protein with an OTU domain and an unknown protein. We were also able to show that Ctb1 is likely to be associated with anther length, which is one of major factors in cold tolerance at the booting stage.     

Identification of two closely linked quantitative trait loci for cold tolerance on chromosome 4 of rice and their association with anther length

Norin-PL8 is a cold-tolerant variety of rice (Oryza sativa L.) that was developed by introgressing chromosomal segments from a cold-tolerant javanica variety, Silewah. We previously detected quantitative trait loci (QTLs) for cold tolerance of Norin-PL8 in the introgressions on chromosomes 3 and 4. We provide fine mapping of the QTLs on chromosome 4 and the association between the QTLs and anther length, which has been reported to be a major component of cold tolerance. Interval mapping using a segregating population derived from an advanced backcross progeny indicated that a QTL for cold tolerance is probably located from the center to the proximal end of the introgression. For fine mapping, we developed a set of near-isogenic lines (NILs) from recombinants in the segregating population. Comparison of cold tolerance between the NILs indicated that either the proximal end or the center of the introgression is necessary for cold tolerance. From these results, we concluded that there are at least two QTLs for cold tolerance, tentatively designated as Ctb-1 and Ctb-2, in the introgression on chromosome 4. The map distance between Ctb-1 and Ctb-2 is estimated to be 4.7–17.2 cM. In order to investigate the mechanism underlying cold tolerance by the QTLs, we compared anther lengths of the NILs. The results indicate that both Ctb-1 and Ctb-2 are associated with anther length. Received: 17 July 2000 / Accepted: 1 February 2001     

QTLs conferring cold tolerance at the booting stage of rice using recombinant inbred lines from a <Emphasis Type="Italic">japonica</Emphasis> × <Emphasis Type="Italic">indica</Emphasis> cross

Low temperature stress is common for rice grown in temperate regions and at high elevations in the tropics. The most senstive stage to this stress is booting, about 11 days before heading. Japonica cultivars are known to be more tolerant than indicas. We constructed a genetic map using 191 recombinant inbred lines derived from a cross between a temperate japonica, M-202, and a tropical indica, IR50, in order to locate quantitative trait loci (QTLs) conferring cold tolerance. The map with a total length of 1,276.8 cM and an average density of one marker every 7.1 cM was developed from 181 loci produced by 175 microsatellite markers. Cold tolerance was measured as the degree of spikelet sterility of treated plants at a 12 degrees C temperature for 5 days in the growth chamber. QTLs on chromosomes 1, 2, 3, 5, 6, 7, 9 and 12 were identified to confer cold tolerance at the booting stage. The QTL contribution to the phenotypic variation ranged from 11 to 17%. The two QTLs with the highest contribution to variation, designated qCTB2a and qCTB3, were derived from the tolerant parent, M-202, each explaining approximately 17% of the phenotypic variance. Two of the eight QTLs for cold tolerance were contributed by IR50.     

A quantitative trait locus for cold tolerance at the booting stage on rice chromosome 8

A quantitative trait locus (QTL) for cold tolerance at the booting stage of a cold-tolerant rice breeding line, Hokkai-PL9, was analyzed. A total of 487 simple sequence repeat (SSR) markers distributed throughout the genome were used to survey for polymorphism between Hokkai-PL9 and a cold-sensitive breeding line, Hokkai287, and 54 markers were polymorphic. Single marker analysis revealed that markers on chromosome 8 are associated with cold tolerance. By interval mapping using an F₂ population between Hokkai-PL9 and Hokkai287, a QTL for cold tolerance was detected on the short arm of chromosome 8. The QTL explains 26.6% of the phenotypic variance, and its additive effect is 11.4%. Substitution mapping suggested that the QTL is located in a 193-kb interval between SSR markers RM5647 and PLA61. We tentatively designated the QTL as qCTB8 (quantitative trait locus for cold tolerance at the booting stage on chromosome 8).