【作者】 雷永；

【导师】 廖伯寿；

【作者基本信息】 中国农业科学院 ， 作物遗传育种， 2010， 博士

【摘要】 花生(Arachis hypogaea L)是世界上重要的油料和经济作物之一。提高花生及其制品的油酸含量是改进产品营养价值和保障质量安全的关键关键,高油酸育种是当前花生品质改良研究的重要方向。为此,本研究在明确高油酸花生种子脂肪酸代谢规律和高油酸性状遗传分子机制的基础上,建立了高效的花生高油酸遗传改良技术体系,对于深化花生品质育种具有重要的理论和实用价值。为研究和揭示花生高油酸遗传和生化基础,本研究首先系统分析了高油酸和普通油酸花生材料在种子发育、萌发过程中脂肪酸积累和降解模式的差异,比较了成熟种子不同部位的脂肪酸组成。结果表明：1)高油酸花生种子中油酸的大量积累主要发生在种子发育的后期,同时伴随着亚油酸含量的快速下降,高油酸和普通油酸材料在种子发育的早期均存在较高比例的亚麻酸。2)花生种子胚和子叶的脂肪酸组成存在显著差异,胚中油酸含量较低而含有较高比例的棕榈酸和亚油酸。3)高油酸和普通油酸的花生在种子萌发过程中子叶的脂肪酸组分比例变化差异不显著,且没有新的脂肪酸生成,说明花生无论高油酸还是普通油酸的花生种子在萌发过程中不存在优先利用某种脂肪酸的现象。利用3个普通油酸和高油酸的花生配制杂交组合并利用其F2分离群体,分别以卡方测验、主基因与多基因混合遗传模型分析了花生高油酸性状的遗传特性。结果表明：花生高油酸性状的遗传主要受两对隐性基因的调控,表现为两对连锁隐性主效基因的上位性+微效多基因加性修饰的特点。通过分析ahFAD2A等位基因(ahFAD2A-wt、ahFAD2A-m)在中国花生小核心种质中的分布,结合油酸含量的测定,明确了密枝亚种(普通型和龙生型变种)花生的油酸含量普遍高于疏枝亚种(珍珠豆和多粒型变种)的原因与密枝亚种材料中存在较高比例的ahFAD2A突变型基因(ahFAD2A-m)密切相关,进一步明确了ahFAD2A等位基因在调控花生种子油酸含量上的重要性。通过对重组近交系群体不同油酸含量株系材料的基因型分类和表型鉴定,明确并验证了花生油酸含量受两个隐性主效基因调控的分子机制。本研究建立了一种以油脂折光指数鉴定高油酸材料的新方法,可定量或定性地检测和判断高油酸的花生材料,可高效地用于花生高油酸育种研究。在明确花生高油酸性状的遗传和分子机制并建立高通量的简便筛选技术的基础上,提出了一套完整的花生高油酸育种技术体系,其核心是基于杂交F2基因型判断的早期世代选择,关键技术包括：1)亲本基因型的选择；2)高效的高油酸鉴定方法；3)利用F2单株上的F3种子的混合样的油酸含量表型判断F2单株的基因型。利用这套技术体系可在杂交后的F2代高效地鉴定出具有纯合双隐性基因型(ol1ol1ol2ol2)的杂交后代(ol1ol1ol2ol2)。在花生高油酸育种实践中证实上述技术体系可靠性高,方法简便实用,可显著提高育种效率。更多还原

【Abstract】 Peanut (Arachis hypogaea L.) is widely used as an oilseed and cash crop around the world and as a source of edible oil and protein in the developing countries. Properties of peanut oil are determined by the fatty acid composition. Increasing the oleic acid content in peanut seed and its products has been one of the most important goals for improving the peanut quality. Based on investigating of the fatty acid accumulation pattern in developing seeds and the molecular mechanism of high oleic acid, it would be of important value to establish a cost-effective system for gegentic improvement of high oleic acid in peanut.Comparison of fatty acid accumulation pattern in seed development of the high oleic and normal oleic acid peanut genotypes revealed that oleic acid accumulated during the latter seed development stage while more linolenic acid appeared in the early developing stage. Higher palmitic and linoleic acid was found in the embryo of the matured peanut seeds than in the cotyledon. During the germination of the high oleic acid genotype, there was no significant change of the fatty acid, which implied that high oleic character did not affect the seed germination.The inheritance of the high oleic content was reconfirmed by the F2 segerating progenies of normal and high oleic acid cross combinations. Two main-effects with recessive-linked-additional genes plus additional poly-minor-effect gene were found to determine the oleic acid content in the peanut seeds. We characterized two homeologous genes that directly control oleic acid content in the oil, ahFAD2A, ahFAD2B, and these two genes have two alleles (ahFAD2A-wt ahFAD2A-m; ahFAD2B-wt, ahFAD2B-m) in various peanut germplasm accessions. We further confirmed that there was only ahFAD2B-wt allele and no ahFAD2B-m in the Chinese germplasm collection. At the same time, ahFAD2A-wt and ahFAD2A-m were found in the most accessions in the Chinese mini-core collection, the mutant allele ahFAD2A-m was frequent among subspecies hypogaea accessions but absent from subspecies fastigiata accessions. A highly positive correlation between present of the ahFAD2A-m and the higher oleic acid content was observed.A cost-effective refractive index (RI) method was developed to identify the high oleic acid materials, which is useful for high oleic breeding in peanut. Based on the understanding of the molecular mechanism of high oleic acid character, a new system for the high oleic in peanut was developed. The parental lines in breeding should be genotyped to estimate the ratio of the high oleic acid in the F2 population. An easy method using RI was established to identify high oleic phenotypes among F2:3 lines with two recessive genes (ol1ol1ol2ol2).更多还原