【作者】 吴殿星；

【导师】 夏英武；

【作者基本信息】 浙江大学 ， 生物物理， 2001， 博士

【摘要】 品质改良是近来水稻的研究重点。尽管各地食用习惯有所差异，软而不粘的中等AAC品种为消费者普遍所喜爱。我国水稻食用品质改良已取得了明显进展，但由于育种技术尚未取得突破，目前存在两大突出问题：很多常规早稻新品种、杂交水稻不育系和恢复系表观直链淀粉含量偏低，不适应市场要求；很多中等AAC品种食用品质仍较差。本研究通过研究反映淀粉外观、分子和理化三方面特性的标记或指标，旨在建立一套综合辅助选择技术为食用品质改良提供技术保障。主要结果如下： 1．云雾性状是低表观直链淀粉含量（Apparent amylose content，AAC）育种材料特有的胚乳外观，其形成的生理基础与胚乳内淀粉粒的形态和结构关联。极端老化试验表明，降低种子水分和加速种子老化是快速识别云雾性状的两条重要途径。采用高温保湿预处理、变温烘干、太阳晒干和室内阴干等处理，发现在40℃下随处理时间的增加，低AAC品种的胚乳外观由透明状变为云雾状；45℃烘干和40℃保湿预处理有利于云雾性状的快速显现。综合考虑处理时间和种子发芽率，初步认为40℃保湿4h+40℃烘16h是识别胚乳云雾性状的最佳处理。以建立的方法处理，发现中低AAC杂交群体中呈现乳白色、云雾状、透明状和混合状的各类胚乳表现型。AAC与胚乳表型间关系密切：云雾状和乳白色的AAC一般较低，云雾状与低AAC早籼亲本相仿；透明状的AAC变幅较大，部分与中等AAC亲本相仿。遗传研究表明，胚乳云雾性状为一隐性性状，受单一隐性基因控制，与其相关的低AAC由一主效基因和若干微效基因控制。上述结果表明，在育种早期分离世代，可以云雾性状为外观标记特异性剔除低AAC育种材料。 2．采用粘度速测仪（Rapid Visco Analyzer，RVA）分析，发现以消减值和崩解值等RVA谱特征值为指标，不仅可区分品种AAC的高低，也可鉴定水稻食用品质的优劣。对影响RVA测定的主要干扰因子研究，发现高温烘干前处理和粉样虽影响测定结果，但并不影响对品种品质的评价，水质干扰效应轻微，样品量严重影响测定结果和品种鉴定。利用简化实用的分析体系，分析调查了低AAC品种（浙辐504）与中等AAC品种（IR64）杂交后代的RVA谱变异性。为探索亚种间或品种间淀粉粘滞性转移的可行性，对早籼稻与粳稻、爪哇稻、中籼杂交后代进行了评价。结果表明，由三类供体衍生的低AAC材料间淀粉品质类似，但中等AAC品系的淀粉粘滞性因亲本间遗传距离不同存在显著差异：釉／舢杂交后代，易选择到与IR64相仿淀粉粘滞性的新品系；枷爪杂交后代，尽管频率较低，但仍可入选到与Lem。nt淀粉粘滞性相似的新品系；釉l粳杂交，因遗传障碍未筛选到与供体秀水 11淀粉特性相似的新品系。以 RVA辅助选择为手段，从龙特甫B／Lemollt和密阳46／Lemont回交群体筛选出淀粉品质改良的杂交水稻保持系和恢复系。 3．以WX UpZN85为引物，发现Wx基因微卫星标记不仅能区分出中低＊＊C的亲本或品种，也可测定新品系AAC类型和鉴定品系的遗传稳定性。遗传研究表明。Wx微卫星标记为共显性标记，在釉爪遗传背景下按孟德尔规律分离。采取综合辅助选择技术，对中低AAC杂交后代（295－Z10／Lemo叫按先控制直链淀粉含量后确定淀粉分子、理化特性的原则加以筛选，成功鉴定出与Lemont淀粉品质相仿的早舢新品系。以辐射当代为材料，研究发现在幼苗期可利用微卫星标记预测潜在的WX突变，并在随后的M。和M3胚乳突变得到了证实。 4．以胚乳外观标记研究空间技术诱发产生的水稻早熟突变体，成功筛选出几个云雾状突变体。对转基因Bt抗虫水稻鉴定发现，转基因品系的品质性状和成分未发生显著的变化，但个别品系的淀粉粘滞性完全不同，并在不同TRO来源的品系间发现TJ3NA插人的位置效应；采用相仿AAC的不同类型水稻和不同AAC的早舢稻为材料，研究了辐照对淀粉粘滞性、理化品质和淀粉粒的影响，结果表明辐照可产生改性的米粉和食用品质。以早舢糯稻品种越糯1号为轮回亲本，与粳稻秀水 11和爪哇稻 Lemont后代，凭借标记辅助选择成功构建 Wx近等基因系。更多还原

【Abstract】 Breeding for rice grain quality is receiving more and more attentions lately. Rice with intermediate amylose content that cook moist and tender and retain a soft texture upon cooling is generally preferred in most of rice-growing areas, although consumers’ preferences vary greatly due to the regional differences in eating habits. Obvious advances in improvement of rice eating quality have been achieved in China. Currently, there are two major problems due to a lack of breakthroughs in breeding techniques. Many recently released conventional early indica rice varieties, cytoplasmic male sterile (CMS) lines or restorers of hybrid rice have a low apparent amylose content (AAC) and fail to meet the demand of the rice market, and many varieties with intermediate AAC still have a poor cooked rice texture. The objective of current study is to develop a combined assisted-selection method in support of rice eating quality breeding programs, by examining the "mist" trait, the Wx microsatellite marker, and starch pasting viscosity. These three properties reflect exterior, molecular and physical/chemical properties of starch quality, respectively.The "mist" trait is a distinct endosperm specific to breeding materials with low AAC roughly ranging from 9% to 15%. Physiologically, the formation of the mist trait is related to the morphology and structure of starch granules in the endosperm. The extreme aging experiment (100% RH at 40癈) indicated that there might be two feasible ways to quickly identify the mist trait via decreasing seed moisture and an aging treatment. Based on this information, the methods for rapid identification of low AAC varieties were tentatively explored. Endosperm appearance of low AAC varieties would change from transparent to misty as the treatment time at 40癈 increases. At 40癈 for 40h, all low AAC varieties expressed the mist trait, however they kept transparent endosperm when exposed to sunshine or were kept in room conditions. Higher temperature (45癈) and maintaining moisture pretreatment at 40癈 significantly accelerated the expression of the mist trait. A 40癈 for 4h pretreatment plus 40 for 16h was preliminarilyregarded as the optimal treatment for the detection of the mist trait, depending on treating time and seed germination rate. Using this method, endosperm phenotypes such as milky white (white), mist, transparency and mixtures were observed in the segregating populations, which were derived from different crosses between low amylose early indica and intermediate amylose rice. AAC was closely related to endosperm phenotypes. Generally, milky white (white) endosperm was very low in AAC, and mist endosperm was basically similar to the low amylose early indica parent. However, transparent endosperm had a variable AAC with some being similar to the intermediate AAC parent. Genetic studies revealed that the mist trait was controlled by a single recessive gene, and its related low AAC was regulated by a major gene with slight modifications by minor gene(s). The results above suggested that the mist endosperm be used as phenotypic marker to assist in the elimination of low AAC materials at an early breeding generation.Starch pasting viscosity indicates changes in rice texture during cooking. During the heating, higher temperature, and cooling processes, rice flour has a pasting viscosity profile, which can be determined by Rapid Visco Analyser (RVA). RVA analysis can be used to distinguish low AAC varieties from intermediate AAC varieties and evaluate eating quality based on the major characters of an RVA profile, the setback value (SBV) and breakdown value (BDV). Studies on major interfering factors indicated that higher temperature pretreatment and rice flour power types did not affect the evaluation of rice quality, although they influenced RVA results to a great extent. Water resources had a slight impact on RVA testing, while sample quantity had serious effects on the final result and subsequent assessment of rice eating quality. A simplified protocol for RVA determination was f更多还原