八棱海棠遗传多样性及其主要加工品质性状的关联分析

It is imperative to develop apple deep processing for conversion and increasing benefits of the apple industry. However, the lack of processing varieties has become a bottleneck restricting the development of apple processing industry. Among the Chinese species, one of the oldest cultivated species Malus robusta has the potential of processing value，and its genetic diversity and processing quality traits have not been systematically studied. We have finished the collection, phenotypic identification and SNP marker development based on Specific Locus Amplified Fragment Sequencing (SLAF). This study intends to study the genetic differentiation and identify the level of gene diversity of Malus robusta by use of the SNP microarray technology. Processing quality traits the content of soluble sugars, titratable acids and polyphenols will be determined, and after the analysis of genetic association of them the correlation between SNP loci and major processing quality traits will be identified in genome-wide. The alleles and their effects will be explored at associated loci of different processing quality traits. Molecular mechanism of different processing quality traits will be studied. Our study will lay the foundation for exploring the related control genes of apple processing traits and screening germplasms with excellent variation, provide basic information for the efficient utilization of apple germplasm resources and genes suitable for processing. Our final purpose is to speed up the process of breeding of processed apple, provide scientific basis for improving the theory and technology system of breeding of processed apple.

发展苹果深加工对实现苹果业的转化增效势在必行，但加工品种资源的匮乏成为制约苹果加工产业发展的瓶颈。中国栽培种中栽培历史悠久的果中珍品八棱海棠是果品加工潜力资源，其遗传多样性和加工品质性状尚未进行系统研究。本研究拟在前期对八棱海棠苹果资源进行充分收集、表型鉴定评价和简化基因组测序开发SNP标记的基础之上，利用SNP芯片技术研究其遗传分化，明确其基因多样性水平；测定其主要加工品质性状可溶性糖、可滴定酸和多酚含量，通过与SNP标记的关联分析，在全基因组范围内扫描SNP基因位点与主要加工品质性状的相关性，分析挖掘不同性状关联位点的等位变异及其效应，探讨不同加工品质性状差异形成的分子机制，为深入发掘苹果加工性状相关控制基因以及筛选携带优良变异的种质奠定基础，为适宜加工苹果种质资源和加工品质特性控制基因的高效利用提供基本资料，加速加工型苹果的育种进程，并为完善加工苹果育种的理论与技术体系提供科学依据。

八棱海棠是中国原产苹果属植物栽培种的主要代表种，其遗传变异极其丰富，是栽培历史悠久并且用途广泛的优良树种，其果实则具有果形美、色泽好、含糖量高、耐贮运、口味佳等优点，既可以鲜食，也是加工的好原料。基于近些年在中国河北怀来、涿鹿等八棱海棠密集分布地区收集八棱海棠种质资源的表型和SSR分子标记鉴定遗传多样性分析，筛选34份遗传多样性丰富的种质资源开展简化基因组测序，获得46460个多态性SNP标记，明确八棱海棠的遗传多样性水平高于苹果属植物平均遗传多样性水平，高于栽培种中国苹果、楸子和花红的遗传多样性水平，也高于苹果属植物代表野生种新疆野苹果的遗传多样性水平，仅次于野生种变叶海棠的遗传多样性水平。八棱海棠与苹果属34个种的亲缘关系，可以分为明显的5个类群，八棱海棠分布在以5 个苹果属植物栽培种中国苹果、八棱海棠、花红、楸子和海棠花为主的类群，八棱海棠与中国原产苹果属植物栽培种的亲缘关系更近。通过八棱海棠可溶性糖组分、可滴定酸等适宜加工品质性状的鉴定，明确八棱海棠主要适宜加工品质性状的变异范围，其总体可溶性糖的变化范围为8.11%～15.12%，可滴定酸的变化范围为0.17%～1.691%。基于连续两年测定的八棱海棠资源的适宜加工品质性状测定数据，优先进行可溶性糖和可滴定酸的SNP标记关联分析，可溶性糖含量性状的关联分析定位到在同一条染色体上位置比较接近的3个SNP位点，可滴定酸含量性状的关联分析定位到关联度比较高的2个SNP位点，为进一步进行适宜加工品质性状相关基因的挖掘以及性状形成机理解析等奠定坚实基础。