西藏大麦春化和光周期反应基因的等位变异与效应分析

Qing-Tibet highland is one of the important center of barely domestication and rich of genetic resource are available in this region. Barely is main food crop in Tibet. The adaptability of variety to local climate is main subject of barley breeding in Tibet due to special ecosystem. .Heading date is closely linked with agronomic performance, which is responsible for the regional and seasonal adaptation of barley varieties. Heading at the appropriate time of the year, is not only essential for the completion of barley life cycle, but also a premise to achieve high-yield. .The transition from vegetative to reproductive growth is a critical developmental switch and a key adaptive trait in both crop and wild cereal species that ensures that plants set their flowers at an optimum time for pollination, seed development, and dispersal. All plants undergo several developmental transitions during their life cycle and, like many of these, the transition from vegetative to reproductive phase is stimulated by environmental and developmental signals. Physiologically, barley can be categorized according to their response to prolonged periods of cold (vernalization) and daylength (photoperiod). Autumn sown (winter barley) varieties require vernalization to promote subsequent flowering, and commonly display a strong promotion of flowering in response to growth under LDs. Spring-sown (spring barley) varieties lack a vernalization requirement and can display a weak or strong response to LDs. The use of substitution lines and crosses between winter and spring types has identified a number of discrete loci that mediate the response to such environmental signals. Two important pathways within this network include the vernalization (Vrn) and photoperiod (Ppd) genes..Vernalization genes HvVRN1, HvVRN2, HvVRN3 and photoperiodgenes PPD-H1, PPD-H2 are responding to the seasonal growth habit and flowering time in barley. In this study, a set of Tibet barley germplasm was used for maker based genotyping, gene re-sequencing and allelic variation analysis of these genes. In the meantime, the genome-wide association analysis wasperformed based on the genotyping and multi-ecological environment phenotyping.

青藏高原是我国栽培大麦的重要驯化中心，具有丰富的大麦种质资源。由于气候的复杂性，选育广适性的青稞品种，对高产、稳产等具有十分重要的意义。抽穗期是决定大麦品种的种植区域范围与季节适应性的重要农艺性状，在合适的时间开花是完成正常生命周期所必需的。大麦春化基因HvVRN1、HvVRN2、HvVRN3和光周期调控基因PPD-H1和PPD-H2的分离和克隆，加深了人们对于春化和光周期基因调控开花的遗传机理的认识。本研究通过对大量的青稞样本进行光周期和春化基因的等位变异分析，全面了解这些基因在西藏农家品种中的分布与演化特点，分析春化基因和光周期基因的不同单倍型在西藏育种实践中的应用情况，并据此对这些资源进行系统分类，筛选出携有不同等位变异位点的青稞种质进行多年多点鉴定，揭示等位变异对抽穗期、分蘖、株高等性状的效应，并开发相应等位变异的特异分子标记，为更好地研究和利用西藏大麦的优异基因提供理论基础。

为提高青稞种质资源的利用效率并筛选优异杂交亲本，进行1605份青稞资源的冬春性鉴定、抽穗期多样性分析和春化基因相关的单倍型分析。结果表明，96.2%的西藏青稞地方品种为春性，在西藏三个生态区均有分布；冬性品种仅有3.8%，且主要分布在以林芝为主的藏东南生态区。针对春化基因型，我们共分析了1852份材料，包含1560份农家品种、102份育成品种和190份野生质资源中春化基因HvVRN1共发现6种单倍型：即Hvvrn1（v1）、HvVRN1-1（V1-1）、HvVRN1-4（V1-4）、HvVRN1-6（V1-6）、HvVRN1-8（V1-8）和HvVRN1-9（V1-9）。在HvVRN2基因座位上，大多数材料携带显性等位基因HvVRN2（V2），仅有10份材料携带隐性等位基因Hvvrn2（v2）。半野生青稞和地方品种单倍型较其他类型品种更为丰富，在野生青稞中V1-8和V1-4是主要的单倍型，在地方品种中，V1-8和V1-9是主要的单倍型。西藏育成品种中，V1-8和V1-9分别是冬性和春性的优势单倍型，单倍型V1-8在所有生态区均有分布，地方品种的V1-9和半野生青稞的V1-4主要分布在林芝地区，其余单倍型分布在昌都、山南和拉萨等生态区。本研究为全面理解西藏青稞资源的冬春性、抽穗期多样性和环境稳定性提供了参考，为广适应性青稞品种培育筛选出环境稳定性佳的亲本材料。