中国野生大麻遗传多样性研究及特异种质资源发掘

Hemp (Cannabis sativa L.) is a very important industrial crop and has been distributed worldwide by humans. As part of the center of origin for wild-type hemp, China maintains a rich wild-type hemp germplasms, and has the largest area in cultivation among the hemp growing countries. These wild types of hemp germplasms are crucial for breeding new cultivars because they contain potential genes that may increase seed productivity, and improve certain qualitative characters such as fiber production, genotypes with novel high value applications, as well as genes that help this plant grow well under adverse conditions, such as draught and disease. However, research related to wild-type hemp populations is rare. The genetic diversity of wild-type hemp remains largely unexploited while wild-type populations in China are facing serious habitat losses; and certain populations are even in the danger of extinction. Based on extensive inventories, this project will investigate the population genetic diversity using the genomic ISSR and SSR, as well as fast evolving chloroplast gene loci such as rpL16，trnQ-5'rpS16, and petL-psbE. Besides, the agronomic character screening and chemical content analysis of the wild-type populations will also be carried out. The specific aims of this study are: 1) to elucidate the distribution patterns of wild-type hemp populations in China, and determine their genetic diversity and structure; 2) to infer the relationships between and among the wild-type populations and their relationship with dominant populations of the cultivated-types, and screen potential promising germplasms with desirable traits for breeding use; and 3) based on the results of the comprehensive data analyses, to propose suitable methodology for the protection and sustainable usage of the wild-type hemp germplasms.

大麻是全球重要经济作物。中国拥有丰富的大麻种质资源，是野生大麻重要起源地，大麻种植面积居世界首位。由于历史上的禁种、生境破坏及人为铲除，大麻野生资源在我国的生存形势严峻，部分资源已濒临灭绝，但对其研究利用却几为空白，亟待开展。本项目拟对中国野生大麻居群进行广泛野外调查、样本采集及种子的补充收集保存，在开展细致的生物学特征观察和重要化学成分鉴定评价基础上，通过叶绿体基因中进化速率较快的非编码片段序列差异分析，结合ISSR、SSR等分子标记技术，对中国大麻野生群体进行遗传多样性研究，旨在：（1）深入认识我国野生大麻居群现状、遗传多样性及分布格局，阐明各野生居群之间及与栽培大麻的亲缘关系；（2）揭示各野生大麻居群的遗传多样性和遗传结构，提出合理的保护策略；（3）掌握我国野生大麻资源的特点，发掘特异种质。研究结果将为大麻野生资源的保存和保护提供科学依据，为大麻育种及利用提供重要信息和特异种质材料。

大麻是全球重要经济作物和近年倍受关注的热点作物，中国拥有丰富的大麻种质资源，是野生大麻的重要起源地和驯化地。野生作物资源在农业的可持续发展中具有不可忽视的价值。在对中国现存野生大麻居群进行广泛的野外调查、样本采集、种质资源收集基础上，同时开展了两年表型及化学成分鉴定评价、并利用叶绿体基因片段、ISSR、gSSR、EST-SSR、WGR分子标记进行了遗传多样性与遗传结构研究，获得以下主要结果和新见解：.1.抢救式收集和保存22份野生大麻和15份栽培型大麻种质资源，建立1个大麻野生资源库和2个数据库（表型和SSR指纹库），发现了部分在CBD、油脂成份方面表现优异的特异材料。.2.对大麻物种的界定与分类进行了澄清，主张大麻属为单型属仅包括1个种，即大麻这个物种（Cannabis sativa L.），种下包括三个亚种，即subsp. sativa，subsp. indica 和subsp ruderalis，并推测大麻植物最早起源于低纬地区。.3.揭示了人类对大麻这个作物的驯化是发生于不同地区的，即多地驯化起源历史。.4.对全国13个省区的重点区域进行野外实地调查显示：我国野生大麻分布总体呈现东北、西北、西南的间断型分布，生境多样，主要致危原因为基因渗入和生境散失。鉴于大麻植物的特殊性（管制植物、风媒易于引起与毗邻栽培品种基因互渗）及客观条件的限制，目前最为可行和有效的保护是将野生大麻资源迁地保存于种质库中，同时因地制宜实施原位保护。.5.以6份代表性栽培品种为对照，对24份野生种质资源进行为期两年的田间鉴定评价。结果表明：我国野生大麻具有丰富的表型多样性，在诸多表型特征上存在丰富的变异，变异与纬度极显著相关；野生种质表型在地理分布上呈现南、北种质两大类群。.6.开发cpDNA标记引物5对和gSSR引物20000多对。 cpDNA、ISSR、gSSR、EST-SSR分子标记一致地揭示了中国野生大麻呈区域性分布的规律，明确了其遗传背景，同时在分子上高的遗传多样性也印证了我国野生大麻在生境和表型上丰富的遗传多样性。