大豆无根瘤突变基因GmNN1的精细定位与图位克隆

The key scientific issue on symbiotic nitrogen-fixing is to establish the high efficiency nitrogen-fixing system and automatic nitrogen-fixing of the non-legumes plants. It is a prerequisite for solving the scientific issue to elucidate the interaction molecular mechanism between leguminous plants and rhizobia. Soybean is an important economic crop and its mechanism of nitrogen-fixing is little known. A non-nodulation soybean mutant (Nod-) was isolated from the Jidou16 parent by the ethyl methanesulphonate mutagenesis. Nod- mutant is caused by a single dominant genic gene mutation. The mutation gene is termed GmNN1. Two F2 mapping populations were constructed from the cross Nod- mutant with a distantly related cultivar soybean (Glycine max) Gaofeng1 and a wild type (Glycine soja) accession ZYD02738, respectively. GmNN1 was located chromosome 8 flanked by marker Satt158 and Sat_294 with genetic distances 8.6cM and 4.3cM, respectively. GmNN1 is not allelic to early nodulation genes cloned from soybean, which is a novel gene. Based on previous results, the project will initiate to clone the GmNN1 and characterize its biological function. This will lay a foundation for elucidating the molecular mechanism and improving the efficiency of soybean nitrogen fixation, as well as giving a scientific guide for improving yield.

共生固氮研究的关键科学问题是获得最佳的固氮体系和建立非豆科植物的自主固氮体系，而解决这一科学问题的前提之一是需阐明共生固氮体系中豆科植物与根瘤菌相互作用的分子机理。大豆是一种重要的经济作物，其共生固氮的分子机理知之甚少。在前期工作中，通过EMS诱变，从大豆冀豆16中分离到无根瘤突变体（Nod-），Nod-是由单个核基因引起的可稳定遗传的突变，将该基因暂命名GmNN1。以Nod-作父、母本分别与栽培大豆高丰1号和野生大豆ZYD02738杂交，构建2套F2作图群体。GmNN1初步定位于大豆第8染色体Satt158和Sat_294标记之间，遗传距离分别为8.6cM和4.3cM。GmNN1与大豆中已克隆的早期结瘤基因不等位，是一个新基因。本研究拟在前期工作基础上，通过图位克隆的方法克隆GmNN1基因并验证其生物学功能。这为阐明大豆固氮的分子机理奠定基础，也为提高大豆固氮效率和产量提供科学依据。