苜蓿与根瘤菌专一性共生及可遗传性共生体选育

Specific symbiosis and breeding of heritable symbi⁃ onts between alfalfa and rhizobia

摘要:

根瘤菌(Rhizobium)与豆科植物的共生结瘤固氮效应对提高植物产量和改善品质、减少工业化肥使用、推进农业高质量发展具有重要意义。根瘤菌侵入苜蓿植株后能在植株体内不断繁殖、运移并最终定殖到种子。种子内生根瘤菌可通过种子在代际间垂直续传且保持稳定的共生性状，结瘤固氮能力突出。通过接种将优良根瘤菌株导入其共生性状相向变异强烈的苜蓿植株，构建内生根瘤菌的苜蓿种子共生体，可以培育出与根瘤菌共生的苜蓿新种质或新品种。从苜蓿与根瘤菌共生结瘤固氮效应高效利用的角度出发，基于植物与微生物的共生特性，提出了“共生育种”的概念；介绍了苜蓿与根瘤菌共生育种的理论基础和实施过程，归纳了苜蓿与根瘤菌共生育种的一般性程序，为创制苜蓿与根瘤菌共生体种质和培育新品种奠定基础。

Abstract:

The symbiotic nitrogen‐fixation effects between Legumes and Rhizobium play vital roles in improving plants yield，altering quality，reducing industrial fertilizer utilization，and promoting high‐quality development of agri‐ culture. Rhizobia could propagate，migrate and eventually colonize into seeds after invading alfalfa plants. Seed endo‐ phytic rhizobia can vertically transmit from seeds to the next‐generation with stable symbiotic character maintained，as well as predominant nodulation and nitrogen‐fixation ability. A new germplasm or variety of alfalfa symbiosis with rhi‐ zobium can be bred by inoculating and introducing excellent rhizobium strains into alfalfa plants possessing intense op‐ posing variation of symbiotic traits，and constructing alfalfa seed symbionts containing endophytic rhizobia. Here， based on symbiotic characteristics of plants and microorganisms，the concept of "symbiosis breeding" was put forward from the perspective of efficiently utilizing symbiotic nitrogen‐fixation effects of alfalfa and rhizobium. The theoretical basis，implementation processes and general procedures of alfalfa ‐ rhizobia symbiosis breeding were explained and summarized，which laid a foundation for the creation of alfalfa and rhizobia symbiosis germplasm and the cultivation of new varieties.