田菁茎瘤固氮根瘤菌对小麦种子侵染的促生作用及其在根系内的定殖

选取8个常见小麦品种,通过室内限菌试验筛选出对于田菁茎瘤固氮根瘤菌Azorhizobium caulinodans ORS571 (A.caulinodans) 侵染响应敏感的品种,研究了浸种侵染、菌液浓度和添加葡萄糖对接菌小麦幼苗生长的影响,并结合荧光显微镜检测绿色荧光蛋白（GFP）标记A.caulinodans在小麦幼苗根系内的分布与定殖规律。结果表明:小偃22为响应敏感品种;在室内限菌条件下,浸种侵染小偃22幼苗平均根长和平均株高分别较对照增加了17.04%和8.37%;最适菌液浓度为1.0108个/mL;在菌液中添加1g/L葡萄糖有助于A.caulinodans浸种侵染和定殖。荧光显微镜检测结果显示,GFP标记A.caulinodans从小麦幼苗根毛和侧根裂隙处进入,定殖于根维管组织等部位。田间试验结果进一步表明A.caulinodans浸种侵染对不同小麦品种均具较明显的促生作用。

Promotion for wheat growth and root colonization after infecting wheat seeds with Azorhizobium caulinodans

Common eight wheat cultivars were selected and the sensitive cultivars were screened out through gnotobiotic condition test in the laboratory after infecting of the Azorhizobium caulinodans ORS571(A.caulinodans) to wheat seeds.Infection method of seed soaking,the density of A.caulinodans and adding glucose are also studied,and the colonization of green fluorescence protein(GFP)-labeled A.caulinodans in the wheat seedling were detected by fluorescence microscope.The results show that Xiaoyan22 is the most sensitive wheat cultivar to A.caulinodans,in the gnotobiotic condition the root length and shoot height are increased by 17.04% and 8.37% respectively compared to the control,the optimum dilution proportion of A.caulinodans is 1.0×108/mL,and it is helpful for the infection to add 1 g/L glucose in A.caulinodans PBS solution.With fluorescence microscope detection the result shows that GFP-labeled A.caulinodans infects from wheat seeding root hairs and lateral root fractures,and it can colonize in the vascular bundle of root.The field test shows that there is obvious promotion for wheat growth after infecting wheat cultivars seeds with A.caulinodans.