费氏中华根瘤菌HN01DL在大豆根圈的定殖动态与结瘤研究

Root colonization and nodulation of Sinorhizobium fredii HN01DL in Glycine max rhizosphere

以发光酶基因luxAB为标记 ,在根盒缩影条件下研究了费氏中华根瘤菌HN0 1DL在大豆根圈的定殖动态、分布范围及其结瘤情况 .结果表明 ,HN0 1DL在根盒 灭菌土壤和非灭菌土壤缩影中的大豆全根系定殖动态与水平明显不同 ,前者在第 1 2d时达到最高定殖密度 (8.65logcfu·g- 1 ) ,而后者的早期定殖数量下降较快 ,且于第 1 5d时达到最高定殖密度 (6 .88logcfu·g- 1 ) .HN0 1DL在大豆播种 5d后在大豆根部的A(0～ 4cm)区根段上达到最高定殖密度 (7.0 5logcfu·g- 1 ) ,然后开始缓慢下降 ,至第 1 9d时仍维持相对稳定 ,在第 33d时又开始回升 .至播种后第 46d时HN0 1DL可散布至种子下方 1 6cm处的根段部位 .HN0 1DL在A区根段的定殖密度持续较高 ,所形成的发光根瘤总数 (1 6 .3个 )及发光比例 (68.8% )最高 ,且发光根瘤主要集中于该区段主根上 .发光根瘤比例沿A E区段逐渐下降 。

Rhizobox soil microcosms studies on the colonization, dispersal and nodulation of Sinorhizobium fredii HN01DL marked with luxAB gene in Glycine max rhizosphere showed that the colonization dynamics and the density of HN01DL in non sterilized rhizobox soil microcosms were different from those in sterilized rhizobox soil microcosms. The colonization density of the former reached the maximum (8.65 log cfu·g -1 root) 12 days after the coated seeds planted,and that of the latter decreased rapidly at the early stage and achieved the maximum (6.88 log cfu·g -1 root) 15 days afterwards. Furthermore, the colonization density of HN01DL reached the maximum ( 7.05 log cfu·g -1 root) in section A (0～4 cm) of root system 5 days after seeds planted,decreased slowly and kept a relative stable level until 19 days, and began to rise up again 33 days afterwards.The strain could also disperse to the place of 16 cm from seed to root tip by 46 days after seed planted. HN01DL maintained a constantly higher colonization density level in section A of root system, formed the largest number of luminescent nodules (total 16.3, dominantly located in main root of section A) ,and had the highest luminescent percentage ( 68.8 %). The luminescent nodule percentage decreased gradually along section A to E of root system,and no luminescent nodule was detected in section E of root system.