发光酶基因标记的华癸根瘤菌JS5A16L在紫云英根圈的定殖动态

CLONIZATION OF MESORHIZOBIUM HUAKUII JS5A16L MARKED WITH LUXAB GENES IN THE RHIZOSPHERE OF ASTRAGALUS SINICUS

在土壤一盒栽、盆栽微宇宙系统（Ｍｉｃｒｏｃｏｓｍ）中和田间条件下，研究了发光酶基因（ｌｕｘＡＢ）标记的华癸根瘤菌ＪＳ５Ａ１６Ｌ在紫云英根圈的定殖动态、分布范围及结瘤情况。在盒栽系统中，ＪＳ５Ａ１６Ｌ的定殖密度在紫云英出苗２天后达到最高水平（７．８８ ｌｐｇ ｃｆｕ／克根）（ｃｆｕ为ｃｏｌｏｎｙ ｆｏｒｍｉｎｇ ｕｎｉｔ的缩写），然后开始下降，并保持在一个相对稳定的水平；５８天后又有所回升，且能散布至种子下方２２ｃｍ处的根段部位。盆栽条件下的定殖动态与盒栽系统中的相似，紫云英播种３天后，ＪＳ５Ａ１６Ｌ可达最高定殖水平（６．９２ ｌｏｇ ｃｆｕ／株根系），随后开始缓慢下降，直至３２天时仍维持在一个相对稳定水平。ＪＳ５Ａ１６Ｌ在田间条件的定殖动态则不同，播种后３０天时定殖密度达到最大值（７ ．０３ ｌｏｇ ｃｆｕ／克根），９０天后降到最低值（５． ２４ ｌｏｇ ｃｆｕ／克根），然后又开始上升，１６０天时为７．８７ ｌｏｇ ｃｆｕ／克根，甚至在地上部植株收割后２０天仍可维持在７．８９ ｌｏｇ ｃｆｕ／克根。接种该菌株可显著提高紫云英的生物学产量。

Colonization density of Mesorhizobium huakuii JS5A16L marked with luxAB genes on the root of Astragalus sinicus reached to the maximum (7.88 log cfu/g root) in rhizobox-soil microcosm 2 days after seed planted, then reduced and kept in a stable level fot a long time. After 58 days, it rose up a little, and also the strain could dispersed to the place of 22cm from seed to root tip. The colonization dynamics in pot-soil microcosm is similar with those in rhizobox-soil microcosm. Under the field conditions, however, it reached to the maximum (7.03 log cfu/g root) 30 days after seed planted, afterward declined to the minimum (5.24 log cfu/g root) 90 days later, then began to go up to 7.89 log cfu/g root 20 days after plant harvested. Inoculation of JS5A16L strain could increase the plant biomass of Astragalus sinicus in a large scale.