棉花内生细菌的分离及生防益菌的筛选

对不同品种和不同种植地区的健康棉花植株组织中内生细菌进行分离,共得到102个菌株.经鉴定分属于芽孢杆菌属(Bacillus sp.)、黄单孢菌属(Xanthomonas sp.)、假单孢菌属(Pseudomonas sp.)、欧文氏菌属(Erwinia sp.)及短小杆菌属(Curtobacterium sp.),其中芽孢杆菌的分离频率最高,为优势种群.对内生细菌数量测定表明,棉花种子、根、茎、叶柄、叶片等组织内均存在大量的内生细菌.不同品种、组织及种植地,内生细菌的数量不同.各组织中内生细菌的种群密度的分布特点是种子中最多,其次为根,再次为茎,叶片、花蕾,叶柄中最少.从87个棉花内生菌的分离菌株中筛选出对棉花枯萎病菌有体外拮抗活性的菌株22个,占菌株总数的25;;15株对立枯丝核菌有抑制作用,占菌株总数的17;.15株对两种病原菌都有抑菌作用,其中有些菌株表现出较强抑菌活性,具有作为生防菌的潜能.

Isolation of Endophytic Bacteria from Cotton and Screening of Antagonistic Bacteria

252 bacteria strains were isolated from different internal tissues of cotton cultivars collected from Xinjiang regions. These strains were preliminarily classified as Bacillus sp., Xanthomonas sp., Pseudomonas sp., Erwinia sp., and Curtobacterium sp. Among these five genera,Bacillus sp. was the most prevalent endophytic bacterium in cotton. Results indicated that population densities of endophytic bacteria ranged from 1.0×10 to 1.4×10~8 cfu/g fresh weight although it might vary depending on cultivar ,tissue and region of the plant. Population of the endophytic bacteria is the largest in seed, small in root,smaller in stem, leaf and bud, the smallest in petiole. Of the 87 isolates, 22 strains are known to express antibiosis activities against Fusarium oxysporium f.sp., and 15 strains are known to express antibiosis activities against Rhizoconia solani kuhn, 15 strains were determined in vitro antagonism to both of the pathogens.This study indicaes that selected endophytic bacteria trains have potential for biological control of cotton disease.