棉花黄萎病内生拮抗细菌L-4-2的鉴定及定殖

Identification and Colonization of an Antagonistic Endophytic Bacterium L-4-2 against Cotton Verticillium Wilt

从棉花健株茎内分离筛选到一株棉花黄萎病内生拮抗细菌L-4-2,通过形态特征观察、生理生化试验及16SrDNA同源性序列分析,鉴定该菌为解淀粉芽孢杆菌(Bacillus amyloliquefaciens)。通过逐步提高药物质量浓度的方法,获得能在含利福平100mg/L NA培养基中生长并对棉花黄萎病菌(Verticillium dahliaeKleb)拮抗活性稳定的L-4-2抗性菌株,测定L-4-2在棉花根、茎内的定殖能力。结果表明,拮抗菌L-4-2能在棉花根、茎内很好地定殖和传导;接种第7天根内的定殖数量达到最大,为2.3×105 cfu/g;接种第14天茎内定殖数量达到最大,为1.6×105 cfu/g;随后在根、茎内的定殖数量有所下降;接种35d后在棉花根、茎内仍有很强的定殖能力,定殖数量分别为9.6×103 cfu/g和3.24×104 cfu/g。

An antagonistic endophytic bacterium L-4-2 against cotton verticillium wilt isolated from healthy cotton plant was identified as B.amyloliquefaciens through morphologic,physiologic biochemical characterization,and molecular 16S rDNA sequence analysis.The rifampicin marked strain L-4-2 with stably antagonistic activity against cotton verticillium wilt at 100 mg/L level was developed through gradually increased drug dose test.The colonization ability of the strain L-4-2 was test on the marked strain.The results showed that the antagonistic strain L-4-2 could colonize and transmit very well in root and stem.After 7 days inoculation,the colony amount of the strain L-4-2 reached the maximum to 2.3×105 cfu/g and 1.6×105 cfu/g in root and stem,respectively.Then the amount dropped slightly after 14 days inoculation.While 35 days after inoculation,the strain L-4-2 still showed strong colonization ability in cotton,with 9.6×103 cfu/g and 3.24×104 cfu/g in root and stem,respectively.