波尔多液对烟草叶际微生物群落结构与代谢功能的影响

测定了波尔多液对烟草赤星病菌的毒力，并采用高通量测序与Biolog代谢表型技术分别测定了其对烟叶健康与感病组织叶际微生物群落结构和代谢功能的影响。结果表明:波尔多液对烟草赤星病菌的抑制活性较弱，其抑制菌丝生长和孢子萌发的EC₅₀值分别为450.19和757.17 mg/L。健康与感病烟叶组织叶际细菌均分布于变形菌门 (6.93%和39.07%) 和厚壁菌门 (16.45%和0.65%)，优势细菌均有Kosakonia (3.46%和22.38%) 和假单胞菌属 (0.22%和5.95%)；真菌均分布于子囊菌门 (63.82%和93.74%) 和担子菌门 (6.82%和2.53%)，优势真菌有链格孢属 (36.48%和84.52%) 、Symmetrospora (5.56%和2.27%) 和枝孢霉属 (14.87%和6.66%)。波尔多液1 500 g/hm2处理对健康和感病烟叶叶际细菌和真菌群落结构与代谢功能均有影响，处理5 d时降低了叶际Kosakonia、鞘脂单胞菌属和乳杆菌属的相对丰度，增加了假单胞菌属、劳尔氏菌属等6种细菌菌属的相对丰度；降低了链格孢属、Symmetrospora等6种真菌属的相对丰度，增加了亚隔孢壳属、绿僵菌属等10种真菌属的相对丰度。处理10和15 d时对叶际真菌、细菌的影响逐渐降低。健康与感病烟叶叶际微生物均可高效代谢糖类、氨基酸类、羧酸类、双亲化合物、聚合物和胺/氨基化合物等29种碳源，但对α-丁酮酸的代谢较弱。波尔多液处理对烟叶叶际微生物的代谢抑制活性随时间延长逐渐减弱。研究结果揭示了波尔多液施用不同时期后对烟叶叶际微生物的影响规律，为了解药剂持效期的生态效益提供了参考依据。

Effects of Bordeaux mixture on the community structure and metabolic function of tobacco phyllosphere microorganisms

In this paper, the virulence of Bordeaux mixture against Alternaria alternata was determined, and the effects of Bordeaux mixture on phyllosphere microbial community structure and metabolic function of healthy and diseased tobacco leaves were determined by high-throughput sequencing and Biolog metabolic phenotype technology. Results showed that Bordeaux mixture had a weak inhibitory activity against A. alternata with EC₅₀ values for inhibiting mycelial growth and spore germination of 450.19 and 757.17 mg/L, respectively. The phyllosphere bacteria in both healthy and diseased tobacco were distributed in Proteobacteria (6.93% and 39.07%) and Firmicutes (16.45% and 0.65%), and the dominant bacterial genera were Kosakonia (3.46% and 22.38%) and Pseudomonas (0.22% and 5.95%). The phyllosphere fungi in both healthy and diseased tobacco were distributed in Ascomycota (63.82% and 93.74%) and Basidiomycota (6.82% and 2.53%), and the dominant fungal genera were Alternaria (36.48% and 84.52%), Symmetrospora (5.56% and 2.27%) and Cladosporium (14.87% and 6.66%). Bordeaux mixture at 1 500 g/hm2 affected the community structure and metabolic function of phyllosphere bacteria and fungi in healthy and diseased tobacco. In the bacterial and fungal communities, the relative abundances of Kosakonia, Sphinomonas, and Lactobacillus decreased, while the relative abundances of 6 bacterial genera including Pseudomonas, Ralstonia increased after 5 days of treatment. The relative abundance of 6 fungal genera including Alternaria, Symmetrospora decreased, while the relative abundance of 10 fungal genera including Didymella, Metarhizium increased after 5 days of treatment. The effects of Bordeaux mixture on phyllosphere fungi and bacteria gradually decreased after 10 and 15 days of treatment. Twenty-nine carbon sources including carbohydrates, amino acids, carboxylic acids, amphiphiles, polymers, and amine/amino compounds could be efficiently metabolized by phyllosphere microorganisms of healthy and diseased tobacco leaves, but the metabolism of α-butyric acid was weak. The metabolic inhibition activity of Bordeaux mixture on phyllosphere microorganisms decreased gradually with the increase of time. The results of the study revealed the regularity of the effect of Bordeaux mixture on the microbes of tobacco leaves after different periods of application and provided a reference for understanding the ecological benefits of the fungicide in the effective period.