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United States Department of Agriculture

Agricultural Research Service

Title: Comparative Evaluation of Endophytic Bacteria from Chinese and U.S. Cotton Cultivars

Authors
item Mcinroy, John - DEPT. PLANT PATH AUBURN U
item Qi, Wang - PLANT ECO. ENG. CHINA AGU
item Mahaffee, Walter
item Lu, Suyun - PLANT ECO. ENG. CHINA AGU
item Mei, Ruhong - PLANT ECO. ENG. CHINA AGU
item Kloepper, Joseph - DEPT. PLANT PATH AUBURN U

Submitted to: Pacific Northwest Plant Disease Control Handbook
Publication Type: Proceedings
Publication Acceptance Date: November 1, 1997
Publication Date: N/A

Interpretive Summary: This manuscript presents preliminary investigations into the role of bacterial endophytes in inherent disease resistance of cotton cultivars. The data indicates that differences in bacterial communities are associated with cultivar resistance. Endophytes were isolated from stems of the five cotton cultivars grown in the greenhouse and in the field. Cotton grown in the Greenhouse was planted in a soilless potting mix, while field-grown cotton was planted in sandy and clay soils. Endophytic bacteria were identified by fatty acid analysis using Sherlock System. Significantly more Bacillus species were isolated from Chinese cultivars than from U.S. cultivars. Population density of total endophytes was also determined but had no relationship to cultivar resistance or susceptibility. An additional 900 strains were isolated from seedlings of the five cultivars germinated on water agar to identify seed associated endophytes. Identification of these seedling endophytes confirmed a higher percentage of Bacillus spp. from Chinese cultivars. Testing of the seedling endophytes for in vitro antibiosis against four fungal pathogens (Fusarium oxysorum, Rhizoctonia solani, Pythium ultimum, and Phytophthora capsici) revealed higher percentages of antagonistic endophytes from resistance cultivars than from susceptible cultivars. This effect was seen in both U.S. and Chinese cotton cultivars.

Technical Abstract: A preliminary investigation was conducted to determine whether resistance to Fusarium wilt in cotton could be correlated to differences in community structure of bacterial endophytes. Selected cotton cultivars differed in their inherent resistance to Fusarium wilt, with two of the cultivars being from the United States and three from China. Endophytes were isolated from stems of the five cotton cultivars grown in the greenhouse and in the field. Cotton grown in the Greenhouse was planted in a soilless potting mix, while field-grown cotton was planted in sandy and clay soils. Endophytic bacteria were identified by fatty acid analysis using Sherlock System. Significantly more Bacillus species were isolated from Chinese cultivars than from U.S. cultivars. Population density of total endophytes was also determined but had no relationship to cultivar resistance or susceptibility. An additional 900 strains were isolated from seedlings of the five cultivars germinated on water agar to identify seed associated endophytes. Identification of these seedling endophytes confirmed a higher percentage of Bacillus spp. from Chinese cultivars. Testing of the seedling endophytes for in vitro antibiosis against four fungal pathogens (Fusarium oxysorum, Rhizoctonia solani, Pythium ultimum, and Phytophthora capsici) revealed higher percentages of antagonistic endophytes from resistance cultivars than from susceptible cultivars. This effect was seen in both U.S. and Chinese cotton cultivars.

Last Modified: 12/22/2014
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