棉 花 学 报 Cotton Science 2007，19(4)：286-290
The Effects of Cotton Root Exudates on Growth and Development of Verticillium dahliae Abstract：The effects of upland cotton root exudates on the growth and development of Verticillium dahliae were studied，through the compared analysis of the root exudates components between the resistant and susceptive cotton materials，using a pair of resistant and susceptive isogenic lines to Verticillium wilt，Z5629 and Z421，as well as four other upland cotton cultivars with different level of Verticillium wilt resistance. The results showed that the kinds of amino acids in the root exudates of resistant cultivars were much less than that of susceptible ones. Compared with susceptible ones，the root exudates of resistant cultivars were lack of aspartic acid，threonine，glutamic acid，alanine，isoleucine，leucine，phenylalanine，lysine and proline，but they did have arginine that was lack in the susceptive ones on the contrary. The saccharide types in the root exudates had no difference between the susceptive and resistant cultivars，but the concentrations of glucose，fructose and sucrose in the root exudates of susceptible varieties were much higher than those in resistant ones. The experiment of Verticillium dahliae，culture showed that the cotton root exudates from resistant cotton cultivars could restrain the spore germination and mycelium growth of Verticillium dahliae effectively，due to poor nutrition of root exudates from the resistant cotton cultivars mainly. Among the amino acids in the root exudates，the arginine，which was lack in susceptive cotton cultivars，was a special one that could control the growth and development of the Verticillium dahliae. However，the cotton root exudates from susceptive cotton cultivars could improve the growth and development of Verticillium dahliae，among those amino acids in the exudates，the alanine was the most active one in the stimulated function. According to this experiment，it is suggested that the cotton root exudates could be used as a biochemical marker in selection of the cotton materials for Verticilium wilt resistance. Those having lesser kinds and lower concentrations of amino acids and saccharides in the root exudates may be the resistant ones which can be used in cotton breeding program，except for arginine which is the exclusive amino acid without in susceptive cotton root exudates and have the strong restrained effect to the growth and development of the Verticillium dahliae，being a resistant biochemical maker.
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