西瓜和水稻根系分泌物中糖和氨基酸对西瓜枯萎病病原菌生长的影响

The effects of sugars and amino acids in watermelon and rice root exudates on the growth of Fusarium oxysporum f.sp. niveum

以不同抗性西瓜品种以及化感水稻品种为试验对象,对其根系分泌物中可溶性糖和游离氨基酸的含量和组成进行分析,并研究了氨基酸对西瓜专化型尖孢镰刀菌(Fusarium oxysporum f.sp.niveum)生长的影响。结果表明:西瓜根系分泌物中的可溶性糖含量及游离氨基酸的含量和种类显著多于水稻根系分泌物中的,而感病西瓜品种根系分泌物中的又显著多于抗病品种根系分泌物中的。与感病西瓜品种相比,抗病西瓜品种根系分泌物中不含酪氨酸,水稻根系分泌物中不含天冬氨酸、丝氨酸、谷氨酸、缬氨酸、甲硫氨酸、异亮氨酸、酪氨酸、苯丙氨酸和精氨酸这9种氨基酸。综合西瓜专化型尖孢镰刀菌孢子萌发和产孢能力两项测定结果,供试的8种外源氨基酸中丙氨酸、谷氨酸、天冬氨酸、精氨酸为主要促菌氨基酸;甲硫氨酸、甘氨酸、苯丙氨酸均促进西瓜专化型尖孢镰刀菌孢子萌发却抑制其孢子产生,而丝氨酸为抑菌氨基酸。因此,水稻、西瓜根系分泌物在糖和氨基酸含量及组成方面存在的显著差异,可以使连作条件下西瓜单作和西瓜/旱作水稻间作对根际微生物的养分供应不同,对其生长的影响也随之改变,这为阐释连作条件下西瓜单作发病严重而间作发病减轻的机制提供了科学依据。

Two watermelon cultivars and rice were used to study the contents and components of the soluble sugars and free amino acids in the root exudates and their effects on the growth of Fusarium oxysporum f.sp.niveum.The results obtained were listed as follows.The contents and types of soluble sugars and free amino acids in root exudates of the two watermelon cultivars were both much more than those in rice,and they increased with increasing of the susceptibility to Fusarium in these two watermelon cultivars.Compared with susceptible watermelon cultivar,the root exudates of resistant cultivar was lack of the Tyr,and the rice cultivar was lack of the Asp,Ser,Glu,Val,Met,Ile,Tyr,Phe and Arg.The spore germination and sporulation of F.oxysporum f.sp.niveum were promoted by Ala,Glu,Asp and Arg,while they were inhibited by Ser.Although Met,Gly and Phe stimulated the spore germination,they all significantly inhibited the sporulation of F.oxysporum f.sp.niveum.It was concluded that the significant difference of the contents and kinds of soluble sugars and free amino acids in root exudates between the watermelon and rice provided scientific basis for evaluating the pathogenesis of Fusarium wilt disease in watermelon and the mechanism of watermelon/aerobic rice intercropping system affecting the pathology of wilt disease.