Effect Of Sugar And Its Pyrolysis Products On Growth Of Villosiclava Virens

Sugar is the basic nutrient of plant pathogenic fungi.In this paper,the effects of ribose,xylose,sorbose,and their corresponding pyrolysis products on the growth and development of Villosiclava virens were determined by common culture method.The results were as follows.1.Effect of sugar on the growth of V.virensThe effects of ribose,xylose and sorbose on colony growth,sporulation of thin-walled conidia and germination of the conidia of fungus V.virens were observed on media of water agar or potato agar,by method of mixing these media with the sugar sterilized by filtration.The follow findings was made by using sucrose and clear water as control.Sporulation of the conidia was promoted by ribose,but both colony growth and germination of the conidia were not affected significantly by ribose.Colony growth,sporulation and germination of the conidia were inhibited by xylose.Colony growth and sporulation of the conidia were inhibited by sorbose.Pigment synthesis was promoted by xylose and sorbose.These results indicated that an effect of different sugar on growth of the fungus was varied greatly.2.Effect of pyrolysis products of sugar on growth of V.virensPyrolysis product of a sugar was obtained by heating of the corresponding sugar solution at common high temperature,126℃ for 30 minutes.The effects of three pyrolysis products,i.e.,pyrolysis product of ribose,pyrolysis product of xylose and pyrolysis product of sorbose,on growth of V.virens were determined,by a comparison with other four plant pathogenic fungi(i.e.,Botrytis cinerea,Fusarium oxysporum f.sp.cubense,Colletotrichum gloeosporioides and Alternaria brassicae).A clear colony of V.virens on culture plate of ribose,xylose and sorbose was obtained,but the colony on culture plate of corresponding pyrolysis products of the three kinds of sugar could not be observed.The inhibition rate of the three pyrolysis products on the germination of thin-walled conidia of V.virens was more than 85%.The results showed that the growth of V.virens was inhibited strongly by the three pyrolysis products.However,a little inhibitory or no significant inhibitory on the four reference fungi was observed,which indicated that the fungus V.virens was highly sensitive to the three pyrolysis products of sugar.3.Relationship between nutrient components of culture medium and sporulation of V.virensThe relationship between nutrient components and sporulation of fungus V.virens was determined by using plate medium,and the sporulation potential of the fungus on three kind of media was compared.The conidia yield increased with the increase of potato content in the case that the potato content was less than 200 g/L.The conidia yield increased with the increase of ribose content in the case that the ribose content was less than 20 g/L.The conidia yield of the fungus on medium of potato ribose agar was 3.84 times of that on medium of potato sucrose agar,and that on medium of potato agar was 3.17 times of that on medium of potato sucrose agar.The results showed that the sporulation yield of thin-walled conidia could fluctuate greatly with different nutrient composition of the culture medium.The medium of potato ribose agar was the best for sporulation of the conidia.