Grape white rot is a destructive fungal disease occurring worldwide.Recently,Coniella vitis was identified as the predominant pathogen causing this disease in China.As the periderms of grape shoots are severely degrad...Grape white rot is a destructive fungal disease occurring worldwide.Recently,Coniella vitis was identified as the predominant pathogen causing this disease in China.As the periderms of grape shoots are severely degraded by C.vitis,it was speculated that cell wall-degrading enzymes(CWDEs)might play a key role in the pathogenesis of this disease.Therefore,this study aimed to examine the hydrolytic activity of the CWDEs of C.vitis.The results showed that xylanase(Xy)and xyloglucanase(XEG)had high levels of hydrolytic activity both in vitro and in vivo.Furthermore,a high-virulence fungal strain exhibited higher levels of Xy and XEG activities compared with a low-virulence strain.The genome of the fungus was found to harbor two XEG-coding genes CvGH74A and CvGH74B,which belonged to the glycoside hydrolase(GH)74 family.The expression level of CvGH74A was found to be high during pathogen infection.CvGH74A gene deletion mutants were generated using the split-marker method.The deletion of CvGH74A decreased both the hydrolytic activities of XEG and Xy and also the ability of the fungus to infect the grape leaves.No differences in the hyphal growth,morphology of colonies,or conidiation were found between theΔCvGH74A mutant strains and the wild-type strain.Together,these results suggested that CvGH74A acted as an important virulence factor,and its enzymatic activity might regulate the virulence of the pathogen.This study was novel in reporting that GH74 XEG acted as a virulence factor in C.vitis.展开更多
The experiment was conducted mainly to investigate the effect of change in sowing dates on disease severity of Roselle (Hibiscus sabdariffa L) leaf spot caused by Coniella musaiensis Var hibisci, plant height, number ...The experiment was conducted mainly to investigate the effect of change in sowing dates on disease severity of Roselle (Hibiscus sabdariffa L) leaf spot caused by Coniella musaiensis Var hibisci, plant height, number of branches, number of fruits and calyx yield of Roselle (H. sabdariffa L). Five dates were selected with an interval of fourteen days (14) between the dates for two years (2003 and 2004) to determine the most appropriate time to sow the crop using two Roselle accessions;green (Acc1) and red (Acc3).The first date was determined by the establishment of the rains in the season. It was observed that change in sowing dates had significant (p = 0.05) effect on disease severity but not on plant height, number of branches, number of fruits and calyx yield. Plants sown on July 18/27 had lowest disease indices;and are thus the best and therefore recommended for cropping of Roselle.展开更多
A study on the comparative effect of cow dung, wood ash and benlate for the control of leaf spot disease of Roselle (Hibiscus sabdariffa L.) was carried out following the preparation and foliar application of the mate...A study on the comparative effect of cow dung, wood ash and benlate for the control of leaf spot disease of Roselle (Hibiscus sabdariffa L.) was carried out following the preparation and foliar application of the materials on selected Roselle plants of the green and red accessions (Acc<sub>1</sub> & Acc<sub>3</sub>) in the field. The cow dung was fermented for 14 days while sour milk was added to wood ash, dissolved and all filtered and labeled. The spraying commenced soon after the plants were thinned to one and was done weekly until after 50% of the plants had flowered. Results showed significant (p = 0.05) difference between benlate, the synthetic fungicide and the bio-fertilizers (cow dung and wood ash) for the two years of the study. Disease severity was significantly lower in the benlate than in the bio-fertilizers. There was no significant difference in yield between the treatments although higher yield was recorded in benlate. Though the bio-fertilizers could not suppress infection, they aided the growth of the plants by boosting luxuriant growth. The result showed that these bio-fertilizers cannot be used as substitute to the synthetic fungicide for the control of this leaf spot disease caused by Coniella musaiensis var. hibisci. However, since they give equally good yield the bio-fertilizers can still be used to minimize the reliance upon use of chemical fungicides.展开更多
基金This study was supported by the earmarked fund for China Agriculture Research System(CARS-28).
文摘Grape white rot is a destructive fungal disease occurring worldwide.Recently,Coniella vitis was identified as the predominant pathogen causing this disease in China.As the periderms of grape shoots are severely degraded by C.vitis,it was speculated that cell wall-degrading enzymes(CWDEs)might play a key role in the pathogenesis of this disease.Therefore,this study aimed to examine the hydrolytic activity of the CWDEs of C.vitis.The results showed that xylanase(Xy)and xyloglucanase(XEG)had high levels of hydrolytic activity both in vitro and in vivo.Furthermore,a high-virulence fungal strain exhibited higher levels of Xy and XEG activities compared with a low-virulence strain.The genome of the fungus was found to harbor two XEG-coding genes CvGH74A and CvGH74B,which belonged to the glycoside hydrolase(GH)74 family.The expression level of CvGH74A was found to be high during pathogen infection.CvGH74A gene deletion mutants were generated using the split-marker method.The deletion of CvGH74A decreased both the hydrolytic activities of XEG and Xy and also the ability of the fungus to infect the grape leaves.No differences in the hyphal growth,morphology of colonies,or conidiation were found between theΔCvGH74A mutant strains and the wild-type strain.Together,these results suggested that CvGH74A acted as an important virulence factor,and its enzymatic activity might regulate the virulence of the pathogen.This study was novel in reporting that GH74 XEG acted as a virulence factor in C.vitis.
文摘The experiment was conducted mainly to investigate the effect of change in sowing dates on disease severity of Roselle (Hibiscus sabdariffa L) leaf spot caused by Coniella musaiensis Var hibisci, plant height, number of branches, number of fruits and calyx yield of Roselle (H. sabdariffa L). Five dates were selected with an interval of fourteen days (14) between the dates for two years (2003 and 2004) to determine the most appropriate time to sow the crop using two Roselle accessions;green (Acc1) and red (Acc3).The first date was determined by the establishment of the rains in the season. It was observed that change in sowing dates had significant (p = 0.05) effect on disease severity but not on plant height, number of branches, number of fruits and calyx yield. Plants sown on July 18/27 had lowest disease indices;and are thus the best and therefore recommended for cropping of Roselle.
文摘A study on the comparative effect of cow dung, wood ash and benlate for the control of leaf spot disease of Roselle (Hibiscus sabdariffa L.) was carried out following the preparation and foliar application of the materials on selected Roselle plants of the green and red accessions (Acc<sub>1</sub> & Acc<sub>3</sub>) in the field. The cow dung was fermented for 14 days while sour milk was added to wood ash, dissolved and all filtered and labeled. The spraying commenced soon after the plants were thinned to one and was done weekly until after 50% of the plants had flowered. Results showed significant (p = 0.05) difference between benlate, the synthetic fungicide and the bio-fertilizers (cow dung and wood ash) for the two years of the study. Disease severity was significantly lower in the benlate than in the bio-fertilizers. There was no significant difference in yield between the treatments although higher yield was recorded in benlate. Though the bio-fertilizers could not suppress infection, they aided the growth of the plants by boosting luxuriant growth. The result showed that these bio-fertilizers cannot be used as substitute to the synthetic fungicide for the control of this leaf spot disease caused by Coniella musaiensis var. hibisci. However, since they give equally good yield the bio-fertilizers can still be used to minimize the reliance upon use of chemical fungicides.
