Transcriptional Response and Carbohydrate Metabolism of Citrus Infected with Candidates Liberibacter Asiaticus, the Causal Agent of Huanglongbing in Florida
Huanglongbing (HLB) is a devastating disease of citrus occurring in most citrus growing regions worldwide. It is caused by a phloem-limited, fastidious bacterium of the genus Candidatus Liberibacter, which is transmitted through insect vector and has not been obtained in culture. HLB causes the decline of trees within a few years after infection and is one of the greatest challenges the citrus industry is currently facing in Florida, where disease incidence has been reported to exceed 80％ in some areas. Not much is known about the molecular and physiological processes implicated in the interaction of the pathogen with its citrus host. This study investigates the transcriptional response of sweet orange (Citrus sinensis L. Osbeck) trees to Ca. L. asiaticus infection with respect to carbohydrate metabolism. Semi-quantitative RT-PCR analysis detected a large abundance of transcripts for ADPglucose pyrophosphorylase and glucose-6phosphate/phosphate translocator in leaves of infected plants, primarily at a time when disease symptoms were not prominent. Both proteins are closely associated with starch biosynthesis in the plastids. Soluble sugar- and starch concentrations were measured in leaves from naturally infected field-grown sweet orange trees and found to be highest in symptomatic leaves. Whereas glucose and fructose levels were increased up to five-fold, sucrose levels increased no more than 34％ or remained unchanged. It is suggested that sugar utilization is a major component of pathogenicity of Ca. L. asiaticus in citrus, possibly involving activation of the sucrose-hydrolyzing enzyme invertase by the pathogen.
Citrus greening Phloem-limited bacteria Gene expression
Ute Albrecht Kim D. Bowman
U. S. Horticultural Research Laboratory, U. S. Department of Agriculture, Agricultural Research Service, 2001 South Rock Road, Fort Pierce, FL 34945, USA
国际会议
11th International Citrus Congress(第11届国际柑橘大会)
武汉
英文
1008-1015
2008-10-01（万方平台首次上网日期，不代表论文的发表时间）