Expression Profiling of Huanglongbing Disease in Kinnow (Citrus reticulata) and Succari (Citrus sinensis) Leaves

Abstract

Huanglongbing (HLB), also called as citrus greening disease, is the most destructive and prevalent disease of citrus. In this study, for HLB diagnosis in the leaf samples of Succari sweet orange [Citrus sinensis (L.) Osbeck] from field, conventional polymerase chain reaction (PCR) technique was employed. Asian citrus psyllid was collected from HLB positive sweet orange field trees and released on healthy plants of succari and kinnow for infestation in the growth room under controlled conditions. Candidatus Liberibacter asiaticus was detected in the inoculated citrus by Taqman based real time PCR using primers set HLBas fpr. SYBR green based real time qPCR was performed to differentiate expression of seven genes in HLB infected and healthy leaf samples of Succari sweet orange and Kinnow mandarin. Conventional PCR results were obtained with discrete bands having amplicon size of 1160bp, 800bp and 700bp for OI1/OI2c, OI2/23S1 and A2/J5, respectively. Succari proved to be good indicator plant for HLB symptoms expression. Gene expression data analysis results represented Kinnow mandarin is less susceptible to HLB as compared to Succari sweet orange.