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ARS Home » Southeast Area » Fort Pierce, Florida » U.S. Horticultural Research Laboratory » Subtropical Plant Pathology Research » Research » Publications at this Location » Publication #320918
Title: Transcript Profiling of Huanglongbing (HLB) Tolerant and Susceptible Citrus Plants Reveals the Role of Basil Resistance in HLB Tolerance

Author
item WANG, YUNSHEN - Clemson University
item ZHOU, LIJUAN - University Of Florida
item YU, XIAOYUE - Clemson University
item Stover, Eddie
item LUO, FENG - Clemson University
item Duan, Ping

Submitted to: Frontiers in Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/13/2016
Publication Date: 6/28/2016
Citation: Wang, Y., Zhou, L., Yu, X., Stover, E.W., Luo, F., Duan, Y. 2016. Transcript Profiling of Huanglongbing (HLB) Tolerant and Susceptible Citrus Plants Reveals the Role of Basil Resistance in HLB Tolerance. Frontiers in Plant Science. 7:933. https://doi.org/10.3389/fpls.2016.00933.
DOI: https://doi.org/10.3389/fpls.2016.00933

Interpretive Summary: Huanglongbing (HLB) is currently the most destructive disease of citrus worldwide. Although there is no immune cultivar, field tolerance to HLB within citrus and citrus relatives has been observed at the USDA Picos farm at Ft. Pierce, Florida, where plants have been exposed to a very high level of HLB pressure since 2007. To reveal the molecular mechanism of HLB tolerance and susceptibility at the gene expression level, we conducted RNA-Seq analysis on two closely related cultivars of HLB-tolerant ‘Jackson’ grapefruit trees and HLB susceptible ‘Marsh’ grapefruit trees after HLB infection. From this project, we identified a total of 686 differentially expressed (DE) genes between two groups of plants. Among them, 247 genes were up-regulated and 439 were down-regulated in tolerant citrus trees. We also identified a total of 619 genes with significantly differential expression of alternative splicing isoforms between HLB tolerant and HLB susceptible citrus trees. We analyzed the functional categories of DE genes using two methods, and revealed that many DE genes were related to the activation of basal resistance in HLB tolerant citrus trees. We have experimentally verified the expressions of 14 up-regulated genes and 19 down-regulated genes on HLB-tolerant ‘Jackson’ trees and HLB-susceptible ‘Marsh’ trees using real time PCR. The results showed that the gene expressions of most genes in agreement with the RNA-Seq results and had similar expression pattern with or without infection. It is evident that some citrus cultivars are more tolerant to HLB. By profiling the transcriptome of HLB tolerant and HLB susceptible citrus trees, we found that multiple pathways have been suppressed or activated in HLB tolerant citrus tree, which lead to the activation of the basal resistance or immunity of citrus trees. This study provided not only new insights into HLB-tolerance, but also useful guidance for breeding HLB-tolerant citrus in the future.

Technical Abstract: Huanglongbing (HLB) is currently the most destructive disease of citrus worldwide. Although there is no immune cultivar, field tolerance to HLB within citrus and citrus relatives has been observed at the USDA Picos farm at Ft. Pierce, Florida, where plants have been exposed to a very high level of HLB pressure since 2007. In this study, we examined the expression differences between two closely related cultivars of HLB-tolerant ‘Jackson’ grapefruit trees and HLB susceptible ‘Marsh’ grapefruit trees after HLB infection using RNA-seq. A total of 686 differentially expressed (DE) genes between two groups were identified. Among them, 247 genes were up-regulated and 439 were down-regulated in tolerant citrus trees. We also identified a total of 619 genes with significantly differential expression of alternative splicing isoforms between HLB tolerant and HLB susceptible citrus trees. We analyzed the functional categories of DE genes using two methods, and revealed that many DE genes were related to the activation of basal resistance in HLB tolerant citrus trees. We have experimentally verified the expressions of 14 up-regulated genes and 19 down-regulated genes on HLB-tolerant ‘Jackson’ trees and HLB-susceptible ‘Marsh’ trees using real time PCR. The results showed that the gene expressions of most genes in agreement with the RNA-Seq results and had similar expression pattern in different plants. This study provided new insights into HLB-tolerance and useful guidance for breeding HLB-tolerant citrus in the future.