Transcriptome analysis of ‘Valencia’ sweet orange response to citrus huanglongbing (HLB) infection
E. LOUZADA (1), C. C. Parra (1), J. V. da Graça (1), M. Sétamou (1), M. Kunta (1). (1) Texas A&M University-Kingsville, Weslaco, TX, U.S.A.
The pathogen, ‘<i>Ca.</i> Liberibacter asiaticus’ was detected in Florida in 2005 and it has been causing enormous economic losses to that citrus industry. Currently, the bacterium has been introduced to all major U.S. citrus producing areas and it has the potential to cause huge economic turmoil. The bacterium does not have uniform distribution in the plant and it has a long latency period before visual symptom development in the leaves. It is very important to understand how the plant counterattacks the bacterium in an attempt to survive. To address this issue we performed transcriptome analysis by RNA-Seq to compare the response of HLB-infected ‘Valencia’ sweet orange with control non-infected plants. Out of 25 million reads, over 17 million were mapped to the citrus genome with over 12 million perfect matches. There were 6606 differential expressed genes with 11% being involved in plant-pathogen-interaction. Many of the new transcripts expressed in the diseased plant was the result of alternative splicing as several splicing factors were up-regulated and the alternative splicing events were increased drastically in diseased plants. Another group of genes that were highly affected were those involved in calcium signals, which are known to be in the front line of defense against biotic stresses. Real-time PCR confirmed the results of RNA-Seq. Additional results will be presented.
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