Identification of defense related transcripts in robusta coffee (Coffea canephora) in response to infestation by coffee white stem borer (Xylotrechus quadripes) using forward subtracted suppression subtractive hybridization library

Abstract

AbstractCoffea arabica L (arabica), the most widely cultivated coffee species is susceptible to Xylotrechus quadripes (coffee white stem borer - CWSB), while C. canephora Pierre (robusta) the only other commercially cultivated coffee species is resistant to CWSB. We constructed a forward subtracted suppression subtractive hybridization (fSSH) cDNA library from bark tissue of C. canephora Cv CxR experimentally infested with CWSB larvae towards understanding the genetic mechanism of resistance. The library provided 292 unique transcripts (expressed sequence tags - ESTs). While 272 ESTs were from C. canephora, 20 ESTs were from X. quadripes. Transcripts from C. canephora matched 204 genes, 4 pseudogenes and 4 lncRNA, several of which are considered to be involved in mounting defense reactions against CWSB or in repairing or mitigating the damage caused by the pest. Most striking finding was overwhelming presence of transcripts of Cc08_g08430 isoleucine N-monooxygenase 2 like gene belonging to CYP79 family. Quantitative real time polymerase chain reaction (qRT PCR) revealed that the gene was strongly induced by CWSB infestation. We obtained complete cDNA sequence, as well as, 593 bp upstream sequence of the gene. The CYP79 proteins are known to be involved in the biosynthetic pathways leading to at least 3 well known groups of plant defense compounds against herbivory – viz., cyanogenic glucosides, glucosinolates and herbivore induced volatile compounds. The Cc08_g08430 isoleucine N monooxygenase 2 like gene (CYP79) is predicted to be involved in one of these biosynthetic pathways and a strong candidate for defense reaction of robusta against CWSB.