Analysis of genes differentially expressed in Fuerte avocado fruit in response to Colletotrichum gloeosporioides infection

[摘要] The anthracnose pathogen, Colletotrichum gloeosporioides (Penz.) Penz. & Sacc., is amajor cause of disease in the avocado industry, causing significant economic losses, andinfects all cultivars. In South Africa, Fuerte and Hass varieties are the most widely grown.Identification of genes differentially expressed in avocado during infection with the fungusrepresents an important step towards understanding the plant’s defence responses andwould assist in designing appropriate intervention strategies. In this study, 454 sequencingand analysis of the transcriptome of infected Fuerte avocado fruits were performed usingthe Roche 454 GS FLX Titanium platform. cDNA libraries enriched for differentiallyexpressed genes were constructed from unharvested and harvested avocado fruit tissuescollected after 1, 4 and 24 h post-infection and after 3, 4, 5 and 7 day post-infection, thensequenced.The expression profiles of the genes expressed were measured by a hierarchicalclustering algorithm.Subsequently, quantitative real-time PCR was employed to measurethe expression of some candidate resistance genes to anthracnose disease and to validatethe sequencing results. The single sequencing run produced 215 781 reads from thetranscriptome. A total of 70.6 MB of sequence data was generated and subjected to BLASTsearches of which about 1500 genes encoding proteins predicted to function in signaltransduction, transcriptional control, metabolism, defence, stress response, transportationprocesses and some genes with unknown functions were identified. The expression profilesstudies showed that many expressed genes were either up or down regulated after infectionin avocado fruits when compared to the uninfected sample. Salicylic acid and ethylenewere identified to be involved in the signalling networks activated in avocado fruit duringC. gloeosporioides infection. This study showed that avocado is able to respond to C.gloeosporioides infection by exhibiting a sophisticated molecular system for pathogenrecognition and by activating structural and biochemical defence mechanisms.

[发布机构] University of the Witwatersrand