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Unveiling the Involvement of Oxidases in the Resistance of Coffea spp. to Colletotrichum kahawae

This paper is available in a repository.
This paper is available in a repository.

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Abstract

Cytological, biochemical and molecular studies were undertaken to elucidate the role of oxidases in coffee resistance to Colletotrichum kahawae (Ck). Hypocotyls of the coffee variety Catimor 88, resistant to Ck isolate Que2 (from Kenya), were used and compared with the susceptible variety Caturra. Coffee resistance was characterized by a restricted fungal growth associated with hypersensitive-like cell death (HR), monitored by cell autofluorescence and/or browning. The activity of the oxidative enzymes peroxidase (POD) and polyphenol oxidase (PPO) was evaluated. For both genotypes the activity of POD and PPO measured in the infected tissues was, on average, higher than in control samples. Moreover, in the resistant genotype, POD activity started to increase at 24hai which was coincident with the beginning of the observation of HR. At the molecular level, 33 unigenes with oxidative-related function were identified in an Illumina RNA-seq coffee-Ck database as differentially expressed in Catimor 88 and Caturra infected by C.kahawae comparatively with their controls, and grouped into six main classes: multicopper, peroxidase, polyphenoloxidase, germin-like, redoxin domain and isoflavone reductase-like protein. For 20 unigenes, a predominant expression profile showing an increase of activation at 48 and/or 72hai in Catimor 88 when compared to Caturra was detected. For the other 13 unigenes, the main expression profile revealed repression at all time points, for both genotypes. Gene validation and expression profiling is being performed through qPCR during key stages of the infection process.