RNAi-induced silencing of the succinate dehydrogenase subunits gene in Colletotrichum abscissum, the causal agent of postbloom fruit drop (PFD) in citrus

Abstract

The citrus crop is one of the most important culture worldwide, being Brazil the world highest producer of sweet oranges. The challenge for this culture is the constant attack by several pathogens that cause economically losses. Among the fungal diseases the post-bloom fruit drop causes dramatically losses in production, characterized by damages in the blossoms that causes fruit infeasibility and early drop, one of the causal agent is Colletotrichum abscissum. The pathogen control is based in chemical applications, irrespective of crops and fungicides used, development of fungicide-resistant pathogen populations is a problem in agriculture. New technologies are being applied every year to better understand the pathogens biology, which can contribute to plant diseases control as an alternative to chemical compounds. The RNA interference emerged as a potential technology for gene function studies as well as an approach for pathogens control. The fungicides compounds have action in different targets, such as the succinate dehydrogenase (SDH), which plays a hole in cell respiration. Therefore, here we investigate the functionality of the RNAi machinery of C. abscissum and test genetically whether the chemically pre-defined fungal SDH target may represent a promising target gene in RNAi based control strategies. The C. abscissum RNAi machinery was functionally proven by silencing of gene report. Then, the silencing of SDH subunits were induced and verified. In addition, the C. abscissum mutants generated for this study made possible the fungus infection process investigation. Furthermore, knockdown mutants of succinate dehydrogenase subunits genes resulted in morphological and significant pathogenicity changes. Thus, in conclusion, we suggest that the RNA interference is an important tool that can be exploited to post bloom fruit drop disease control and also the chemical fungicide target are still useful in the new technologies control strategies.

Keywords: Colletotrichum abscissum; DsRed mutants; Fungicide; Gene expression analysis; Gene silencing; RNAi; Succinate dehydrogenase.