Vegetative compatibility and heterokaryon formation between different isolates of Colletotrichum lindemuthianum by using the nit mutant system

Abstract

Colletotrichum lindemuthianum, the causative agent of bean anthracnose, is one of the most common pathogens leading to expressive damage to plants beyond presenting noticeable variability. The knowledge on vegetative compatibility groups (VCGs) is of particular interest in asexual fungi as they subdivide the population in groups that can exchange genetic information via heterokaryosis and the parasexual cycle.Among the techniques used in studies about vegetative compatibility groups, the obtainment of nit mutants is apparent. This paper is aimed at obtaining heterokaryons between different isolates of C. lindemuthianum, grouping them in VCGs and evaluating their genetic variability by using the nit mutants system. Nit mutants were obtained from 20 single spore isolates. The mutants were phenotypically classified and paired for complementation and formation of heterokaryons so as to group them in VCGs. Seventeen mutants from the different phenotypic-rates were recovered: nit1, nit2, nit3 and nitM. At the same time, 10 mutants were selected for pairing and division of the anastomosis groups. Nine heterokaryons were obtained and the isolates were divided into 9 vegetative compatibility groups. In the combinations for the formation of anastomosis, 31 compatible combinations and 24 incompatible combinations were observed. It was concluded that the methodology used to select nit mutants in C. lindemuthianum made it possible to determine the vegetative compatibility groups and that such a technique was adequate to prove genetic variability.

Plant growth-promoting activity of wild-type and bromate-resistant mutant of the endophytic fungus Colletotrichum karstii

“…The description of auxotrophic mutants of the Colletotrichum genus has been previously described, especially strains resistant to potassium chlorate (KClO 3 ) (Prado et al, 2007;Rosada et al, 2010;Santanna et al, 2010). In 2011, Carvalho and Costa (2011) studied the genetic variability and vegetative compatibility of nit mutant strains of C. lindemuthianum and reported, similar to the authors of current study, auxotrophic mutants for uric acid (UA). Most studies aimed at isolating Colletotrichum mutants use the chlorate resistance system, while in current assay the authors are reporting for the first time retrieval of Colletotrichum mutants through the potassium bromate resistance system (KBrO 3 ), similar to the one previously mentioned for the Aspergillus species (Kanan, 2002;Kanan & Al-Najjar, 2010).…”