Expression of the defense-related genes in Guilan local bean (Phaseolus vulgaris L.) under the Sclerotium rolfsii fungus infection

Bean is one of the protein-rich legumes that can cause collar rot and severe loss of yield due to Sclerotium rolfsii. Bean cultivation in Guilan is mainly devoted to spring and summer cultivation date of some kind of dwarf local beans with red and red veins on the seeds. The 30 selected local beans in Guilan, with the most pathogenic strain of S. rolfsii, were subjected to artificial infection in the greenhouse. Disease Severity Index (DSI) and morphological traits associated with the reaction to the fungus were measured. Eight linked SCAR markers with resistance to bean fungal disease were also used for additional evaluation. Expression changes of the three defense genes including of chitinase (Chiti), chalcone isomeras (ChI), and phenylalanine ammonia lyase (PAL) were analyzed using Real -time PCR in selected lines from each of the resistant, tolerant and sensitive groups, with intervals. They were evaluated at 2, 4 and 6 days after artificial infection with S. rolfsii fungus. Statistical analysis and screening of genotypes using greenhouse data and SCAR markers led to the separation of genotypes and the identification of one resistant, 21 tolerant and semi-susceptible and 8 fully sensitive genotypes. The results showed that the Chiti gene had a similar trend with a gradual increase in expression over the time in resistant and tolerant lines, although the rate of expression in resistant was higher than tolerances. Although the expression of ChI and PAL genes was increasing in resistant genotypes, the expression changes over the time were not the same as the Chiti gene trend. Therefore, the Chiti gene may be a major factor in the resistance of S. rolfsii fungi to local beans in Guilan.