Eliciting Plant Defense on Anthracnose Disease in Chili (Capsicum annuum Linn.) by Sodium Nitroprusside Solution

Abstract

The study on the induction of plant defense against to anthracnose disease of chili by sodium nitroprusside solution was investigated during pre- and post-harvest. Pre-harvest treatment was conducted by spraying the chili plants with sodium nitroprusside (SNP, nitric oxide donor) solution at 0 (control), 0.05 and 0.1 mM every 3 days for 9 times before inoculating with the spore suspension of Colletotrichum gloeosporioides (the causal agent of anthracnose disease) and then sprayed with SNP again 1 time after inoculating. The results revealed that 0.1 mM SNP was the best concentration to suppress anthracnose disease by reducing disease incidence and disease index on chili leaves, and showing the lowest loss of yield caused by anthracnose disease. This founding also showed that either pathogenic inoculation or SNP treatment had ability to induce the activities of peroxidase (POD) and phenylalanine ammonia lyase (PAL) of chili leaves, particularly the chili plant inoculated with pathogenic fungi followed by treated with 0.1 mM SNP showed the highest POD and PAL activities. Post-harvest treatment was done by inoculating the mature chilli fruit with C. capcisi for 4 h and followed by dipping in 0 (control) and 4 mM SNP. All fruit samples were kept at 13C for 15 days. The results showed that chili fruit dipped with 4 mM SNP reduced disease incidence, disease index, delayed weight loss, respiration rate, ethylene production, and also maintained the changes of fruit color (ΔE) better than non-treated fruit (control). The activities of chitinase (CHI) and β-1,3-glucanase (GLU) in chili fruit were induced by SNP with the highest peak on day 6 of storage but they were not significant different with the control fruit. These results indicated that SNP might potential leading to the reduction of anthracnose disease in chili by eliciting plant defense related enzymes in both pre- and post-harvest periods.