Induction of local and systemic resistance to Colletotrichum coccodes in pepper plants by DL-β-amino-n-butyric acid

DL-beta-amino-n-butyric acid (BABA) that was applied as a foliar spray or soil drench to pepper plants induced local and systemic resistance to a challenge infection with Colletrichum coccodes. About 85 and 100% protections against the anthracnose were achieved by a relatively high concentration of BABA at 1000 mu g/ml, which had no antifungal activity in vitro against C. coccodes. Protection was expressed as a reduction in the number and size of lesions. DL-alpha-amino-n-butyric acid (AABA) was not so effective as BABA, whereas DL-gamma-amino-n-butyric acid (GABA) provided a little protection against anthracnose. At least 5 days were needed after BABA treatment as a soil drench in order to induce resistance in pepper plants. After BABA treatment as a soil drench. the plants remained protected over 15 days. Application of BABA to the lower leaves significantly protected the leaves above the treated leaves from C. coccodes infection, which suggested that systemic resistance to the anthracnose was induced in pepper plants by BABA. The leaves above the BABA-treated lower leaves were strongly protected by reduction of the number and size of lesions.