Comparison of in vitro analysis protocols for Ascochyta rabiei detection in chickpea seeds

PASTOR, SILVINA ESTELA; ALEJANDRO PEREZ; BUSTAMANTE MACARENA; CROCIARA CLARA; VALETTI, LUCIO; SPRING ESTEFANIA

Congreso; El 5to Congreso Argentino de Fitopatología y 59na Reunión de la División Caribe de la APS; 2021

Ascochyta blight caused by Ascochyta rabiei is a devastating disease on chickpea. This is endemic in Córdoba producing area of Argentina. Seeds carrying A. rabiei introduce the disease, and the fungus survives 3?4 years within the infected crop debris. Producers worldwide recommend planting chickpea with 0?0.3% A. rabiei seed infection (ArSI). To determine ArSI in vitro analysis (agar plate test-APT) is necessary. This type of analysis maximizes A. rabiei development and prevents its masking by other fungi. In this work, we compared different APT protocols to determine ArI in seeds and select the most efficient one. Three hundred fifty seeds of the same naturally infected sample were evaluated using three protocols: T1-2? disinfection (NaCl 0.1% Cl/l), placed on PDA; T2-5? washing under running water, placed on agar-water (AA) + Streptomyces (150 mg/L); T3-2? disinfection (NaCl 0.1%-Cl/L), placed on AA + Streptomyces (150 mg/L); T0-without disinfection, PDA plated. Plates were incubated at 21°C, alternating 12 h white light/UV-400 nm. Petri dishes were observed under a microscope for up to 15 days. LSD comparison indicated that ArSI in T3 (13.3%) and T2 (8.5%)were the highest ones, but no differences were observed between them. ArSI of T1 and T0 were 6.85% and 3.81% respectively. In T2, the fungal development was completed at 7 days of incubation. The most efficient protocols to determine ArSI were T2 and T3, with T2 being the one with the lowest incubation time until the final reading