Infection by Colletotrichum truncatum in resistant and susceptible lentil genotypes

Abstract

The process of infection of lentil (Lens culinaris Medik.) by Colletotrichum truncatum (Schwein.) Andrus and W.D. Moore was studied on lentil on a partially resistant line and a susceptible cultivar, using one highly virulent and one moderately virulent isolate. Leaves and stem tissue were sampled at regular intervals from 1 to 144 h postinoculation (hpi). Infection was characterized by a symptomless phase lasting 3 days and a destructive phase between 3 and 6 days after inoculation. Conidia germinated within 3–6 hpi and formed appressoria at 6–12 hpi. Infection pegs from the appressoria penetrated the cuticle and epidermal cells directly. Hyphae in host tissues grew inter- and intra-cellularly, starting at 24 hpi. Differences in pathogen development on the two lentil genotypes became apparent at 48 hpi. In the resistant line, deposits of material stained with aniline blue were prominent during infection by the moderately virulent isolate, but were not produced during infection by the highly virulent isolate. No deposits were observed in the susceptible cultivar. Also, hyphal spread was slower and phenolic compounds accumulated more quickly in the resistant line, resulting in fewer, smaller lesions than in the susceptible cultivar.