Tf. Hsieh et al., Light and scanning electron microscopy studies on the infection of oriental lily leaves by Botrytis elliptica, EUR J PL P, 107(6), 2001, pp. 571-581
Light, scanning electron and fluorescent microscopy were used to observe th
e infection process of Botrytis elliptica on leaves of oriental lily (cv. S
tar Gazer). At 20 degreesC and 100% relative humidity, conidia germinated o
n both adaxial and abaxial foliar surfaces, but germ tubes failed to invade
epidermal cells on the adaxial surface. On abaxial surfaces, short (< 20 m
um) swollen germ tube appressoria penetrated through stomatal openings (19%
), through the epidermis near guard cells (52%), or directly through epider
mal cells (29%). Esterase activity was detected on germ tubes and conidia a
fter 6 h of incubation, and deformation of the cuticle on abaxial surfaces
of lily was observed surrounding infection sites. By 3 h after inoculation,
almost 70% of the conidia had germinated, but no penetration was observed.
At 6 h after inoculation, almost one-third of germinated conidia had penet
rated epidermal cells, and water-soaked lesions were associated with 20% of
the penetrations. By 9 h after inoculation, approximately 60% of the germi
nated conidia had penetrated plant tissues, and water-soaked lesions were a
ssociated with 60% of the infections. Fluorescent microscopy with a specifi
c fungal stain allowed assessment of successful infection and visualization
of sub-epidermal hyphae. We conclude that penetration of abaxial foliar su
rfaces of oriental lilies by B. elliptica occurs via short swollen germ tub
e appressoria mostly near stomata.