Characterization and density of trichomes on three common bean cultivars

Trichomes have been implicated as a mechanism which can confer resistance to both plant pests and drought. A study was conducted to provide information regarding genetic variability for trichome distribution and density among three diverse dry bean (Phaseolus vulgaris L.) cultivars, and to characterize the types of trichomes present among the cultivars. Trichomes on the leaf surfaces were micrographed with a scanning electron microscope (SEM) and counted using a stereomicroscope on both the abaxial and adaxial leaf surfaces of the cultivars ‘Bill Z’, ‘Pompadour Checa’ and ‘Diacol Calima’. Straight, hooked, and glandular trichomes were observed on the leaf surfaces of each cultivar. SEM micrographs are presented for the leaf surfaces of each cultivar and trichome type. The abaxial leaf surface had more straight trichomes than the adaxial leaf surface for ‘Pompadour Checa’ and ‘Diacol Calima’, however ‘Bill Z’ had more on the adaxial surface. The opposite relationship existed among the cultivars and leaf surfaces for the hooked trichomes.