Ultrastructural and Cytochemical Observations onChenopodium AmaranticolorTrichome

Abstract

SUMMARYThis study gives the results of investigations made on the ultrastructure of Chenopodium amaranticolor Coste & Reyn foliar trichomes. These hairs, when localized on subapical leaves, have a pigmentation which is due to the presence of betalains. This investigation has given information both on the ultrastructure of plastids in pigmented hipsophylls and on the ultrastructure and development of this trichome, which for many aspects results similar to the « hair of salt ». PTAC staining has evidenced, both on stalk and bladder cell, the presence of plasmalemma invaginations that seem to originate vesicles that maintain PTAC positivity. PTAC positive vesicles are therefore present in the cytoplasm of both hair cells; some of them take connection with the bladder cell tonoplast and others are close to the cell wall. Cytochemical pyrantimonate localization of cations has also been employed: reaction products are found in cytoplasm, mitochondria, chloroplasts and vacuole. The presence of hairs with gland-like ultrastructure, of vesicles behaving like plasmalemma and of ion localization are discussed.