Cytokinin control of sequential leaf senescence in tobacco

Conference · Tue May 01 04:00:00 EDT 1990 · Plant Physiology, Supplement; (USA)

OSTI ID:5628378

Singh, S ^[1]; Letham, D S; Parker, C W ^[2]

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1. Univ. of Saskatchewan, Saskatoon (Canada)
2. Australian National Univ., Canberra (Australia)

Exogenously applied cytokinins (especially dihydrozeatin) retarded senescence of leaf disks, detached and intact leaves of tobacco. The cytokinin complex in tobacco leaves of various maturities was characterized by radioimmunoassay. Zeatin was the major base whereas zeatin riboside was identified as the main riboside in both young (green) and senescing leaves. The basal, senescing leaves had lower levels of both cytokinin bases and ribosides. Exogenous applications of dihydrozeatin and zeatin to detached tobacco leaves delayed leaf senescence and elevated cytokinin base levels. These differences in endogenous levels of active cytokins in senescent and non-senescent leaves may be involved in the regulation of sequential leaf senescence in tobacco. There was no appreciable difference in either translocation or metabolism of xylem supplied tritium-labelled dihydrozeatin riboside between upper green and lower senescing leaves. The apical, green leaves (and not the basal, yellowing leaves) exhibited incorporation of ({sup 14}C)adenine into zeatin. The differing cytokinin levels in leaves of various maturity levels may be due to difference in cytokinin biosynthetic capacity.

• OSTI ID: 5628378
• Report Number(s): CONF-9007196--
• Conference Information: Journal Name: Plant Physiology, Supplement; (USA) Journal Volume: 93:1
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
BIOSYNTHESIS
CARBON 14 COMPOUNDS
ISOTOPE APPLICATIONS
KININS
LABELLED COMPOUNDS
LEAVES
MAGNOLIOPHYTA
MAGNOLIOPSIDA
NICOTIANA
ORGANIC COMPOUNDS
PEPTIDES
PLANTS
POLYPEPTIDES
PROTEINS
RIBOSIDES
SYNTHESIS
TRACER TECHNIQUES