Main Article Content
Senescence activity in extracts from fruiting <I>Bidens pilosa</I> plants
Abstract
Senescence activity of extracts from the leaves of Bidens pilosa was
determined using Rumex and bean plants as bioassay systems. Ethanolic
extracts of non-senescent and senescent leaves were chromatographed (TLC) using
a solvent system of benzene : ethyl acetate : acetic acid 50:5:2 (v/v). Fraction
1 (Rf 0.0–0.1) from both non-senescent and senescent leaves, eluted
with methanol, induced senescence of bean leaves in the light. In Fractions
that were eluted with ethyl acetate, senescence-inducing activity was detected
from non-senescent but not from senescent leaf extracts, using the bean explant
bioassay. This senescence activity was not detected in Fraction 1 but in Fractions
3 (Rf 0.1–0.25), 4 (Rf 0.25–0.35), 6 (Rf 0.6–0.7)
and 7 (Rf 0.9–1.0). On the TLC plates, Fractions 3 and 4 co-chromatographed
with abscisic acid and 4-chloroindole acetic acid respectively. The results
suggest that plant extracts contain senescence factors which operate during
the active terminal phase of growth, in the presence of light.
South African Journal of Botany 2002,
68: 376–381
determined using Rumex and bean plants as bioassay systems. Ethanolic
extracts of non-senescent and senescent leaves were chromatographed (TLC) using
a solvent system of benzene : ethyl acetate : acetic acid 50:5:2 (v/v). Fraction
1 (Rf 0.0–0.1) from both non-senescent and senescent leaves, eluted
with methanol, induced senescence of bean leaves in the light. In Fractions
that were eluted with ethyl acetate, senescence-inducing activity was detected
from non-senescent but not from senescent leaf extracts, using the bean explant
bioassay. This senescence activity was not detected in Fraction 1 but in Fractions
3 (Rf 0.1–0.25), 4 (Rf 0.25–0.35), 6 (Rf 0.6–0.7)
and 7 (Rf 0.9–1.0). On the TLC plates, Fractions 3 and 4 co-chromatographed
with abscisic acid and 4-chloroindole acetic acid respectively. The results
suggest that plant extracts contain senescence factors which operate during
the active terminal phase of growth, in the presence of light.
South African Journal of Botany 2002,
68: 376–381
