Role of Ethylene in Abscisic Acid-induced Callus Formation in Citrus Bud Cultures.

Promotion of callus formation by abscisic Acid in citrus bud cultures.

Differential effects of sucrose, abscisic Acid, and benzyladenine on shoot growth and callus formation in the abscission zone of excised citrus buds.

The omission of sucrose from the basal medium stimulated callus formation in bud explants of Citrus sinensis (L.) Osbeck. Moreover, it increased the abscisic acid-induced callus proliferation reported earlier in the presence of 5% sucrose (Altman and Goren, Physiol. Plant. 32: 55, 1974). The inhibition of callus formation by the addition of sucrose was not due to the high osmotic potential of t...

Transitions in the functioning of the shoot apical meristem in birch (Betula pendula) involve ethylene.

In many trees, a short photoperiod (SD) triggers substantial physiological adjustments necessary for over-wintering. We have used transgenic ethylene-insensitive birches (Betula pendula), which express the Arabidopsis ethylene receptor gene ETR1 carrying the dominant mutation etr1-1, to investigate the role of ethylene in SD-induced responses in the shoot apical meristem (SAM). Under SD, the et...

Ethylene-induced Formation of ABA in Citrus Peel as Related to Chloroplast Transformations.

When mature green harvested Shamouti oranges (Citrus sinensis L. Osbeck) were exposed to 35 mul/liter of ethylene, a 3-fold increase in free abscisic acid (ABA) of the flavedo could be detected after 12 hours and a 10-fold increase after 24 hours, while chlorophyll destruction did not exceed 20%. The increase in free ABA continued up to 24 hours and leveled off. Bound ABA accumulated strongly a...

Characterization of abscisic Acid-induced ethylene production in citrus leaf and tomato fruit tissues.

Abscisic acid (ABA) significantly stimulated ethylene production in citrus (Citrus sinensis [L.] Osbeck, cv Shamouti orange) leaf discs. The extent of stimulation was dependent upon the concentration of ABA (0.1-1 milimolar) and the duration of treatment (15-300 minutes). Aging the discs before applying ABA increased ABA-induced ethylene production due to enhancement of both ethylene-forming en...