Gibberellin physiology of safflower: endogenous gibberellins and response to gibberellic acid

Abstract

Endogenous gibberellins (GAs) were extracted from safflower (Carthamus tinctorius L .) stems and detected by capillary gas chromatography-mass spectrometry from which GA,, GA 3 , GA ' ,, GA,,, GA,,, and probably, GA" were detected . The detection of these GAs suggests that the early 13-OH biosynthetic pathway is prevalent in safflower shoots . Deuterated GAs were used as internal standards and GA concentrations were determined in stems harvested at weekly intervals . GA I and GA 19 levels per stem increased but concentrations per gram dry weight decreased over time . GA 20 was only detected in young stem tissue .Gibberellic acid (GA 3 ) was also applied in field trials and both GA 3 and the GA biosynthetic inhibitor, paclobutrazol, were applied in growth chamber tests . GA 3 increased epidermal cell size, internode length, and increased internode cell number causing stem elongation . Conversely, paclobutrazol reduced stem height, internode and cell size, cell number and overall shoot weight . In field tests, GA 3 increased total stem weight, but decreased leaf weight, flower bud number and seed yield . Thus, GA 3 promoted vegetative growth at the expense of reproductive commitment . These studies collectively indicate a promotory role of GAs in the control of shoot growth in safflower, and are generally consistent with gibberellin studies of related crop plants.

Relationship between gibberellins, height, and stress tolerance in barley (Hordeum vulgare L.) seedlings

“…The chlorenchyma was poorly developed or absent and the cortical and pith cells are shorter by 50 to 60%. Similarly, reduced internodal elongation, cell length and number further exemplify the reduction in height of treated safflower (Carthamus tinctorius L.) (Potter et al, 1993).…”

Paclobutrazol-induced Leaf, Stem, and Root Anatomical Modifications in Potato

“…Various authors reported different results in various plant species with respect to PBZ induced stem anatomical modifi cations. PBZ reduced both cell number and length in saffl ower (Carthamus tinctorius L.) stem (Potter et al, 1993). Burrows et al (1992) reported that PBZ treatment brought about a 50% reduction in chrysanthemum stem diameter because of an enhanced development of secondary xylem and a marked reduction in the number of sclerenchyma bundle caps.…”

Growth and Yield of the Common Bean in Response to Combined Application of Nitrogen and Paclobutrazol

“…The favorable responses to growth reduction and an increase in production in the bean plants have maximum effect up to a concentration of 8 mg L -1 PBZ ( Figure 1); from 10 mg L -1 responses are inhibited, a fact also confirmed by Yin et al (2011). It is expected that an increase in grain yield up to the inhibitory concentration of PBZ is probably due to the action of gibberellic acid concurrently stimulating the increase in stem biomass and inhibiting the formation of reproductive organs (POTTER et al, 1993).…”