Gibberellic acid

About: Gibberellic acid is a research topic. Over the lifetime, 6597 publications have been published within this topic receiving 109294 citations. The topic is also known as: GIBBERELLIN A3.

Gibberellic Acid and Ion Release from Barley Aleurone Tissue Evidence for Hormone-dependent Ion Transport Capacity

Abstract: The release of potassium, magnesium, and phosphate ions from aleurone cells of barley (Hordeum vulgare L. cv. Himalaya) is a gibberellic acid-dependent process. The release of these ions is preceded by a lag period of 6 to 8 hours after gibberellic acid addition. The effect of gibberellic acid on the release of ions is not mediated through an effect on ion solubilization. Thus, gibberellic acid does not apreciably affect the sum of extracted and released ions relative to controls. Rather, the effect of the hormone is on the release process itself. Inhibitors of oxidative phosphorylation when added with gibberellic acid or at times up to 6 hours after gibberellic acid inhibition release. When these inhibitors are added after ion release has begun, however, rapid efflux of ions occurs. These results suggest a strong correlation between energy levels and ion transport capacity. Inhibitors of RNA and protein synthesis also inhibit gibberellic acid-stimulated ion release. Evidence suggests that RNA and protein synthesis are required to establish and maintain ion release capacity of aleurone cells.

Exogenous phytohormones and the induction of plant galls by insects

Abstract: The mechanism of gall induction by insects has remained elusive. Previous studies have met with limited success in attempting to induce galls by injection or application of chemical compounds. To determine whether an exogenous source of phytohormones plays a role in gall induction, we injected cytokinin (CK), auxin (IAA), gibberellic acid (GA), and abscisic acid (ABA) in various concentrations, ratios, and combinations into leaf petioles of Capsicum annuum L. cv. California Wonder (Solanaceae). We found that CK + IAA injections lead to gall-like growth in C. annuum. GA enhanced and ABA inhibited gall growth except in the presence of GA. Isopentenyl adenine (IP) was the most effective type of CK at inducing growth. Our work is consistent with the hypothesis that exogenous CK + IAA produced and supplied by insects leads to gall induction. We hypothesize that insects have obtained the capability to induce galls via acquisition of the biosynthetic pathways to produce IAA and trans-zeatin family CKs through microbial symbiosis or lateral gene transfer.

A distinction between the actions of abscisic acid, gibberellic acid and cytokinins in light-sensitive lettuce seed.

Abstract: Using isolated lettuce seed embryos it can be shown that the inhibitory effect of abscisic acid upon germination is reversed solely by cytokinin In the intact seed, however, gibberellic acid is also required for this reversal to be manifested in germination

Effect of the Rht3 dwarfing gene on dynamics of cell extension in wheat leaves, and its modification by gibberellic acid and paclobutrazol

Abstract: The second leaf of wheat was used as a model system to examine the effects of the Rht3 dwarfing gene on leaf growth. Compared to the rht3 wild type, the Rht3 allele decreased final leaf length, surface area and dry mass by reducing the maximum growth rates, but without affecting growth duration. Gibberellic acid (GA 3 ) increased final leaf length and maximum growth rate in the rht3 wild type, but was without effect on the Rht3 mutant, which is generally regarded as being non-responsive to gibberellin (GA). Paclobutrazol, an inhibitor of GA biosynthesis, decreased final leaf length and maximum growth rate in the rht3 wild type to values similar to those in the untreated Rht3 mutant. Neither GA 3 nor paclobutrazol affected the duration of leaf growth. The decrease in leaf length was produced by reduction of cell length rather than cell number. The maximum relative elemental growth rate (REGR) for cell extension was essentially the same in all treatments, as was the time between the cells leaving the meristem and achieving maximum extension rate. The differences between the genotypes and treatments were all almost entirely due to differences in the time taken from the attainment of maximum REGR of cell extension to the cessation of extension. This was reflected in the length of the extension zone, which was approximately 6-8 per cent of final leaf length. The effects of the Rht3 allele, GA 3 and paclobutrazol all appear to be on the processes which promote the cessation of cell elongation.

Effects of temperature, light, nitrate and pre chilling on seed germination of grassland plants

Abstract: SUMMARY The effects of factorial combinations of alternating (20/10 oC) and constant temperature (20 oC), of light (intermittent) and dark, and of distilled water and nitrate on the germination of a range of species of indigenous grassland were investigated in 1979, and in 1980 when the effects of pre-chilling were also studied Species differed greatly in their response to the eight sets of environmental conditions in 1979 With the exception of Lolium perenne ssp perenne and Cynosurus cristatus, only a small percentage of seeds of most species was able to germinate in constant temperature in the dark However, when light was supplied there was moderate germination of Anthoxanthum odoratum, Cerastium fontanum ssp glabrescens, Festuca rubra, Holcus lanatus and Poa trivialis Alternating temperature greatly increased the germination of most species and nitrate further increased germination of Agrostis capillaris, Deschampsia caespitosa, H lanatus, Poa annua and P trivialis In alternating temperatures, light increased germination of these species even more than did nitrate A capillaris, D caespitosa and P annua required all three factors for maximum germination, and another 7% of seeds of A capillaris also required gibberellic acid Germination responses following sequential application of factors often differed from those resulting from simultaneous treatment: in particular, the germination of Ranunculus species was greatly enhanced Although seeds of the species tested in 1980 were more germinable than those of the same species in 1979, they responded similarly to the different factors Light increased the germination of both Taraxacum officinale and Plantago lanceolata in constant but not in alternating temperature, while nitrate was much more stimulatory to the latter species About half the seeds of P lanceolata were dormant Pre-chilling at 4oC for 7 days increased subsequent germination of all species when followed by constant temperature, except of A capillaris in the dark and C cristatus (already maximal) in the light When followed by alternating temperature in the dark, pre-chilling greatly decreased germination of A capillaris In the light, where germination of most species was maximal, there was little effect of pre-chilling Longer durations (21 and 42 days) of chilling of older seed gave similar results to the 7 day pre-chilling