Showing papers on "Gibberellic acid published in 1996"
TL;DR: It is determined that both long-day (LD) photoperiod and gibberellin (GA) stimulate trichome formation, and a difference between the adaxial and abaxial surfaces in their response to GA with regard to trichomes formation is demonstrated.
Abstract: In wild-type (WT) Columbia and Landsberg erecta ecotypes of Arabidopsis thaliana (L.) Heynh., trichomes are present on the adaxial surfaces of all rosette leaves but are absent from the abaxial surfaces of the first-formed leaves. We have determined that both long-day (LD) photoperiod and gibberellin (GA) stimulate trichome formation. WT plants grown in LD conditions produce the first abaxial trichome on earlier leaves than plants grown in short-day (SD) conditions. Photoperiod sensitivity of abaxial trichome formation on WT plants develops gradually over time, reaching the maximum sensitivity about 24 d after germination. Application of gibberellic acid to WT plants growing in SD conditions accelerates the onset of abaxial trichomes. Conversely, application of 20 to 80 mg L-1 paclobutrazol, a GA biosynthesis inhibitor, to wild-type plants suppresses trichome initiation on the abaxial epidermis. The GA-deficient mutants ga1-5 and ga4-1 and the GA-insensitive mutant gai-1 exhibit delayed onset of abaxial trichomes when grown in LD conditions. The null mutant ga1-3 produces completely glabrous leaves when grown in SD conditions. Application of gibberellic acid to glabrous ga1-3 plants consistently induces earlier formation of trichomes on the adaxial epidermis than on the abaxial epidermis, demonstrating a difference between the adaxial and abaxial surfaces in their response to GA with regard to trichome formation.
222 citations
TL;DR: Phytagar tissue culture grade proved superior to other agars tested, increasing bud induction frequency from 0-33% to 80–93% and eliminating explant hyperhydricity.
Abstract: Chile pepper (Capsicum annuum L.) plants were regenerated from cotyledon explantsin vitro in four major stages: bud induction, bud enlargement, shoot elongation, and root development. Bud induction medium contained 0.5 mg/L (2.9μM) indole-3-acetic acid and 2 mg/L (8.9 μM) N6-benzyladenine. Bud enlargement occurred, and an occasional shoot appeared when medium with 2 mg/L (6μM) gibberellic acid, 2 mg/L (8.9 μM) N6-benzyladenine, and 5 mg/L (29.4 μM) silver nitrate was used. Most shoots elongated after placement on a third medium without plant growth regulators or on fresh plates of bud enlargement medium. Incubations were for 2, 2, and 4 weeks, respectively, at 28.5°C and continuous light. Treatment with silver nitrate was necessary for multiple shoot production and elongation to occur in the third culture stage and was most effective when present in the second-stage medium but not in the bud induction medium. Sixteen to 26% of the shoots rooted in medium with 1 mg/L (5.4 μM) 1-naphthaleneacetic acid after 1 month. Additional shoots transferred to a second rooting medium with 0.1 or 1.0 mg/L (0.54 or 5.4 μM) 1-naphthaleneacetic acid developed roots, increasing the overall rooting efficiency to 70–72%. Most rooted shoots grew well and produced viable seeds when grown in the greenhouse. Other cytokinins tested for plant regeneration were zeatin and thidiazuron. Zeatin induced few shoots and fewer well-developed plants. Thidiazuron induced multiple shoots 4 months after culture began, but many were small and did not elongate further. Phytagar tissue culture grade proved superior to other agars tested, increasing bud induction frequency from 0-33% to 80–93% and eliminating explant hyperhydricity.
118 citations
TL;DR: The results are consistent with a role for thioredoxin h in initiating the mobilization of nitrogen and carbon needed for germination and seedling development.
Abstract: Thioredoxin of the h-type — earlier linked to the reduction of wheat (Triticum durum Desf. cv. Monroe) endosperm proteins — was converted from an oxidized to a partially reduced state during germination and seedling development. While the abundance of thioredoxin progressively decreased during this period, the availability of reducing equivalents, defined as the product of the relative abundance of thioredoxin and the percent reduction, increased. The amount of the enzyme catalyzing the reduction of thioredoxin h (NADP-thioredoxin reductase) remained constant. The activities of enzymes generating the NADPH needed for the reduction of thioredoxin (glucose 6-phosphate and 6-phosphogluconate dehydrogenases) increased. The level of thioredoxin h in the endosperm appeared to be controlled by the embryo via hormones. Gibberellic acid enhanced the disappearance of thioredoxin, whereas abscisic acid showed the opposite effect. Moreover, uniconazole, an inhibitor of gibberellic acid synthesis, slowed seedling growth and inhibited the disappearance of thioredoxin in a manner reversible by gibberellic acid. The results are consistent with a role for thioredoxin h in initiating the mobilization of nitrogen and carbon needed for germination and seedling development.
99 citations
TL;DR: DFMO strongly inhibits root growth and arbuscular mycorrhizal infection of Pisum sativum and this inhibition is reversed when exogenous polyamine (putrescine) is included in the DFMO treatment, suggesting that ODC may have a role in root Growth and myCorrhizals infection.
99 citations
TL;DR: The effect of exogenously applied gibberellic acid (GA3) on the postharvest color change of strawberry fruit was evaluated through their external color and surface color parameters and a significant delay on color evolution was observed.
Abstract: The effect of exogenously applied gibberellic acid (GA3) on the postharvest color change of strawberry fruit was evaluated through their external color and surface color parameters. A significant delay on color evolution was observed in fruits treated with GA3. The evolution of activities of phenylalanine ammonia-lyase (PAL), chlorophyllase, and peroxidase was also analyzed. PAL activity increased during strawberry ripening, but in fruits treated with GA3 the increase in such activity was slower, and, probably as consequence, the development of red color was delayed. Moreover, the activity of chlorophyllase and peroxidase, enzymes possibly involved in chlorophyll metabolism, decreased during strawberry ripening. However, a delay was observed in the decrease of such activities in GA3-treated fruits.
83 citations
TL;DR: Findings suggest that both ABA and GA3 could be involved in theregulation of nucleic acid and protein metabolism during dormancy, acting antagonistically in these processes and, specifically, in the regulation of the synthesis of the two proteins that appear to play a role in the maintenance of dormancy in these seeds.
Abstract: Study of the factors involved in the dormancy of Fagus sylvatica seeds shows that such dormancy is due partly to the seed coats and partly to endogenous factors Seed coat removal accelerates both the release from dormancy and the effects of the other treatments that abolish it The dormancy of these seeds is eliminated by cold treatment at 4°C over a period longer than 8 weeks, and exogenous application of abscisic acid (ABA) reverses the effects of low temperature, the seeds remaining in an ungerminated state Additionally, ABA reduces protein synthesis but slightly increases RNA synthesis, which suggests its involvement in the synthesis of RNAs related to this process In vitro translation of the RNAs isolated from these seeds shows that ABA delays the disappearance of at least 2 polypeptides (of ca 22 and 24 kDa), which are abundant in dormant seeds and under conditions that prevent the release from dormancy, but which disappear under treatments that abolish it Exogenous application of gibberellic acid (GA3) proved to be efficient in breaking the dormancy of these seeds and in substituting for cold treatment as well as in antagonizing the effects of ABA on the synthesis of both DNA and proteins GA3 also accelerates the disappearance of the two polypeptides abundant in dormant seeds and in ABA-treated seeds These findings suggest that both ABA and GA3 could be involved in the regulation of nucleic acid and protein metabolism during dormancy, acting antagonistically in these processes and, specifically, in the regulation of the synthesis of the two proteins that appear to play a role in the maintenance of dormancy in these seeds
80 citations
TL;DR: The results of the present work support the possible role of gip in GA-induced corolla and stem elongation and identify a short, highly hydrophobic N-terminal region in the deduced sequence.
Abstract: Gibberellins (GAs) regulate petunia corolla pigmentation and elongation. To study this hormone's effect at the molecular level, we used the tomato gast1 gene as a probe to isolate a gibberellin-induced gene (gip) from petunia corollas. The deduced sequence of gip exhibited 82% identity with GAST1 protein and contained a short, highly hydrophobic N-terminal region. High levels of gip expression were detected in elongating corollas and young stem internodes. When detached corollas were grown in vitro in sucrose medium, gip expression was strongly induced by gibberellic acid (GA3). GA3-induced gip expression in corollas was inhibited by abscisic acid (ABA). The expression of the gene was also induced by GA3 in detached young stem segments. Sucrose was not essential for GA-induced gip expression in corollas but enhanced its effect. In stems, on the other hand, sucrose inhibited the effect of the hormone. The results of the present work support the possible role of gip in GA-induced corolla and stem elongation.
74 citations
01 Jan 1996
TL;DR: In this paper, the authors found that Phanerochaete chrysosporium ME446 synthesized the growth substances IAA, GA3, ABA and zeatin as primary and secondary metabolites.
Abstract: Besides higher plants, there is evidence that fungi synthesize IAA, GA3, ABA and zeatin as well. According to our findings, Phanerochaete chrysosporium ME446 synthesized the growth substances IAA, GA3, ABA and zeatin as primary and secondary metabolites. Recovery of IAA, GA3, ABA and zeatin were respectively 55.5±10%, 74.6±8%, 51.6±10% and 56.63±6%. We have demonstrated that one can use the same extraction method to determine the different growth substances at the same time, thus this method will be primary and the only method that is applied in this research area.
72 citations
TL;DR: Two wheat cultivars, Spica and Lerma 52, were crossed with a set of four near-isogenic lines carrying the tall (rht) allele or one of the dwarfing genes Rht1, Rht2 or Rht3 (GA-insensitive alleles) to suggest that gibberellic acid is involved either directly or indirectly in this phenomenon.
Abstract: Two wheat cultivars, Spica and Lerma 52, which consistently produce high levels of α-amylase during the later stages of grain development (late maturity α-amylase), were crossed with a set of four near-isogenic lines carrying the tall (rht) allele or one of the dwarfing genes Rht1, Rht2 or Rht3 (GA-insensitive alleles). The F1 and F2 populations were developed and analysed for grain α-amylase and plant height. The Rht3 gene exhibited the strongest influence on plant height and strongly inhibited new α-amylase synthesis during the later part of grain ripening. By comparison, Rht1 and Rht2 had a less pronounced effect but still significantly reduced the expression of late maturity α-amylase. These observations suggest that gibberellic acid is involved either directly or indirectly in this phenomenon. The implications of the effect of dwarfing genes on expression of late maturity α-amylase are discussed in relation to cultivar improvement and to the identification and control of high α-amylase germplasm.
41 citations
TL;DR: The plants of mustard were treated with 0, 25 and 50 ΜM gibberellic acid (GA3) at three fully developed leaf stage and treatment enhanced all the characteristics studied.
Abstract: The plants of mustard (Brassica juncea L.) were treated with 0, 25 and 50 ΜM gibberellic acid (GA3) at three fully developed leaf stage (30 d after sowing). Effect of GA3 on carbonic anhydrase activity, photosynthetic rate, leaf area index and dry mass was studied at 50, 70 and 90 d after sowing. At harvest 1000 seed mass, pod number and seed yield were recorded. GA3 treatment (50 ΜM) enhanced all the characteristics studied.
40 citations
Journal Article•
TL;DR: Multiple shoots were produced from nodal explants of cassava by a two-step procedure: a 6- to 8-day exposure to 0.11–0.22 µM thidiazuron (TDZ) and culture on agar-solidified MS medium supplemented with 2.2 µM 6-benzyladenine (BA) and 1.6 μM gibberellic acid (GA3).
Abstract: Multiple shoots were produced from nodal explants of cassava (Manihot esculenta Crantz) by a two-step procedure: a 6- to 8-day exposure to 0.11–0.22 µM thidiazuron (TDZ) in liquid Murashige and Skoog (MS) medium followed by culture on agar-solidified MS medium supplemented with 2.2 µM 6-benzyladenine (BA) and 1.6 μM gibberellic acid (GA3). TDZ caused the nodal explants to expand and this expansion (growth) continued during culture with BA and GA3. From this expanded explant, clusters of buds and fasciated stems developed continuously and these gave rise to shoots. The shoot proliferation process was open-ended, yielding an average of 31.5 shoots per nodal explant after 10 weeks of culture with genotype CG 1–56. A positive response was also obtained from seven other genotypes evaluated with this protocol.
TL;DR: The systems of plant regeneration from root explants established here would provide a useful system for vegetative propagation of female spinach plants.
TL;DR: The expression of β-amylase genes in rice and its regulation by phytohormones gibberellic acid and abscisic acid represented a new interaction of ABA and GA.
Abstract: The expression of β-amylase genes in rice (Oryza sativa) and its regulation by phytohormones gibberellic acid (GA) and abscisic acid (ABA) were examined. Upon germination β-amylase is synthesizedde novo in aleurone cells and (GA) is not required. Exogenous addition of GA does not enhance the β-amylase activity, while ABA inhibits the β-amylase activity, mRNA accumulation, and the germination of rice seeds. GA can reverse ABA inhibition of β-amylase expression, but not ABA inhibition of seed germination. Such regulation represents a new interaction of ABA and GA.
TL;DR: In general, application of 4-CI-IAA plus GA3 replaced the seed effects on pericarp protein synthesis, supporting the hypothesis that both hormones are involved in peaPericarp development.
Abstract: Developing pea fruits (Pisum sativum L.) offer a unique opportunity to study growth and development in a tissue that is responsive to both gibberellins (GAs) and auxin (4-chloroindole-3-acetic acid[4-CI-IAA]). To begin a molecular analysis of the interaction of GAs and auxins in pea fruit development, in vivo labeling with [35S]methionine coupled with two-dimensional gel electrophoresis were used to characterize de novo synthesis of proteins during gibberellic acid (GA3)-, 4-CI-indoleacetic acid-, and seed-induced pea pericarp growth. The most significant and reproducible polypeptide changes were observed between molecular weights of 20 and 60. Comparing about 250 de novo synthesized proteins revealed that seed removal changed the pattern substantially. We identified one class of polypeptides that was uniquely seed induced and five classes that were affected by hormone treatment. The latter included 4-CI-IAA-induced, GA3-induced, GA3- and 4-CI-IAA-induced, 4-CI-IAA-repressed, and GA3- and 4-CI-IAA-repressed polypeptides. Similar patterns of protein expression were associated with both hormone treatments; however, changes unique to GA3 or 4-CI-IAA treatment also indicate that the effects of GA3 and 4-CI-IAA on this process are not equivalent. In general, application of 4-CI-IAA plus GA3 replaced the seed effects on pericarp protein synthesis, supporting our hypothesis that both hormones are involved in pea pericarp development.
TL;DR: The results from these experiments revealed that the morphogenetic pathway (shoot versus root differentiation) can be manipulated on flax explants by raising the 2,4-D level from 0.05 to 3.2 mg l−1 in the induction medium.
Abstract: The effects of plant growth regulators (PGR) on calli induction, morphogenesis and somatic embryogenesis of flax were studied. The organogenic and callus formation capacity were assessed for different types of source explants. Root and shoot explants were equally good material for calli production but the former produced calli without shoot regeneration capacity. Under the experimental conditions tested, 2,4-dichlorophenoxyacetic acid (2,4-D) + zeatin was the most efficient PGR combination on calli induction and biomass production. The calli were green but with no rhizogenic capacity. In contrast, and at similar concentrations, indole-3-butyric acid (IBA) + kinetin induced white or pale green friable calli with a good root regeneration capacity (60%). A factorial experiment with different combinations of 2,4-D + zeatin + gibberellic acid (GA3) levels revealed that the direction of explant differentiation was determined by specific PGR interactions and concentrations. The results from these experiments revealed that the morphogenetic pathway (shoot versus root differentiation) can be manipulated on flax explants by raising the 2,4-D level from 0.05 to 3.2 mg l−1 in the induction medium. The induction and development of somatic embryos from flax explants was possible in a range of 2,4-D + zeatin concentrations surrounding 0.4 mg l−1 2,4-D and 1.6 mg l−1 zeatin, the most efficient growth regulator combination.
TL;DR: The sucrose reduction induced by PCB was effectively reversed by simultaneous GA3 applications, and the involvement of nonstructural sugars in shoot growth of citrus seedlings was studied.
Abstract: SummaryThe involvement of nonstructural sugars in shoot growth of citrus seedlings was studied in ‘Carrizo’ citrange (Citrus sinensis (L.) Osb. × Poncirus trifoliata (L.) Raf.) rootstocks by foliage applications of gibberellic acid (GA3) and paclobutrazol [(2RS, 3RS)-1-(4-chlorophenyl)-4,4-dimethyl-2-(1,2,4-triazol-lyl)penta-3-ol] (PCB) and subsequent determinations of sucrose, glucose, fructose, and starch. PCB inhibited length (21%) and dry weight (19%) of the stem, whereas GA3 increased both (79 and 27%, respectively) in the absence or presence of PCB. On a dry weight basis, GA3 increased hexoses (22.5 mg g−1) and starch (48.4 mg g−1) in shoots (control values were 14.7 and 35.4 mg g−1, respectively), and PCB reduced sucrose (43%) and increased starch (36%). The sucrose reduction induced by PCB was effectively reversed by simultaneous GA3 applications. In roots, GA3 did not modify the levels of the nonstructural sugars, while PCB enhanced the amount of starch (38%). On a per plant basis, GA3 (38.8 mg) ...
TL;DR: Lesquerella fendleri, a short-lived perennial mustard of the desert Southwest, is examined and effects of GA on both dormancy and postgermination traits varied among maternal sibships, indicating that for this species and this concentration of GA, morphological effects can be substantial.
Abstract: To assess the evolutionary significance of persistent seed banks, phenotypes of naturally germinating seeds must be compared with those that remain dormant under the same environmental conditions. Dormant seeds can often be induced to germinate by application of gibberellic acid (GA). However, this method is valid only if there are no phenotypic "side effects" of GA that could confound comparisons between dormant and naturally germinating seeds. We examined this assumption in Lesquerella fendleri, a short-lived perennial mustard of the desert Southwest. We exposed 3840 seeds from 16 maternal sibships to two different GA treatments (0 or 1 g/L GA) in two different germination environments (greenhouse and growth chamber), and measured germination and postgermination traits. As expected, application of GA increased germination. GA also had strong and long-lasting effects on seedling morphology. Seeds that received GA developed into seedlings that were taller, with fewer but longer leaves, than seeds that did not receive GA. Effects of GA on both dormancy and postgermination traits varied among maternal sibships. Our results indicate that for this species and this concentration of GA, morphological effects can be substantial. Further study is required to determine whether such side effects are found for lower concentrations of GA, or under conditions that encourage faster seedling growth. Nonetheless, the present results illustrate the importance of testing potential confounding effects of GA in studies of the evolution of seed dormancy and its influence on postgermination traits.
TL;DR: For interspecific hybrids, a 5-day pre-incubation of the embryos on a liquid formulation was better than the solid formulation as it promoted better growth and vigour of the normally abortive interspecific hybrid embryos.
Abstract: An improved embryo-rescue protocol was developed for embryos (90 days old) of Carica papaya L. (Clone 2001), and subsequently was utilised for efficient production of interspecific hybrids of C. papaya × C. cauliflora Jacq. from 90- to 120-day-old embryos. Pre-incubation of C. papaya embryos for 7 days on a germination medium containing half-strength De Fossard nutrients supplemented with gibberellic acid (10 μM), 6-benzylamino-purine (0.25 μM), alpha-naphthalene-acetic acid (0.25 μM). sucrose (58 mM) and agar (8 g L-1) supported 100% germination. Subsequent transfer of germinated embryos to a nutrient medium that was identical, except that it was free of plant growth regulator, allowed good growth but induced shoot etiolation and callus production. Reducing the pre-incubation of C. papaya embryos on this medium to 5 days before transfer to the medium free of plant growth regulator produced similarly high germination (96%), but allowed for the production of good quality seedlings that were unetiolated and free of unwanted callus. For interspecific hybrids, a 5-day pre-incubation of the embryos on a liquid formulation was better than the solid formulation as it promoted better growth and vigour of the normally abortive interspecific hybrid embryos. Using the improved protocol, 1981 of 2100 (94%) interspecific hybrid embryos consisting of single and multiple forms were germinated. In all cases, the germinating multiple embryos underwent further embryogenesis that allowed for the production of 485 (25%) morphologically normal hybrid plants grown in soil in the glasshouse.
TL;DR: The results obtained are discussed in relation to the possible involvement of endogenous ethylene in the regulation of germination of A. retroflexus seeds.
Abstract: Dormant Amaranthus retroflexus seeds do not germinate in the dark at temperatures below 35°C. Fully dormant seeds germinate only at 35–40°C whereas non-dormant ones germinate within a wider range of temperatures (15 to 40°C). Germination of non-dormant seeds requires at least 10% oxygen, but the sensitivity of seeds to oxygen deprivation increases with increasing depth of dormancy. 10−6 to 10−4M ethephon, 10−3M 1-aminocyclopropane 1-carboxylic acid (ACC) and 10−3M gibberellic acid (GA3) break this dormancy. In the presence of 10−3M GA3 dormant seeds are able to germinate in the same range of temperatures as non-dormant seeds. The stimulatory effect of GA3 is less dependent on temperature than that of ethephon, while ACC stimulates germination only at relatively high temperatures (25–30°C). The results obtained are discussed in relation to the possible involvement of endogenous ethylene in the regulation of germination of A. retroflexus seeds.
TL;DR: In this article, the detection of dwarf offtypes produced by micropropagation of Cavendish bananas (Musa spp.) cultivars New Guinea Cavendish and Williams was achieved by spraying gibberellic acid (GA3) solution (289 pmol/L) onto deflasked plants and measuring various plantlet responses.
Abstract: Detection of dwarf offtypes produced by micropropagation of Cavendish bananas (Musa spp.) cultivars New Guinea Cavendish and Williams was achieved by spraying gibberellic acid (GA3) solution (289 pmol/L) onto deflasked plants and measuring various plantlet responses. The most useful identification criterion was elongation of the sheath of the first leaf to form after GA3 application. Elongation of this structure was about 2-fold greater in normal plants than observed in dwarfs. Similar measurements taken earlier during in vitro culture or later during plant establishment in soil were not as useful in discriminating between normals and dwarfs as the measurements made at deflasking. The similar GA3-induced elongation response of the dwarf offtype and that of the naturally occurring dwarf cultivar Dwarf Parfitt suggests that the mechanism for dwarfism could be the same in the 2 cases.
TL;DR: The addition of 20 mM nitrogen (in the form of NaNO3) inhibited after 50 d the activities of carbonic anhydrase and nitrate reductase and net photosynthetic rate as discussed by the authors.
Abstract: In mustard(Brassica juncea L.) addition of 20 mM nitrogen (in the form of NaNO3) inhibited after 50 d the activities of carbonic anhydrase and nitrate reductase and net photosynthetic rate. However, when nitrogen was applied in association with the foliar spray of gibberellic acid, the inhibition was reversed and the above parameters and also leaf area index and dry mass were enhanced.
TL;DR: Rooting was succesfully achived with 100% rooted plants in all cultivars, with no differences significant differences among rooting media.
Abstract: Experiments were carried out aiming to develop techniques for in vitro propagation of blackberries (Rubus spp.) plants. Multiplication were done from axillary buds wich were placed in MS (MURASHIGE & SKOOG, 1962) medium, supplemented with BA (benzylaminopurine), NAA (naphthaleneacetic acid) and GA3 (gibberellic acid) in different concentrations and combinations. Subsequently, studies were done to determine the influence in rooting of the MS medium with all the salts reduced to 1/3, and with different concentrations of IBA (indolbutyric acid). Results indicated that the best multiplication of shoots was obtainned with BA (1.0 and 2.0 mg/l). The addition of NAA and GA3 in media in these experiments didn't improve the multiplication rate. Rooting was succesfully achived with 100% rooted plants in all cultivars, with no differences significant differences among rooting media.
TL;DR: In this article, the decomposition of GA 3 in buffered aqueous solutions at pH 5 and 7 was studied by spectrophotometry, measuring the appearance of gibberellenic acid at 254 nm, and using a bioassay by measuring the induction of α-amylase in barley endosperm.
TL;DR: Medium supplemented with 2 μM 6-benzylaminopurine induced adventitious shoots on mature endosperm explants, whilst gibberellic acid (GA3) and casein hydrolysate stimulated growth and development of these shoot primordia.
Abstract: Murashige and Skoog (1962) medium supplemented with 2 μM 6-benzylaminopurine (BA) induced adventitious shoots on mature endosperm explants, whilst gibberellic acid (GA3) and casein hydrolysate stimulated growth and development of these shoot primordia. Plantlets were successfully weaned in vivo. These plants were found to be triploid and flowered, although fruit set was not observed.
TL;DR: A genetic and molecular analysis, based on the characterization of the flanking genomic sequences of the T-DNA insert, showed that ABC33 is a new loss-of-function allele at theGA1 locus.
Abstract: Seed viability, dormancy and germination efficiency are very important aspects of the life cycle of plants and their potential to survive and spread in the environment. To characterize the genes controlling these processes, we have devised a technique for the selection of mutants impaired in seed germination. Selection for such a trait is complicated by physiological factors that interact with these processes and affect seed germination efficiency. The distinction between low seed germination potential due to physiological factors that interfere with seed maturation or germination and germination deficiency due to genetic factors was based on screening for tagged mutations.Arabidopsis thaliana T-DNA primary transformants obtained by an in planta transformation technique are all heterozygotes. We screened for lack of germination of 1/4 of the seeds in the progeny of independent transformants, and simultaneously for the abnormal segregation (2:1 instead of 3:1) of a kanamycin resistance marker carried by the T-DNA inserted into the genome of these primary transformants in the plants that germinate. This yielded several mutants affected in the germination processes. One of the mutants, designated ABC33, was further characterized. Once the viable embryos from non-germinating seeds were removed from their testa, they grew and displayed a dwarf phenotype which could be complemented by providing gibberellic acid. A genetic and molecular analysis, based on the characterization of the flanking genomic sequences of the T-DNA insert, showed that ABC33 is a new loss-of-function allele at theGA1 locus.
TL;DR: The critical period for GA3 treatment extended from glume differentiation to premeiotic interphase in the oldest florets of the spike, though differences were found between GA-sensitive and GA-insensitive genotypes in the extension of this period.
Abstract: The effect of gibberellic acid (GA3) on male fertility was investigated in wheat. Greenhouse and field experiments were carried out. GA3 induced high levels of male sterility both in gibberellin (GA)-sensitive and GA-insensitive genotypes. The optimum concentration was 2000 ppm of GA3 when applied at successive sprays. The critical period for GA3 treatment, in the general sense, extended from glume differentiation to premeiotic interphase in the oldest florets of the spike, though differences were found between GA-sensitive and GA-insensitive genotypes in the extension of this period. The effect of GA3 on plant height was also studied. The potential use of GA3 as a chemical hybridizing agent in wheat breeding is discussed.
TL;DR: The results suggest that the two de-N-glycosylation enzymes are differentially regulated during plant development.
Abstract: The activities of the de-N-glycosylation enzymes endo-N-acetyl- [beta]-D-glucosaminidase (ENGase; EC 3.2.1.96) and peptide-N4- (N-acetyl-[beta]-D-glucosaminyl) asparagine amidase (PNGase; EC 3.5.1.52) were monitored during germination and postgerminative development in radish (Raphanus sativus L. cv Flamboyant). The ENGase activity was detected only during postgermination, whereas the PNGase activity was present at high levels in both stages. When germination was inhibited with abscisic acid or cycloheximide, PNGase activity was detected at a basic level and ENGase activity was not detected at all. PNGase is present as an active protein in dry seeds and is apparently synthesized during seed formation. Conversely, the absence of ENGase in dry seeds suggests that its activity is dependent on the protein synthesis that occurs during and after germination. Treatment with gibberellic acid confirmed the production of both de-N-glycosylation enzymes after germination, and demonstrated a temporal delay between the production of the two enzymes during this period. Our results suggest that the two de-N-glycosylation enzymes are differentially regulated during plant development.
TL;DR: The complete or partial removal of the olive blossoms strongly increased flowering and fruit production in the year following treatment and slightly increased vegetative growth in both the treatment year and the following year.
Abstract: SummaryIn 1992, the following treatments were applied to olive trees, cv. Maurino, which had average flowering: removal of 50% and 100% of the flowers in mid-June, leaf treatment with gibberellic acid (GA3) at 60 ppm in mid-July, at the end of August, in mid-October and in July, August and October, leaf treatment with paclobutrazol (PP333) at 1000 ppm at the end of October, treatment of the soil with asparagine (10–5M) and glutamine (10–5M) at the end of December. Thinning and complete removal of the blossoms stimulated vegetative activity. Treatments with GA3 in July slightly increased vegetative growth in both the treatment year and the following year, while the later treatments and those with asparagine and glutamine stimulated growth only in the following year. PP333 reduced plant growth in the year following treatment. The complete or partial removal of the olive blossoms strongly increased flowering and fruit production in the year following treatment. Treatment with GA3 and PP333 did not significan...
TL;DR: In this article, the postharvest development of Botrytis blight in rose flowers ( Rosa × hybrida cv. Mercedes) was suppressed when flower buds were sprayed with 1 mM solution of gibberellic acid.