The Effect of Gibberellic Acid on Cell Width and the Cell-wall of Some Phloem Fibres

Treatment of plants of Cochorusoiltorius L., Hibiscus cannabinusL., and Cannabis sativa L. with gibberellic acid induced highlysignificant increases in cell diameter and wall thickness ofproblem fibres. This difference varies along the shoot and ismaximal in the middle region, internodes 10–15. The ratio is higher in treated plants. Gibberellic acid reduces the angle of orientation of the pits to the cellwall and also the pit frequency. Pits in treated plants arelonger and narrower in surface view.     

The Role of Roots in Control of Bean Shoot Growth

Restriction of root growth by growing bean plants (Phaseolusvulgaris L.) in very small pots led to the development of dwarfplants. The leaves of those plants were smaller and their internodesshorter than those of control plants which were grown in largerpots and had developed a more extensive root system. A largequantity of starch—much more than in control plants —accumulated in the leaves and shoots of the dwarf plants. Increasingthe amount of minerals which was supplied to the roots, enhancedleaf growth of the control plants but failed to affect the dwarfones, in spite of the fact that in both cases the treatmentincreased the content of N, P and K in all the plant organs.The leaf water content was similar in both treatments, but theleaf water potential was higher in the dwarf plants. Exogenousapplication of gibberellic acid (GA₃) to the dwarf plants overcamethe reduction of stem growth completely, and that of the leavespartially. Application of the cytokinin, benzyladenine (BA)did not affect stem growth, but increased that of the primaryleaves. A combined supply of GA₂ + BA restored completely thegrowth of the stem and the primary leaves, and partially thatof the trifoliate leaves. It is concluded that a limited rootsystem restricts shoot growth through an hormonal system inwhich at least gibberellins and cytokinins are involved, andthat the dwarfing is not a consequence of mineral or assimilatedeficiency, or due to water stress. Phaseolus vulgaris L., leaf growth, stem growth, root restriction, gibberellic acid, benzyladenine, cytokinin     

Synergism between Gibberellin and Auxin in the Growth of Intact Tomato

Gibberellin A_4&7 was more effective than gibberellic acid in increasing shoot elongation when applied to the apex of intact Lycopersicum esculentum seedlings of Tiny Tim, a dwarf cultivar, and Winsall, a tall cultivar. After 14 days, gibberellic acid and gibberellin A_4&7 stimulated growth of the dwarf more than the tall tomato. In tall tomato the application of indole-3-acetic acid alone (6.1 μg/plant) showed an inhibitory growth effect, but when applied with 17.5 μg per plant of gibberellic acid, it had a synergistic effect at 7 days but not at 14 days. When the auxin concentration was reduced to 0.61 μg per plant a synergistic effect was observed on tall plants at 7 and 14 days between indole-3-acetic acid and gibberellic acid. Application of gibberellin A_4&7 with auxin did not give a synergistic response in tall or dwarf tomato.     

The genetically unstable dwarf locus in azuki bean (Vigna angularis (Willd.) Ohwi & Ohashi)

We characterized a spontaneous dwarf mutant showing extremely short internodes and dark green leaves originating from azuki bean (Vigna angularis (Willd.) Ohwi & Ohashi) cultivar "Erimo-shouzu." F(1) plants of 3 cross combinations between the dwarf mutant and several representative wild-type plants, Erimo-shouzu, V. angularis accession Acc2265 and wild relative V. riukiuensis accession Acc2482, supported the dwarf genotype being recessive. In a total of 3328 F(2) progeny of these 3 crosses, 65 dwarfs (2.0%) and 5 chimeric dwarfs (0.2%) segregated and the remainder were wild-type plants (97.8%). In F(3) progeny derived from self-pollinated dwarf F(2) plants, we observed wild type (54.3%), dwarf (39.1%), and chimeric dwarf (6.5%) plants. Two types of chimeric plants were observed: dwarf branches on the axils of wild-type plant stems and wild-type branches on the axils of dwarf stems. In 21 dwarf F(2) plants, the dwarf trait cosegregated with simple sequence repeat marker CEDG154 on chromosome 4. Conversely, homozygote F(2) plants at this chromosomal segment from the dwarf mutant frequently (>90%) expressed the wild-type phenotype. We concluded that the dwarf phenotype is mitotically and meiotically inheritable and controlled by a single genetically unstable locus, designated Azuki Dwarf1 (AD1), which converts between 2 phenotypic states bidirectionally.     

Vegetable Plant Part Relationships. III. Modification of Carrot (Daucus carota L.) Root and Shoot Weights by Gibberellic Acid and Daminozide

Aqueous foliar sprays of N-dimethylaminosuccinamic acid (daminozide)at 2000 p.p.m. and gibberellic acid (GA) at 100 p.p.m. wereapplied 45, 59, 82 and 100 days after sowing to Chantenay carrotswith population densities of 244, 495 and 883 plants m^–2.The plants were harvested on ten approximately weekly occasions;fresh weights were determined and d. wt estimates were obtainedfor the separated shoots (s) and roots (r). Allometric linearregressions of the logarithm of s on that of r at each harvestseparately, clearly showed that GA always increased shoot: rootratio and reduced root yield (by approximately 35 per cent)but could sometimes also increase whole-plant weight. Daminozideincreased root yield (by approximately 7 per cent from 80 tonnesha^–1) and tended to have effects opposite to those ofGA. Daucus carota L., carrot, root weight, shoot weight, N-dimethylaminosuccinamic acid (daminozide), gibberellic acid     

REGULATORY ROLE OF INDOLE-3-ACETIC ACID AND GIBBERELLIC ACID IN VEGETATIVE DEVELOPMENT OF XANTHIUM PENNSYLVANICUM

A single application of gibberellic acid to young internodes significantly accelerated the rate of internode growth and the rate of leaf production in shoots of Xanthium pennsylvanicum Wallr. The average duration of one plastochron in treated plants was reduced to 43% of control levels. Gibberellic acid also had a pronounced morphogenetic effect on leaves so that the area and leaf length of treated plants were both significantly reduced. Depending upon concentration, auxin had both inhibitory and promotive effects on Xanthium shoots. Indole-3-acetic acid markedly altered the response of the gibberellic acid-treated internodes and those located above and below the site of application. In addition, high auxin concentrations induced the formation of adventitious roots in treated internodes. Auxin also brought about significant reductions in the length and area of leaves developed under the influence of this hormone.     

PHYSIOLOGICAL ACTIVITIES OF HELMINTHOSPOROL AND HELMINTHOSPORIC ACID: I. EFFECTS ON GROWTH OF INTACT PLANTS

Helminthosporol (H-ol) and helminthosporic acid (H-acid) wereeffective in promoting elongation of leaf sheaths of rice, Japanesebarnyard grass and dwarf maize (d-2 and d-5) and of hypocotylsof taisai (Brassica chinensis), but inactive in leaf sheathsof oat and wheat, hypocotyls of sesame and morning glory (Pharbitisnil) and epicotyls of Pharbitis and dwarf and tall peas. Onthe elongation of the leaf sheath of maize d-1, H-ol was promotivebut the activity of H-acid was doubtful. On hypocotyls of lettuceand daikon (Raphanus sativus), only H-acid was active. Multiplicationrate and size of fronds of Lemna perpusila were not affectedby either of the substances. Compared with gibberellic acid for the effect on the shoot growth,H-ol and H-acid were weak in activity and narrower in the scopeof plants that responded. H-ol and H-acid characteristicallypromoted the elongation of the primary root. Comparative effectivenessof H-ol and H-acid varied with plant species or parts examined. ¹ This study was supported in part by grant-in aid of the Ministryof Education (No. 0417). The results reported here were presentedat the Annual Meeting of the Botanical Society of Japan at Kanazawain 1964 (S).     

Dwarf plants of diploid <Emphasis Type="Italic">Medicago sativa</Emphasis> carry a mutation in the gibberellin 3-β-hydroxylase gene

In this paper we describe the identification of a gene, MsDWF1 coding for a putative gibberellin 3-beta-hydroxylase (GA3ox), whose natural mutation is conditioning a dwarf growth phenotype in Medicago sativa. The dwarf phenotype could not be complemented with grafting, which indicates that the bioactive gibberellin compound necessary for shoot elongation is immobile. On the contrary, exogenously added gibberellic acid restored normal growth. The genetic position of the Msdwf1 gene was mapped to linkage group 2 (LG2) and the physical location was delimited by map-based cloning using Medicago truncatula genomic resources. Based on the similar appearance and behavior of the dwarf Medicago sativa plants to the pea stem length mutant (le) as well as the synthenic map position of the two genes it was postulated that MsDWF1 and pea Le are orthologs. The comparison of wild type and mutant allele sequences of MsGA3ox revealed an amino acid change in a conserved position in the mutant allele, which most probably impaired the function of the enzyme. Our results indicate that the dwarf phenotype was the consequence of this mutation.     

Procera is a putative DELLA mutant in tomato (Solanum lycopersicum): effects on the seed and vegetative plant

The procera (pro) mutant of tomato exhibits a well-characterizedconstitutive gibberellic acid (GA) response phenotype. The tomatoDELLA gene LeGAI in the pro mutant background contains a pointmutation that results in an amino acid change in the conservedVHVID putative DNA-binding domain in LeGAI to VHEID. This samepoint mutation is in four different genetic backgrounds exhibitingthe pro phenotype, suggesting that this mutation co-segregateswith the pro phenotype. Complementation of the mutant with aconstitutively expressed wild-type LeGAI gene sequence was notconclusive due to the infertility of transgenic plants. Thepro mutation alters tomato branching architecture through differentialsuppression of axillary bud development, indicating a role forDELLA proteins in the regulation of plant structure. Isolatedgib-1 pro double mutant embryo axes, which are unable to synthesizeGA, germinate faster than their wild-type counterparts, andexert greater embryo growth potential. The pro mutation is thereforeregulating GA responses within the tomato embryo. Transientexpression of a LeGAI–GFP (green fluorescent protein)fusion protein in onion epidermis results in its location tothe nucleus, and this protein is rapidly degraded by the proteasomein the presence of GA. Key words: Branching pattern, DELLA, embryo growth potential, tomato seed germination Received 12 October 2007; Revised 27 November 2007 Accepted 28 November 2007     

Effects of Hormones on Morphogenesis and Cold Resistance in Berseem Clover (Trifolium alexandrinum L.)

Plants of berseem clover (Trifolium alexandrinum L.) cv. Taborwere raised under conditions inhibiting the acquisition of coldhardiness (non-hardened) or inducing cold hardiness (hardened).All non-hardened plants developed an elongated shoot and exhibitedconsiderable frost sensitivity, as measured by the extent ofthe reduction in yield of variable chlorophyll fluorescenceafter exposure to sub-zero temperature. Hardened plants developeda shorter shoot, with fewer leaves and a greater percentageof dry matter in the root system. These parameters were associatedwith a marked increase in frost resistance. Exogenous applicationof ABA to plants effected similar morphological modificationsin both hardening and non-hardening temperature regimes; plantsdeveloped a shorter primary shoot axis and leaves exhibiteda marked increase in frost hardiness. In berseem clover ABAcan thus substitute, at least partially, for the low temperaturetreatment required to induce cold hardiness. Spraying plantsraised under hardening conditions with gibberellic acid reversedthe effects of the hardening treatment, since they developedan elongated shoot and exhibited frost sensitivity comparableto non-treated plants grown under non-hardening conditions.It is concluded that these endogenous hormones are directlyinvolved in triggering changes in morphogenesis which accompanyphysiological and metabolic events associated with the inductionof plant cold hardiness. Key words: Frost resistance, morphogenesis, abscisic acid, giberellic acid, Trifolium alexandrinum     

The effects of temperature and the Rht3 dwarfing gene on growth, cell extension, and gibberellin content and responsiveness in the wheat leaf

The effects of low temperature and the Rht3 dwarfing gene onthe dynamics of cell extension in leaf 2 of wheat were examinedin relation to gibberellin (GA) content and GA-responsivenessof the extension zone. Leaf 2 of wild-type (rht3) wheat closelyresembled that of the Rht3 dwarf mutant when seedlings weregrown at 10C. The maximum relative elemental growth rate (REGR)within the extension zone in both genotypes was lower at 10Cthan at 20C, but the position with respect to the leaf basewas unaffected by temperature. The size of the extension zoneand epidermal cell lengths were similar in both genotypes at10C. Growth at 20C, instead of 10C, increased the lengthof the extension zone beyond the point of maximum REGR in thewild type, but not in the Rht3 mutant. Increasing temperatureresulted in longer epidermal cells in the wild type. Treatingwild-type plants at 10C with gibberellic acid (GA₃) also increasedthe length of the extension zone, but the Rht3 mutant was GA-non-responsive.However, the concentrations of endogenous GA₁ and GA₃ remainedsimilar across the extension zone of wild-type plants grownat both temperatures, despite large differences in leaf growthrates. The period of accelerating REGR as cells enter the extensionzone, and the maximum REGR attained, are apparently not affectedby GA. It is proposed that GA functions as a stimulus for continuedcell extension by preventing cell maturation in the region beyondmaximum REGR and that low temperature increases the sensitivitythreshold for GA action. Key words: Cell extension, gibberellin, Rht3 dwarfing gene, temperature, wheat leaf     

The Effect of Single and Repeated Gibberellic Acid Treatment on Internode Number and Length in Dwarf Peas

In long-term experiments comparing the results of single and repeated treatment of dwarf peas with gibberellic acid, both once-treated and weekly-treated plants formed more internodes than control plants. The initial high rate of internode formation in the once-treated peas dropped rapidly reaching that of control plants three weeks after treatment. Weekly-treated plants maintained a higher rate of internode formation. The ratio of internode lengths of once-treated plants to control plants was high (over 3) for the internodes which were elongating during or shortly after the single treatment but dropped rapidly and approached unity in later-developed internodes. The ratio of internode lengths of weekly-treated plants to control plants continued to be high throughout the experiment.     

Effects of 2-Chloroethylphosphonic Acid and Gibberellic Acid on Sex Expression and Growth of Pumpkins

Treatment of pumpkin plants with 2-chloroethylphosphonic acid (CEPHA) induced a greater production of female flowers, shorter internodes and earlier fruit set while treatment with gibberellic acid (GA) induced a greater production of male flowers, longer internodes and later fruit set. Although CEPHA induced the production of a greater number of female flowers, the bulk of the flowers aborted and only a slight increase in the number of fruits per pumpkin plant occurred. The addition of equal concentrations of CEPHA and GA resulted in pumpkin plants with longer internodes and a greater number of female flowers than the untreated plants, although GA partially overcame the effect of CEPHA. The mode of action of CEPHA and GA on sex expression is discussed.     

Runner Formation in Everbearing Strawberry as Influenced by Growth-Promoting and Inhibiting Substances

The interactive effects of gibberellic acid, abscisic acid,and benzyladenine were studied in relation to runner formationof the everbearing strawberry. In two of three cultivars studied,Ozark Beauty and Superfection, exogenous gibberellic acid stimulatedrunner formation and inhibited flowering. In the Geneva cultivar,a shy runner producer, gibberellic acid application as a foliarspray failed to induce runners. When applied in combinationwith benzyladenine, gibberellic acid greatly stimulated runnerformation Benzyladenine alone had no effect on runnering. Exogenous abscisic acid inhibited petiole length and runnerformation and had no influence on the number of inflorescencesinitiated. Response to exogenous gibberellic acid or abscisicacid varied according to the reproductive or vegetative stagethe plant exhibited at the time of treatment. Activity of endogenous gibberellin-like substances was not substantiallydifferent between flowering and non-flowering field-grown Genevaplants when sampled in long day lengths of August. Endogenousinhibitors were highly active in flowering Geneva plants andrelatively inactive in non-flowering plants The implications of these findings on hormonal balance in thestrawberry are discussed.     

Internode Length in Pisum. A New Allele at the le Locus

In Pisum sativum L. a third, more severe, allele at the internodelength locus le is identified and named le^d. Plants homozygousfor le^d possess shorter internodes and appear relatively lessresponsive to GA₂₀ than comparable le (dwarf) plants. Gene le^dmay act by reducing the 3ß-hydroxylation of GA₂₀ tothe highly active GA₁ more effectively than does gene le. Theresults indicate that le is a leaky mutant and therefore thatendogenous GA₁ influences internode elongation in dwarf (le)plants. Pisum sativum, peas, internode length, genetics, gibberellin, dwarf elongation     

Growth Pattern of Tall and Short Lines of Rice and their Response to Gibberellin

The growth pattern of two types of dwarfness in rice was studied.The difference in height of the tall and short Peta plants wasapparent even at the seedling stage. In the dwarf and in thenormal Century Patna 231 the difference in height was apparentonly after panicle initiation. The four lines had the same numberof elongated internodes, with the taller lines having longerinternodes. The application of gibberellin resulted in increased plant height,longer internodes, blades and leaf sheaths, and decreased tillernumber. Century Patna 231-dwarf showed the least, and shortPeta the greatest, response to gibberellin application.     

ABA content in shoots and roots of pea mutants af and tl as related to their growth and morphogenesis

The comparative study of shoot and root growth was carried out, and the level of ABA therein determined in the mutant af and tl and wild-type isogenic lines of pea. The recessive af mutation transformed the leaflets into tendrils, and the tl mutation transformed the tendrils into leaflets. These mutations did not affect the length and number of internodes. In all plants, the level of ABA in the leaves was 3–10 times greater than in the roots, and in the course of vegetative growth it rose in both organs. An increase in the shoot area of tl mutant did not change the dry weight of underground and above-ground parts; therefore, the ratio shoot/root in the mutant was identical to that in the wild-type plants. The maintenance of shoot dry weight in the tl mutant at the level of wild-type plant while its area considerably increased was accounted for by a decrease in the thickness of the leaflet and stipule blades. The level of ABA in the stipules of mutant plants was greater than in the wild-type plants. A decrease in the shoot area in the af mutant brought about a decline in its dry weight; however, the ratio root/shoot was maintained at the wild-type level due to a reduced accumulation of dry weight by the root. The level of ABA in the roots of the af mutant was twice greater than in the leafy forms. ABA was assumed to participate in the control over the root growth exerted by the shoot. The absence of leaflets in the af plants was partially compensated for by expanding stipules. The level of ABA therein was three times higher than in the plants of wild type and comparable with the level in the leaflets of the tl mutant and in the wild-type plants. The role of ABA in the growth and final size of leaf blades is discussed.     

ent-Kaurene Biosynthesis in Cell-Free Extracts of Excised Parts of Tall and Dwarf Pea Seedlings

Investigations on the sites of ent-kaur-16-ene (ent-kaurene) biosynthesis were conducted with cell-free extracts from several excised parts of 10-, 13-, and 16-d-old tall and dwarf pea (Pisum sativum L.) seedlings. [¹⁴C]Mevalonic acid was incorporated into ent-kaurene in cell-free extracts from young developing leaves and elongating internodes of tall (`Alaska') and dwarf (`Progress No.9') pea seedlings at all three stages of development. ent-Kaurene biosynthesis also occurred readily in cell-free extracts from shoot tips, petioles, and stipules near the young elongating internodes. The ent-kaurene-synthesizing activity found in young developing tissues declined as tissues matured. Little or no activity was detectable in enzyme extracts from cotyledons and root tips at different stages. In light grown tall pea internodes ent-kaurene-synthesizing activity was low as they began to elongate, reached a maximum when the internodes reached about 2 cm in length and declined as they matured. Activity in extracts of dwarf shoot tips and internodes was generally lower than in equivalent tall plants, but the activity in dwarf leaves and stipules was somewhat higher than in tall plants. With the exception of root tips, there is a strong correlation between growth potential of a tissue and the rate of ent-kaurene biosynthesis in extracts from that tissue.     

Abscisic Acid and Apical Dominance in Phaseolus coccineus L. The Role of Tissue Age

Abscisic acid (ABA) applied to the decapitated second internodeof runner bean plants enhanced outgrowth of lateral buds onlywhen internode stumps were no longer elongating. Applied toelongating internodes of slightly younger plants, ABA causesinhibition of bud outgrowth. Together with 10^–4 M indol-3-ylacetic acid (IAA), ABA stimulated internode elongation and interactedadditively in the inhibition of bud outgrowth. A mixture of10^–5 M ABA and 10^–6 M gibberellic acid (GA₃ ) causedsimilar effects on internode growth as IAA + ABA, but was mutuallyantagonistic in effect on growth of the lateral buds. Abscisic acid, apical dominance, gibberellic acid, indol-3yl acetic acid, Phaseolus coccineus, bean     

蒺藜苜蓿株高控制基因COSTIN的克隆及功能研究

株高是影响植物株型建成的重要农艺性状之一,直接决定作物的倒伏性和生物产量,但目前关于苜蓿等豆科牧草株高性状形成的分子调控机制尚不清楚。通过定向筛选豆科模式植物蒺藜苜蓿Tnt1逆转座子插入突变体库,分离鉴定了一个蒺藜苜蓿矮化突变体compact stalk internodes(costin),该突变体的矮化表型是由于茎节伸长受到抑制所致。通过基因表型连锁分析成功克隆了COSTIN基因,该基因编码一个钙离子交换蛋白,与拟南芥的CALCIUM EXCHANGER 7(CAX7) 基因高度同源。qRT-PCR检测发现COSTIN基因在茎、叶和果荚等组织中有较高的表达。进一步研究发现在costin突变体中赤霉素合成途径关键基因MtCPS、MtKAO1、MtGA20ox4、MtGA20ox7和MtGA3ox1表达下调;外施赤霉素GA3可以恢复costin突变体的矮化表型。上述研究表明COSTIN基因通过影响植物激素赤霉素的生物合成来调控蒺藜苜蓿的茎节伸长。