Physiological Responses of Pea Plants to Salinity and Gibberellic Acid

Pea is a seed legume.It is rich in cellulose fibre and protein.It is also a significant source of minerals and vitamins.In this paper,we set out to better characterize the physiological responses of Pisum sativum L.to the combined effects of NaCl,100 mM and gibberellins(GA3).Our analysis revealed that NaCl caused a decrease in growth resulting in a reduction in root elongation,distribution and density,leaf number and leaf area,and a decrease in dry matter of roots and shoots.However,the contribution of GA3 in the salty environment induced an increase in these different parameters suggesting an improving effect of this hormone on growth of pea in presence of salt.NaCl also led to a disturbance of the photosynthetic machinery.Indeed,level of chlorophyll pigments(a and total)and photosynthetic activity were decreased compared to the control plants.However,the exogenous supply of GA3 restored this decrease in net CO_(2) assimilation,but not in chlorophyll content.Additional analyses were performed on the effect of salinity/GA3 interaction on osmolytes(soluble sugars and starch).Our results showed an increase in sugars and a decrease in starch in the presence of 100 mM NaCl.The salt-GA3 combination resulted in compensation of soluble sugar contents but not of starch contents,suggesting a beneficial effect of GA3 under saline stress conditions.Level of three main polyamines putrescine,spermidine,and spermine increased significantly in all organs of salt-treated plants.

Effect of Pre-Harvest Application of Gibberellic Acid on Fruit Quality and Shelf Life of Mandarin (Citrus reticulata Blanco)

Mandarin (Citrus reticulata Blanco) is a promising fruit crop gaining popularity for its human nutrition and economic importance in Nepal. The qualitative losses during pre-harvest stage hinder the productivity and subsequently shorten the on-tree storability. An experiment was conducted to assess the effect of gibberellic acid on quality and shelf life of the mandarin fruit. GA3 at 10, 20, and 30 ppm as against of control were evaluated. Observations on fruit weight (g), fruit firmness (kg/cm2), rind colour (1 - 5 index), juice recovery (%), TSS/acid ratio, PLW (%), decay loss (%), and ascorbic acid (mg/100 ml) were recorded at three harvesting dates i.e. 20 Nov, 5 Dec, and 20 Dec and storage condition. It has been revealed that the fruits treated with GA3 at 20 ppm retained higher fruit weight (128.6 g), more firmness (3.54 kg/cm2), better juice recovery (57.75%), and greater TSS/acid ratio (21.24) at the end of study (20 December). The PLW was found less with GA3 at 30 ppm in both ambient (5.17%) and cellar (6.69%) condition as against untreated fruits (9.52% and 11.76%). Similarly, the decay loss was minimum in the fruits treated with GA3 at 30 ppm both with ambient (1.02%) and cellar condition (8.21%) as against control with ambient (5.54%) and cellar (21.58%).

Response of axillary bud development in garlic(Allium sativum L.) to seed cloves soaked in gibberellic acid(GA3) solution

Gibberellins(GAs) are important phytohormones that regulate many developmental processes in plants. Clove, as the reproductive organ of garlic, dramatically affected garlic bulb development. Considering the potential of gibberellins in plant development and our previous studies, we investigated the effect of soaking two types of seed cloves(seed clove-I: without root/shoot sprouting;seed clove-II: with root/shoot sprouting) in GA3 solution on axillary bud development and examined the effect of soaking seed cloves in GA3 solution on bulb development, phytohormone level and sugar content in this study.Results indicated seed clove types, soaking liquids and their interaction significantly affected the number of cloves per bulb and the rate of single-clove bulb. Moreover, soaking seed cloves in 1 mmol L^-1 GA3 solution for 24 h not only promoted axillary bud formation and secondary plant growth(equal to tillering or branching), but also slightly increased the number of cloves per bulb and changed bulb structure with a low yield and marketable quality. On the 40 th day after GA3 treatment(at axillary bud outgrowth stage), zeatin riboside(ZR) and soluble protein in stem were sharply increased with the increase of GA3, sucrose, fructose and soluble protein in leaf. However, GA3, indole-3-acetic acid(IAA), soluble sugar and sucrose in stem(3.52 ng g^-1 fresh weight(FW), 19.88 ng g^-1 FW, 237.3 mg g^-1 FW, and 8.24 mg g^-1 FW, respectively) were significantly decreased on the 40 th day after GA3 treatment, compared to the control of water treatment(5.56 ng g^-1 FW, 32.96 ng g^-1 FW, 263.6 mg g^-1 FW, and 10.37 mg g^-1 FW, respectively). To our knowledge, these novel results indicate seed cloves soaked in GA3 solution promotes axillary bud formation and outgrowth that caused the changes in plant architecture and bulb structure. Meanwhile, our findings suggest that the level of endogenous plant hormone(GA3, IAA and ZR) cooperates with the content of sugar(sucrose and fructose) in leaf and stem to regulate axillary bud outgrowth in garlic.

Performance of chick pea under the influence of gibberellic acid and oxygenated peptone during germination

The experiments were carried out at the Post Graduate Research Center, to study the influence of Gibberellic Acid (50 ppm) and Oxygenated Peptone (1% aqueous solution) on chick pea (Cicer arietinum L. cv. Vijay) during germination by giving pre-sowing soaking treatment for 6 hours using petriplate method. Both the treatments enhanced the germination process. GA treatment was useful to increase shoot length, mobilization efficiency, emergence index, speed of germination and co-efficient of germination while oxygenated peptone showed an upper hand in root length, shoot/root ratio, biomass and vigour index. GA led to comparatively more synthesis of nucleic acids while oxygenated peptone showed more increase in total carbohydrates and soluble protein content. However, the activity of enzymes like amylase, catalase and protease showed upper hand with oxygenated peptone as compared to GA. In fact GA is costlier and can not be used in organic farming as it enters metabolic pathways of plant and alters them. Hence the use of oxygenated peptone is recommended being less expensive and usable under organic farming condition as it does not enter the plant metabolic pathways and yet brings about significant positive effect.

Effect of Dominant Semi-Dwarf Gene on Plant Height and Its Related Traits and Sensitivity to Gibberellic Acid in Rice

Six pairs of tall and dwarf near-isogenic lines derived from a dominant semi-dwarf mutant （Y98149） were selected to study height expression and sensitivity to gibberellic acid （GA3）. The lengths of the 4-5th internode, the 3rd, 2nd, 1st internodes from the top and the panicle length in the six dwarf near isogenic lines were 97.2%, 53.3%, 65.1%, 61.9% and 94.7% of those in the six tall ones, respectively, indicating that the dominant semi-dwarfing gene significantly inhibited the internode elongation. Moreover, Y98149 （mutant type） was more sensitive to GA3 than Y98148 （wild type）, and had a lower GA3 concentration in plant, about 78% of Y98148.

Effects of gibberellic acid on tiller-bulb number and growth performance of Lilium davidii var. unicolor

Lilium davidii var.unicolor(Lanzhou lily)is an important economic crop in the northwest cold and arid regions of China.Effective regulation of tiller-bulb development and plant growth is the key to improving yield and quality of the lily.This study attempted to evaluate the effect of gibberellic acid(GA3)on tiller-bulb development and plant growth of Lanzhou lily by applying GA3 at various concentrations(0 mg/L,10 mg/L,30 mg/L,60 mg/L,and 100 mg/L)before planting and in the seedling period.Results showed that the 60-mg/L GA3 application had an inhibiting effect on tiller-bulb formation and increased the ratios of single and double bulbs but decreased the ratios of bulbs with three or more tiller bulbs,as com pared to the control(CK)and other GA3 treatments.The difference in flower number did not reach significant levels among the treatments.The tillering-related endogenous hormones IAA(indole-3-acetic acid)and Z(zeatin)content de creased,while IAA/Z increased with the 60-mg/L GA3 treatment during tiller initiation.And also,the shoot-bulb number and total daughter-bulb number decreased significantly with the 60-mg/L GA3 treatment.Furthermore,the 10-mg/L GA3 application promoted growth of Lanzhou lily significantly and resulted in an increase in plant height;bulb diameter;bulb circumference;and biomass of shoots,bulbs,fibrous roots,and the whole plant.Therefore,GA3 application is promising as a new regulation method for inhibiting tiller-bulb development and promoting bulb growth in Lanzhou lily production.

Sweet Cherry (<i>Prunus avium</i>L.) Fruit Drop Reduction by Plant Growth Regulators (Naphthalene Acetic Acid NAA and Gibberellic Acid GA₃)

This study was conducted during 2019/2020 on sweet cherry trees (Prunus Avium L.) (Bing and Hardy Giant) cultivar planted at Sergaya-Al_Zabadani area of Rural Damascus, to reduce fruit drop of sweet cherry. The experiment included 4 foliar applications: T1: control, T2: GA3 (100 ppm), T3: NAA (20 ppm), T4: (100 ppm GA3 + 20 ppm NAA). Fruit set and fruit drop percentage, fruiting factor, and yield were recorded. The results showed that treatment with (100 ppm GA3 + 20 ppm NAA) recorded higher fruit set percentage (73.81% and 75.62%), and fruiting factor (48.38% and 50.04%) respectively; In addition to fruit yield (40.19 and 41.21 kg/tree) for both cultivars, compared to the control (9.13, 6.60 kg/tree). Therefore, it can be concluded that GA3 + NAA treatment reduced Sweet cherry fruit drop better than other treatments, where fruit drop percentage didn’t exceed (63.11% and 62.01%) in both cultivars (Bing and Hardy Giant) respectively, compared to the control (80.92% and 80.64%).

Effects of Exogenous Plant Hormones on Growth Status and Secondary Metabolism of Houttuynia cordata Thunb.

[Objectives]To improve the yield and secondary metabolite content of medicinal plants and to further develop and utilize the medicinal and other functions of medicinal plants.[Methods]We used the sterile tissue culture method with Houttuynia cordata Thunb.as the research object.Different concentrations of 1-naphthalene acetic acid(NAA),auxin(indole-3-acetic acid,IAA)and gibberellin acid(GA_(3))were added to the group culture medium of H.cordata to investigate the effects of exogenous plant hormones on plant height,root length,fresh weight,morphological characteristics,four phenolics and 20 volatile compounds.[Results]The results showed that the exogenous plant hormone of 3 mg/L GA_(3)significantly increased plant height by 79.9%over the control;the exogenous plant hormone of 3 mg/L IAA significantly increased root length by 52.6%over the control;and the exogenous plant hormone of 1 mg/L GA_(3)significantly increased fresh weight of single plant by 458.2%over the control.In the treatment group of 1 mg/L NAA,chlorogenic acid content was significantly increased by 52.6%compared with the control;in the treatment group of 1 mg/L IAA,chlorogenic acid,rutin,isodendrin and quercetin content were significantly increased by 109.1%,100.6%,173.8%,and 198.7%compared with the control,respectively;in the treatment of 3 mg/L GA_(3),chlorogenic acid,rutin,isoquercitin,and quercitin content were significantly increased by 65.3%,104.9%,139.0%and 191.2%over the control.In addition,the content of volatile compounds was significantly higher in all H.cordata treated with exogenous plant hormones of 2 mg/L NAA,1 mg/L IAA,and 3 mg/L GA_(3);however,the content of volatile compounds was lower in all of the treatments with 2 mg/L GA_(3).[Conclusions]Different exogenous plant hormones have certain effects on the growth morphology and secondary metabolic content of H.cordata,which provides theoretical basis and technical support for the development and utilization of medicinal plants.

GID1 modulates stomatal response and submergence tolerance involving abscisic acid and gibberellic acid signaling in rice

Plant responses to abiotic stresses are coordinated by arrays of growth and developmental programs. Gibberellic acid （GA） and abscisic acid （ABA） play critical roles in the developmental programs and environmental responses, respectively, through complex signaling and metabolism networks. However, crosstalk between the two phytohormones in stress responses remains largely unknown. In this study, we report that GIBBERELLIN-INSENSITIVE DWARF 1 （GID1）, a soluble receptor for GA, regulates stomata[ develop- ment and patterning in rice （Oryza sativa L.）. The gidl mutant showed impaired biosynthesis of endogenous ABA under drought stress conditions, but it exhibited enhanced sensi- tivity to exogenous ABA. Scanning electron microscope and infrared thermal image analysis indicated an increase in the stomatal conductance in the gidl mutant under drought conditions. Interestingly, the gidl mutant had increased levels of chlorophyll and carbohydrates under submergence conditions, and showed enhanced reactive oxygen species （ROS）-scavenging ability and submergence tolerance compared with the wild-type. Further analyses suggested that the function of GID1 in submergence responses is partially dependent on ABA, and GA signaling by GID1 is involved in submergence tolerance by modulating carbohydrate consumption. Taken together, these findings suggest GID1 plays distinct roles in stomatal response and submergence tolerance through both the ABA and GA signaling pathways in rice.

Effects of Gibberellic Acid on Primary Terpenoids and △^9 -Tetrahydrocannabinol in Cannabis sativa at Flowering Stage

Plants synthesize an astonishing diversity of isoprenoids, some of which play essential roles in photosynthesis, respiration, and the regulation of growth and development. Two independent pathways for the biosynthesis of isoprenoid precursors coexist within the plant cell： the cytosolic mevalonic acid （MVA） pathway and the plastidial methylerythritol phosphate （MEP） pathway. However, little is known about the effects of plant hormones on the regulation of these pathways. In the present study we investigated the effect of gibberellic acid （GA3） on changes in the amounts of many produced terpenoids and the activity of the key enzymes, 1-deoxy-D-xylulose 5-phosphate synthase （DXS） and 3-hydroxy-3-methylglutaryl coenzyme A reductase （HMGR）, in these pathways. Our results showed GA3 caused a decrease in DXS activity in both sexes that it was accompanied by a decrease in chlorophylls, carotenoids and Ag-tetrahydrocannabinol （THC） contents and an increase in α-tocopherol content. The treated plants with GA3 showed an increase in HMGR activity. This increase in HMGR activity was followed by accumulation of stigmasterol and β-sitosterol in male and female plants and campestrol in male plants. The pattern of the changes in the amounts of sterols was exactly similar to the changes in the HMGR activity. These data suggest that GA3 can probably influence the MEP and MVA pathways oppositely, with stimulatory and inhibitory effects on the produced primary terpenoids in MVA and DXS pathways, respectively.

Control of Negative Gravitropism and Tension Wood Formation by Gibberellic Acid and Indole Acetic Acid in Fraxinus mandshurica Rupr. var. japonica Maxim Seedlings

In the present study, we Investigated the role of glbberelllc acid （GA3） and Indole acetic acid （IAA） In the gravity response of stems and tension wood formation using two-year-old stems of Fraxinus mandshurica Rupr. var. Japonica Maxim seedlings. Forty-five seedlings were used and divided Into nine groups that Included five seedlings In each group. Seedlings were treated with applications of GA3 alone at concentrations of 2.89×10^-8 and 2.89×10^-7 μmol/L, IAA alone at concentrations of 5.71×10^-8 and 5.71×10^-7 μmol/L, or their combination to the apical bud of the stem using a mlcroplpette. Seedlings were positioned horizontally after the first treatment. The same treatments were repeated six times per week. At the end of the experiment, all seedlings were harvested. Then, stem segments were cut under a light microscope. Application of exogenous GA3 at the higher concentration stimulated the upward bending of stems, whereas exogenous IAA had no effect. A synergistic effect of GA3 and IAA on upward stem bending was observed following application of the two combinations of GA3 and IAA. Moreover, application of exogenous GA3 at the higher dose stimulated wood formation on both the upper and lower sides of the stems, whereas the mixture of GA3 and IAA had a synerglstic effect on wood formation In horizontal stems. Application of exogenous IAA alone at the lower concentration （5.71×10^-8 μmol/L） or application of a mixture of the higher concentrations of GA3 （2.89×10^-7 μmol/L） and IAA （5.71×10^-7 μmol/L） Inhibited the development of gelatinous fibers （the G-layer） of tension wood on the upper side of the horizontal stems. The differentiation of gelatinous fibers of tension wood was not Inhibited by GA3 when It was applied alone, whereas the development of the gelatinous fibers of tension wood was strongly affected by the application of IAA. The findings of the present study suggest that the development of the G-layer Is not related to the dose of GA3, but needs a relatively lower concentration of IAA.

Regulation of Seed Germination:The Involvement of Multiple Forces Exerted via Gibberellic Acid Signaling

Seed germination is a key step in the life cycle of all seed plants, and it is of immense significance in agriculture.Germination is controlled by multiple environmental cues such as light and moisture,and endogenous factors,especially phytohormones.Gibberellic acid (GA)has long been identified as a critical hormone in the regulation of seed germination by countering the inhibition imposed by abscisic acid (ABA)(Holdsworth et al.,2008;Lee et al.,2010).

Insights into pH-dependent transformation of gibberellic acid in aqueous solution:Transformation pathway,mechanism and toxicity estimation

Gibberellic acid(GA_(3))is widely used in agriculture and maybe transfer with groundwater flow,which is an endocrine disruptor,but few studies have focused on the transformation pathway and toxicity assessment of GA_(3)and its products.Here,GA_(3)and its transformation products in aqueous solution were identified and quantified by liquid chromatography mass spectrometry hybrid ion trap time-of-flight(LCMS-IT-TOF)and high-performance liquid chromatography(HPLC),respectively.The results showed that the half-life of GA_(3)transformation in ultrapure water was 16.1–24.6 days at p H=2.0–8.0,with the lowest half-life occurring at p H=8.0 and highest half-life occurring at p H=3.3.Isomerized gibberellic acid(Iso-GA_(3))and gibberellenic acid(GEA)were the main transformation products with a little hydroxy gibberellic acid(OH-GA_(3)).In North China groundwater,the mass balance of GA_(3)and its products was 76.2%,including Iso-GA_(3)(58%),GEA(7.9%),GA_(3)(7.3%)and OH-GA_(3)(3%)after reaching transformation equilibrium.Using Gaussian 09 for chemical computation,it was found that the transformation mechanism of GA_(3)was dependent upon the bond energy and the stereochemical feature of its molecular structure.GA_(3)always isomerized from theγ-lactone ring due to the lowest bond energy between the oxygen terminus of theγ-lactone ring and A ring.While GA_(3)and its transformation products all had developmental toxicity,the predicated LC 50(96 hr)and LD 50 of the main products of GA_(3)were much lower than those of GA_(3),indicating GA_(3)would be transformed into higher toxicity derivatives in water environments,posing a significant health risk to humans and the environment.

Downregulation of the Basic Peroxidase Isoenzyme from Zinnia elegans by Gibberellic Acid

Hypocotyl formation during the epigeal germination of seedlings is under strict hormonal regulation. In a 3 d old Zinnia elegans seedling system, gibberellic acid （GA3） exerts an opposite effect to that exerted by light on hypocotyl photomorphogenesis because GAz promotes an etiolated-like growth with an inhibition of radial （secondary） growth. For this reason, the effect of GA3 on the basic peroxidase isoenzyme from Z. elegans （ZePrx）, an enzyme involved in hypocotyl lignin biosynthesis, was studied. The results showed that GA3 reduces ZePrx activity, similarly to the way in which it reduces seedling secondary growth. This hormonal response is supported by the analysis of the ZePrx promoter, which contains four types of GA3-responsive cis.elements： the W Box/O2S; the Pyr Box; the GARE; and the Amy Box. Taken together, these results suggest that ZePrx is directly regulated by GA3, with this effect matching the inhibitory effect of GA on the hypocotyl secondary growth.

Separation of gibberellic acid (GA3) by macroporous adsorption resins

The adsorption effects of several macroporousadsorption resins for gibberellic acid (GA3) were investigated.The dynamic adsorption capacity is 58.38 mg/g drybeads for resin R4 and 96.46 mg/g dry beads for resin R5which is consistent with the surface area. Aqueous methanol(50%, V/V) is a good eluent and the yield of GA3 isabove 95%. The concentration of GA3 could increase fivefoldafter an adsorption-elution cycle and this is importantwhen considering further crystallization of GA3 in anindustrial process.

Effects of Gibberellic Acid (GA_(3)) and Salicylic Acid (SA) postharvest treatments on the quality of fresh Barhi dates at different ripening levels in the Khalal maturity stage during controlled atmosphere storage

Barhi dates at Khalal maturity stage are well-known with their pleasant taste,crispy texture,and bright yellow color.It is necessary to extend the duration of Barhi Khalal stage which is too short for effective marketing.This study aimed to inspect the effects of Gibberellic Acid(GA_(3))and Salicylic Acid(SA)postharvest treatments on retaining the high quality of Khalal Barhi fruits during controlled atmosphere storage.Fresh samples of Barhi fruits at Khalal stage harvested at three different ripening levels were dipped after harvesting in GA3(150 ppm)or SA(2.0 mmol/L)and subsequently stored in controlled atmosphere(0°С,5%O_(2),5%CO_(2),80%±5%RH).The results revealed that the GA_(3) and SA treatments reduced the percentage of weight loss and decay in the fruits,while the total soluble solids increased.Moreover,GA_(3) and SA treatments were significantly efficient in limiting the changes in fruit color and texture of Barhi dates compared to the control.Sensorial results support the experimental data and disclosed that the GA_(3)(150 ppm)treatment in the controlled atmosphere(CA)storage was better in conserving the quality of Barhi at the Khalal maturity stage and delaying ripening process.

Roles of abscisic acid and gibberellins in maintaining primary and secondary dormancy of Korean pine seeds

Primary dormancy of seeds of Korean pine(Pinus koraiensis Sieb.et Zucc.)after dispersal in the autumn and the induction of secondary dormancy the fi rst summer following seed dispersal limit the regeneration of mixed broadleaved Korean pine forests in Northeast China.This study was to determine how changes in the levels of abscisic acid(ABA)and gibberellic acid(GA)maintain primary and secondary dormancy of Korean pine seeds under germination conditions.We transferred seeds with one of fi ve primary dormancy states or three secondary dormancy states to germination conditions and measured changes in the levels of ABA,GA 1+3(GA 1 and GA 3)and GA 4+7(GA 4 and GA 7)in the seed coat,megagametophyte and embryo during incubation.Seed coat ABA levels in primary dormant seeds(PDS)and ABA levels in various parts of secondary dormant seeds(SDS)gradually declined during incubation but were still higher than in seeds for which dormancy was progressively released.GA 4+7 and GA 1+3 levels in embryos greatly decreased 35%and 24%,respectively,during incubation of SDS,and thus,the ratio of ABA to GA 4+7 in embryos and megagametophytes signifi cantly increased.The ratio of ABA to GA 1+3 in various parts of SDS increased slightly during incubation.In contrast,in seeds for which secondary dormancy was already released,GA 4+7 and GA 1+3 levels in the embryo,GA 4+7/ABA ratio in the embryo and seed coat,and the GA 1+3/ABA in the embryo and megagametophyte signifi cantly increased during incubation.There was no trend in the changes in the levels of ABA,GA 4+7 or GA 1+3 in embryos and megagametophytes of PDS or the levels of GA 4+7 or GA 1+3 in megagametophytes of SDS during incubation.The results suggest that high ABA levels in the seed coat maintain primary dormancy of Korean pine seeds.Maintenance of secondary dormancy involves a reduction of GA 4+7,GA 1+3,GA 4+7/ABA,and GA 1+3/ABA and the retention of high ABA levels.

Effect of exogenous GA3 on flowering quality, endogenous hormones, and hormone-and flowering-associated gene expression in forcing-cultured tree peony（Paeonia suffruticosa）

Gibberellins(GAs)promote flowering in the forcing-cultured tree peony(Paeonia suffruticosa),however,the mechanism of regulating flowering is not fully understood.In this study,exogenous GA3 was applied to five-year-old Luoyang Hong plants to explore responses in terms of endogenous hormones,flowering quality,and the hormone-and flowering-associated gene expression.Exogenous GA3 application significantly promoted flower bud development and new branch growth,as well as improved flowering quality.Exogenous GA3 application also stimulated the synthesis of endogenous GA3 and indole-3-acetic acid(IAA)but reduced abscisic acid(ABA)levels.To further elucidate the regulatory mechanism,eight genes for GA biosynthesis and signaling,including PsCPS,PsKS,PsGA3ox,PsGA2ox,PsGID1b,PsGID1c,PsDELLA,and PsGID2 were cloned for the first time,and sequence analysis was also performed.The results suggested that all the cloned genes have conserved structure as each homologous gene reported in the other species.Phylogenetic trees constructed by the each cloned gene showed that the phylogenetic evolutionary relationship of P.suffruticosa was closely related to Vitis vinifera.The expression patterns of the above genes,and genes for ABA and IAA biosynthetic and signaling,and the flowering time were also investigated.Most of the above genes showed higher expression in the control buds than those in the GA3 treated buds at six developmental stages,whereas the expression levels of PsSOC1 and PsSPL9 were up-regulated by GA3 treatment.The results also showed that the GA-biosynthetic and signaling pathways are conserved in tree peony,and the PsCPS,PsGA3ox,PsGA2ox,PsGID1,PsDELLA,and PsGID2 genes are necessary for feedback regulation of GAs.Furthermore,hormone changes promoted PsSOC1 and PsSPL9 expression,and repressed PsSVP expression,which contributed to the improvement flowering quality in tree peony of forcing culture.

Effects of tallowtree seed coat on seed germination

We measured physiological parameters including water uptake in-vitro embryo germination ratio, and seed coat structure observed by scanning electron microscopy （SEM） to explore the influence of seed coat on the germination of seeds of tallow tree （Sapium sebiferum （Linn） Roxb.）. Tallow tree seeds had good water permeability. We found that germination of cabbage seeds was inhibited when cabbage seeds were soaked in extracted solutions from tallow tree seed coat. Seed coat structure at the side of the radicle appeared to be a barrier to seed germination. We tested methods to break tallow tree seed dormancy. Dormancy of tallow tree seeds was overcome by soaking the seeds in 500 mg·L^-1 or 1000 mg·L^-1 GA3, followed by 100 days of cold stratification.

Divergence in homoeolog expression of the grain length-associated gene GASR7 during wheat allohexaploidization

Hexaploid wheat has triplicated homoeologs for most of the genes that are located in subgenomes A, B, and D. GASR7, a member of the Snakin/GASA gene family, has been associated with grain length development in wheat. However, little is known about divergence of its homoeolog expression in wheat polyploids. We studied the expression patterns of the GASR7 homoeologs in immature seeds in a synthetic hexaploid wheat line whose kernels are slender like those of its maternal parent(Triticum turgidum, AABB, PI 94655) in contrast to the round seed shape of its paternal progenitor(Aegilops tauschii, DD, AS2404). We found that the B homoeolog of GASR7 was the main contributor to the total expression level of this gene in both the maternal tetraploid progenitor and the hexaploid progeny, whereas the expression levels of the A and D homoeologs were much lower. To understand possible mechanisms regulating different GASR7 homoeologs, we firstly analyzed the promoter sequences of three homoeologous genes and found that all of them contained gibberellic acid(GA) response elements, with the TaG ASR7 B promoter(pT aG ASR7B) uniquely characterized by an additional predicted transcriptional enhancer. This was confirmed by the GA treatment of spikes where all three homoeologs were induced, with a much stronger response for TaG ASR7 B. McrB C enzyme assays showed that the methylation status at pT aG ASR7 D was increased during allohexaploidization, consistent with the repressed expression of TaG ASR7 D. For pT aG ASR7 A, the distribution of repetitive sequence-derived 24-nucleotide(nt) small interfering RNAs(siR NAs) were found which suggests possible epigenetic regulation because 24-nt siR NAs are known to mediate RNA-dependent DNA methylation. Our results thus indicate that both genetic and epigenetic mechanisms may be involved in the divergence of GASR7 homoeolog expression in polyploid wheat.