Internode length in Pisum. III The effect and interaction of the Na/na and Le/le gene differences on endogenous gibberellin-like substances

In the garden pea ( Pisum sativum L.), shoots of the extremely short plants with the mutant na (phenotype nana) are found by bioassay to contain undetectable levels of gibberellin-like substances. This is confirmed by the use of near isogenic lines differing at the Na locus. Thus, mutant na appears to block a step early in the pathway of gibberellin synthesis. It is suggested that the polar gibberellin-like substance found in the apical portion of shoots of tall ( Le ) but not dwarf ( le ) peas could be GA₁. Extracts of shoots of na Le peas treated with GA₂₀ (the major active gibberellin in dwarf peas) possess a large amount of GA₁-like activity whereas extracts of shoots of na le peas treated with GA₂₀ possess a much reduced amount. Thus, gene Le may allow the conversion of a less active gibberellin (GA₂₀) into one more active in stimulating elongation in the pea (the GA₁-like compound). In contrast to their influence in the shoot, the na and Le genes do not appear to be operative in controlling the gibberellin content of developing seed, indicating that organ specific gibberellin biosynthesis and metabolism occur in peas.     

Internode length in Pisum. IV. The effect of the Le gene on gibberellin metabolism

The highly active, polar gibberellin-like substance found in the apical region of shoots of tall (genotype Le ) peas ( Pisum sativum L.) is shown by combined gas chromatography-mass spectrometry (GC/MS) to be GA₁. This substance is either absent or present at only low levels in dwarf ( le ) plants. Multiple ion monitoring (MIM) tentatively suggests that GA₈ may also be present in shoot tissue of tall peas. Gibberellin A₁ is the first 3 β-hydroxylated gibberellin positively identified in peas, and its presence in shoot tissue demonstrates the organ specificity of gibberellin production since GA₁ has not been detected in developing seeds. Application of GA₁ can mask the Le/le gene difference. However, whilst Le plants respond equally to GA₂₀ and GA₁, le plants respond only weakly to GA₂₀, the major biologically active gibberellin found in dwarf peas. These results suggest that the Le gene controls the production of a 3 β-hydroxylase capable of converting GA₂₀ to GA₁. Further support for this view comes from feeds of [³H] GA₂₀ to Le and le plants. Plants with Le metabolise [³H] GA₂₀ to three major products whilst le plants produce only one major product after the same time. The metabolite common to Le and le plants co-chromatographs with GA₂₉. The additional two metabolites in Le peas co-chromatograph with GA₁ and GA₈.     

Internode length in Pisum. Biochemical expression of the le gene in darkness

Ross, J. J. and Reid, J. B. 1989. Internode length in Pisum. Biochemical expression of the Le gene in darkness.
The Le gene appears to be biochemically expressed in dark-grown pea ( Pisum sativum L.) plants since the previously reported difference in metabolism of [³H]-GA₃₀ between light-grown Le and Le plants was also observed in darkness. Furthermore, both light- and dark-grown Le plants contained more endogenous GA¹, -like substance than did comparable Le plants. Darkness did not appear to significantly increase the accumulation of GA¹, in either Le or Le plants, although confirmation of GA¹ levels by gas chromatography-selected ion monitoring is still required. The results support previous findings that the overall metabolism of [³H]-GA₂₀, is accelerated by darkness. The evidence presented here supports previous suggestions that darkness acts on internode length by increasing some aspect of GA sensitivity.     

Internode length in Pisum. Action of gene lw

Jolly, C. J., Reid, J. B. and Ross, J. J. 1987. Internode length in Pisum. Action of gene lw.
Mutant K29 of Pisum sativum L. is shown to possess a recessive gene at a new locus, lw , which results in reduced internode length, delayed flowering and increased symptoms of water congestion compared with the parental cv. Torsdag. The interaction of gene lw with the internode length genes na, le, la and cry ⁵ is examined. Extracts from the shoots of Iw plants are shown to contain similar levels of gibberellin (GA)-like substances to comparable Lw plants, but Iw plants do not elongate to the same extent as Lw plants when treated with GA₁₉ GA₁₉, or GA₂₀. The effect of gene Iw is not graft-transmissible. Unlike essentially isogenic dwarf lines possessing the GA-synthesis genes le, Ih or Is, lw plants show a relative increase in elongation similar to Torsdag in response to photoperiod extensions from sources rich in far-red light. These results suggest that gene lw probably does not reduce elongation by influencing GA-synthesis and that the response to photoperiod extensions with far-red light may depend on the level of GA.     

Internode length in Pisum. A new allele at the Lh locus

A new allele at the Lh locus has been identified in Pisum sativum L. and named lhⁱ . This allele results in reduced GA levels in young shoots, and a dwarf phenotype. Gas chromatography-selected ion monitoring (GC-SIM) with dideuterated internal standards has been used to demonstrate a quantitative relationship between the level of endogenous GA₁ and internode length using the three alleles ( Lh, lh and lhⁱ ) at the Lh locus. These results are consistent with previous findings in peas (for alleles at the Le locus) and other species possessing a predominant early 13-hydroxylation pathway for GA biosynthesis and support the role of GA₁ as the major native GA in peas with biological activity in its own right. However, in contrast to alleles at the Le locus, GA₂₀ levels are also reduced in lh and lhⁱ plants. The lhⁱ allele also has possible pleiotropic effects on seed abortion, leading to a reduction in seed yield compared to plants homozygous for the previously characterised Lh or lh alleles.     

Internode length in Pisum. Further studies on the 'micro' gene, lm

Reid, J. B. and Ross, J. J. 1988. Internode length in Pisum. Further studies on the 'micro' gene, lm . - Physiol. Plant. 72: 547–554.
In the garden pea, Pisum sativum L., gene lm confers the micro phenotype. The shoots of lm plants may be described as scaled-down versions of comparable Lm plants, with reduced internode length, leaflet size and rate of leaf expansion. However, the first phenotypic effect of gene lm is on root morphology. The gene results in curling and reduced elongation of the roots and, eventually, degeneration of the root cortex. These changes commence prior to any major visible effects in the shoot. The primary action of the lm gene does not appear to be confined to the root system, however, since epicotyl grafts between Lm and lm plants showed no graft-transmissible effects. The effects of gene lm are also apparent in dark-grown plants. Microdwarf plants ( lm le ) respond well to gibberellin A₁ (GA₁), but do not elongate to the same extent as dwarf ( Lm le ) plants. The two genotypes contain the same complement of GA-like substances. It is argued that gene lm is unlikely to be directly involved with GA-metabolism or the reception of the GA signal, but rather reduces the GA response by influencing some aspect of normal cell development, which results in the wide range of pleiotropic effects observed. Consequently, it may be misleading to continue to classify this gene simply as an internode length mutant.     

Internode length in Pisum. Estimation of GA1 levels in genotypes Le, le and led

The levels of GA₁, 3-epiGA₁ and GA₈ in genotypes Le, le and le^d of Pisum sativum L. were determined by gas chromatography-selected ion monitoring (GC-SIM) after feeds of [³H, ¹³C]-GA₂₀ to each genotype. The levels of endogenous and [¹³C]-labelled metabolites were determined by reverse isotope dilution with unlabelled GA₁, 3-epiGA₁ and GA₈. The results demonstrate a quantitative relationship between the level of GA₁ and the extent of elongation both on a per plant and a per g fresh weight basis. These results are consistent with previous findings in peas and other species possessing a predominant early 13-hydroxylation pathway for GA biosynthesis.
The levels of 3-epiGA₁ also decreased in the genotypic sequence Le, le, le^d although not as rapidly as for the level of GA₁. This may suggest that the alleles at the le locus also influence the formation of 3-epiGA₁.     

Internode length in Pisum sativum L. The kinetics of growth and [3H]gibberellin A20 metabolism in genotype na Le

The relationship between shoot growth and [³H]gibberellin A₂₀ (GA₂₀) metabolism was investigated in the GA-deficient genotype of peas, na Le. [17-¹³C, ³H₂]gibberellin A₂₀ was applied to the shoot apex and its metabolic fate examined by gas chromatographic-mass spectrometric analysis of extracts of the shoot and root tissues. As reported before, [¹³C, ³H₂]GA₁, [¹³C, ³H₂]GA₈ and [¹³C, ³H₂]GA₂₉ constituted the major metabolites of [¹³C, ³H₂]GA₂₀ present in the shoot. None of these GAs showed any dilution by endogenous ¹²C-material. [¹³C, ³H₂]GA₂₉-catabolite was also a prominent metabolite in the shoot tissue but showed pronounced isotope dilution probably due to carry-over of endogenous [¹²C]GA₂₉-catabolite from the mature seed. In marked contrast to the shoot tissue, the two major metabolites present in the roots were identified as [¹³C, ³H₂]GA₈-catabolite and [¹³C, ³H₂]GA₂₉-catabolite. Both of these compounds showed strong dilution by endogenous ¹²C-material. Only low levels of [¹³C, ³H₂]GA₁, [¹³C, ³H₂]GA₈, [¹³C, ³H₂]GA₂₀ and [¹³C, ³H₂]GA₂₉ accumulated in the roots. It is suggested that compartmentation of GA-catabolism may occur in the root tissue in an analogous manner to that shown in the testa of developing seeds. Changes in the levels of [1,3-³H₂]GA₂₀ metabolites over 10 d following application of the substrate to the shoot apex of genotype na Le confirmed the accumulation of [³H]GA-catabolites in the root tissues. No evidence was obtained for catabolic loss of [³H]GA₂₀ by complete oxidation or conversion to a methanol-inextractable form. The results indicate that the root system may play an important role in the regulation of biologically active GA levels in the developing shoot of Na genotypes of peas.Abbreviations GA_n gibberellin A_n - GC-MS gas chromatography-mass spectrometry - HPLC high-pressure liquid chromatography     

Internode length in Pisum. The involvement of ethylene with the gibberellin-insensitive erectoides phenotype

The gene lk in peas ( Pisum sativum L.) confers the erectoides phenotype. This phenotype possesses much reduced internode and petiole lengths and is practically insensitive to applied GA₁, compared with Lk plants. Application of the ethylene synthesis inhibitor, aminoethoxyvinylglycine (AVG), resulted in increased internode elongation and increased GA-sensitivity in lk plants, but not in the Lk line, L53. The ethylene-releasing compound, ethephon, had the reverse effect when applied to the Lk line, L58, reducing internode length and GA-sensitivity. Ethylene production was higher in lk segregates than in Lk segregates under the conditions used, and the shoot anatomy of lk segregates was consistent with these higher ethylene levels.
These results suggest that the phenotypic effects of gene lk may be due, at least in part, to increased ethylene production in erectoides plants. However, AVG application to lk plants did not produce true phenocopies of comparable lk plants and ethephon application to Lk plants did not produce the erectoides phenotype. Further work is therefore required to determine whether the effect of the gene lk on ethylene production is the primary action of this gene or merely a secondary consequence.     

Internode length in Pisum. Comparison of genotypes in the light and dark

There is a strong relationship across the full range of gibberellin deficient, internode length genotypes ( le, lh, is, na ) between internode length in the dark and in red or white light. Further, the new, more severe allele at the le locus. Ie ^d, is shown to influence growth in the dark as well as in the light. These results suggest that darkeness does not specifically overcome any of the steps blocked by the gibberellin (GA) synthesis genes contrasting with the conclusions drawn by other workers. Supporting this conclusion in relation to the Ie gene are results which show that, at least at certain dosage rates, dark-grown Ie na plants respond better to GA₁ than to GA₂₀ similar to the response previously reported in light grown plants.
The greater response by plants of the nana line NGB1766 ( na ) to GA₁ in the dark than in the light suggests that light may influence internode length by altering GA-sensitivity. These results are discussed in relation to previous views on the control of stem elongation by light.     

The effect of fruit-removal on cytokinins and gibberellin-like substances in grape leaves

Removal of fruit from potted cuttings of Vitis vinifera L. increased the concentration of a cytokininglucoside in leaf tissue extracts and decreased the level of extractable gibberellin-like substances. The glucoside (of zeatin riboside) is not present in xylem exudate of V. vinifera L., and appears to be synthesized in the leaves. Berry extracts contain zeatin-riboside and smaller amounts of cytokinin-glucoside. The changes in the level of these hormones are discussed in relation to previous results on abscisic acid and phaseic acid levels in grape leaves.Abbreviations ABA abscisic acid - PA phaseic acid - GA gibberellin     

Photoinhibition of radish (Raphanus sativus L) seed germination: control of growth potential by cell-wall yielding in the embryo

The biophysical mechanism underlying photoinhibition of radish (Raphanus sativus L.) seed germination was investigated using three cultivars differing in sensitivity to continuous irradiation with far-red light (high-irradiance reaction of phytochrome). Sensitivity of germination to the inhibitory action of light was assessed by probing germination under osmotic stress (incubation in media of low water potentials adjusted with polyethylene glycol 6000) and expressed in terms of ‘germination potential’ (positive value of the water potential at which germination is inhibited by 50%). Far-red light decreases the germination potential to various degrees in the different cultivars, reflecting the light-sensitivity of germination in water. Removal of the seed coat increases the germination potential by a constant amount in darkness and light. It is concluded that germination depends on the expansive force of the embryo which can be drastically diminished by far-red light. Seed-coat constraint and expansive force of the embryo interact additively on the level of the germination potential. Photoinhibition of germination was accompanied by an inhibition of water uptake into the seed. Analysis of seed water relations showed that osmotic pressure and turgor assumed higher levels in photoinhibited seeds, compared to seeds germinating in darkness, while the water potential was close to zero under both conditions. Far-red light produced a shift (to less negative values) in the curve relating water-uptake rate to external water potential, i.e. a reduction in the driving force for water uptake. It is concluded that photoinhibition of germination results from the maintenance of a high threshold of cell-wall extensibility in the embryo.     

花椒品种间化感效应的差异

实验对4个常见的花椒品种(大红袍、汉源椒、大毛椒和七月椒)的化感效应进行了研究。花椒叶的浸提液分成2.5、5.0、10.0、20.0和40.0g·L-15个浓度,以紫花苜蓿种子作为受试植物。结果表明,与对照相比,各品种叶浸提液都显著地抑制了苜蓿种子萌发和幼苗生长,同时也促进了幼苗根和茎生物量的增加。4个品种间对种子萌发的化感效应有轻微的差异,而对幼苗生长和生物量的影响由于品种的不同而有所不同。4个品种叶的浸提液化感效应依次增强的顺序为:汉源椒、七月椒、大毛椒和大红袍。另外,花椒人工林地内的土壤对紫花苜蓿的生长发育也产生了显著的化感效应。最后,对4个花椒品种的叶挥发油进行了GC-MS化学成分分析,结果显示:不同品种的花椒体内化感物质的含量有区别,但它们的挥发油主要成分都包括桉树酚(cineole)、里哪醇(linalool)、乙酸里哪(醇)酯(linalylacetate)、β-石竹烯(beta-caryophyllene)和萜品-4-醇(terpinen-4-ol)等。     

Effects of aqueous extract of rice plants (Oryza sativa L.) on seed germination and radicle elongation of Monochoria vaginalis var. plantaginea

Laboratory experiments were conducted to examine the allelopathic potentials of rice plants (Oryza sativa L.) on seed germination and radicle elongation of Monochoria vaginalis (Burm. f.) Presl var. plantaginea (Roxb.) Solms-Laubat. To compare the relative allelopathic potentials of rice plants at different growth stages, aqueous extracts of dried tissues were obtained from the seeds, husks, and seedlings harvested 10, 20, 40 and 120 days after seeding. When M. vaginalis seeds were incubated in solutions containing aqueous extracts, significant increases in the germination rate were observed for all the aqueous extracts except for the extract of 10 d-old shoots at higher dosages. When partitioned with ethyl acetate, the germination-promoter(s) in the aqueous extracts remained in the aqueous phase while some inhibitors were extracted with ethyl acetate. In contrast, aqueous shoot extracts added to the incubation media at the same dosage for promotion of seed germination inhibited radicle elongation of M. vaginalis, indicating that the sensitivity of the weed varies between these two growth stages.     

Effect of polythene covers, a flower inducing treatment, on the content of endogenous gibberellin-like substances in grafts of Norway spruce

In shoots of 12-year-old Norway spruce [Picea abies (L.) Karst.] grafts the content of endogenous gibberellin-like substances was analysed. Covering the crowns with polythene on the turn of June and July stimulated induction of male strobiles and significantly increased the levels of gibberellins. Polar gibberellin (at R_f 0.0–0.2) increased immediately and the less polar ones after one day. After 2 weeks the increased level was maintained only at R _f 0.4–0.6 and 9 days later the differences between covered and not covered grafts disappeared. Removal of the covers did not affect gibberellin levels. It is suggested that covering with polythene stimulates floral induction through an increase in endogenous gibberellin levels.     

褐藻胶寡糖对豌豆种子萌发和幼苗的某些生理特性的影响

褐藻胶寡糖(ADO)对豌豆种子萌发和幼苗生长有促进作用,种子发芽率升高,幼苗高度.根长、生物量均有增加;幼苗叶中叶绿素含量增高;叶片净光合速率、胞间CO_2浓度、气孔导度和蒸腾速率增加;根系活力增强;种子中α和β-淀粉酶活性增强。低浓度ADO的效果明显优于高浓度的ADO,其中以0.125?O的效果最佳。     

The effect of copper on length increase in Ascophyllum nodosum (L.) Le Jolis

The increase in length of Ascophyllum nodosum (L.) Le Jolis was measured in copper concentrations varying from 14–5000 μg/1 sea water. The growth was unaffected by concentrations of 33 μg/1 or less added for a period of 11 days, but at higher concentrations growth was gradually reduced. When the number of days (x) of exposure to a concentration (y) (y > 33 μg/1) is compared with z (the corresponding percentage reduction of growth rate), the data fit the equation z = 0.084 xy up to at least z = 60%.     

The effect of phenols on respiratory enzymes in seed germination

Low molecular weight phenolic compounds were identified in two soilswith different vegetative cover, Fagus sylvatica, L. andPinus laricio, Poiret, spp. calabrica, and were tested atdifferent concentrations on seed germination of Pinuslaricio, and on respiratory and oxidative pentose phosphate pathwayenzymes involved in the first steps of seed germination. The data obtained showthat there are marked differences in the phenolic acid composition of the twoinvestigated soils. All the phenolic compounds bioassayed inhibited seedgermination and those extracted from Pinus laricio soilwere particularly inhibitory. We also found that the non-germination of seedsisstrongly correlated to the inhibition of the activities of enzymes ofglycolysisand the oxidative pentose phosphate pathway.