Morphogenetic Effects on Vegetative Plants of Poa pratensis L. of 6-Azauracil, (2-Chloroethyl)- phosphonic acid, and (2-Chloroethyl) trimethyl-ammonium chloride and their Interaction with Gibberellic Acid

Fresh and dry weights and leaf size of Poa pratensis were reducedwhen treated with 6-azauracil (AzU), (2-chloroethyl)phosphonicacid (CEPA), or (2-chloroethyl)trimethylammonium chloride (CCC).AzU and CEPA inhibited epidermal cell division without inhibitingcell elongation, while CCC inhibited mainly cell elongationand cell division to a small extent. The ratio of blade lengthto sheath length and the blade length/width ratio were reduced,but leaf emergence and tillering were increased by AzU and CEPA.CCC affected only the latter three features. Like GA₃, CEPAinduced stem formation, but internodes were shorter. GA₃ was ineffective in preventing leaf-growth inhibition byAzU, which inhibited Ga₃-induced cell elongation. The inhibitoryeffect of CEPA on leaf growth was apparently reversed by GA₃,but this was due solely to increased cell elongation, the reductionin cell number being unaffected. Ga₃ reversed the effect ofCCC on leaf length, as well as on cell size and number. Simultaneousapplication of the inhibitors produced a complex interactionin reducing leaf length and number and size of epidermis cells.It is postulated that AzU, CEPA, and CCC have different modesof action because they have specific effects on plant growthand different effects on GA₃-induced cell elongation.     

Influence of chlorocholinechloride and ethrel on chlorophyll content and the “epinastic response” of the primary leaf of wheat seedlings

Wheat seedlings were cultivated in nutrient solutions containing 10^-3 M CCC, 10^-3 M CEPA or 5 × 10^-4 M CCO and CEPA, respectively. CCC applied alone or mixed with CEPA increased chlorophyll content per unit fresh matter but had no influence on the epinastio response of the primary leaf. In contrast, CEPA had no influence on chlorophyll content but greatly increased the epinastic response. The different response to the application of these substances with regard to chlorophyll content ha been claimed in a previous paper to be due to their different effect on cell extension and cell division. The epinastic response of the primary leaf suggests that ethylene participates in the reaction chain of CEPA effect on plant tissues.     

Growth, Sex Expression and Yield of Squash Melon (Citrullus vulgarisvar. fistulosus) as Influenced by 2(chloroethyl)phosphonic acid, 2,3,5-tri-iodobenzoic acid and (2-chloroethyl) trimethyl-ammonium chloride

Single aqueous sprays of 2(chloroethyl)phosphonic acid (CEPA) 250, 500 and 1000 mg/1; 2,3,5-triiodobenzoic acid (TIBA) 25, 50 and 100 mg/1; and (2-chloroethyl) trimethyl-ammonium chloride (CCC) 250, 500 and 1000 mg/1 were applied to squash melon (Citrullus vulgaris Schrad. var. fistu-losus Stocks.) at the 2–3 leaf stage. Though the final length of the main axis and number of lateral branches were not affected by any treatment, CEPA retarded growth of young plants by reducing the internodal length. It did not change the flowering pattern but delayed flowering and reduced the production of both pistillate and staminate flowers. However, it increased the per cent femaleness as a result of comparatively more suppression of staminate flowers. The TIBA 25 and 50 mg/1 and CCC 500 mg/1 did not affect the staminate flower production but increased the pistillate flowers, which increased the per cent femaleness. The CEPA decreased while both TIBA 25 and 50 mg/1, and CCC 500 mg/1 increased the number of fruits per plant and the yield. The mode of action of the chemicals has been discussed.     

Einfluss von Chlorcholinchlorid und Ethrel auf Zellteilung und Zellstreckung bei Primärblättern von Weizenkeimpflanzen

Both chlorcholinchloride and ethrel are used as growth retardants in cereal cultivation. Wheat seedlings were cultivated in nutrient solutions containing 10^-3M CCC, CEPA or 5 × 10^-4M CCC and CEPA, respectively. The epidermis of full-grown primary leaves was analysed. CCC relatively equally decreases the length of leaves and long epidermal cells, whereas CEPA mainly inhibits cell division. Leaf growth is always a little more inhibited than the number of stomata and trichomes is reduced by CCC or CEPA. This results in an increased frequency of stomata and trichomes by about 14 to 16 per cent. This means that retardants can strongly influence the length of leaves and the length or number of long epidermal cells but, due to the mechanism of programmed determination, the frequency of stomata and trichomes is kept constant within relatively narrow limits. Furthermore it can be concluded that long epidermal cells function as pace-makers in the growth of leaves of monocotyledonous plants.      

Die Wirkung Des »Gibberellinantagonisten« 2-Chloräthyltrimethylammoniumchlorid (CCC) auf die Stecklingsbewurzelung Windender und nicht Windender Pflanzen

Summary Root initiation at cuttings is inhibited by application of gibberellin. CCC does not antagonize this inhibition. However, CCC stimulates root initiation at cuttings of three different species of twining plants known to be rich in endogenous gibberellin. CCC seems to be an antagonist for endogenous but not for exogenous gibberellin, which suggests that CCC influences gibberellin biosynthesis.     

Changes in the relationship between growth of leaves and stem in cabbage caused by treatments with growth retardants

A cabbage variety with particularly strongly developed leaves and extremely shortened stems (tight heads) was treated during the first year of its development with growth retardants (CCC and CEPA, Ethephon) at different concentrations. A 4-fold treatment with CCC, CEPA or a mixture of both proved to be most effective Leaf growth was inhibited by this treatment (head mass decreased) but stem growth increased. Only in treated plants the bud of the stem apex could break through the leaf sheath and develop generative stem. The results are discussed as examples of correlative relations between leaf and stem growth. Presented at the International Symposium “Plant Growth Regulators” held on June 18-22, 1984 at Liblice Czechoslovakia     

Die induktion eines trenngewebes bei früchten von Prunus avium L. durch 2-Chloräthylphosphonsäure

Summary 2-Chloroethylphosphonic acid (CEPA) facilitates the separation of the fruit from the pedicel significantly. The application of 2,000 and 4,000 ppm CEPA in four sweet cherry varieties during maturation resulted in the formation of a complete abscission layer in the transition zone between pedicel and fruit. In contrast, in the untreated fruit no abscission layer was evident at maturity. The walls of the cells in the abscission layer contained less total polysaccharides than adjacent cells. Cellulose was partially broken down, and the pectins were degraded. The Ca and Mg content in the cell walls decreased. Thus the same histochemical changes are involved in natural and CEPA induced abscission.     

Effects of 2-Chloroethyl Trimethylammonium Chloride (CCC) and 2-Chloroethylphosphonic Acid (CEPA) on Dry Matter Distribution in the Cowpea (Vigna Unguiculata L.)

Effects of foliar applications of CCC and CEPA on dry matterdistribution in two cowpea cultivars which exhibit differentdegrees of premature abscission of fruits were investigated.At the concentration of 0-1 mg1^–1, CCC increased stemweight in the cultivar Adzuki, but had no effect on the cv.Mala (which exhibits a relatively high degree of premature abscission).While CCC did not significantly influence root weight in Adzuki,the concentrations of 1 and 10 mg 1^–1 increased root weightin Mala. In both cultivars, the 1000 mg1^–1 treatment decreasedseed weight, with a greater decrease in Adzuki. All concentrations of CEPA, up to 1000 mg 1^–1, decreasedstem and root weights in Mala, and leaf weight in Adzuki. The10 mg1^–1 concentration increased seed weight in Mala by100 percent, and leaf weight by 28 percent, without any significanteffect on pod weight, or on the weight of the whole plant. Therewas also no increase in pod number. Overall, Mala was more responsive than Adzuki to the growthregulators, particularly CEPA. In the low concentration responses,CEPA increased seed weight not by increasing gross plant weight,but mainly by causing a change in distribution of dry matter.     

Flower Bud Atrophy in Baccara Roses. V. The Effect of Different Growth Substances on Flowering

The effect of various growth regulators on the atrophy of terminal flower buds was tested on Baccara roses. Treatments with gibberellic acid (GA) and 2-chloroethyl trimethyl ammonium chloride (CCC) reduced the atrophy of the flowers. The application of 2-chloroethyl phosphonic acid (CEPA) to the buds enhanced abortion, and the effect was more marked on the lower than on the upper shoot. The stage most sensitive to CEPA was when the shoots were 8–35 cm long. Treatment with abscisic acid (ABA) had no effect of the degree of “blindness”, nor did kinetin applied to the apex affect flowering. Spraying with benzyl adenine increased both the rate of sprouting of the lateral buds and the extent of “blindness” of the sprouting shoots, but did not reduce the number of flowers per branch.     

Reduction of the Gibberellin Content of Pharbitis Seeds by CCC and After-Effects in the Progeny

Plants of Pharbitis nil were treated with the growth retardant (2-chloroethyl) trimethylammonium chloride (CCC) shortly before and after anthesis. Fresh and dry weight of immature seeds were not affected by the CCC treatment.

The level of gibberellin-like activity in Pharbitis seeds as compared to control seeds was strongly reduced by CCC application. The progenies of the treated plants also had a much reduced GA content in the seedling stage. These results are interpreted to indicate that CCC blocks gibberellin biosynthesis in higher plants, as it does in the fungus Fusarium.

CCC applied via the roots accumulated in the immature seeds and was carried over to the following generation. Consequently, growth of CCC progenies was dwarfed and flower formation inhibited. Both phenomena were overcome by application of gibberellin A₃.

Three gibberellin-like substances (called fractions I, II, and III) were present in Pharbitis seeds and could be separated by thin-layer chromatography. All 3 fractions were also present in seeds treated with CCC. Fractions II and III were present in much higher quantities than fraction I. Both fractions II and III promoted growth of d5 corn but only fraction II was active in dwarf peas grown under red light.

     

Ethylene production by growing and senescing pear fruit cell suspensions in response to gibberellin

A pear (Pyrus communis L. cv Passe Crassane) cell suspension was used as a model system to study the influence of gibberellin on processes related to fruit ripening. Growth of the cell cultures was inhibited and their loss of viability was accelerated when 0.5 millimolar gibberllic acid (GA₃) was added to suspensions at two stages of cell development, namely, growth and quiescence. Cell respiration rate was unaffected up to 2 millimolar GA₃ but ethylene production, both basal and 1-aminocyclopropane-1-carboxylic acid-induced, was inhibited at all stages of cell development. However, the degree of inhibition decreased as the cell cultures aged. The site of ethylene inhibition by GA₃ appeared to be related to the ethylene-forming enzyme. The coincident acceleration of cell senescence and inhibition of ethylene production indicate that the pear cell suspension cannot serve as an analogous model for studying the mode of action of gibberellin in delaying ripening and senescence of fruits in its entirety, although certain specific effects might be relevant.     

CCC-Induced increase of gibberellin levels in pea seedlings

Summary Pea seedlings (cv. Alaska), were treated with two concentrations of (2-chloroethyl)trimethylammonium chloride (CCC) and choline chloride. Treatment with 1 mg/l CCC resulted in as much as a 150fold increase in endogenous gibberellin (GA) levels without there being any parallel stimulation of growth. Plants grown in 1,000 mg/l CCC were severely dwarfed but contained GA levels not significantly different from control plants grown in distilled water. CCC also retarded GA₃-induced growth of pea seedlings. These effects appear to be CCC specific as the CCC analogue choline chloride affected neither the GA content of pea seedlings nor their response to GA₃. The lack of correlation between endogenous GA levels and stem height suggests that in peas the predominant factor in CCC-induced inhibition of stem growth is not related to an effect of CCC on GA biosynthesis.Supported by National Research Council (Canada) grant A-5727.Supported by a Postdoctoral Fellowship from NRC Grant A-2585 to R.P. Pharis.     

New bioregulators of gibberellin biosynthesis in Gibberella fujikuroi

A number of new inhibitors of gibberellin (GA) biosynthesis in Gibberella fujikuroi are reported, including secondary, tertiary and quaternary amines. Octyltrimethylammonium iodide and 3-chloropropyltrimethylammonium iodide were equally as effective as 2-chloroethyltrimethylammonium chloride (CCC). At least two of the other inhibitors reported, diethyloctylamine hydrochloride and octyltriethylammonium iodide, showed a different pattern of accumulation of GAs and kaurenoic acids than did CCC.     

ClSnRK2.3 negatively regulates watermelon fruit ripening and sugar accumulation

Watermelon(Citrullus lanatus) as non-climacteric fruit is domesticated from the ancestors with inedible fruits. We previously revealed that the abscisic acid(ABA) signaling pathway gene ClSnRK2.3 might infuence watermelon fruit ripening. However,the molecular mechanisms are unclear. Here,we found that the selective variation of ClSnRK2.3 resulted in lower promoter activity and gene expression level in cultivated watermelons than ancestors, which indicated ClSnRK2.3 might be a negative regulator ...