The Effect of (2-chloroethyl)-trimethylammonium Chloride on the Growth of Barley

Barley (Hordeum vulgare L. C.I.666) was shown to be susceptibleto the growth retardant (2-chloroethyl)-trimethylammonium chloride(CCC). The estimation of cell number in the dwarfed third leafblade indicated that a decrease in mitotic activity had occurredin treated plants. There was also a decrease in cell size intreated plants. The dwarfing action of CCC was reversed by exogenousgibberellic acid (GA₃) but this was shown to be the result ofincreased cell elongation only. GA₃ did not promote cell divisionin healthy or CCC-treated plants. Assay of endogenous gibberellinsshowed a significant reduction in the level of a substance correspondingto GA₃ in CCC-treated plants. It is suggested that CCC-induceddwarfing of barley is largely the result of a reduction in meristematicactivity. This may be related to an effect on gibberellin biosynthesisbut is not reversed by the application of exogenous GA ₃.     

Genetically controlled differences in the effects of chlormequat on tetraploid wheat (Triticum turgidum)

Two crosses between Triticum turgidum wheat lines differing in their response to chlormequat (CCC) were tested. In the F₂ population of one cross, which was segregating for the Rht1 dwarfing allele, each plant was cloned by separation of two tillers, one of which was treated with CCC. The tall (rht1/rht1) and the intermediate (Rht1/rht1) genotypes showed a greater response to CCC than the semi-dwarf (Rht1/Rht1) genotype, as expressed by culm length and date of ear emergence. The F₃ families of another cross and their two semi-dwarf parents were grown in a three-replicated field test in paris of rows, one of which was treated with CCC. In one of the parents and in 1/4 of the F₃ families CCC induced a wide-angled tiller growth, suggesting a monogenic control of this growth habit in response to CCC.Based on an M.Sc. thesis presented by the senior author to the Faculty of Agriculture of The Hebrew University of Jerusalem.     

中国春小麦株高、育性近等基因系的建立及应用

以矮败小麦和中国春小麦为材料,经过杂交和连续回交,得到了中国春小麦遗传背景的分别表现矮秆不育、矮秆可育、高秆不育、高秆可育的近等基因系。根据近等基因系各成员系的株高表现,计算出矮秆基因Rht10的降秆强度是69.8%。借助于赤霉酸处理,在幼芽期就可分出矮败中国春小麦后代的不育株与可育株。 Abstract：　Use Dwarfing Male-sterile Wheat and cv. Chinese Spring as parents, after cross and continuously back cross, the isogenic lines with Chinese Spring background were developed. These lines include dwarfing male-sterile line, dwarfing fertile line, tall male-sterile line and tall fertile line. The dwarfing intensity of gene Rht10 was calculated to be 69.8% according the differences between the isogenic lines. Treated with GA3solution, the male-sterile and fertile plants in Chinese Spring Dwarfing Male-sterile Wheat can be identified clearly when they are seedlings.     

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.     

Effects of the d 2 dwarfing gene in pearl millet

Summary Dwarf varieties have had virtually no impact on the production of pearl millet, in contrast to the case of wheat, rice, and sorghum. This research compared tall and dwarf near-isogenic F₁ hybrids to attempt to determine if there were deleterious effects of the d ₂ dwarfing gene that might account for the lack of release/cultivation of dwarf pearl millet cultivars. Dwarf isohybrids on average yielded less than the tails, because of a smaller average seed size combined with a similar grain number per unit area. There was, however, a larger contribution of background genetic variation (pollinator, male-sterile, and interaction effects) to hybrid variation for nearly all characters measured, including seed size, than there was of the dwarfing gene. Selection of dwarf parents capable of producing hybrids with equal seed size and yield to that of tall parents should not be difficult.Journal article no. 1469 of the International Crops Research Institute for the Semi-Arid Tropics, Patancheru, A.P. 502 324, India     

The effect of cotyledons on hypocotyl elongation in light-grown bean seedlings: Comparison between dwarf and tall varieties

Hypocotyl sections with and without the cotyledons were cutfrom bean seedlings and incubated under white light of 6000lux. The cotyledons had an inhibitory effect as well as a promotiveeffect on hypocotyl growth. The former effect was more strikingin the dwarf variety, and the latter in the tall variety. Whenthe hypocotyl units were exposed to light for shorter times(6 hr or less) or incubated under weaker light (1600 and 50lux), the inhibitory effect of the cotyledons decreased greatly,and in the tall variety the presence of cotyledons producedno inhibition, but a promotion of hypocotyl growth. GA treatmentenhanced hypocotyl growth and counteracted the growth inhibitioncaused by the cotyledons. On the whole, the GA effect was moremarked in the tall variety than in the dwarf. The elongation of bean hypocotyls may be controlled by a balancebetween the inhibitory and promotive effects of cotyledons,and the predominance of the former over the latter may be oneof the causes for expressing dwarfing. (Received November 13, 1976; )     

The Relationship Between the Effects of CCC on Root Growth and Cytokinin Levels in the Bleeding Sap of Vitis vinifera L.

The growth retardant (2-chloroethyl)trimethylammonium chloride(CCC) induced swollen root tips on seedlings of grape vines(Vilis vinifera L.) as well as on plants grown from cuttings.In both cases CCC had to be applied to the growth medium forthe response to be expressed; spraying the shoots reduced stemgrowth without inducing swollen roots. N-dimethylarminosuccinamicacid (B995) was ineffective in causing these root symptoms ongrapes, nor did root swellings appear on five other speciestreated with CCC. On the other hand, kinetin resulted in graperoots which in some respects resembled those treated with CCC. Two regions of cytokinin activity were detected on chromatogramsof bleeding sap from grape-vines grown in serated nutrientculture solutions compared with only one region in sap fromplants grown in soil or other solid media. Activity of a regionof high mobility was increased by CCC applications to the culturesolutions; effects of CCC on a region of low mobility, whichmay be a bound derivative of the other, were variable. Boththe concentration and absolute amounts of cytokinin activityin the sap were increased by CCC, indicating that this retardantprobably affected cytokinin synthesis by the root tip. The effectof CCC on cytokinin levels in the sap diminished during thebleeding period. The results are interpreted to indicate that in grapes, CCCacts directly on the root meristem to increase cytokinin production.Swelling of the tips is probably a consequence of the elevatedcytokinin levels in this region.     

Carbon monoxide sensitivity of cytochrome oxidase in wheat leaves in relation to dwarfing genes (Rht) in wheat cultivars

Summary Leaves of young seedlings of a number of tall cultivars of wheat, lacking the dwarfing Rht genes, readily responded to a brief 2 min exposure to CO, as assessed by in vivo aerobic assay of nitrate reductase. This test depends on the inhibition of cytochrome c oxidase by CO, which in turn renders cytosolic NADH available for the reduction of nitrate to nitrite in vivo. Semi-dwarf cultivars of wheat (Rht present) did not respond to CO in this way. Since CO forms a complex only with reduced cytochrome a₃, the results indicate differences in the redox state of cytochrome a₃, during in situ respiration of leaves from tall and semi-dwarf plants which are likely to be under genetic control.     

Contribution of the wheat (Triticum aestivum L.) flag leaf to grain yield in response to plant growth regulators

In West-Europe, intensive cereal management uses plant growth regulators (PGRs) especially for wheat. A green-house experiment compared the effects of two PGRs on flag leaf characteristics and yield of winter wheat. Chlormequat chloride + choline chloride (CCC) and chlormequat chloride + choline chloride + imazaquin (CCC+I) were applied to winter wheat at growth stage 5 (Feekes Large scale). CCC and CCC+I significantly increased flag leaf surface area at anthesis. Both treatments also enhanced chlorophyll content of the main stem flag leaf. The grain filling period was extended with PGR application by 2 days. CCC and CCC+I significantly increased net CO₂ assimilation rates during the flag leaf life. No effects of PGR spraying were observed on the pattern of ¹⁴C labelled assimilate distribution. Increased grain yield was due to the increase in average grain weight. The results indicate that PGR treatments increased flag leaf contribution to grain filling. The addition of imazaquin (I) to chlormequat (CCC) improved the effects of CCC.     

No effect of the plant growth regulator, chlormequat, on boar fertility

Chlormequat is a commonly used plant growth regulator in agriculture. Defined levels of chlormequat residue are allowed in food and an acceptable daily intake is defined for humans. However, there are results in the literature suggesting that a daily intake below the acceptable level for human is detrimental for mammalian reproduction. In the present experiment we investigated the effect of chlormequat at levels up to that acceptable for humans on reproduction in male pigs. Chlormequat (also known as chlorocholine chloride (CCC)) was mixed into the diet and given to the experimental animals at three levels (three treatment groups), i.e. 0 mg CCC/kg BW per day (Control), 0.025 mg CCC/kg BW per day and 0.05 mg CCC/kg BW per day. Eight mother sows per treatment group were used in the experiment. From the day of insemination, the mother sows received the experimental diets. The piglets were weaned at 4 weeks of age and two boar littermates continued on the same treatment as the dam until maturity and delivery of semen for in vitro fertilization (IVF) and in vivo fertilization. Semen volume, sperm concentration and fraction of live sperms were not (P 0.46) detrimentally affected by chlormequat intake. The fraction of oocytes developing to more than the one-cell stage at day 5 after IVF was not (P = 0.88) detrimentally affected by chlormequat intake. Chlormequat intake did not detrimentally affect the fraction of gilts being pregnant after one insemination (P = 0.65) or the number of embryos in the pregnant gilts (P = 0.36). Serum chlormequat concentration was 0.9 μg/kg in the 0.025 mg CCC/kg BW per day group and 1.8 μg/kg in the 0.05 mg CCC/kg BW per day group, but was below the detection limit in control animals. In conclusion, the plant growth regulator chlormequat could not be proven to be detrimental to the selected reproduction traits in male pigs. This is in contrast to existing results from the male mouse.     

The effect of daylength on photosynthate partitioning into leaf starch and soluble sugars in a gibberellin-deficient dwarf mutant of Zea mays

The possibility that gibberellins (GAs) mediate the photoperiodic regulation of photosynthate partitioning into stored leaf carbohydrates (starch and soluble sugars) was investigated with the dwarf-5 mutant of Zea mays L., a single-gene recessive mutant with greatly reduced endogenous GA content relative to tall maize. The mutant responded to daylength as did tall maize, with higher rates of carbohydrate accumulation observed under short daylength (8.5 h of light) than under long day-length (14 h of light). Neither inhibitors of GA biosynthesis (CCC, [(2-chloroethyl) trimethylammonium chloride], ancymidol[α-cyclopropyl-α-( p -methoxy-phenyl)-5-pyrimidine methyl alcohol], and tetcyclacis [5-(4-chlorophenyl)- 3,4,5,9, 10-penta-azatetracyclo-5,4,1,0^2.6,0^8.11-dodeca-3.9-diene]) nor treatment with GAs further modified the response of partitioning to daylength even though biologically active GAs stimulated plant growth. The results indicate that photoperiodic modulation of endogenous GA titre is unlikely to be responsible for the photoperiodic response of photosynthate partitioning in Z. mays .     

Gibberellins are not essential for photoperiodic flower induction of Pharbitis nil

The influence on photoperiodic flowering of (2-chloroethyl)trimethylmmonium chloride (CCC), an inhibitor of gibberellin (GA) biosynthesis, was studied in the short-day plant Pharbitis nil cv. Violet. The cotyledons contained high levels of endogenous bioactive gibberellins, whereas in the plumules and first leaves the levels were low or undetectable. The first leaf responded to a single'dark treatment by inducing flowering when it was 10 mm or wider. Similar seedlings, but without cotyledons, were used as the assay plants to study the effect of CCC on photoperiodic flowering. Treatment with CCC had no effect on flowering of seedlings without cotyledons, although stem elongation was inhibited. By contrast. CCC inhibited flowering of the intact seedlings with cotyledons. Gibberellic acid applied to the shoot apex or to the first leaf promoted flowering in the CCC-treated seedlings without cotyledons. The results indicate thai gibberellins are not essential for the flower induction process in leaves, but that they promote flower initiation and/or later processes in the shoot apices.     

Response of Cowpeas to Salinity and (2-Chloroethyl) trimethyl-ammonium Chloride (CCC)

Recent investigations have demonstrated that the growth retardant, (2-chloroethyl) trimethyl-ammonium chloride (CCC) inhibits several aspects of vegetative growth. In solution culture experiments, reduction in plant growth and dry matter production was confirmed in cowpeas, Vigna unguiculata L, (cv. Makueni II), when treated with CCC. The growth retardant had negligible effect on the rate of transpiration per unit leaf area although it slightly increased the relative water content of leaves. Stomatal opening was suppressed by CCC treatment but the number of stomata per unit leaf area was increased by the growth retardant. Variations in mineral element content (K, Ca, N and Na) of shoots are presented and discussed in relation to CCC treatment.     

Identification and genetic mapping for <Emphasis Type="Italic">rht-DM</Emphasis>, a dominant dwarfing gene in mutant semi-dwarf maize using QTL-seq approach

Semi-dwarfism is an agronomically important trait in breeding for stable high yields and for resistance to damage by wind and rain (lodging resistance). Many QTLs and genes causing dwarf phenotype have been found in maize. However, because of the yield loss associated with these QTLs and genes, they have been difficult to use in breeding for dwarf stature in maize. Therefore, it is important to find the new dwarfing genes or materials without undesirable characters. The objectives of this study were: (1) to figure out the inheritance of semi-dwarfism in mutants; (2) mapping dwarfing gene or QTL. Maize inbred lines ‘18599’ and ‘DM173’, which is the dwarf mutant derived from the maize inbred line ‘173’ through ⁶⁰Co-γ ray irradiation. F₂ and BC₁F₁ population were used for genetic analysis. Whole genome resequencing-based technology (QTL-seq) were performed to map dwarfing gene and figured out the SNP markers in predicted region using dwarf bulk and tall bulk from F₂ population. Based on the polymorphic SNP markers from QTL-seq, we were fine-mapping the dwarfing gene using F₂ population. In F₂ population, 398 were dwarf plants and 135 were tall plants. Results of χ² tests indicated that the ratio of dwarf plants to tall plants was fitted to 3:1 ratio. Furthermore, the χ² tests of BC₁F₁ population showed that the ratio was fitted to 1:1 ratio. Based on QTL-seq, the dwarfing gene was located at the region from 111.07 to 124.56 Mb of chromosome 9, and we named it rht-DM. Using traditional QTL mapping with SNP markers, the rht-DM was narrowed down to 400 kb region between SNP-21 and SNP-24. The two SNPs were located at 0.43 and 0.11 cM. Segregation analysis of F₂ and BC₁F₁ indicated that the dwarfing gene was likely a dominant gene. This dwarfing gene was located in the region between 115.02 and 115.42 Mb on chromosome 9.     

Efficient micropropagation and chlorocholine chloride induced stevioside production of Stevia rebaudiana Bertoni

A promising method of micropropagation of Stevia rebaudiana Bertoni has been developed with an aim to increase the biomass, survivability of the plantlets and stevioside production, using chlorocholine chloride (CCC). Microshoots transferred to the MS medium containing different combinations CCC and IBA were found to be most effective in terms of growth pattern, hardening ability of the plantlets and stevioside content, compared to MS medium containing either IBA or CCC. Among other combinations tested, MS medium supplemented with 3 mg/l CCC and 3 mg/l IBA was found most effective in inducing significant changes like reduced shoot length, increased number of roots, higher leaf size, increased biomass and chlorophyll retaining capacity, higher survival percentage and most importantly the elevated stevioside content. Collectively, the major observations of this research indicate that application of CCC in micropropagation of S. rebaudiana Bertoni is a promising approach and has commercial prospects.     

Camptothecin and 10-hydroxycamptothecin accumulation in tender leaves of Camptotheca acuminata saplings after treatment with plant growth regulators

The effect of plant growth regulators (PGRs) on the accumulation of the alkaloid camptothecin (CPT) and its analogue 10-hydroxycamptothecin (HCPT) in tender leaves of Camptotheca acuminata saplings was studied. In screening experiments for PGRs, 40?mg/L dose of thiourea, triacontanol, and ascorbic acid (V_C) had no positive effects on the accumulation of the alkaloids. However, treatments with 40?mg/L of chlormequat chloride (CCC), choline chloride, paclobutrazol (PBZ), and daminozide (B₉) induced CPT and HCPT accumulation in both pre-harvest and postharvest stages. On that basis, five levels of PGRs at 0, 20, 40, 60, 80?mg/L were sprayed on tender leaves of C. acuminata saplings at pre-harvest and postharvest stages. Treatment by 40?mg/L CCC dramatically enhanced HCPT production by 308?% in pre-harvest, treatment by 60?mg/L CCC enhanced HCPT production by 100?% in postharvest. Spraying the leaves with 60?mg/L choline chloride resulted in 94?% increase of CPT and spraying with 40?mg/L of the PGRs reached 167?% increase of HCPT in the pre-harvest treatment, respectively; treatments with 60?mg/L choline chloride resulted in 64?% increase of CPT and 525?% increase of HCPT in postharvest, respectively. 52?% increase of CPT and 86?% increase of HCPT in pre-harvest, 22?% increase of CPT and 33?% increase of HCPT in postharvest were obtained by spraying leaves with 60?mg/L PBZ. Treatments with 40?mg/L B₉ had the highest impact on CPT (12?% increase in pre-harvest, 11?% increase in postharvest) and HCPT (167?% increase in pre-harvest, 173?% increase in postharvest) accumulation. The optimal PGR for obtaining the highest levels of CPT and HCPT was treatment with 60?mg/L choline chloride. In most case, the pre-harvest treatment was better than the postharvest one. These preliminary results suggest that the application of PGRs may be a useful and feasible method to increase CPT and HCPT levels in C. acuminata.     

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.     

Modification of growth habit of Majestic potato by growth regulators applied at different times

The effect of gibberellic acid, CCC (2-chloroethyltrimethylammonium chloride) and B 9 (N-dimethylaminosuccinamic acid) was studied on growth of potato plants in pots. Growth was analysed on four occasions and changes in habit defined in terms of internode lengths, leaf areas and growth of lateral branches. Soaking seed pieces for 1 hr. in GA solution caused six internodes to elongate greatly, an effect not prevented by CCC applied when the shoot emerged from the soil. The effects on internode extension were determined by the length of the interval between GA treatment and CCC treatment. Treatment at emergence with CCC shortened all internodes and more CCC applied 4 weeks later had no effect. Late application of CCC or B9 shortened the top two lateral branches, usually very long in untreated plants. The regulators affected leaf growth differently from internode growth: usually growth regulators had less effect on leaf growth. Effects on growth depended on when the regulators were applied. Treatment with GA alone inhibited bud development at higher nodes than in untreated plants; when followed by late treatment with CCC, lateral growth at higher nodes was also less. CCC retarded development of lateral branches especially when applied early. B9 had a similar effect to CCC applied late. When regulators retarded growth of lower laterals, upper laterals often grew more than in untreated plants. Treatments did not affect the number of leaves on the main stem at first but later GA hastened senescence. GA increased the number of leaves on lateral stems, and the effect was enhanced by CCC. CCC alone increased the number of first- and second-order lateral leaves. GA lengthened and CCC shortened stolons. The effect of CCC persisted throughout the life of the plant. CCC or B 9 shortened stolons whenever applied. CCC hastened tuber initiation but slowed tuber growth. CCC at first retarded formation of lateral tubers but had no effect on the ultimate numbers of lateral and terminal tubers. The value of E (net assimilation rate) did not alter with time. CCC applied at emergence increased E, probably because it hastened tuber initiation and temporarily increased sink capacity. Although tubers formed earlier with CCC, their growth was slower and their demand for carbohydrate was also less. The increase in second-order laterals in CCC-treated plants indicates that they utilize carbohydrate that would normally go to tubers. This experiment also demonstrates that crowding leaves by shortening stems did not diminish E, possibly because another over-riding process (bigger sinks) offsets the effect of shading.     

Partial Reversal by Cytokinin and (2-Chloroethyl)-Trimethylammonium Chloride of Near-Ultraviolet Inhibited Growth and Morphogenesis in Callus Cultures

Callus cultures of Haplopappus gracilis, Nicotiana tabacum and Allium cepa var. proliferum were in varying degrees inhibited by blue to near-UV light obtained from fluorescent tubes. The inhibition was considerably reduced for Haplopappus cultures by 6-(3-methyl-2-buten-1-ylamino)-purine (2 iP) and (2-chloro-ethyl)-trimethylammonium chloride (CCC) in combination. Even separately these compounds stimulated growth in blue but not in white light. A high concentration of 2 iP reduced the inhibiting effects of near-UV on tobacco tissue cultures, and a synergism was observed between 2 iP and CCC in respect to shoot formation in blue light. Allium callus was not significantly affected by CCC. It was also observed that the concentration of indol-3-acetic acid (IAA) was more important for the growth of tobacco cultures in blue than in white light. It is believed that the light-inhibition of growth is partly due to a photoinactivation of IAA and that 2 iP and CCC might be active through processes controlling the levels of IAA and other growth hormones.     

Effects of (2 Chloro-Ethyl) Trimethlammonium Chloride on Plant Growth, Leaf Area, and Net Assimilation Rate

Both under glasshouse conditions and in a constant environmentwith light from fluorescent tubes, mustard plants' treatmentwith (2 chloro-ethyl) trimethylammonium chloride (CCC) respondedby an increase in total leaf area. In the glasshouse the increasewas due to the production of more lateral leaves, and in thegrowth chambers to the enlargement of stem leaves, since lateralbranches did not form. Despite the increase in area, the netassimilation rate fell; this may be attributable to an effectof CCC on the photosynthetic mechanism or to an increase inthe mutual shading of leaves, but it is more probable that theinhibition of stem growth also caused by CCC decreases the demandfor photosynthate and leaves photosynthesise less. The leafarea of mustard (a long-day plant) is increased also by short-daytreatment, and here again there is a concomitant shorteningof the stem. Chlorophyll content, both per leaf and per unit area, and totaldry matter per unit area, were increased in tobacco plants grownin culture solutions containing CCC. The treatment affectedthe distribution of nitrogen, increasing the amount per leafand decreasing it per stem.