Comparative Efficacy of Abscisic Acid and Methyl Jasmonate for Indirect Somatic Embryogenesis in Medicago sativa L.

The effects of methyl jasmonate (MeJA) in relation to abscisic acid (ABA) on different phases of somatic embryogenesis were studied in Medicago sativa L. Different concentrations of both the growth inhibitors (0.0, 0.5, 5.0, 50.0 and 500.0 μM) were tested in five distinct phases of somatic embryogenesis, viz., induction, proliferation, differentiation, maturation and regeneration. Like ABA, MeJA also inhibited callus induction, callus growth, proliferation of embryogenic suspension as well as germination and conversion of somatic embryos. However, its inhibitory effects on various phases of somatic embryogenesis were less pronounced as compared to that due to ABA. In contrast to ABA, MeJA did not have any significant influence on the development of somatic embryos when applied in the differentiation phase. The study showed that ABA used routinely as an inducer of somatic embryo maturation in M. sativa could not be replaced by MeJA.     

The Effect of Abscisic Acid and Methyl Jasmonate on Carbonic Anhydrase Activity in Pea

Short-term (2 h) treatment with 10 μM abscisic acid decreased stomatal conductance and net photosynthetic rate, and increased carbonic anhydrase activity in pea seedlings. The treatment with 10 μM methyl jasmonate did not significantly affect these parameters. This revised version was published online in June 2006 with corrections to the Cover Date.     

The Effect of Abscisic Acid and Methyl Jasmonate on Carbonic Anhydrase Activity in Pea

Short-term (2 h) treatment with 10 µM abscisic acid decreased stomatal conductance and net photosynthetic rate, and increased carbonic anhydrase activity in pea seedlings. The treatment with 10 µM methyl jasmonate did not significantly affect these parameters.     

Inter-organ Control of Greening in Etiolated Cucumber Cotyledons

Inter-organ control of greening in etiolated cucumber (Cucumis sativus L. cv. Aonagajibae) cotyledons was investigated. Four- or six-day-old excised or intact etiolated cucumber cotyledons were illuminated under aerobic conditions. Excised cotyledons without hypocotyl hooks produced chlorophyll without a prolonged lag phase and the rate of chlorophyll formation was not depressed if they were illuminated immediately after excision. If the excised cotyledons were incubated in the dark before illumination, chlorophyll accumulation at the end of 6 h of continuous illumination was remarkably lowered as the dark period lengthened, especially in 6-day-old cotyledons. The rapid loss of chlorophyll-forming capacity of excised cotyledons during dark preincubation suggests a stimulatory effect of hypocotyls on the greening in cotyledons. The treatment of excised cotyledons with bleeding sap in the dark for 18 h resulted in the promotion of chlorophyll formation during subsequent continuous illumination. Partial fractionation of bleeding sap with organic solvents and paper chromatography indicates that the active substances showed the same behavior as cytokinins. These facts add weight to the hypothesis that cytokinins from roots flow into cotyledons and stimulate greening.     

Effects of Cytokinin and Light on Polyamines during the Greening Response of Cucumber Cotyledons

The cucumber cotyledon greening test was used as a model systemto study possible relationships between cytokinins and polyaminesduring the greening process. When cytokinin was applied to dark-growncotyledons, large increases in chlorophyll and putrescine levelswere observed. However, inhibition of putrescine biosynthesiswith D-arginine and difluoromethylarginine did not affect chlorophyllproduction, and applied polyamines proved inhibitory to greening.Addition of 50 mM K^$ to the cytokinin treatments increased chlorophyllsynthesis but caused a marked reduction in putrescine levels.These results indicate that the large increase in putrescinecontent that derives from cytokinin treatment of the cotyledonsis not essential for the cytokinin-induced greening response. ¹Present address: Crop Science Department, University of Guelph,Guelph, Ontario, Canada, NIG 2W1.²Present address: Agrogen Biotechnologies Inc., 520W. 6th Ave.,Vancouver, B.C., Canada, V5Z 4H5. (Received June 29, 1987; Accepted October 9, 1987)     

专一识别脱落酸甲酯的单克隆抗体的制备与应用

专一识别２－顺（Ｓ）ＡＢＡ甲酯的单克隆抗体来源于以ＡＢＡ分子中的１－ＣＯＯＨ为偶联位点合成的免疫原。它与游离态ＡＢＡ和结合态ＡＢＡ葡萄糖酯的交叉反应仅分别为１％与３．５％,而与ＡＢＡ类似物,如２－顺－黄质醛、紫黄质以及ＡＢＡ的２－反式异构体和（Ｒ）－对映体则无交叉反应。利用该抗体建立的高度灵敏和精确的ＡＢＡｍｅ酶联免疫测定法,其检测线性范围为０．０４８～１．５２ｐｍｏｌ。通过ＡＢＡｍｅＥＬＩＳＡ和ＧＡ１＋３ＥＬＩＳＡ分析可知羊蹄叶片衰老与内源ＧＡ１＋３／ＡＢＡ比值的下降有关。     

脱落酸的发酵法生产及应用

脱落酸是重要的植物激素之一,可以增强作物对环境逆因子如干旱、寒冷等的抵抗能力,在抵抗农业自然灾害、植树造林、生态植被建设、城市园林绿化等领域有广阔的应用前景.施用脱落酸可减少化学农药的使用,保护自然环境.本文概述了脱落酸生产和应用方面的研究进展,包括产生菌的筛选、诱变、外施脱落酸在提高作物抗逆性上的应用,以及脱落酸抗肿...     

Formation of Chlorophyll-Protein Complexes in Greening Cucumber Cotyledons in Light and then in Darkness

The changes in chlorophyll-protein complexes (CPs) in cucumbercotyledons during illumination and subsequent dark incubationwere studied by SDS-polyacrylamide gel electrophoresis. Whenetiolated cucumber seedlings were illuminated, chlorophyll wassynthesized and CPs were formed. In the early phase of greening(6 h of illumination), light-harvesting chlorophyll a/b-proteincomplex (LHCP) was the main GP. As the greening proceeded, P700chlorophyll a-protein complex (CP1) accumulated. When 6-h illuminatedseedlings were transferred to darkness, CP1 accumulated concomitantlywith a decrease in LHCP without new chlorophyll synthesis. Thechanges in the amounts of CPs in the dark became smaller withthe progress of greening and were not observed after 72 h ofillumination. These changes were confirmed by examining thechlorophyll/P700 ratio and the low temperature absorption spectrumof cotyledons. These results suggest that in the early phaseof greening, CPs were unstable and their chlorophyll moleculeseasily exchanged with those of other kinds of CPs. (Received October 14, 1982; Accepted December 1, 1982)     

茉莉酸甲酯和脱落酸对绿豆下胚轴质膜H+-ATPase水解活性的影响

茉莉酸甲酯(MeJA)促进绿豆下胚轴质膜H+-ATPase水解活性.活体条件下,50μmol·L-1 MeJA处理7 h的酶活性提高30%;离体条件下,10 μmol·L-1 MeJA处理2 h的酶活性最大,即提高30%.壳梭孢素(FC)和MeJA在离体条件下对H+-ATPase活性的促进效应相同,均提高30%左右,无协同效应;活体条件下,FC促进质膜H+-ATPase水解活性可达70%,而MeJA仅为30%.离体条件下,脱落酸(ABA)对H+-ATPase水解活性无明显促进;而活体条件下则有一定的抑制.     

Jasmonic Acid and Methyl Jasmonate in Pollens and Anthers of Three Camellia Species

Jasmonic acid (JA), which showed a nontoxic inhibitory effecton pollen germination in Camellia sinensis, was identified inpollens and anthers of C. sinensis, C. japonica and C. sasanquatogether with its methyl ester (JA-Me); the possibility thatJA is an endogenous pollen germination regulator is suggested.As JA-Me showed no effect on pollen germination, it may be formof JA inactive in pollen germination regulation. (Received April 15, 1982; Accepted June 15, 1982)     

Amelioration of Chilling Injuries in Cucumber Seedlings by Abscisic Acid

Exposure of cucumber seedlings (Cucumis sativus L.) to chilling temperature resulted in injuries such as increased leakage of cellular materials, loss of water and wilting. In addition, the development of the seedlings after the exposure to chilling was impaired. Abscisic acid applied to the seedlings prior to chilling significantly ameliorated these injuries.     

Identification of Putative Artemisia annua ABCG Transporter Unigenes Related to Artemisinin Yield Following Expression Analysis in Different Plant Tissues and in Response to Methyl Jasmonate and Abscisic Acid Treatments

Artemisinin has attracted interest due to its medicinal value in treating malaria and its potential for use against certain cancers and viral diseases. Trichome density and capacity determine artemisinin content in Artemisia annua plants. Thus, the ATP-binding cassette transporter G (ABCG) subfamily involved in trichome cuticle development may also influence artemisinin accumulation. In this study, putative A. annua ABC transporter unigenes were identified and classified from the unigene sequences up to date in the National Center for Biotechnology Information database, and nine putative A. annua ABCG transporter unigenes that may be involved in cuticle development were selected for expression analyses. Two of them, AaABCG6 and AaABCG7, showed parallel expression pattern as two artemisinin biosynthesis-specific genes (amorpha-4, 11-diene synthase and a cytochrome P450-dependent hydroxylase, CYP71AV1) in different tissues and different leaf development stages and also showed similar induction in the plants after methyl jasmonate or abscisic acid treatments. Identification of these putative A. annua ABCG transporter unigenes could provide the basis for cloning of the full-length genes and further functional investigation to find the artemisinin relevant transporters, which could be used for improving artemisinin yield in both A. annua plants and heterologous systems using transgenic technology.     

荣莉酸甲酯对丹参培养细胞中迷迭香酸生物合成及相关酶活性的影响

茉莉酸甲酯是植物细胞响应外界刺激产生的重要信号分子,与植物次生代谢物的生物合成有关。本研究考察了茉莉酸甲酯（methyl jasmonate,MeJA）对丹参培养细胞中迷迭香酸（rosmarinic acid,RA）生物合成的影响。结果显示,诱导24h后可显著提高丹参愈伤细胞中RA的积累量及其相关酶（PAL、TAT）的活性,在48h时RA积累量和酶活性达到最大。布洛芬（IBu）处理可抑制MeJA对RA积累量和相关酶活性的促进作用,外源施加MeJA可部分解除IBU对RA合成及其相关酶活性的抑制作用。说明MeJA可以显著促进丹参培养细胞中RA的生物合成,IBU抑制了MeJA合成、PAL和TAT活性,从而导致了RA合成受阻。     

Mechanism of Benzyladenine-Induced Stimulation of the Synthesis of 5-Aminolevulinic Acid in Greening Cucumber Cotyledons: Benzyladenine Increases Levels of Plastid tRNAGlu

The mechanism of the stimulatory effect of a cytokinin, namely,benzyladenine (BA), on the synthesis of 5-aminolevulinic acid(ALA) in cucumber cotyledons was studied. The rate of synthesisof ALA by plastids isolated from BA-treated cotyledons was twicethat by plastids from untreated controls. Western blot analysisof stromal proteins showed that BA did not affect the levelof glutamyl-tRNA synthetase or of glutamate l-semialdehyde (GSA)aminotransferase. Analysis of free amino acids revealed thatBA did not increase the level of glutamate in the stroma. However,the amount of total plastidic RNA was doubled in BA-treatedcotyledons. Northern blot analysis showed that the level ofplastid tRNA^Glu was increased by treatment with BA to the sameextent as that of another plastid tRNA, reflecting an increasein total plastidic RNA. The rate of formation of glutamyl-tRNAwas also doubled in plastids from BA-treated cotyledons. Theresults indicate that stimulation of the synthesis of ALA byBA is due to an increased level of tRNA^Glu in plastids. (Received June 6, 1993; Accepted November 26, 1993)     

茉莉酸及其甲酯与植物诱导抗病性

介绍了茉莉酸 (JA)及其甲酯 (MeJA)在植物抗病中的作用及其诱导植物抗病的机制 ,并概述了目前这一领域需要进一步研究解决的若干问题     

Effects of Benzylaminopurine and Abscisic Acid on Distribution of rRNA in the Palisade Cells of Excised Cucurbita Pepo Cotyledons

rRNA was labelled with RNase-gold complexes applied to ultrathin Lowicryl sections of excised Cucurbita pepo L. (zucchini) cotyledons grown in darkness. Benzylaminopurine-caused stimulation of cotyledon growth decreases the density of ribosomes in palisade cells despite stimulating rRNA synthesis. Abscisic acid inhibits RNA synthesis and transport, but does not visibly affect the number of pre-existing ribosomes in retarded growth cells. The amount of rRNA in the cells of 24 h treated cotyledons is rather consequence of the growth rate than its leading factor.     

茉莉酸甲酯和水杨酸对丹参幼苗中蔗糖代谢和酚酸类物质积累的影响

以丹参幼苗为材料,研究了茉莉酸甲酯(MeJA)和水杨酸(SA)对其地上地下部分蔗糖代谢和根系中酚酸类物质积累的影响.结果显示:(1)外源施用MeJA能够显著增强幼苗叶片和根中酸性蔗糖转化酶活性,促进蔗糖降解,减少根系中蔗糖含量;同时根中丹参素(来源于酪氨酸-衍生物支路)、原儿茶酸(类苯丙烷支路的中间产物)、咖啡酸(来源于类苯丙烷支路)、迷迭香酸(来源于类苯丙烷支路和酪氨酸-衍生物支路)、丹酚酸B(丹参素、咖啡酸、迷迭香酸的衍生物)以及总酚酸含量均显著增加.(2)外施SA可显著降低幼苗叶片和根中酸性蔗糖转化酶活性及叶片中性蔗糖转化酶活性,抑制蔗糖降解,显著增加地上部分蔗糖含量,根中蔗糖含量和对照相比差异不显著;同时根中丹参素含量减少,但原儿茶酸、咖啡酸以及迷迭香酸含量增加,丹酚酸B和总酚酸类物质含量与对照相比差异不显著.因此推测,植物中蔗糖代谢影响丹参素合成的酪氨酸-衍生物支路,而不影响原儿茶酸、咖啡酸及迷迭香酸等合成的类苯丙烷支路.     

Functional aspects of Abscisic Acid Metabolism in Cotyledons of Phaseolus vulgaris L. Seedlings

During the early stages of germination and vegetative development,cotyledons of intact bean (Phaseolus vulgaris L.) seedlingsshowed active ABA catabolism causing a low endogenous ABA content.At the end of the substrate mobilizing phase, when the cotyledonsbecame senescent, a drastic increase of the endogenous ABA contentlinked with a decrease of the ABA catabolic activity was observed.This indicates that a close connection exists between senescenceand endogenous ABA content and metabolism in bean cotyledons. Removal of the apical growth region induced in the cotyledonsactivation of the ABA catabolism and the endogenous ABA concentrationdecreased below the detection limit (0.1 ng/g fr wt) at theonset of the outgrowth of the axillary buds. From then, apicaldominance was restored and the cotyledons returned to the senescentstate, which was correlated with a drastic increase of theirendogenous ABA content. ¹ Bevoegd verklaard navorser N. F. W. O.² Wetenschappelijk medewerker F. K. F. O. (Received November 25, 1980; Accepted February 13, 1981)     

Chloroplast Biogenesis: XX. Accumulation of Porphyrin and Phorbin Pigments in Cucumber Cotyledons during Photoperiodic Greening

A study of greening in cucumber (Cucumis sativus L.) cotyledons grown under a light (14-hour) dark (10-hour) photoperiodic regime was undertaken. The pools of protoporphyrin IX, Mg-protoporphyrin IX monoester, protochlorophyllide, and protochlorophyllide ester were determined spectrofluorometrically. Chlorophyll a and b were monitored spectrophotometrically. Pigments were extracted during the 3rd hour of each light period and at the end of each subsequent dark period during the first seven growth cycles. Protoporphyrin IX did not accumulate during greening. Mg-protoporphyrin IX monoester and longer wavelength metalloporphyrins accumulated during the light cycles and disappeared in the dark. Their disappearance was accompanied by the accumulation of protochlorophyll. Higher levels of protochlorophyll were observed in the dark than in the light, and the greatest accumulation occurred during the third and fourth dark cycles. Protochlorophyllide was present in 3- to 10-fold excess over protochlorophyllide ester; it was detectable during the period of net chlorophyll accumulation as well as afterward. In contrast, protochlorophyllide ester was observable only during the first four photoperiodic cycles, suggesting that it was a metabolic intermediate only during the early stages of chlorophyll accumulation. Between the third and fourth growth cycles, a rapid increase in area and fresh weight per cotyledon began. This was accompanied by a 250-fold increase in the level of chlorophyll a + b during the three subsequent growth cycles. No lag period in the accumulation of chlorophyll b was observed, and at all stages of greening, the chlorophyll a/b ratio was approximately 3.