外源阿魏酸对离体培养棉纤维生长发育的影响

通过建立新疆陆地棉品种'新陆早36号'的体外胚珠培养棉纤维体系,利用图像数字化处理技术和电镜切片观察,探索体外培养条件下不同浓度外源阿魏酸(FA)对棉纤维生长发育的影响.结果表明:(1)随着培养时间的延长,培养棉胚珠的体积、棉纤维长度、纤维团生长面积和纤维细胞壁厚度均显著增加.(2)FA的影响在培养15 d后达到显著水...     

Jasmonic Acid Inhibits the IAA-Induced Elongation of Oat Coleoptile Segments: a Possible Mechanism Involving the Metabolism of Cell Wall Polysaccharides

The effects of jasmonic acid (JA) on the IAA-induced elongationof segments of etiolated oat (Avena sativa L. cv. Victory) coleoptileswere studied. Exogenously applied JA substantially inhibitedIAA-induced elongation of oat coleoptile segments. The inhibitionof the growth of oat coleoptile segments due to JA appeared2 h after the application of JA with IAA. JA did not affectthe consumption of oxygen by the segments, the osmolarity ofthe cell sap or the IAA-induced loosening of cell walls, whichwas recognized as a decrease in the minimum stress-relaxationtime (T₀). JA was extremely effective in preventing increasesin the amount of the cell wall polysaccharides in both the non-cellulosicfraction and the cellulosic fraction during coleoptile growthin the presence and in the absence of IAA. Inhibition of thegrowth of oat coleoptile segments induced by JA was partiallyreversed by the simultaneous addition of sucrose to the testsolution. From these results, it appears that JA inhibits IAA-inducedelongation of oat coleoptile segments by interfering with someaspects of sugar metabolism that are related to the degradationand/or the synthesis of cell wall polysaccharides. (Received March 15, 1994; Accepted August 2, 1994)     

Laticifer Differentiation in Hevea brasiliensis: Induction by Exogenous Jasmonic Acid and Linolenic Acid

Laticifer differentiation of Hevea brasiliensis was investigatedby application of lanolin containing jasmonic acid (JA) or otherchemicals to the surface of young stems in epicormic shoots.The young stems had primary laticifers and no secondary laticifers.When applied to extending young stems, JA led to a significantincrease in primary laticifer number but did not induce secondarylaticifer differentiation. Secondary laticifer differentiationand a less significant increase in primary laticifer numberwere caused by JA application to the extended young stems. Theinduction of the secondary laticifers was dependent on the concentrationof JA applied. Cambium cell division leading to the formationof secondary phloem was not accelerated by JA treatment. Treatedbark tissues showed no visible changes except for the additionallaticifers, which were normal in ultrastructure. The secondarylaticifers were also induced by the application of linolenicacid, a precursor of JA biosynthesis. Abscisic acid, ethephonand salicylic acid had no detectable effect on laticifer differentiation.Copyright 2000 Annals of Botany Company Hevea brasiliensis, laticifer differentiation, jasmonic acid, linolenic acid, vascular cambium.     

The Regulation of Exogenous Jasmonic Acid on UV-B Stress Tolerance in Wheat

Enhanced ultraviolet-B radiation (UV-B, 280?C320?nm) is recognized as one of the environmental stress factors that cannot be neglected. Jasmonic acid (JA) is an important signaling molecule in a plant??s defense against biotic and abiotic stresses. To determine the role of exogenous JA in the resistance of wheat to stress from UV-B radiation, wheat seedlings were exposed to 0.9?kJ?m^?2?h^?1 UV-B radiation for 12?h after pretreatment with 1 and 2.5?mM JA, and the activity of antioxidant enzymes, the level of malondialdehyde (MDA), the content of UV-B absorbing compounds, photosynthetic pigments, and proline and chlorophyll fluorescence parameters were measured. The results of two-way ANOVA illustrated that the activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), MDA level, anthocyanin and carotenoid (Car) content, and almost all chlorophyll fluorescence parameters were significantly affected by UV-B, JA, and UV-B?×?JA (P?<?0.05) [the maximal efficiency of photosystem II photochemistry (F _v/F _m) was not affected significantly by UV-B radiation]. Duncan??s multiple-range tests demonstrated that UV-B stress induced a significant reduction in plant photosystem II (PSII) function and SOD activity and an increased level of membrane lipid peroxidation, indicative of the deleterious effect of UV-B radiation on wheat. JA pretreatment obviously mitigated the detrimental effect of UV-B on PSII function by increasing F _v/F _m, reaction centers?? excitation energy capture efficiency (F _v??/F _m??), effective photosystem II quantum yield (??PSII), and photosynthetic electron transport rate (ETR), and by decreasing nonphotochemical quenching (NPQ) of wheat seedlings. Moreover, the activity of SOD and the content of proline and anthocyanin were provoked by exogenous JA. However, the MDA level was increased and Car content was decreased by exogenous JA with or without the presence of supplementary UV-B, whereas the contents of chlorophyll and flavonoids and related phenolics were not affected by exogenous JA. Meanwhile, exogenous JA resulted in a decrease of CAT and POD activities under UV-B radiation stress. These results partly confirm the hypothesis that exogenous JA could counteract the negative effects of UV-B stress on wheat seedlings to some extent.     

Synchronous Transcription of Cytoskeleton-Associated Genes is Critical to Cotton Fiber Elongation

Journal of Plant Growth Regulation - Cytoskeleton-associated genes’ expression in the&nbsp;modern cotton fibers has selectively been&nbsp;evolved under domestication. Since...     

The R3-MYB Gene GhCPC Negatively Regulates Cotton Fiber Elongation

Cotton (Gossypium spp.) fibers are single-cell trichomes that arise from the outer epidermal layer of seed coat. Here, we isolated a R3-MYB gene GhCPC, identified by cDNA microarray analysis. The only conserved R3 motif and different expression between TM-1 and fuzzless-lintless mutants suggested that it might be a negative regulator in fiber development. Transgenic evidence showed that GhCPC overexpression not only delayed fiber initiation but also led to significant decreases in fiber length. Interestingly, Yeast two-hybrid analysis revealed an interaction complex, in which GhCPC and GhTTG1/4 separately interacted with GhMYC1. In transgenic plants, Q-PCR analysis showed that GhHOX3 (GL2) and GhRDL1 were significantly down regulated in −1–5 DPA ovules and fibers. In addition, Yeast one-hybrid analysis demonstrated that GhMYC1 could bind to the E-box cis-elements and the promoter of GhHOX3. These results suggested that GhHOX3 (GL2) might be downstream gene of the regulatory complex. Also, overexpression of GhCPC in tobacco led to differential loss of pigmentation. Taken together, the results suggested that GhCPC might negatively regulate cotton fiber initiation and early elongation by a potential CPC-MYC1-TTG1/4 complex. Although the fibers were shorter in transgenic cotton lines than in the wild type, no significant difference was detected in stem or leaf trichomes, even in cotton mutants (five naked seed or fuzzless), suggesting that fiber and trichome development might be regulated by two sets of genes sharing a similar model.     

茉莉酸生物合成的调控及其信号通路

茉莉酸类化合物作为一种细胞信号分子,在植物的生长发育、机械损伤、代谢调节及诱导防御相关基因表达等方面起着重要的作用。本文概述了茉莉酸的生物合成调控以及人们目前对茉莉酸信号通路的认识,并对该研究领域存在的问题及今后可能的研究方向进行展望。     

机械伤害和外施茉莉酸对巴西橡胶树次生乳管分化的局部效应及其与茉莉酸分布的关系

采用同位素示踪技术和实验形态学的方法揭示茉莉酸在木本植物巴西橡胶树(Hevea brasiliensis Mull.Arg.)中的分布和运输的特点,并分析其与机械伤害和外施茉莉酸对巴西橡胶树次生乳管分化的诱导效应之间的关系.外施的茉莉酸进入体内后,在较长时间内大部分集中在施用部位.机械伤害阻止外施的茉莉酸进入体内,同时,又使进入的茉莉酸阻滞在受伤部位的附近.与茉莉酸在草本植物中可以向上和向下运输的情况不同,茉莉酸在木本植物巴西橡胶树中主要是向下运输的.机械伤害和外施茉莉酸对巴西橡胶树次生乳管分化的诱导效应是局部的,只在受伤和施用茉莉酸部位的树皮中诱导次生乳管的形成.机械伤害削弱外源茉莉酸对次生乳管分化的诱导效应,这与机械伤害阻止外源茉莉酸进入有关.研究结果表明,体内高水平的茉莉酸是诱导巴西橡胶树次生乳管分化所必需的.     

机械伤害和外施茉莉酸对巴西橡胶树次生乳管分化的局部效应及其与茉莉酸分布的关系

采用同位素示踪技术和实验形态学的方法揭示茉莉酸在木本植物巴西橡胶树(Hevea brasiliensis Mull．Arg．)中的分布和运输的特点,并分析其与机械伤害和外施茉莉酸对巴西橡胶树次生乳管分化的诱导效应之间的关系。外施的茉莉酸进入体内后,在较长时间内大部分集中在施用部位。机械伤害阻止外施的茉莉酸进入体内,同时,又使进入的茉莉酸阻滞在受伤部位的附近。与茉莉酸在草本植物中可以向上和向下运输的情况不同,茉莉酸在木本植物巴西橡胶树中主要是向下运输的。机械伤害和外施茉莉酸对巴西橡胶树次生乳管分化的诱导效应是局部的,只在受伤和施用茉莉酸部位的树皮中诱导次生乳管的形成。机械伤害削弱外源茉莉酸对次生乳管分化的诱导效应,这与机械伤害阻止外源茉莉酸进入有关。研究结果表明,体内高水平的茉莉酸是诱导巴西橡胶树次生乳管分化所必需的。     

局部灼伤对茉莉酸在蚕豆幼苗中运输和分配的影响

用示踪技术研究了3 H_JA (jasmonicacid)在双子叶植物蚕豆 (ViciafabaL .)中的运输和分配规律以及局部灼伤对其运输与分配的影响。外源3 H_JA能够以高于 4～ 5cm·min-1的速率在蚕豆幼苗体内向上和向下运输。幼叶局部灼伤能提高3 H_JA的向上运输能力 ,促进3 H_JA向受伤部位的调运 ;增加3 H_JA向成熟叶片下表皮的运输分配比率 ;阻止3 H_JA从受伤部位的向外输出。据此推测 ,伤胁迫下JA的运输与分配的改变可能与植物体防御伤反应密切相关 ,并有可能参与了对气孔运动的调控     

局部灼伤对茉莉酸在蚕豆幼苗中运输和分配的影响

用示踪技术研究了3H-JA (jasmonic acid)在双子叶植物蚕豆(Vicia faba L.)中的运输和分配规律以及局部灼伤对其运输与分配的影响.外源3H-JA 能够以高于4～5 cm*min-1的速率在蚕豆幼苗体内向上和向下运输.幼叶局部灼伤能提高3H-JA的向上运输能力,促进3H-JA向受伤部位的调运;增加3H-JA向成熟叶片下表皮的运输分配比率;阻止3H-JA从受伤部位的向外输出.据此推测,伤胁迫下JA的运输与分配的改变可能与植物体防御伤反应密切相关,并有可能参与了对气孔运动的调控.     

Correlation Between Responses of Elongation of Wheat Coleoptile Segments to Abscisic Acid and Exogenous ATP

The time course of elongation and oxygen consumption of wheat coleoptile segments in 38μM ABA solution and 5 × 10-5 M 2,4-DNP solution were investigated. At the same time, effects of exogenous ATP (1 mM) on elongation and ABA response in wheat coleoptile segments were observed. Within the first hour of treatment, ABA and 2,4-DNP rapidly inhibited elongation in the coleoptile segments. Exogenous ATP stimulates elongation in coleoptile segments. When segments pretreated with ATP and then transfered into ABA solution, elongation in coleopfile segments were not inhibited. On the basis of the similarities of action pattern of ABA and 2,4-DNP and marked decrease of ABA inhibiting effect in presence of exogenous ATP, it is testified that uncoupling of respiration and oxidative phosphorylation is one of ABA important effects, so it is suggested that ABA inhibiting elongation of wheat coleoptile segments by decreasing tissue energy (ATP) levels necessary for synthetic reactions, including nucleic acid and protein, and associated with elongation.     

A Cotton Annexin Protein AnxGb6 Regulates Fiber Elongation through Its Interaction with Actin 1

Annexins are assumed to be involved in regulating cotton fiber elongation, but direct evidence remains to be presented. Here we cloned six Annexin genes (AnxGb) abundantly expressed in fiber from sea-island cotton (G. barbadense). qRT-PCR results indicated that all six G. barbadense annexin genes were expressed in elongating cotton fibers, while only the expression of AnxGb6 was cotton fiber-specific. Yeast two hybridization and BiFC analysis revealed that AnxGb6 homodimer interacted with a cotton fiber specific actin GbAct1. Ectopic-expressed AnxGb6 in Arabidopsis enhanced its root elongation without increasing the root cell number. Ectopic AnxGb6 expression resulted in more F-actin accumulation in the basal part of the root cell elongation zone. Analysis of AnxGb6 expression in three cotton genotypes with different fiber length confirmed that AnxGb6 expression was correlated to cotton fiber length, especially fiber elongation rate. Our results demonstrated that AnxGb6 was important for fiber elongation by potentially providing a domain for F-actin organization.     

茉莉酸及其信号传导研究进展

茉莉酸及其衍生物茉莉酸甲酯等统称为茉莉酸盐,是广泛存在于植物中的一种生长调节物质,在植物细胞中起着非常重要的作用.茉莉酸作为信号分子广泛参与调节植物的生长发育和胁迫响应过程.本文主要就茉莉酸的生物合成、茉莉酸的信号传导途径和调控机制、茉莉酸的信号传导途径与乙烯、脱落酸、水杨酸和一氧化氮信号传导途径的相互关系进行了综述.     

棉花143-3L基因的分子鉴定及其在纤维发育中优势表达分析

14-3-3蛋白以二聚体形式存在于所有真核生物中,是一种高度保守的调节蛋白,在细胞生长、增殖、凋亡、信号转导等生命活动中发挥着重要调控作用。我们在棉纤维cDNA文库中分离克隆到1个基因(cDNA),编码14-3-3蛋白类似物,命名为Gh14-3-3L(Gossypiumhirsutum14-3-3-like)。该cDNA长度为1,029bp,包含762bp开放阅读框,其编码蛋白由253个氨基酸组成。Gh14-3-3L与其他真核生物的14-3-3蛋白具有较高的同源性,并具有14-3-3蛋白的基本结构:二聚体结构域、磷酸化丝氨酸富集识别序列、4个CC结构和1个EFHand结构。Northern杂交分析显示Gh14-3-3L在棉纤维发育早期优势表达,且在10DPA棉纤维细胞中表达量最高,这表明Gh14-3-3L基因可能涉及棉纤维细胞伸长过程的调节。研究还表明,该基因在胚珠和花瓣组织中也有较强的表达,但在其他组织中表达较弱或不表达。     

茉莉酸信号转导突变体ber15 的分离和基因克隆表明油菜素内酯的合成影响茉莉酸信号转导

bestatin是一种氨肽酶抑制剂, 能够激活茉莉酸信号转导途径而诱导抗性相关基因的表达, 从而为用化学遗传学手段解析茉莉酸途径提供了一个有效的工具。ber15是我们鉴定到的一个对bestatin不敏感的拟南芥突变体, 随后的研究表明该突变体对外源茉莉酸的敏感性也明显降低, 表明相应的野生型基因BER15在茉莉酸信号转导中起重要作用。图位克隆结果表明BER15编码一个细胞色素P450单加氧酶, 是植物激素油菜素内酯合成途径中的一个关键酶。对BER15基因功能的深入研究将会为了解油菜素内酯的合成与茉莉酸信号途径间的互作关系提供证据。     

茉莉酸信号转导突变体ber15的分离和基因克隆表明油菜素内酯的合成影响茉莉酸信号转导

bestatin是一种氨肽酶抑制剂,能够激活茉莉酸信号转导途径而诱导抗性相关基因的表达,从而为用化学遗传学手段解析茉莉酸途径提供了一个有效的工具。ber15是我们鉴定到的一个对bestatin不敏感的拟南芥突变体,随后的研究表明该突变体对外源茉莉酸的敏感性也明显降低,表明相应的野生型基因BER15在茉莉酸信号转导中起重要作用。图位克隆结果表明BER15编码一个细胞色素P450单加氧酶,是植物激素油菜素内酯合成途径中的一个关键酶。对BER15基因功能的深入研究将会为了解油菜素内酯的合成与茉莉酸信号途径间的互作关系提供证据。     

Potential Role of Abscisic Acid in Cotton Fiber and Ovule Development

Fibers and ovules of a cotton cultivar (Gossypium hirsutum L. Trambak-108) were analyzed for growth and free abscisic acid (ABA) content by indirect enzyme immunoassay. An inverse correlation between fiber elongation and ABA content was observed. In the seed, accumulation of ABA was observed during secondary thickening and the maturation phase. The potential role of ABA in fiber and seed development is discussed. Received June 25, 1997; accepted October 15, 1997