生长素信号转导途径及参与的生物学功能研究进展

生长素参与植物生长和发育诸多过程,调控众多生理反应,在植物整个生命周期中自始至终发挥着调节作用.研究生长素的作用机制,对深入认识植物生长发育的生理过程有着重要的意义.综述了与生长素信号转导途径相关的3类主要蛋白组分:生长素/吲哚乙酸蛋白(auxin/indoleacetic acids proteins,Aux/IAAs)、生长素响应因子(auxin response factors,ARFs)和SCF(SKP1-CDC53/CUL1-F-box)复合体,及相关的SGT1(suppressor of the G2 allele of skp1)基因,并对生长素相关基因表达的模式及其生物学功能进行了总结.

生长素响应因子与植物的生长发育

生长素响应因子(Auxin response factor,ARF)作为一类调控生长素响应基因表达的转录因子,是生长素研究的重要内容。它可与生长素响应基因启动子区域内的生长素响应元件结合,促进或抑制基因的表达。文章介绍了植物体内ARF家族的分子生物学近年来的研究进展,同时也讨论了ARF转录因子的结构、ARF基因的表达调控、ARF在植物生长发育及信号转导中的作用以及ARF对靶基因的调控机制等内容。植物ARF成员都有一定的同源性,大多含有4个结构域,在多种组织和器官中都有表达,其表达受到转录及转录后调控,并且在介导生长素与其它激素之间相互作用方面扮演重要角色。

植物的生长素结合蛋白

就植物中分离出的多种生长素结合蛋白,及其在植物体内的分布、分子结构和在生长素信号转导中的有关作用的研究进展作了介绍。

生长素代谢、运输及信号转导调控水稻粒型研究进展

水稻(Oryza sativa)是世界主要粮食作物。随着我国经济飞速发展,耕地面积逐年减少,提高水稻总产量唯有依靠单产的增加。粒重是决定水稻产量的重要因素之一,其遗传稳定,受外界环境因素影响较小。粒重由粒型和灌浆程度决定,而粒型性状包括粒长、粒宽、粒厚和长宽比。水稻种子颖壳和胚乳发育决定了粒型和粒重,颖壳细胞的增殖和扩张限制籽粒发育,胚乳占据成熟种子的大部分体积。而生长素调控受精后颖壳和胚乳的发育,是调控种子发育和影响水稻产量的重要植物激素。生长素的时空分布受生长素代谢、运输和信号转导的动态调节,以维持生长素在种子发育中的最适水平。该文综述了生长素代谢、运输和信号转导调控水稻粒型的研究进展,以期为深入探究生长素调控水稻粒型发育机制和提高水稻产量提供线索。

Evidence That the Auxin Signaling Pathway Interacts with Plant Stress Response

Auxin influences a variety of developmental and physiological processes. Early reports, suggested that auxin might affect plant stress response. We have identified a number of auxin responsive genes in Arabidopsis thaliana (L.) Heynh. by using cDNA an-ay and found that stress responsive genes, such as,Arabidopsis homolog of MEK kinase 1 (ATMEKK1), ReL/SpoT homolog 3 ( At-RSH3), Catalase 1 ( Cat1) and Ferritin 1 (Fer1), were down-regulated by auxin, indicating that auxin regulates ale expression of stress responsive genes. We also demonstrated that nitrilase genes, nitrilase I ( NIT]) and nitrilase 2 (NIT2) involving in indole-3-acetic acid (IAA) biosynthesis, were induced by salinity stress, suggesting that the level of IAA might increase in response to salinity stress. To dissect the signal pathway involved in the interaction, two auxin insensitive mutants, auxin resistant 2 (axr2) and auxin resistant 1-3 (axrl-3) were used. Stress responsive genes were induced by salt stress in wild type and axr2, but not in axr1-3. The result suggests that die interaction between auxin and stress responses may be linked in the ubiquitin pathway.

Effect of Acupuncture-moxibustion on the Expression of IGF-1 and SOCS2 in Colonic Mucosa of Rats with Ulcerative Colitis

Objective： To observe the effect of acupuncture-moxibustion on the expression of insulin-like growth factor-I （IGF-I） and suppressor of cytokine signaling-2 （SOCS2） in colonic mucosa of rat models of ulcerative colitis （UC）, and explore the mechanism of acupuncture- moxibustion therapy in treating UC. Methods： The rats were randomized into a normal control （NC） group, a model control （MC） group, an herb-partitioned moxibustion （HPM） group and an electroacupuncture （EA） group, 8 in each group. The rat models of UC were established by immunological methods combined with local stimulation. The rats in the HPM and EA groups were given herb-partitioned moxibustion and electroacupuncture treatments respectively, once every day, lasting for 14 d. The morphological variations of rat＇s colonic mucosa were observed under light microscope; the colonic mucosal mucin was detected by PAS-AB and HID-AB staining methods; the expression of IGF-1 and SOCS2 was assayed by the immunohistochemical method. Results： In the rat models of UC, ulceration and inflammation of the colon were revealed by light microscope. The concentration of colonic mucosal mucin was reduced （P〈0.01）, while the expression of IGF-1 had an increase （P〈0.01）, and the expression of SOCS2 was reduced （P〈0.01）. After HPM or EA treatment, the pathological injuries of colonic mucosa had improved, the concentration of mucin increased （P〈0.01）, the expression of IGF-1 decreased （P〈0.01）, and the expression of SOCS2 increased （P〈0.01）. Conclusion： The secretion of mucosal mucin in rat UC decreased, the expression of IGF-1 was significantly higher, while the expression of SOCS2 was remarkably lower; both HPM and EA can help improve the damage of colonic mucosa in rat UC, and modulate the secretion of mucin, as well as regulate the expression of IGF-1 and SOCS2 in the colonic mucosa.

基于转录组数据发掘三岛柴胡侧根发育的关键基因

目的 发掘生长素信号转导途径中可能参与三岛柴胡Bupleurum. falcatum侧根发育的关键基因。方法 采用Illumina Hiseq2500高通量测序平台对三岛柴胡不同发育阶段的根组织进行转录组测序,筛选差异表达的生长素信号转导基因。通过使用外源生长素(indole-3-acetic acid,IAA)与生长素抑制剂(2,3,5-triiodobenzoic acid,TIBA)处理苗期柴胡,考察生长调节剂对三岛柴胡侧根发育及差异表达基因的影响。结果 在三岛柴胡的苗期根转录组中共鉴定到138个属于生长素信号转导通路中的差异表达基因,其中73个基因在15日龄的三岛柴胡主根(S3)中特异性高表达。相关性分析表明,Bf IAA9/14/16、Bf ARF6/19、Bf GH3.6、Bf LAX3等31个差异基因表达模式高度相关,可能共同参与了三岛柴胡的侧根发育过程。外源激素诱导结果显示,低浓度的IAA和TIBA处理均可显著增加三岛柴胡侧根数目,并促进Bf IAA9/14/16、Bf ARF19等基因的表达。进一步证实了转录组的筛选结果的准确性,其中Bf IAA9/14/16、Bf ARF19可能是正向调控三岛柴胡侧根发育的关键基因。结论 揭示了三岛柴胡根系在不同发育阶段和组织中生长素信号转导通路基因的显著差异表达模式,其中在S3组织中高表达的基因可能与侧根发育密切相关。