为探究生长调节剂对红海榄（Rhizophora stylosa）幼苗生长及营养物质的影响,以红海榄实生苗为试验材料,选择6-BA、NAA、GA₃和IAA 4种生长调节剂,各设置3个浓度,测定不同处理下红海榄幼苗的株高、茎粗、叶片形态、生物量、根系指标及可溶性糖、可溶性蛋白含量。结果表明,与CK相比,各生长调节剂处理总体上提高了红海榄幼苗的株高、茎粗和生物量及根系指标;除NAA 100和150 mg/L处理降低叶长外,其他生长调节剂处理总体上可提高叶片形态指标;各处理的可溶性糖和可溶性蛋白含量均随种植时间波动变化,各生长调节剂处理总体上可提高两种营养物质的含量。4种生长调节剂分别以6-BA 400 mg/L、NAA 50 mg/L、GA₃ 100 mg/L和IAA 150 mg/L效果较佳;其中,GA₃ 100 mg/L处理效果最好。适宜浓度的生长调节剂对红海榄幼苗生长及营养物质含量均有较好的促进效果。

菊花品种万代风光(Chrysanthemum × morifolium ‘Wandai Fengguang’)的色素背景适宜利用分子育种技术调控花瓣铁离子浓度进而培育蓝色花, 且其在夏秋两季均可开花, 是研究菊花开花期分子调控机理的重要材料, 但缺少高效的再生体系和遗传转化体系。以该品种为实验材料, 研究不同外植体类型和植物生长调节剂组合对其再生的影响, 并探讨农杆菌介导的遗传转化方法中相关因素对遗传转化效率的影响。结果表明, 适宜菊花万代风光再生的最适外植体为茎间薄层, 最适培养基为MS+1.5 mg∙L^-1 6-BA+0.6 mg∙L^-1 NAA, 分化率为70.06%, 不定芽生成系数为3.37; 实验确定茎间薄层分化和不定芽生根的卡那霉素选择压分别为7.5 mg∙L^-1和5.0 mg∙L^-1。预培养1天、OD₆₀₀=0.8、处理5分钟及黑暗条件下共培养3天为最佳遗传转化体系。经过卡那霉素筛选共获得抗性苗15株, PCR鉴定发现2株阳性苗, 转化效率为13.33%。研究结果为利用这一独特品种资源解析菊花基因功能和进行定向改良的分子育种奠定了基础, 也为其它菊花品种的再生和转化体系建立提供参考。

【目的】了解木槿扦插生根机制,探索植物生长调节剂萘乙酸(NAA)和吲哚丁酸(IBA)对木槿嫩枝扦插的影响,筛选提高木槿扦插成活的配方,为木槿扦插繁殖提供参考。【方法】以木槿1年生嫩枝为试验材料,采用3种质量浓度(100、300、600 mg/L)的NAA和IBA溶液处理插穗,以清水为对照(CK)进行完全随机区组扦插试验,对插穗解剖结构、生根性状和叶片生理指标进行观测,测定了插穗的生根率(RR)、根鲜质量(RFW)、根系TTC还原强度(RA)、TTC还原总量(TTC_RA)、平均根长(ARL)、根平均直径(RAD)、根表面积(SA)、根体积(RV)、根尖数(RT)、根长密度(RLD)、比根长(SRL)、叶绿素含量(Chl)和净光合速率(P_n)等。【结果】①显微观察发现,木槿不定根原基最先由位于插穗形成层和髓射线结合点处钝圆锥形的薄壁细胞群分裂分化而成,不定根发生后通过皮孔向外伸出;②与CK相比,300 mg/L的IBA处理下,木槿插穗的生根性状和生理指标中RR、RFW、RA、TTC_RA、ARL、RAD、SA、RV、RT和RLD分别增加了554%、527%、58%、892%、198%、50%、282%、457%、126%、198%,而SRL、Chl和P_n分别降低了52%、51%和82%;③相关性分析发现,木槿插穗叶片Chl、P_n与大部分根系指标呈负相关;④通过隶属函数法对各处理生根能力评价可知,IBA处理下插穗生根能力比NAA处理的高,300 mg/L的 IBA处理下生根能力最强。【结论】木槿插穗以皮部生根为主;木槿插穗生根过程中地上部分生长与地下部分生根存在竞争关系,两种植物生长调节剂能够促进木槿插穗地下部分生根,抑制地上部分生理性状;植物生长调节剂具有浓度阈值效应,300 mg/L IBA处理是促进木槿扦插生根最适宜的配方。

为研究不同植物生长调节剂、浓度和处理时间对三叶木通扦插生根效果的影响，以三峡植物园引种的三叶木通为材料，采用正交试验设计，以清水浸泡处理作为对照，设置因素A植物生长调节剂种类[3个水平为IBA、NAA和IBA+NAA(1:1)]、因素B浓度（3个水平为50、150、250 mg/L）和因素C处理时间（3个水平为2、4、6 h）共10个处理，扦插3个月后统计各处理的插穗存活率、生根率、平均根数、平均根长、平均根表面积及平均根体积，采用隶属函数法对插穗生根指标进行综合评价。结果显示，三叶木通为皮部生根型，其中枝节处不定根占不定根总数的26.4%，节间处不定根占不定根总数的73.6%。3个因素对生根效果影响为植物生长调节剂处理时间>种类>浓度。在2、4、6 h 这3种处理时间中，处理4 h的生根效果最佳；在植物生长调节剂IBA、NAA和IBA+NAA(1:1)中，IBA+NAA(1:1)表现最佳；不同植物生长调节剂浓度(50、150、250 mg/L)对生根效果无显著影响。研究发现，10个处理组合中，250 mg/L IBA+ 250 mg/L NAA+ 2 h的平均隶属函数值最高，生根效果最佳。研究旨在为三叶木通良种繁育提供科学依据。

为探究不同种类生长调节剂对赤苍藤（Erythropalum scandens）新梢及分枝生长的促进效果,以1年生赤苍藤幼苗为研究对象,探究不同浓度（20、50、80、110、140和170 mg/L）GA₃和6-BA处理下赤苍藤幼苗地上部分生长的情况。结果表明,两种生长调节剂对赤苍藤幼苗萌芽数、新叶面积、新生及基生枝条数量、藤长增量、地径增量和一级分枝粗度增量影响不显著,对新叶数、新枝长度、枝条长度、节间数和新枝粗度影响极显著。隶属度分析结果表明,110 mg/L GA₃处理下赤苍藤幼苗生长状况最佳;GA₃处理下赤苍藤幼苗生长状况大多优于6-BA处理。GA₃处理下赤苍藤幼苗枝条易产生徒长现象,在生产应用中仍需深入探究。

Ammonium (NH4+) phytotoxicity is a worldwide phenomenon, but the primary toxic mechanisms are still controversial. In the present study, we investigated the physiological function of gibberellins (GAs) in the response of rice plants to NH4+ toxicity and polyamine accumulation using GA biosynthesis-related rice mutants. Exposure to NH4+ significantly decreased GA4 production in shoots of wild-type (WT) plants. Both exogenous GA application to the WT and increases in endogenous GA levels in eui1 mutants rendered them more sensitive to NH4+ toxicity. In contrast, growth of sd1 GA-deficient mutants was more tolerant to NH4+ toxicity than that of their WT counterparts. The role of polyamines in GA-mediated NH4+ toxicity was evaluated using WT rice plants and their GA-related mutants. The eui1 mutants with GA overproduction displayed a higher endogenous putrescine (Put) accumulation than WT plants, leading to an enhanced Put/[spermidine (Spd)+spermine (Spm)] ratio in their shoots. In contrast, mutation of the SD1 gene encoding a defective enzyme in GA biosynthesis resulted in a significant increase in Spd and Spm production, and reduction in the Put/(Spd+Spm) ratio when exposed to a high NH4+ medium. Exogenous application of Put exacerbated symptoms associated with NH4+ toxicity in rice shoots, while the symptoms were alleviated by an inhibitor of Put biosynthesis. These findings highlight the involvement of GAs in NH4+ toxicity, and that GA-induced Put accumulation is responsible for the increased sensitivity to NH4+ toxicity in rice plants.© The Author(s) 2019. Published by Oxford University Press on behalf of the Society for Experimental Biology.

Plants, being sessile, have developed complex signaling and response mechanisms to cope with biotic and abiotic stressors. Recent investigations have revealed the significant contribution of phytohormones in enabling plants to endure unfavorable conditions. Among these phytohormones, jasmonic acid (JA) and its derivatives, collectively referred to as jasmonates (JAs), are of particular importance and are involved in diverse signal transduction pathways to regulate various physiological and molecular processes in plants, thus protecting plants from the lethal impacts of abiotic and biotic stressors. Jasmonic acid has emerged as a central player in plant defense against biotic stress and in alleviating multiple abiotic stressors in plants, such as drought, salinity, vernalization, and heavy metal exposure. Furthermore, as a growth regulator, JA operates in conjunction with other phytohormones through a complex signaling cascade to balance plant growth and development against stresses. Although studies have reported the intricate nature of JA as a biomolecular entity for the mitigation of abiotic stressors, their underlying mechanism and biosynthetic pathways remain poorly understood. Therefore, this review offers an overview of recent progress made in understanding the biosynthesis of JA, elucidates the complexities of its signal transduction pathways, and emphasizes its pivotal role in mitigating abiotic and biotic stressors. Moreover, we also discuss current issues and future research directions for JAs in plant stress responses.

\nGrowing degree day models continue to predict plant growth regulator performance in turfgrass.