In response to insect attack,plants use intricate signaling pathways,including phytohormones,such as jasmonate(JA),ethylene(ET),and salicylic acid(SA),to activate defenses.Maize(Zea mays)is one of the most important staple food crops around the world.Previous studies have shown that the JA and ET signaling play important roles in maize defense against insects,but little is known about whether and how SA regulates maize resistance to insect herbivores.In this study,we ectopically expressed the NahG(salicylate hydroxylase)gene in maize plants(NahG maize)to block the accumulation of SA.It was found that compared with the wild-type(WT)maize,the NahG maize exhibited decreased resistance to the generalist insects Spodoptera litura and Spodoptera frugiperda and the specialist Mythimna separata,and the compromised resistance in the NahG maize was associated with decreased levels of defensive me-tabolites benzoxazinoids(Bxs)and chlorogenic acid(CA).Quantification of simulated S.litura feeding-induced JA,JA-isoleucine conjugate(JA-Ile),and ET in the WT and NahG maize indicated that SA does not regulate JA or JA-Ile,but positively controls ET.We provide evidence suggesting that the SA pathway does not crosstalk with the JA or the ET signaling in regulating the accumulation of Bxs and CA.Tran-scriptome analysis revealed that the bHLH,ERF,and WRKY transcription factors might be involved in SA-regulated defenses.This study uncovers a novel and important phytohormone pathway in maize defense against lepidopterous larvae.

植物在生长发育过程中面临各种非生物胁迫.其中干旱胁迫严重影响作物生长,降低其产量.植物中以TB2/DP1结构域为特征的HVA22蛋白参与调控生长发育和非生物胁迫响应.然而,HVA22在番茄(Solanum lycopersicum)干旱胁迫响应中的功能尚不清楚.该研究探索了番茄SIHVA22/基因的功能.结果表明,番茄SIHVA22I与其它双子叶植物中的HVA22I同源蛋白具有较高的序列相似性.表达模式分析显示,SIHVA22/基因表达受干旱胁迫和植物激素(ABA和MeJA)诱导.此外,通过酵母(Saccharomyces cerevisiae)异源表达和病毒诱导基因沉默技术沉默番茄SIHVA22/基因,验证了SIHVA22/基因的抗旱功能.干旱处理后沉默植株表现出较高的过氧化氢(H2O2)和丙二醛(MDA)含量,以及较低的O2-·清除率,且其超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)和抗坏血酸过氧化物酶(APX)的活性较对照显著降低.综上表明,S/HVA22/基因在番茄抵御干旱胁迫中发挥重要作用.

目的 研究生长素(IAA)、细胞分裂素(6-BA)、赤霉素(GA3)、脱落酸(ABA)和乙烯(ET)5种植物激素对白花前胡种子萌发的影响.方法 以宁国产并在室温放置12个月的白花前胡种子为材料,把5种不同的植物激素均配制成4个梯度浓度(1×10-1、1×10-2、1×10-3、1×10-4mg·mL-1),对白花前胡种子进行浸种处理.通过培养皿萌发试验,分析种子的发芽率、根长和鲜重的变化情况.结果 在4个梯度范围内,6-BA对白花前胡种子的生长状态整体起抑制作用.把1 × 10-1 mg·mL-1和1 × 10-2 mg·mL-1设置为高浓度,1 × 10-3 mg·mL-1和1× 10-4 mg·mL-1设置为低浓度.其中6-BA无论是高浓度还是低浓度均对白花前胡种子的生长状态整体起抑制作用.而GA3和ET在高浓度(1 × 10-1 mg·mL-1 和 1 × 10-2 mg·mL-1)及 ABA 和 IAA 在低浓度(1 × 10-3 mg·mL-1和1 ×10-4mg·mL-1)下均对白花前胡种子的萌发率、根长和鲜重都表达出明显的促进作用.结论 植物激素对白花前胡种子的生长发育均有不同程度的影响,其中ET在1 ×10-2 mg·mL-1时,对白花前胡种子的生长发育影响最为显著,白花前胡种子的萌发率,最大根长和最大鲜重均高于其他组.

Phytohormones modulate nearly all aspects of plant biology.Phytohormone signaling and biosynthesis pathways have been characterized mainly through studies of angiosperms,particu-larly the model plant Arabidopsis thaliana(Blázquez et al.,2020).Phylogenetic analyses across plants provide insights into the origins and evolution of phytohormone signaling pathways(Wang et al.,2015).However,these studies come with one caveat:homology at the level of sequences does not necessarily demonstrate functional conservation.Due to the lack of functional verification,much remains obscure and contentious about the origins of phytohormone signaling and biosynthesis pathways.In a recent study,Jia et al.(2023)employed a combined approach of phylogenetic analysis and functional characterization to explore the origin and evolution of the signaling and biosynthesis pathways of salicylic acid(SA),a crucial plant defense hormone.

Phytohormones integrate external environmental and developmental signals with internal cellular re-sponses for plant survival and multiplication in changing surroundings.Jasmonate(JA),which might orig-inate from prokaryotes and benefit plant terrestrial adaptation,is a vital phytohormone that regulates diverse developmental processes and defense responses against various environmental stresses.In this review,we first provide an overview of ligand-receptor binding techniques used for the characterization of phytohormone-receptor interactions,then introduce the identification of the receptor COI1 and active JA molecules,and finally summarize recent advances on the regulation of JA perception and its evolution.

Seed dormancy is nature's strategic pause in the plant life cycle,a purposeful interlude during which a seed,poised on the cusp of potential growth,bides its time in a state of quiescence.This period of dormancy is a crucial adaptation,allowing the seed to withstand unfavorable environmental conditions and syn-chronize germination with optimal circumstances for growth and survival(Née et al.,2017).Dormancy is orchestrated by a complex interplay of genetic,physiological,and environmental factors,including phytohormones like abscisic acid and gibberellins(GAs),as well as specific regulators like DELAY OF GERMINATION1 and others(Née et al.,2017;Liu et al.,2020).

Phosphorus is an essential macronutrient for plant development and metabolism,and plants have evolved ingenious mechanisms to overcome phosphate(Pi)starvation.However,the molecular mechanisms underlying the regulation of shoot and root architecture by low phosphorus conditions and the coordinated utilization of Pi and nitrogen remain largely unclear.Here,we show that Nodulation Signaling Pathway 1(NSP1)and NSP2 regulate rice tiller number by promoting the biosynthesis of strigolactones(SLs),a class of phytohormones with fundamental effects on plant architecture and environmental responses.We found that NSP1 and NSP2 are induced by Oryza sativa PHOSPHATE STARVATION RESPONSE2(OsPHR2)in response to low-Pi stress and form a complex to directly bind the promoters of SL biosynthesis genes,thus markedly increasing SL biosynthesis in rice.Inter-estingly,the NSP1/2-SL signaling module represses the expression of CROWN ROOTLESS 1(CRL1),a newly identified early SL-responsive gene in roots,to restrain lateral root density under Pi deficiency.We also demonstrated that GR244DO treatment under normal conditions inhibits the expression of OsNRTs and OsAMTs to suppress nitrogen absorption but enhances the expression of OsPTs to promote Pi absorption,thus facilitating the balance between nitrogen and phosphorus uptake in rice.Importantly,we found that NSP1p:NSP1 and NSP2p:NSP2 transgenic plants show improved agronomic traits and grain yield under low-and medium-phosphorus conditions.Taken together,these results re-vealed a novel regulatory mechanism of SL biosynthesis and signaling in response to Pi starvation,providing genetic resources for improving plant architecture and nutrient-use efficiency in low-Pi environments.

巴西橡胶树(Hevea brasiliensis)是重要热带经济作物之一,其次生代谢产物天然橡胶(NR)是中国重要的工业原料及战略物资.植物激素对植物生长发育、萌发和环境应答等多方面均具有重要调控作用.本文详细介绍了乙烯、脱落酸、油菜素内酯和赤霉素4种植物激素在橡胶树生长发育、橡胶生物合成、产排胶和品质形成等关键环节中应用的研究进展,并展望4种激素在提高橡胶树产排胶机制研究中的应用前景,为支撑橡胶产业发展提供理论支撑.

水稻穗发芽是指水稻在收获前如遇连续阴雨天气或高温潮湿环境条件,往往诱导籽粒在穗上发芽的现象.穗发芽导致水稻种子活力和品质下降,给水稻生产带来巨大损失.对于水稻抗穗发芽育种,除了扩大对穗发芽突变体的筛选外,挖掘和克隆一些控制穗发芽的新基因并解析其穗发芽调控机制,是水稻抗穗发芽育种的重要工作.穗发芽过程中,水稻的淀粉酶活性增强、可溶性糖含量升高,且水稻籽粒中植物激素 ABA 和 GA 的含量及二者的平衡是决定穗发芽的关键.OsVP1等一些关键基因通过ABA信号通路控制水稻种子休眠,GA则可通过激活GA相关转录因子等调控种子萌发.本文从水稻穗发芽的内部生理因素及环境条件、水稻穗发芽的遗传机制、水稻穗发芽的分子机制和水稻穗发芽的性状改良这四方面进行综述,以期阐述穗发芽的整体调控机制,为水稻抗穗发芽品种的选育提供理论参考.

Exploitation of new gene resources and genetic networks contributing to the control of crop yield-related traits,such as plant height,grain size,and shape,may enable us to breed modern high-yielding wheat varieties through molecular methods.In this study,via ethylmethanesulfonate mutagenesis,we identify a wheat mutant plant,mu-597,that shows semi-dwarf plant architecture and round grain shape.Through bulked segregant RNA-seq and map-based cloning,the causal gene for the semi-dwarf phenotype of mu-597 is located.We find that a single-base mutation in the coding region of TaACTIN7-D(TaACT7-D),leading to a Gly-to-Ser(G65S)amino acid mutation at the 65th residue of the deduced TaACT7-D protein,can explain the semi-dwarfism and round grain shape of mu-597.Further evidence shows that the G65S mutation in TaACT7-D hinders the polymerization of actin from monomeric(G-actin)to filamentous(F-actin)status while attenuates wheat responses to multiple phytohormones,including brassinosteroids,auxin,and gibberellin.Together,these findings not only define a new semi-dwarfing gene resource that can be potentially used to design plant height and grain shape of bread wheat but also establish a direct link between actin structure modulation and phytohormone signal transduction.