Ca^(2+)-homeostasis Differs Between Plant Species with Different Cold-tolerance at 4 ℃ Chilling

A comparative study was carried out on the EM_cytochemical localization of calcium and Ca 2+ _ATPase activity in the suspension_cultured cells between the chilling_sensitive maize ( Zea mays L. cv. Black Mexican Sweet) and chilling_insensitive Trititrigia ( Triticum sect. Trititrigia mackey) at 4 ℃ chilling. When maize and Tyititrigia cells were cultured at 26 ℃, electron microscopic observations revealed that the electron_dense calcium antimonate deposits, an indication of the calcium localization, were localized mainly in the vacuoles, and few was found in the cytosol and nuclei. The electron_dense cerium phosphate deposits, an indication of Ca 2+ _ATPase activity, were abundantly distributed on the plasma membrane (PM). When the cells from both species were cultured at 4 ℃ for 1 and 3 h, an elevation of Ca 2+ level in the cytosol and nuclei was observed, whereas the cerium phosphate deposits on the PM showed no quantitative difference from those of the 26 ℃_cultured cells, indicating that the enzymatic activities were not altered during these chilling periods. However, there was a distinct difference in the dynamics of the Ca 2+ distribution and the PM Ca 2+ _ATPase activity between maize and Trititrigia when chilled at 4 ℃ for 12, 24 and 72 h. In maize cells, a large number of Ca 2+ deposits still existed in the cytosol and nuclei, and the PM Ca 2+ _ATPase became less and less active, and even inactive at all. In Trititrigia cells, the increased cytosolic and nuclear Ca 2+ ions decreased after 12 h chilling. By chilling up to 24 and 72 h, the intracellular Ca 2+ concentration had been restored to a similar low level as those of the warm temperature_cultured cells, while the activity of the PM Ca 2+ _ATPase maintained high. The transient cytosolic and nuclear Ca 2+ increase and the activities of PM Ca 2+ _ATPase during chilling are discussed in relation to plant cold hardiness.

小麦幼叶组织中胞间连丝的多样性(英文)

胞间连丝是植物细胞间物质运输和信息传递的直接通道,对植物的生长与发育,以及植物对环境的反应与适应等诸多方面起着十分重要的作用,是当今细胞生物学中最活跃的研究领域之一。本研究揭示,在小麦幼叶组织细胞壁中存在着胞间连丝的多样性,其中至少有4种类型:(1)具有压缩内质网(ER,中央桥管)的直形通道的胞间连丝;(2)"颈型"胞间连丝,即包含ER的胞间连丝的两端发生收缩,显示一种"颈"现象,甚至在中段形成一种"腹部"现象;(3)分枝型的胞间连丝,包含压缩ER;(4)令人感兴趣的是观察到一种不具中央桥管(不含ER),仅为质膜包围的简单的胞间连丝。这一观察证实,包含ER的胞间连丝不是高等植物的唯一结构类型。这种不具ER的简单胞间连丝对于大分子物质的运输,特别是原生质、染色质及细胞核的胞间迁移,可能是一种更有效的通道。

Wheat breeding for Hessian fly resistance at ICARDA

Hessian fly(HF),Mayetiola destructor(Say)is an important pest of wheat in North Africa,North America,Southern Europe,Northern Kazakhstan,Northwestern China,and New Zealand.It can cause up to 30%yield losses and sometimes can result in complete crop failure if infestation coincides with young stage of the wheat crop.Studies to-date have shown the availability of genetic diversity in the wheat genetic resources(landraces,wild relatives,cultivars,etc.)for resistance to Hessian fly.About 37 resistance genes have been reported from these wheat genetic resources for resistance to Hessian fly,of which,some have been deployed singly or in combination in the breeding programs to develop high yielding varieties with resistance to HF.Deployment of resistant varieties in different agro-ecologies with other integrated management measures plays key role for the control of HF.This paper summarizes the importance,life cycle,mechanisms of resistance,gene mining,and wheat breeding efforts for HF resistance.

Uncovering genetic and metabolite markers associated with resistance against anthracnose fruit rot in northern highbush blueberry

Anthracnose fruit rot(AFR),caused by the fungal pathogen Colletotrichum fioriniae,is among the most destructive and widespread fruit disease of blueberry,impacting both yield and overall fruit quality.Blueberry cultivars have highly variable resistance against AFR.To date,this pathogen is largely controlled by applying various fungicides;thus,a more cost-effective and environmentally conscious solution for AFR is needed.Here we report three quantitative trait loci associated with AFR resistance in northern highbush blueberry(Vaccinium corymbosum).Candidate genes within these genomic regions are associated with the biosynthesis of flavonoids(e.g.anthocyanins)and resistance against pathogens.Furthermore,we examined gene expression changes in fruits following inoculation with Colletotrichum in a resistant cultivar,which revealed an enrichment of significantly differentially expressed genes associated with certain specialized metabolic pathways(e.g.flavonol biosynthesis)and pathogen resistance.Using non-targeted metabolite profiling,we identified a flavonol glycoside with properties consistent with a quercetin rhamnoside as a compound exhibiting significant abundance differences among the most resistant and susceptible individuals from the genetic mapping population.Further analysis revealed that this compound exhibits significant abundance differences among the most resistant and susceptible individuals when analyzed as two groups.However,individuals within each group displayed considerable overlapping variation in this compound,suggesting that its abundance may only be partially associated with resistance against C.fioriniae.These findings should serve as a powerful resource that will enable breeding programs to more easily develop new cultivars with superior resistance to AFR and as the basis of future research studies.

Anchorene,a carotenoid-derived growth regulator,modulates auxin homeostasis by suppressing GH3-mediated auxin conjugation

Anchorene,identified as an endogenous bioactive carotenoid-derived dialdehyde and diapocarotenoid,affects root development by modulating auxin homeostasis.However,the precise interaction between anchorene and auxin,as well as the mechanisms by which anchorene modulates auxin levels,remain largely elusive.In this study,we conducted a comparative analysis of anchorene's bioactivities alongside auxin and observed that anchorene induces multifaceted auxin-like effects.Through genetic and pharmacological examinations,we revealed that anchorene's auxin-like activities depend on the indole-3-pyruvate-dependent auxin biosynthesis pathway,as well as the auxin inactivation pathway mediated by Group II Gretchen Hagen 3(GH3)proteins that mainly facilitate the conjugation of indole-3-acetic acid(IAA)to amino acids,leading to the formation of inactivated storage forms.Our measurements indicated that anchorene treatment elevates IAA levels while reducing the quantities of inactivated IAA–amino acid conjugates and ox IAA.RNA sequencing further revealed that anchorene triggers the expression of numerous auxin-responsive genes in a manner reliant on Group II GH3s.Additionally,our in vitro enzymatic assays and biolayer interferometry(BLI)assay demonstrated anchorene's robust suppression of GH3.17-mediated IAA conjugation with glutamate.Collectively,our findings highlight the significant role of carotenoid-derived metabolite anchorene in modulating auxin homeostasis,primarily through the repression of GH3-mediated IAA conjugation and inactivation pathways,offering novel insights into the regulatory mechanisms of plant bioactive apocarotenoids.

Implications of nitrogen phloem loading for carbon metabolism and transport during Arabidopsis development

Metabolite transport processes and primary metabolism are highly interconnected. This study exam- ined the importance of source-to-sink nitrogen partition- ing, and associated nitrogen metabolism for carbon capture, transport and usage. Specifically, Arabidopsis aap8 （AMINO ACID PERMEASE 8） mutant lines were analyzed to resolve the consequences of reduced amino acid phloem loading for source leaf carbon metabolism, sucrose phloem transport and sink development during vegetative and reproductive growth phase. Results showed that decreased amino acid transport had a negative effect on sink development of aap8 lines throughout the life cycle, leading to an overall decrease in plant biomass. During vegetative stage, photosynthe- sis and carbohydrate levels were decreased in aap8 leaves, while expression of carbon metabolism and transport genes, as well as sucrose phloem transport were not affected despite reduced sink strength. However, when aap8 plants transitioned to reproductive phase, carbon fixation and assimilation as well as sucrose partitioning to siliques were strongly decreased. Overall, this work demonstrates that phloem loading of nitrogen has varying implications for carbon fixation, assimilation and source-to-sink allocation depending on plant growth stage. It further suggests alterations in source-sink relationships, and regulation of carbon metabolism and transport by sink strength in a development-dependent manner.