Community structure and carbon and nitrogen storage of sagebrush desert under grazing exclusion in Northwest China

Overgrazing is regarded as one of the key factors of vegetation and soil degradation in the arid and semi-arid regions of Northwest China.Grazing exclusion(GE)is one of the most common pathways used to restore degraded grasslands and to improve their ecosystem services.Nevertheless,there are still significant controversies concerning GE’s effects on grassland diversity as well as carbon(C)and nitrogen(N)storage.It remains poorly understood in the arid desert regions,whilst being essential for the sustainable use of grassland resources.To assess the effects of GE on community characteristics and C and N storage of desert plant community in the arid desert regions,we investigated the community structure and plant biomass,as well as C and N storage of plants and soil(0-100 cm depth)in short-term GE(three years)plots and adjacent long-term freely grazing(FG)plots in the areas of sagebrush desert in Northwest China,which are important both for spring-autumn seasonal pasture and for ecological conservation.Our findings indicated that GE was beneficial to the average height,coverage and aboveground biomass(including stems,leaves and inflorescences,and litter)of desert plant community,to the species richness and importance values of subshrubs and perennial herbs,and to the biomass C and N storage of aboveground parts(P<0.05).However,GE was not beneficial to the importance values of annual herbs,root/shoot ratio and total N concentration in the 0-5 and 5-10 cm soil layers(P<0.05).Additionally,the plant density,belowground biomass,and soil organic C concentration and C storage in the 0-100 cm soil layer could not be significantly changed by short-term GE(three years).The results suggest that,although GE was not beneficial for C sequestration in the sagebrush desert ecosystem,it is an effective strategy for improving productivity,diversity,and C and N storage of plants.As a result,GE can be used to rehabilitate degraded grasslands in the arid desert regions of Northwest China.     

Mapping the current and future distributions of Onosma species endemic to Iran

Climate change may cause shifts in the natural range of species especially for those that are geographically restricted and/or endemic species. In this study, the spatial distribution of five endemic and threatened species belonging to the genus Onosma (including O. asperrima, O. bisotunensis, O. kotschyi, O. platyphylla, and O. straussii) was investigated under present and future climate change scenarios: RCP2.6 (RCP, representative concentration pathway; optimistic scenario) and RCP8.5 (pessimistic scenario) for the years 2050 and 2080 in Iran. Analysis was conducted using the maximum entropy (MaxEnt) model to provide a basis for the protection and conservation of these species. Seven environmental variables including aspect, depth of soil, silt content, slope, annual precipitation, minimum temperature of the coldest month, and annual temperature range were used as main predictors in this study. The model output for the potential habitat suitability of the studied species showed acceptable performance for all species (i.e., the area under the curve (AUC)>0.800). According to the models generated by MaxEnt, the potential current patterns of the species were consistent with the observed areas of distributions. The projected climate maps under optimistic and pessimistic scenarios (RCP2.6 and RCP8.5, respectively) of 2050 and 2080 resulted in reductions and expansions as well as positive range changes for all species in comparison to their current predicted distributions. Among all species, O. bisotunensis showed the most significant and highest increase under the pessimistic scenario of 2050 and 2080. Finally, the results of this study revealed that the studied plant species have shown an acute adaptability to environmental changes. The results can provide useful information to managers to apply appropriate strategies for the management and conservation of these valuable Iranian medicinal and threatened plant species in the future.     

Diversity,plant growth-promoting traits,and biocontrol potential of fungal endophytes of Sorghum bicolor

The diversity of fungal endophytes in Sorghum bicolor was investigated in samples collected from 10 different geographical regions of Karnataka state, India. A total of 360 endophytes were isolated from leaf, stem, and root tissues and were assigned to 26 fungal species based on morphology and molecular characterization using ITS sequences. All the endophytes belonged to the phylum Ascomycota. The diversity (Shannon H, 2.57; Simpson_1-D, 0.92) and species richness (Margalef's, 4.68; Menhinick, 3.61) were found to be higher for the endophytes isolated from leaf tissues. The species evenness of the endophytic assemblage was strongly influenced by tissue type, followed by geographical location. The biocontrol potential of isolated endophytes was evaluated against economically destructive sorghum grain mould pathogens such as Fusarium thapsinum, Epicoccum sorghinum, Alternaria alternata, and Curvularia lunata using the dual culture method. Biocontrol potential was exhibited by 26 endophytic isolates, of which Trichoderma asperellum recorded broad-spectrum activity against target pathogens, followed by E. nigrum and A. longipes. Most (82%) endophytes showed plant growth-promoting traits. Biosynthesis of indole-3-acetic acid (IAA) was observed in 84% of isolates, and phosphate solubilization, siderophore production, and cellulase activity was observed in 69%, 23%, and 27% of isolates, respectively. Seeds treated with T. asperellum exhibited a significantly higher seed vigour index (2096), germination percentage (94%), and yield under greenhouse and field conditions. The results were substantiated by the confocal microscopy analysis, which clearly demonstrated the colonization of treated endophyte in root tissues. The present study reveals an ecofriendly approach to explore T. asperellum in sorghum disease management.     

一氧化碳(CO)在植物体内的生理生化作用研究进展

为了促进一氧化碳(CO)在植物生理生化方面的研究,本文归纳了CO在植物体中的生物合成途径,CO作为信号分子对植物各种生理功能的调控,以及CO与其他信号分子之间的相互作用。经过分析得出,CO在植物生物胁迫过程中的作用及其作用机制方面的研究还很少,因此,CO在这方面的研究将会成为今后的研究重点。     

新疆南疆机采棉品种株型结构与产量性状的相关性

【目的】分析不同类型陆地棉品种的株型结构及产量性状,研究高产优质机采棉品种的株型结构与产量结构的特点,为棉花结构育种提供理论参考。【方法】测试不同机采棉品种的株型结构性状及产量结构相关指标,利用差异显著性分析、相关分析等统计方法,研究几种机采棉品种的株型性状、产量结构性状及其相关性特点。【结果】籽棉产量与株高、主茎节间长、果枝数、果节数存在正相关但不显著,与果枝始节高度呈负相关;株高与果枝始节高存在显著正相关,与主茎节间长度呈极显著相关; 17N11株型为塔型结构,其底部主茎叶片保留完整、籽棉产量、株高最高,而17N13主茎叶片数最多,17N5则具有最小的叶片脱落率;在棉花株型结构的共性方面,棉花果枝角度具有由上至下呈增大趋势,而变异能力则呈现与之相反的趋势(上部＞中部＞下部)。棉花主茎叶大小具有由上部至下部减小的趋势,变异能力亦呈现与之相反的趋势(下部＞中部＞上部)。【结论】株型结构具备中、上部果枝夹角较小(上部＜32.0°,中部＜50.0°),主茎叶总面积高于320 cm²,下部主茎叶片脱落率低于20%的机采棉品种产量优势显著,中上部果枝夹角、主茎叶总面积、下部主茎叶片脱落率可作为株型育种后代材料选择依据。     

乌苏里瓦韦(Lepisorus ussuriensis(Regel et Maack)Ching)孢子诱导再生植株的研究

乌苏里瓦韦是一种民间常用的药用蕨类植物,本研究首次建立一种以乌苏里瓦韦孢子为外植体形成完整植株的体系,得到了乌苏里瓦韦体外扩增的方法。为了探究最佳的孢子萌发条件,设计使用6种NAA和6-BA激素组合探究孢子的最佳萌发条件,然后取孢子萌发得到的乌苏里瓦韦叶片,分别接种到不同浓度的NAA和活性炭的组合培养基中,探究乌苏里瓦韦生根的最佳条件。结果表明,乌苏里瓦韦孢子的最佳萌发条件是:1/2MS培养基为基本培养基,附加NAA 0.2 mg/L,6-BA 0.5 mg/L蔗糖30 g/L,琼脂7 g/L;生根的最佳条件为:1/2MS培养基为基本培养基,附加NAA 0.4 mg/L,蔗糖30 g/L,琼脂7 g/L,活性炭1.5 g/L。本研究首次报道了乌苏里瓦韦的体外繁殖形成完整再生植株的方法,为乌苏里瓦韦的人工繁殖,同时为乌苏里瓦韦的可持续开发利用打下坚实基础。     

优化的VHb基因和GFMcryIA基因构建的双价基因在烟草中的表达

利用人工合成的、密码子优化后的透明颤菌血红蛋白（VHb）基因与人工合成的GFMcryIA基因构建成双价基因植物高效表达载体。通过根癌农杆菌介导转化烟草,获得了36株卡那霉素抗性植株。经转基因植株的PCR及Southern blot检测,证实了双价基因在35株烟草基因组中的整合。Western blot检测证实了VHb基因的表达,杀虫实验证实GFMcryIA基因也表达出活性毒蛋白。且转基因烟草平均每株干重比非转基因烟草植株高7％。本研究结果表明转基因育种技术在培育出既高产又具抗虫性的作物或经济作物新品种方面具有良好的应用前景。     

基于Micro-CT的玉米籽粒显微表型特征研究

植物显微表型主要是指植物组织、细胞和亚细胞水平的表型信息,是植物表型组学研究的重要组成部分.针对传统籽粒显微性状检测方法效率低、误差大且指标单一等问题,本研究利用Micro-CT扫描技术对5种类型11个品种玉米籽粒开展显微表型精准鉴定研究.基于对CT序列图像的处理解析,共获取籽粒、胚、胚乳、空腔、皮下空腔、胚乳空腔和胚...