Soil salinization poses a significant threat to global agricultural productivity. Understanding the molecular mechanisms that enable plants to cope with salt stress is crucial for developing salt-resilient crops. We found that several Arabidopsis WAK/WAKL genes are upregulated by salt stress, and their loss-of-function mutants exhibit altered salt tolerance compared WT plants. Here, we focused on WAKL4 and demonstrated that it plays a pivotal positive regulatory role in salt tolerance in Arabidopsis thaliana (Arabidopsis). Loss of WAKL4 function resulted in enhanced sensitivity to salt stress, while WAKL4 overexpression conferred enhanced root growth and reduced germination. In addition, WAKL4 only has minor effect on ionic homeostasis regulation during salt response. Importantly, we found that WAKL4 functions in maintaining cell wall integrity under salt stress, primarily through ensuring the normal biosynthesis of pectin. The salt-sensitive phenotype of the wakl4 mutant was associated with deficiency in pectin content and could be effectively rescued by exogenous calcium supplementation. Furthermore, we discovered that WAKL4 is essential for redox homeostasis regulation during salt response. The wakl4 mutant accumulated excessive reactive oxygen species (ROS) compared to WT plants. Interestingly, the expression levels of some ROS-related genes in the wakl4 mutant was also lower than that in WT plants under salt stress. WAKL4 directly interacts with and enhances the enzymatic activity of CATALASE2 (CAT2), a central enzyme in H₂O₂ scavenging. WAKL4 regulates plant salt tolerance partly via the action of CAT2. This study provides insights into plant salt tolerance and offers possible genetic targets for the improvement of crop tolerance in saline soils. WAKL4 positively regulates plant salt tolerance by regulating pectin biosynthesis in cell wall and maintaining cellular redox homeostasisvia CAT2 in Arabidopsis

Salt stress poses a threat to plant water and nutrient uptake and leads to multiple forms of damages in plants, making it a major challenge to global crop production. PHYTOCHROME-INTERACTING FACTOR 3 (PIF3) is a key transcription factor in light signaling and it has been reported to play a critical role in plant responses to salt stress. Here, we demonstrated that PIF3 negatively regulates plant salt tolerance in Arabidopsis, and salt stress significantly enhances the interaction between PIF3 and light-activated PHYTOCHROME B (PHYB), leading to accelerated degradation of PIF3 in light, thus alleviating its negative regulation on plant salt tolerance. Additionally, we identified AGAMOUS-LIKE 21 (AGL21) as a downstream target gene of PIF3. PIF3 directly binds to the promoter of the AGL21 gene to promote its expression. The PIF3-AGL21 module transcriptionally modulates the expression a battery of downstream genes, including those involved in redox homeostasis regulation, thereby leading to accumulation of reactive oxygen species (ROS) and disruption of redox homeostasis within plants in response to salt stress. PHYB-mediated degradation of PIF3 attenuates the PIF3-AGL21 module to restore redox homeostasis and enhance plant tolerance to salt stress.

As a global environmental challenge, drought stress severely restricts plant growth and development. Therefore, improving plant resistance to drought is of great importance in the context of climate change. Transcriptional regulation is essential for plant stress responses and tolerance. Here, we investigated the role of EnWRKY41, a WRKY transcription factor from forage grass Elymus nutans (E. nutans), in drought tolerance using Arabidopsis thaliana (Arabidopsis) as a heterologous system. First, we performed RNA-seq analysis on two wild accessions of E. nutans to identify the potential TFs involved in drought response, and the RNA-seq data indicated that EnWRKY41 might be an essential mediator during drought response in E. nutans. Further analyses demonstrated that EnWRKY41 is drought-inducible in E. nutans, and its heterologous overexpression significantly reduces drought tolerance in Arabidopsis. Transgenic plants exhibit impaired stomatal closure, increased accumulation of reactive oxygen species, and reduced osmotic adjustment capacity during drought response. Electrophoretic mobility shift assays and dual-luciferase reporter assays confirmed that EnWRKY41 directly binds to the W-box sequence in the promoter of EnGlu1, which encodes a β-1,3-glucanase and activates its expression. Consistently, plants overexpressing EnGlu1 also exhibited a drought-sensitive phenotype similar to that of EnWRKY41-overexpressing lines. Furthermore, drought stress significantly enhanced callose deposition in wild-type Arabidopsis plants, whereas this process was markedly suppressed in EnWRKY41- or EnGlu1-overexpressing plants. These results suggest that the EnWRKY41-EnGlu1 module negatively regulates plant drought tolerance possibly by reducing callose deposition and disrupting cellular barrier function.

Elymus sibiricus L., a member of the Triticeae tribe, is a grass widely used for forage and restoring degraded grasslands in the Qinghai-Tibetan Plateau (QTP) region. Here, we present a high-quality reference genome assembly of allotetraploid E. sibiricus, consisting of 14 pseudochromosomes. Our findings suggest that large-scale bursts of retrotransposon activity, especially by Gypsy elements and unclassified retrotransposon elements, have played a critical role in the genome expansion of E. sibiricus as compared with other Triticeae. We identified a translocation between chromosomes Es4H and Es6H with a low recombination rate. Population genomic analysis of 90 E. sibiricus accessions and 25 diploid accessions of proposed ancestors from different habitats revealed four distinct groups, although they are of monophyletic origin. Our population analysis supports the idea that the QTP is likely the center of origin and genetic diversity of E. sibiricus. Selective sweep analysis identified significant pathways related to photosynthesis and metabolism, which are likely associated with the multiple environmental adaptations of this species to the climatic conditions of the QTP. Collectively, our study not only provides genomic resources for genetic improvement of the Elymus genus, but also provides important insights on the evolutionary history of E. sibiricus from population genomic analysis and the evolution of the tribe Triticeae.

Elymus nutans Griseb. (Poaceae: Triticeae, 2n=6x=42) is a dominant perennial plant species in the Qinghai-Tibetan Plateau in China, which is an important forage resource in high-altitude and cold regions and is the most popular species used for high yield artificial grassland planting because of its rich nutritional value and good palatability for herbivorous ruminant animals. In this study, using advanced sequencing technology, we generated an allohexaploid reference genome for E. nutans , representing the three sets of chromosomes (subgenomes St, Y, and H). This is the first study to our knowledge to confirm the origin of the Y subgenome, which shares a close relationship with the V subgenome. We predict that E. nutans arose via two-step hybridization and that its speciation occurred ∼3.16 MYA. The whole genome in this study will update the Triticeae family genomics information and provide theoretical basis for the evolutionary of its related speicies. ### Competing Interest Statement The authors have declared no competing interest.

Drought and cold crucially affect plant growth and distribution. Plants have evolved complex molecular mechanisms to adapt to such adverse environmental conditions. This study examines two Elymus sibiricus (Es) germplasms differing in resilience to these stresses. Analyzing physiological responses and gene expression changes under drought and cold, it reveals the similarities and differences in their molecular mechanisms that underlie these responses. The results indicate that both drought stress and cold stress severely damage the integrity of the cell membrane in Es. Notably, under cold stress, the accumulation of osmotic regulation substances in Es is more significant, which may be related to the regulation of carbohydrate metabolism (CM)-related genes in cold environments. Furthermore, the response to oxidative stress triggered by cold stress in Es is partially inhibited. The enrichment analysis showed that the DEGs responsive to drought stress in Es were mainly related to the pathway of photosynthesis, whereas the DEGs responsive to cold stress were more associated with the protein processing in endoplasmic reticulum (PPER), highlighting distinct molecular responses. In addition, we discovered that the abscisic acid (ABA) signaling transduction plays a dominant role in mediating the drought resistance mechanism of Es. We have identified 86 key candidate genes related to photosynthesis, Phst, CM, and PPER, including 5 genes that can respond to both drought and cold stress. This study provides a foundation for the molecular mechanisms underlying cold and drought resistance in Es, with insight into its future genetic improvement for stress resistance.

Soil salinization threatens global crop production. Here, we report that a receptor-like cytoplasmic kinase, CALMODULIN-BINDING RECEPTOR-LIKE CYTOPLASMIC KINASE 3 (CRCK3), plays an essential role in plant salt tolerance via CATALASE 2 (CAT2), a hydrogen peroxide (H2O2)-scavenging enzyme in Arabidopsis (Arabidopsis thaliana). CRCK3 was induced by salt stress, and its knockout mutant displayed a salt-sensitive phenotype compared with wild-type plants. CRCK3 was activated by salt stress in a calcium-dependent manner, and its kinase activity was required for plant salt tolerance. CRCK3 physically interacted with CAT2, and CRCK3-mediated salt tolerance depended on CAT2. Salt treatment significantly induced CAT2 phosphorylation via the action of CRCK3, and this phosphorylation was required for CAT2-mediated H2O2 scavenging to reduce reactive oxygen species (ROS) content and oxidative damage in plants under saline conditions. CRCK3 phosphorylated CAT2 at the Thr209 residue, resulting in elevated catalase activity to reduce ROS accumulation under saline conditions. Therefore, the CRCK3-CAT2 module mediates plant salt tolerance by maintaining redox homeostasis. This study expands our knowledge of how plants respond to salt stress. CALMODULIN-BINDING RECEPTOR-LIKE CYTOPLASMIC KINASE 3 and CATALASE 2 form an effective module for the regulation of plant salt tolerance by maintaining redox homeostasis in Arabidopsis.

Elymus sibiricus L. (Siberian wildrye, Es ), a species belonging to the wheat tribe, is extensively employed as forage and for the reclamation of degraded grasslands within the Qinghai-Tibet Plateau (QTP). This study provides a high-quality reference genome assembly for the allotetraploid Es , which is composed of 14 pseudomolecules with the total genome size of 6.57 Gb. Our finding suggest that large-scale bursts of retrotransposons are critical for the genome expansion of Es . We discovered a translocation event between the Es 4H and Es 6H chromosomes with a low frequency of combination. Phylogenetic analyses of 90 Es accessions and 25 diploid accessions representing proposed ancestors from various habitats revealed the existence of four distinct populations. We further provided support for the hypothesis that the QTP is the center of origin and genetic diversity for Es . Collectively, our study offers valuable insights into the evolution of Es , as well as providing genomic resources for genetic enhancement in the Elymus genus and wheat tribe.### Competing Interest StatementThe authors have declared no competing interest.

试验以不同地区的10 种沿阶草种质资源为研究对象,通过不同的遮阴程度处理,研究遮阴对光合特性、气孔指标的影响,采用隶属函数方法比较了种质材料间的耐阴性差异,筛选出了适合成都地区种植的耐阴性较好的沿阶草资源材料.结果如下:随着遮阴程度的逐渐增多,处理时间的逐渐增长,试验材料的生理指标的变化各不相同,其中叶绿素(Chl)含量会随着时间的增长而增加、PS Ⅱ(光系统Ⅱ)反映中心捕获激发光能的效率叶绿素荧光(Fv/Fm)值整体随着遮阴强度增加而增加;随着遮阴程度加强,耐阴性好的试验材料气孔密度增大,气孔指数变小;采用隶属函数分析,试验材料的耐阴性排序是:SAG-OJ-19004>SAG-LM-19001>SAG-SY-19005>SAG-DZ-19007>SAG-BJ-19006>SAG-DT-19009>SAG-OJ-19002>SAG-XJ-19008>SAG-OJ-19003>SAG-BQ-19010;结合隶属函数以及田间试验,本研究初步筛选出了适宜在成都地区栽培的耐阴型沿阶草 3 份,分别为SAG-OJ-19004(山麦冬)、SAG-LM-19001(金边阔叶麦冬)、SAG-SY-19005(细叶麦冬).

In order to make better use of the wild resources of Elymus sibiricus germplasm, in this study the 1 723 materials of wild Elymus species resources from the Qinghai-Tibet Plateau, Northwest of China, North China and Northeast of China and some foreign regions were collected, from which, total of 990 wild E. sibiricus germplasm were identified by phenotypic characteristics and the Flow Cytometry detection. The results showed that the DNA content of E. sibiricus was between 5.86～7.30 Gb with average of 6.66Gb. The DNA content of Elymus nutans Griseb was between 9.50～10.36 Gb with average of 9.97Gb. It was found out that dorsal hair appeared in the basal leaf sheath of some wild E. sibiricus materials from Northwest of China, North China and Northeast of China, which was different from the description of the morphological characteristics of E. sibiricus in Chinese Flora,which was positively correlated with longitude and latitude（P ＜ 0.01）,and negatively correlated with altitude, annual mean temperature and annual mean rainfall（P＜0.01）,indicating that there was an inevitable relationship between the existence of the dorsal hair in the basal leaf sheath of E. sibiricus and its environmental factors and which possibly was one of the adaptive mechanisms of E. sibiricus germplasm to its environment. The results of this study provided a new basis for the morphological identification of E. sibiricus,and for the exploring E. sibiricus germplasm resources and breeding application.

为探究垂穗披碱草(Elymus nutans)抗 UV-B辐射能力强弱,筛选出优异种质材料,本研究以9份来自我国不同地区的野生垂穗披碱草为对象,研究其苗期UV-B辐射下的生长特性与生理特性,对其抗UV-B辐射能力进行综合评价.结果表明:随着UV-B辐射程度的加剧,9份材料的生长特性与生理特性均不同程度地受到影响.可将9份材料分为强、中、弱抗UV-B辐射材料.强抗材料为QH009,该材料受UV-B辐射影响最小,叶片受损程度最低,相对含水量下降幅度最小,细胞膜系统指标上升幅度最小,渗透调节物质积累最多,抗氧化系统酶活性显著高于其余材料(P＜0.05),次生代谢物积累最多,光合系统指标下降幅度最小,可作为垂穗披碱草新品种选育与利用的基础材料.

一直以来,四川省都是西南地区玉米种植大省,也是畜牧大省,为了满足畜牧业对饲草料的需要及推进四川农区的粮改饲工作,试验选取了 10个青贮玉米品种进行了品种比较试验,以期筛选出适宜四川农区种植的青贮玉米品种.本试验比较了先锋公司的8个青贮玉米材料在成都平原的生产情况,对照为青贮玉米品种雅玉8号和地方材料凉山玉米.通过比较筛选,筛选出适合成都平原种植的青贮玉米品种.通过对这10种青贮玉米品种进行分析结果表明:30T60和雅玉8号,这两个青贮玉米品种产量高,株高和茎粗均较高,综合性状优异,说明30T60和雅玉8号是适宜四川农区种植的青贮玉米的品种.

High temperature (HT) is an important factor for limiting global plant distribution and agricultural production. As the global temperature continues to rise, it is essential to clarify the physiological and molecular mechanisms of alfalfa responding the high temperature, which will contribute to the improvement of heat resistance in leguminous crops. In this study, the physiological and proteomic responses of two alfalfa (Medicago sativa L.) varieties contrasting in heat tolerance, MS30 (heat-tolerant) and MS37 (heat-sensitive), were comparatively analyzed under the treatments of continuously rising temperatures for 42 days. The results showed that under the HT stress, the chlorophyll content and the chlorophyll fluorescence parameter (Fv/Fm) of alfalfa were significant reduced and some key photosynthesis-related proteins showed a down-regulated trend. Moreover, the content of Malondialdehyde (MDA) and the electrolyte leakage (EL) of alfalfa showed an upward trend, which indicates both alfalfa varieties were damaged under HT stress. However, because the antioxidation-reduction and osmotic adjustment ability of MS30 were significantly stronger than MS37, the damage degree of the photosynthetic system and membrane system of MS30 is significantly lower than that of MS37. On this basis, the global proteomics analysis was undertaken by tandem mass tags (TMT) technique, a total of 6,704 proteins were identified and quantified. Gene Ontology (GO) analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis indicated that a series of key pathways including photosynthesis, metabolism, adjustment and repair were affected by HT stress. Through analyzing Venn diagrams of two alfalfa varieties, 160 and 213 differentially expressed proteins (DEPs) that had dynamic changes under HT stress were identified from MS30 and MS37, respectively. Among these DEPs, we screened out some key DEPs, such as ATP-dependent zinc metalloprotease FTSH protein, vitamin K epoxide reductase family protein, ClpB3, etc., which plays important functions in response to HT stress. In conclusion, the stronger heat-tolerance of MS30 was attributed to its higher adjustment and repair ability, which could cause the metabolic process of MS30 is more conducive to maintaining its survival and growth than MS37, especially at the later period of HT stress. This study provides a useful catalog of the Medicago sativa L. proteomes with the insight into its future genetic improvement of heat-resistance.

本研究以收集自我国7个省的45份野生斑茅(Saccharumarundinaceum)为研究对象,在开放授粉条件下,通过测定斑茅的花粉与胚珠比(Pollen-ovule ratio,P/O)、杂交指数(Outcrossing index,OCI)以及基于简单重复序列(Simple sequence repeats,SSR)分子标记估计交配系统参数这3种方法,探究斑茅繁殖特性及其有性繁殖力的情况,为斑茅资源开发利用、杂交育种及繁殖技术提供基础依据.结果表明:斑茅P/O为5897,杂交指数OCI为2;采用11对SSR引物对随机取样的15个斑茅半同胞家系共计1158个子代进行交配系统参数估计,结果显示斑茅种群具有较高的异交率水平(tm=0.864),多位点异交率和单位点异交率的差值不明显(tm—ts=0.012),亲本近交系数F大于0(F=0.318),表明斑茅以异交为主,并存在部分近交.综上所述,本研究初步认为斑茅的繁殖特性为异交为主、自交为辅的混合交配系统模式.

以物候期、形态特征、越夏性、越冬性及抗病虫害能力为观测指标,系统研究了19种多年生观赏草在成都地区的适应性表现.结果 表明,蒲苇属、芒属、狼尾草属等13种暖季型观赏草中除蒲苇、矮蒲苇、花叶蒲苇四季常绿外,其余草种均在11月末枯黄,次年3月初返青;除白关人狼尾草每年6月和10月2次开花外,其余草种只开花1次且花期均集中在7～11月,花期较长.蓝羊茅、细茎针茅、金叶苔草、细叶苔草、金边阔叶麦冬和黑麦冬6种冷季型观赏草中,细茎针茅和蓝羊茅夏季休眠,其余草种四季常绿;黑麦冬不开花,其余草种花期均集中在3～5月,花期较短.在成都地区19种观赏草除蓝羊茅越夏性差、死亡率高外,其余草种均能适应成都地区的气候环境.

斑茅在我国南方地区广泛分布,抗旱是斑茅作为甘蔗品质改良和能源草利用的重要特性,在甘蔗选育中,斑茅一直作为重点研究对象.本研究在正常浇水和持续干旱胁迫条件下对其抗旱性相关的指标进行方差分析、相关分析与隶属函数分析,采用模糊数学隶属函数法综合评价了参试材料的抗旱性,53份材料中筛选出 3份强抗旱材料,26份较抗旱材料与 24份弱抗旱材料,以期为斑茅及其近缘种育种,转录组分子机理研究以及抗旱基因挖掘提供材料基础.

Erianthus arundinaceus is not only a candidate plant for sugarcane breeding programs, but also a potential bioenergy grass. Genetic variation that is affected by geographic environments and ploidy level is very important for the utilization of Erianthus arundinaceus. In this study, effects of geographic environments and ploidy level on genetic variation were studied through analyzing the genetic diversity, genetic similarity and cluster analysis of 46 E. arundinaceus materials from natural habitats in China by using 7 ISSRs and 15 SSRs. Results showed that: 1) Seven ISSRs generated total 66 bands, of which 77% were polymorphic bands, the Nei's genetic similarity coefficient of tested materials ranged from 0.642 to 0.904 with an average value of 0.765. Fifteen SSRs generated 138 bands, of which 81% were polymorphic bands, the Nei's genetic similarity coefficient of tested materials ranged from 0.634 to 0.963 with an average value of 0.802. The results indicated great genetic diversity existed in the tested materials. 2)The tested materials were clustered into 3 groups and 7 subgroups, which demonstrated a strong geographic effect on variation of the local E. arundinaceus, and weak relationship was found between genetic distance and geographic distance. Five tetraploid materials were not clustered together, and were clustered together with materials from similar geographical location. 3) The genetic variation and cluster results were affected by geographic landforms and environments, the gene flow was blocked by Ocean and mountains, and promoted by river. The effect of ploidy level on genetic variation was little.

The genetic structure of 18 wild Erianthus arundinaceus populations from China were analyzed using 7 ISSR markers.The results showed that:1) 7 ISSR markers generated 69 bands and 83％ were polymorphic bands.There was rich genetic diversity among the tested wild resources of Erianthus arundinaceus.2) The genetic variation within populations was bigger than among populations,which suggested that E.arundinaceus was a cross-pollination species.3) Cluster analysis showed that there was a significant genetic differentiation among populations,the Mantel test of geographic distances and genetic distance showed weak correlation between them.4) The gene flow among populations was small,which was affected by the isolation of geographical environment and the influence of habitat heterogeneity,and then affected the distribution,clustering results and population structure of the populations.

Erianthus arundinaceus is not only an important germplasm resource for sugarcane breeding but also a potential bioenergy plant. Making clear the distribution of the chromosome ploidy of wild E. arundinaceus in china is the premise of the research and utilization of this species. Therefore, the objectives of this study were to determine the ploidy level and DNA content of the 55 E. arundinaceus accessions using flow cytometry and to identify the correlation between ploidy and phenotypic traits. Among the 55 accessions, four tetraploids and 51 hexaploids were identified. The four tetraploids originated from Mengma Yunnan, Shuangjiang Yunnan, Gaozhou Guangdong and Chengle Sichuan. The mean DNA content was 4.82 pg/2C for the tetraploid and 7.30 pg/2C for the hexaploid plants. The ploidy was negatively correlated with cellulose content and positively correlated (P < 0.05) with plant height, stem diameter, leaf width, dry weight per plant, fresh weight per plant and hemicellulose content. However, ploidy was not correlated with leaf length, tiller number and the ratio of dry weight and fresh weight. This study will be useful for revealing the distribution of the ploidy of wild E. arundinaceus in Chin, traits markers analysis, and utilization of this species, such as cultivar improvement and sugarcane breeding in the future.

Two newly emerged, porcine reproductive and respiratory syndrome virus (PRRSV) strains (Henan-A10 and A11) were isolated from the sera of aborting sows. Interestingly, both of the isolates could replicate in primary porcine alveolar macrophage (PAM) cells but not in MARC-145 cells. A phylogenetic tree based on the complete genome was constructed and the results showed that Henan-A10 and A11 were most closely related to other highly pathogenic PRRSV (HP-PRRSV) strains. However, genomic sequence analysis showed that Henan-A10 and A11 shared only 96.8-97.8% nucleotide identity with the representative HP-PRRSV strain JXA1. Notably, a 10 amino acids deletion in the GP2 endodomain was identified for the first time. A full-length, infectious cDNA clone of HuN4-F112 (attenuated strain from a HP-PRRSV) was used to construct a chimeric clone with the corresponding deletion in GP2. We found that the deletion did not affect viral growth in MARC-145 cells, indicating that the endodomain of PRRSV GP2 may be variable. (C) 2015 Elsevier B.V. All rights reserved.