A recent retrotransposon insertion of J caused E6 locus facilitating soybean adaptation into low latitude

Soybean (Glycine max) is an important legume crop that was domesticated in temperate regions. Soybean varieties from these regions generally mature early and exhibit extremely low yield when grown under inductive short-day (SD) conditions at low latitudes. The long-juvenile (LJ) trait, which is characterized by delayed flowering and maturity, and improved yield under SD conditions, allowed the cultivation of soybean to expand to lower latitudes. Two major loci control the LJ trait: J and E6. In the current study, positional cloning, sequence analysis, and transgenic complementation confirmed that E6 is a novel allele of J, the ortholog of Arabidopsis thaliana EARLY FLOWERING 3 (ELF3). The mutant allele e6^PG, which carries a Ty1/Copia-like retrotransposon insertion, does not suppress the legume-specific flowering repressor E1, allowing E1 to inhibit Flowering Locus T (FT) expression and thus delaying flowering and increasing yields under SD conditions. The e6^PG allele is a rare allele that has not been incorporated into modern breeding programs. The dysfunction of J might have greatly facilitated the adaptation of soybean to low latitudes. Our findings increase our understanding of the molecular mechanisms underlying the LJ trait and provide valuable resources for soybean breeding.     

大豆向热带地区发展的遗传基础

大豆(Glycine max)是光周期敏感的植物,该特性是决定其生育期及其生态适应区的关键因素。温带的大豆品种引种到热带地区(短日照)时,开花期和成熟期提前、产量降低,限制了大豆在热带地区的种植。长童期(LJ)大豆品种的发现是解决该问题的重要突破。在短日照条件下,LJ品种比温带品种开花晚、体量大、成熟晚且产量提高。前期研究发现,J位点是控制LJ性状的关键位点。近期,我国科学家通过精细定位克隆了J基因,发现其与拟南芥(Arabidopsis thaliana)早花基因(ELF3)同源。他们通过功能互补和近等基因系等方法验证了J基因的功能,在短日照条件下,等位基因j比J开花晚、成熟晚且产量提高。进一步研究发现,J蛋白与E1基因(豆科植物开花抑制因子)的启动子结合抑制E1基因的表达,从而解除E1对大豆开花基因(FT)的抑制,促进大豆在短日照下开花。研究还发现在大豆种质资源中存在多种j等位变异。该研究引领了大豆生育期遗传研究的新方向,揭示了大豆向热带地区发展的遗传基础。     

Molecular mechanisms for the photoperiodic regulation of flowering in soybean

Photoperiodic flowering is one of the most important factors affecting regional adaptation and yield in soybean (Glycine max). Plant adaptation to long-day conditions at higher latitudes requires early flowering and a reduction or loss of photoperiod sensitivity; adaptation to short-day conditions at lower latitudes involves delayed flowering, which prolongs vegetative growth for maximum yield potential. Due to the influence of numerous major loci and quantitative trait loci (QTLs), soybean has broad adaptability across latitudes. Forward genetic approaches have uncovered the molecular basis for several of these major maturity genes and QTLs. Moreover, the molecular characterization of orthologs of Arabidopsis thaliana flowering genes has enriched our understanding of the photoperiodic flowering pathway in soybean. Building on early insights into the importance of the photoreceptor phytochrome A, several circadian clock components have been integrated into the genetic network controlling flowering in soybean: E1, a repressor of FLOWERING LOCUS T orthologs, plays a central role in this network. Here, we provide an overview of recent progress in elucidating photoperiodic flowering in soybean, how it contributes to our fundamental understanding of flowering time control, and how this information could be used for molecular design and breeding of high-yielding soybean cultivars.     

SoySNP618K array: A high-resolution single nucleotide polymorphism platform as a valuable genomic resource for soybean genetics and breeding

Innovations in genomics have enabled the development of low-cost, high-resolution, single nucleotide polymorphism (SNP) genotyping arrays that accelerate breeding progress and support basic research in crop science. Here, we developed and validated the SoySNP618K array (618,888 SNPs) for the important crop soybean. The SNPs were selected from whole-genome resequencing data containing 2,214 diverse soybean accessions; 29.34% of the SNPs mapped to genic regions representing 86.85% of the 56,044 annotated high-confidence genes. Identity-by-state analyses of 318 soybeans revealed 17 redundant accessions, highlighting the potential of the SoySNP618K array in supporting gene bank management. The patterns of population stratification and genomic regions enriched through domestication were highly consistent with previous findings based on resequencing data, suggesting that the ascertainment bias in the SoySNP618K array was largely compensated for. Genome-wide association mapping in combination with reported quantitative trait loci enabled fine-mapping of genes known to influence flowering time, E2 and GmPRR3b, and of a new candidate gene, GmVIP5. Moreover, genomic prediction of flowering and maturity time in 502 recombinant inbred lines was highly accurate (>0.65). Thus, the SoySNP618K array is a valuable genomic tool that can be used to address many questions in applied breeding, germplasm management, and basic crop research.     

Soybean AP1 homologs control flowering time and plant height

Flowering time and plant height are key agronomic traits that directly affect soybean (Glycine max) yield. APETALA1 (AP1) functions as a class A gene in the ABCE model for floral organ development, helping to specify carpel, stamen, petal, and sepal identities. There are four AP1 homologs in soybean, all of which are mainly expressed in the shoot apex. Here, we used clustered regularly interspaced short palindromic repeats (CRISPR) – CRISPR‐associated protein 9 technology to generate a homozygous quadruple mutant, gmap1, with loss‐of‐function mutations in all four GmAP1 genes. Under short‐day (SD) conditions, the gmap1 quadruple mutant exhibited delayed flowering, changes in flower morphology, and increased node number and internode length, resulting in plants that were taller than the wild type. Conversely, overexpression of GmAP1a resulted in early flowering and reduced plant height compared to the wild type under SD conditions. The gmap1 mutant and the overexpression lines also exhibited altered expression of several genes related to flowering and gibberellic acid metabolism, thereby providing insight into the role of GmAP1 in the regulatory networks controlling flowering time and plant height in soybean. Increased node number is the trait with the most promise for enhancing soybean pod number and grain yield. Therefore, the mutant alleles of the four AP1 homologs described here will be invaluable for molecular breeding of improved soybean yield.     

Adaptive mechanism of Echinochloa crus-galli Beauv. var. formosensis Ohwi under salt stress: Effect of salicylic acid on salt sensitivity

Our previous study revealed that salicylic acid (SA) accumulates in salt-stressed rice (Oryza sativa L. cv. Nipponbare) seedlings, and we hypothesized that the accumulation of SA might potentiate oxidative injury in rice seedlings since the inhibition of SA synthesis alleviated the growth inhibition under high salinity. To further clarify the action of SA under salt stress, we investigated the changes in the SA content, the activities of the antioxidative enzymes, and the effects of exogenous SA on barnyardgrass (Echinochloa crus-galli Beauv. var. formosensis Ohwi), a gramineous weed which shows lower SA content and is more salt tolerant than rice. In E. crus-galli seedlings exposed to high salinity, neither free nor conjugated SA content showed any increase, while the fresh weight of the shoot and chlorophyll fluorescence (Φ_PSII) slightly decreased. When E. crus-galli seedlings were treated with salt after foliar application of SA, the absorbed SA resulted in the enhancement of the salt-induced growth inhibition and a striking reduction of the Φ_PSII value. Catalase (CAT) and superoxide dismutase (SOD) activities of E. crus-galli seedlings were induced by the salt treatment. However, SA pre-treatment suppressed such an induction of CAT activity and further promoted SOD activity, both of which led to the elevation of the leaf hydrogen peroxide (H₂O₂) level. The present results suggested that enlargement of the cellular SA pool facilitates the generation of H₂O₂ through the suppression of CAT activity and through a remarkable promotion of SOD activity, and thereby enhances the oxidative injury caused by salt stress.     

Abscisic acid-dependent PMT1 expression regulates salt tolerance by alleviating abscisic acid-mediated reactive oxygen species production in Arabidopsis

Phosphocholine(PCho) is an intermediate metabolite of nonplastid plant membranes that is essential for salt tolerance. However, how PCho metabolism modulates response to salt stress remains unknown. Here, we characterize the role of phosphoethanolamine N-methyltransferase 1(PMT1) in salt stress tolerance in Arabidopsis thaliana using a T-DNA insertional mutant, geneediting alleles, and complemented lines. The pmt1 mutants showed a severe inhibition of root elongation when exposed to salt stress,...     

不同大花类群淫羊藿属植物的花部特征及生殖特征研究

淫羊藿是我国重要的草本植物,在中药、功能性食品和园林观赏等领域都具有重要用途,受地域差异性影响,淫羊藿属植物的植株形态、花部特征、开花物候和生殖特征各不相同。本研究对四川不同产地野生种群大花类淫羊藿（巫山淫羊藿、粗毛淫羊藿和宝兴淫羊藿）的开花动态、花部特征、访花昆虫与繁殖系统进行了对比研究。结果表明：（1）3种淫羊藿属植物的开花期较为集中,巫山淫羊藿和粗毛淫羊藿的花期为3月下旬～4月下旬,单花花期均为3～4 d;宝兴淫羊藿的花期为4月中旬～5月中旬,单花花期5～6 d;（2）膜翅目和双翅目昆虫为3种淫羊藿属植物的有效访花者,有效访花者访花特性与花部特征之间具有明显的相关性;（3）3种淫羊藿属植物的花序、花和果实的数量受所处环境影响较大,自然结实率：巫山淫羊藿>宝兴淫羊藿>粗毛淫羊藿;温度和光照是最主要的影响因子。     

Understandings and future challenges in soybean functional genomics and molecular breeding

Soybean(Glycine max) is a major source of plant protein and oil.Soybean breeding has benefited from advances in functional genomics.In particular,the release of soybean reference genomes has advanced our understanding of soybean adaptation to soil nutrient deficiencies,the molecular mechanism of symbiotic nitrogen(N) fixation,biotic and abiotic stress tolerance,and the roles of flowering time in regional adaptation,plant architecture,and seed yield and quality.Nevertheless,many challenges remain...     

胡颓子属5种植物果实主要类胡萝卜素成分及含量

利用高效液相色谱法对华东地区常见的胡颓子属(Elaeagnus) 4种生态型的胡颓子(E. pungens)、2个变种的大叶胡颓子(E. macrophylla)、蔓胡颓子(E. glabra)、银果胡颓子(E. magna)和佘山胡颓子(E. argyi) 9个样品成熟果实所含主要类胡萝卜素成分及含量进行了检测。结果表明, 5种胡颓子属植物成熟果实中的主要类胡萝卜素成分为番茄红素, 且在不同种间含量差异显著, 含量最高的是浙江嵊州的胡颓子, 其值为(259.89±26.22) µg·g^-1FW, 最低的是佘山胡颓子, 其含量为(91.19±7.74) µg·g^-1FW; 其中4种生态型的胡颓子的番茄红素含量都较高。研究表明这5种胡颓子属植物果实富含番茄红素, 是一类珍贵的天然番茄红素资源, 具有较大的市场开发应用价值。研究结果为揭示果实高积累番茄红素的机理提供了理想的研究材料。     

玉米逆境响应相关转录因子ZmC2H2-1基因克隆及功能验证

玉米是我国第一大作物,提高玉米的抗逆性是玉米育种的重要目标性状之一。植物C2H2型锌指蛋白广泛参与植物各个时期的生长发育及逆境应答过程。本研究从玉米中分离了转录因子ZmC2H2-1基因并对其功能进行了初步研究。结果表明,ZmC2H2-1属于C2H2锌指蛋白转录因子家族,编码蛋白主要位于细胞核中,酵母自激活实验表明ZmC2H2-1不具有自激活活性;干旱、盐和ABA等逆境可抑制ZmC2H2-1基因在玉米中的表达;过表达ZmC2H2-1基因的拟南芥叶片失水速率更快,在PEG、高盐和ABA处理条件下,与对照相比转ZmC2H2-1基因拟南芥耐逆性降低,以上结果说明ZmC2H2-1基因是作为玉米抗逆的负调控因子参与了逆境胁迫应答。本研究为深入解析玉米ZmC2H2-1的调控网络和玉米的抗逆调控机制奠定了基础。     

盐胁迫下大豆根组织定量PCR分析中内参基因的选择

实时荧光定量PCR已广泛用于基因表达的分析, 适当的内参基因选择是获得准确分析结果的关键。在大豆(Glycine max)分子生物学研究中, 逆境响应基因和microRNA (miRNA)表达的内参辅助检测基因均有哪些目前尚不清楚。该研究选用不同盐梯度和时间点组合处理的大豆根组织为材料, 对已报道的其它条件下表达相对稳定的内参基因(ACT、ACT2/7、CYP2、ELF1A、ELF1B、F-Box、TUA和UBC2)以及miRNA内参基因(U6、miR1515a、miR1520c、miR1520d、miR171a和miR171b)的表达情况进行了全面检测; 并采用Δ-Ct、Bestkeeper、NormFinder和Genorm四种方法对检测结果进行了综合分析, 发现ELF1B和CYP2适合作为大豆根系盐胁迫响应基因研究的内参基因, miR1515a和U6适合作为盐胁迫下大豆根组织miRNA研究的内参。上述研究结果为大豆盐胁迫响应基因和miRNA表达及其进一步的功能研究奠定了基础。     

360度群体遗传变异扫描——大豆泛基因组研究

大豆(Glycine max)是重要的油料和蛋白作物, 其丰富的遗传变异为生物学性状挖掘和育种改良提供了重要的资源基础。然而, 单个基因组信息无法全面揭示种质资源的遗传变异, 泛基因组研究为解决这一不足提供了新方案。近日, 中国科学院遗传与发育生物学研究所田志喜和梁承志研究团队从2 898份大豆种质中选取26份代表性材料, 并整合已有的3个基因组, 构建了包含野生和栽培大豆的泛基因组和图基因组(graph-based genome), 鉴定了整个群体的绝大多数结构变异数据集, 确定了大豆种质的核心、非必需和个体特异的基因集。利用这些数据系统地揭示了生育期位点E3的等位基因变异和基因融合事件、种皮颜色基因I的单体型和演化关系以及结构变异对铁离子转运基因表达和地区适应性选择的影响。该研究为作物基因组学研究提供了一个新的模式, 同时将加速推动大豆遗传变异的鉴定、性状解析和种质创新。     

Advances in research of Achnatherum inebrians-Epichloë endophyte symbionts

有关醉马草(Achnatherum inebrians)内生真菌(Epichloë gansuensis, E. inebrians)共生体的研究, 代表了我国禾草内生真菌研究领域的重要方向, 使中国的醉马草-内生真菌与美国的苇状羊茅(Festuca arundinacea)-内生真菌(E. coenophiana)和新西兰的多年生黑麦草(Lolium perenne)-内生真菌(E. festucae var. lolii)成为禾草内生真菌国际三大研究分支。该文综述了近30年来对醉马草内生真菌共生体的系统研究, 包括: 内生真菌的分布、带菌率、检测方法、多样性, 内生真菌提高宿主的抗旱、耐寒、耐盐碱、耐重金属、抗虫、抗病等抗逆性及其机理, 共生体产生的生物碱等次生代谢物, 对草食动物的毒性, 及其在草地生态系统中的作用等。研究者实验证实了醉马草本身无毒, 只有当内生真菌与醉马草共生并产生麦角新碱和麦角酰胺等麦角类生物碱后才能导致采食醉马草家畜中毒。文章展望了醉马草内生真菌基因组学和功能分析, 利用杀菌剂杀死内生真菌进行醉马草脱毒, 利用无毒内生真菌菌株进行饲用醉马草新品种选育, 利用有毒醉马草内生真菌共生体进行抗虫防鸟的机场绿化新品种选育及生物源农药与医药开发等。     

醉马草内生真菌共生体研究进展

有关醉马草(Achnatherum inebrians)内生真菌(Epichloë gansuensis, E. inebrians)共生体的研究, 代表了我国禾草内生真菌研究领域的重要方向, 使中国的醉马草-内生真菌与美国的苇状羊茅(Festuca arundinacea)-内生真菌(E. coenophiana)和新西兰的多年生黑麦草(Lolium perenne)-内生真菌(E. festucae var. lolii)成为禾草内生真菌国际三大研究分支。该文综述了近30年来对醉马草内生真菌共生体的系统研究, 包括: 内生真菌的分布、带菌率、检测方法、多样性, 内生真菌提高宿主的抗旱、耐寒、耐盐碱、耐重金属、抗虫、抗病等抗逆性及其机理, 共生体产生的生物碱等次生代谢物, 对草食动物的毒性, 及其在草地生态系统中的作用等。研究者实验证实了醉马草本身无毒, 只有当内生真菌与醉马草共生并产生麦角新碱和麦角酰胺等麦角类生物碱后才能导致采食醉马草家畜中毒。文章展望了醉马草内生真菌基因组学和功能分析, 利用杀菌剂杀死内生真菌进行醉马草脱毒, 利用无毒内生真菌菌株进行饲用醉马草新品种选育, 利用有毒醉马草内生真菌共生体进行抗虫防鸟的机场绿化新品种选育及生物源农药与医药开发等。