Leymus chinensis (Trin.) Tzvel. (sheepgrass) is an important forage species, yet the relationships between seed phenotypic traits, agronomic performance, and their underlying genetic mechanisms remain unclear. In this study, we utilized the AIseed high-throughput phenotyping platform to systematically analyze 54 image-based traits (i-traits)—encompassing morphology, color, and texture—in 262 dehusked seeds of sheepgrass. Coupled with 50K single nucleotide polymorphism (SNP) chip genotyping data, we performed a genome-wide association study (GWAS) to elucidate genetic correlations among seed phenotypic traits. Elastic net regression was employed to identify informative phenotypic predictors, revealing significant associations between seed size, seed coat texture, and color with hundred-seed weight (HGW), hundred-seed weight without glumes (HGWwg), and germination rate (GR). Additionally, a germplasm screening approach based on principal component analysis (PCA) achieved a 71% accuracy rate in predicting high-germination germplasm and identified 10 germplasm lines with superior comprehensive performance. GWAS identified several SNPs significantly associated with seed color and morphology, mainly on chromosomes Lc2Xm and Lc6Xm. KEGG analysis highlighted the roles of phenylpropanoid and flavonoid biosynthesis pathways, with candidate genes such as PAL, PER18, PER50, BGLU16, BACOVA_02659, and ANR implicated. This study offers effective phenotypic screening strategies and valuable genetic resources for the molecular breeding of sheepgrass.

随着中科羊草在我国北方大面积推广种植,人工高产优质羊草地建设过程中,水热条件较好的区域倒伏现象时有发生,降低经济效益,羊草基地防止倒伏的研究越发重要.矮壮素能够抑制茎秆生长,使茎秆变矮,在小麦防止倒伏方面广泛应用.本研究通过对不同生育期、不同叶层高度的羊草喷施不同次数的矮壮素,探究羊草对矮壮素的响应效果和规律.结果发现:喷施矮壮素可降低羊草穗高和叶层高度,平均降低幅度为 31.98%和29.97%;矮壮素降低羊草穗长和叶长,平均降低幅度为 8.07%和 14.17%;矮壮素对羊草小穗数、每小穗小花数、叶宽影响较小.喷施矮壮素穗高和叶层高的差值缩小,在矮壮素用量相同的情况下,喷施时间越早,成熟期穗高和叶层高差值越大.整体而言拔节期的早期喷施矮壮素效果较好,便于控制穗高和叶层高度,抑制羊草倒伏的同时有利于机械化收获.

少花蒺藜草(Cenchrus spinifex Cav.)原产于北美洲,上世纪80年代侵入科尔沁草原并在全国多地快速蔓延,成为科尔沁沙地的一大草害.本文通过羊草播种、刈割试验,旨在探索高效、经济控制少花蒺藜草的技术.结果表明:播种30 kg/hm2的中科1号羊草第1年对少花蒺藜草密度抑制率为26.96％;第2年两时期株高抑制率为25.00％、41.27％,第3年两时期株高抑制率为53.28％、90.91％,逐年提升;第2年两时期盖度抑制率为70.15％、78.01％,第3年两时期盖度抑制率为99.18％、100.00％,逐年提升;第2年对生物量抑制率达到87.79％.针对少花蒺藜草,中科1号羊草播种量为30 kg/hm2时已经可以在第3年完全控制少花蒺藜草,无须增大播种量.本研究为大面积利用羊草防除少花蒺藜草提供了科学依据,对保障草原生态安全具有重要意义.

羊草广布于欧亚大陆东部,是我国优势的禾本科多年生优质牧草,具有极高的生态价值.本文全面回顾了我国羊草种质资源的研究历程,将其大体分为四个阶段,分别为:1951～1987年,开始羊草种质资源调查研究和省级项目立项;1988～2000年,培育出第一批国审羊草品种,干草出口日本;2001～2013年,早期品种扩繁推广,羊草有关国家重点研发项目立项;2014～2021年,羊草种质资源研发体系初步建立,第二批5个国审羊草品种育成,种子规模化繁殖面积扩大,生态建设广泛应用.羊草种质资源研发历史、启示、问题及展望的探讨,对促进我国羊草种质资源保护和创新、加速草原生态修复、发展草牧业及国土绿化具有参考价值.

羊草是我国重要的牧草和生态草资源,具有耐盐碱、耐旱、耐低温等特性,是天然的抗逆基因资源库.CBF/DREB属于AP2转录因子家族,在植物抗逆中发挥着重要作用.本研究克隆得到羊草LcCBF6(Leymus chinensis C-repeat binding factor 6)基因,该基因含有AP2结构域,编码245个氨基酸.氨基酸序列比对发现,LcCBF6与蒙古冰草和黑麦的CBF6蛋白的同源性分别为92％和91％.组织特异性表达模式分析表明,LcCBF6基因在羊草根、叶、种子中均有表达,且受盐胁迫诱导表达.过表达LcCBF6能显著提高转基因拟南芥的抗盐性.在盐胁迫条件下,转基因株系的绿色子叶数、根长、植株生物量以及存活率等均明显高于野生型.上述结果表明羊草LcCBF6基因在提高植物盐胁迫抗性方面发挥了重要的作用,将为牧草及重要农作物抗逆分子育种提供优异的基因资源.

Drought stress is one of the major constraints for soybean growth and productivity worldwide. The study was aimed to investigate drought-induced physiological and proteomic changes in soybeans, as well as drought relief using exogenous hydrogen peroxide (H2O2). In drought-stressed plants, H2O2 spray on the leaf surface improved relative water content (RWC), net photosynthetic rate (Pn), and stomatal conductance (Gs). Furthermore, exogenous H2O2 reduced drought stress-induced endogenous MDA and H2O2 levels, as well as increased the key antioxidant enzymes (SOD,CAT, APX and POD) activity and proline content in H2O2-treated soybean plants. These findings showed that H2O2 treatment significantly reduced drought stress by increasing the antioxidative defense system and osmotic adjustment. Furthermore, using matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry, a total of 27 differently expressed proteins was identified, wherein 23 were up-regulated and 4 were down-regulated under drought condition. These proteins were found to be involved in photosynthesis, energy and metabolism, plant defense and antioxidant, signaling and transport, and transcription regulation in response to H2O2 treatment in soybean under drought stress, according to in silico interactome analysis. These findings add to our understanding of H2O2-mediated drought stress alleviation, as well as the physiological and molecular responses of soybean to drought stress.

Sheepgrass is a perennial native grass species with an aggressive and vigorous rhizome system, and it can tolerate high levels of salt stress. Many salt stress-responsive genes have been identified in sheepgrass. Here, we identified and characterized a novel salt-induced gene, LcSAIN3 ( L eymus chinensis salt-induced 3), from sheepgrass. Expression analysis confirmed that LcSAIN3 is induced by PEG, ABA and salt stress. Subcellular localization analysis indicated that the LcSAIN3 protein is mainly localized in the chloroplasts. The heterologous of LcSAIN3 in Arabidopsis increases seed germination under various stress conditions. More importantly, the seedling survival, plant height and weight of the transgenic plants are higher than those of the WT plants under salt stress. The overexpression of LcSAIN3 causes a relatively high accumulation of free proline; enhances SOD activity; and leads to the upregulated expression of several stress-responsive genes, such as AtRAB26 , AtRD29B , AtSOS1 and AtP5CS1 . Our results suggest that LcSAIN3 may be a useful gene for the molecular breeding to improve plants salt stress tolerance.

Background Sheepgrass ( Leymus chinensis (Trin.) Tzvel) is a perennial forage grass that can survive extreme freezing winters (− 47.5 °C) in China. In this study, we isolated an unknown function MYB transcription factor gene, LcMYB4 , from sheepgrass . However, the function of LcMYB4 and its homologous genes has not been studied in other plants. Results The expression of the LcMYB4 gene was upregulated in response to cold induction, and the LcMYB4 fusion protein was localized in the nucleus, with transcriptional activation activity. Biological function analysis showed that compared with WT plants, LcMYB4 -overexpressing Arabidopsis presented significantly increased chilling and freezing tolerance as evidenced by increased germination rate, survival rate, and seed setting rate under conditions of low temperature stress. Furthermore, LcMYB4 -overexpressing plants showed increased soluble sugar content, leaf chlorophyll content and superoxide dismutase activity but decreased malondialdehyde (MDA) under chilling stress. Moreover, the expression of the CBF1 , KIN1 , KIN2 and RCI2A genes were significantly upregulated in transgenic plants with chilling treatment. These results suggest that LcMYB4 overexpression increased the soluble sugar content and cold-inducible gene expression and alleviated oxidative damage and membrane damage, resulting in enhanced cold resistance in transgenic plants. Interestingly, our results showed that the LcMYB4 protein interacts with fructose-1,6-bisphosphate aldolase protein1 (LcFBA1) and that the expression of the LcFBA1 gene was also upregulated during cold induction in sheepgrass, similar to LcMYB4 . Conclusion Our findings suggest that LcMYB4 encodes MYB transcription factor that plays a positive regulatory role in cold stress.

The protein content of plants is commonly estimated by multiplying the total nitrogen content (Kjeldahl; KN) by a nitrogen-to-protein conversion factor of 6.25. This method is based on the incorrect assumption that all nitrogen in the ammonia/ammonium and organic substances in plants is protein nitrogen, usually resulting in overestimation of protein content. We have examined amino acid composition, amino acid nitrogen, total nitrogen (KN), and actual protein content (AP) determined from amino acid residues in 16 accessions of perennial sheepgrass (Leymus chinensis (Trin.) Tzvelev). We determined a new nitrogen-to-protein conversion factor, k P , as the ratio of AP to KN, and applied this factor to estimate the total protein content (TP) as KN × k P . The non-protein nitrogen accounted for 40.5% to 62.4% of the total nitrogen. The average k P value was 3.17 overall, 3.20 in the accessions sampled at the jointing stage, and 3.15 in the accessions sampled at the flowering stage. The TP, calculated as KN × 3.17, was about half that of crude protein contents, calculated as KN × 6.25. Our study suggests that the AP-based k P of 3.17 can be used to more accurately estimate the total protein content in sheepgrass.

Sheepgrass is an advantageous forage grass and ecological grass in China. It could adapt well to various types of ecological environment and could grow in cold, dry, saline-alkali, and arid soil. Its underground sprawling horizontal rhizome helps control wind erosion, desertification, water loss, and soil loss; it plays an important role in the protection of ecological environment and in the governance of the grassland ecological environment and saline land in northern China. Moreover, sheepgrass features high-yield, high protein content, good palatability, strong regeneration capacity, long stay-green period, and high foliage volume. Recently, "Zhongke" series of new varieties such as "Zhongke" No. 1, 2, and 3 were cultivated in a wide area in China, which plays an important role in the development of artificial grassland, ecological restoration of degraded grassland, and development of grassland animal husbandry.

Sheepgrass (Leymus chinensis (Trin.) Tzvel) is the key species which is widely distributed in eastern Eurasia steppe. It is a perennial gramineous plant belonging to Leymus, Triticeae, and Poaceae. As a very important forage grass of great value in animal husbandry, sheepgrass is well known for its abundant foliage, high palatability, and high nutritive content. Sheepgrass is also valuable in grassland repair and reservation since it is a perennial grass with a rhizome network to fix the soil and can survive well in stressful environments. Based on the sufficient morphological and developmental knowledge, the cultivation and plantation of sheepgrass had become the focus of many grass breeders. In recent decades, a variety of new cultivars of sheepgrass such as "Zhongke" series were verified for the grass and seed production. In the artificial grassland establishment of sheepgrass, proper watering and essential fertilizers assure the plant growth and the production of grass and seed. As a fine grass with resistance to various stresses, multiple scientific studies on development and stress tolerance of sheepgrass have drawn the attention of many researchers.

黄河三角洲地区土壤盐碱化程度高,引进耐盐植物改良该地区盐碱地是一种“治标又治本”的办法.但耐盐植物种类繁多,耐盐机制复杂,盲目引种只能加重生态破坏,因此,加强黄河三角洲地区盐碱地现状调查研究,改良培育适宜的耐盐植物是目前研究的重点.本文综述了黄河三角洲地区现状、耐盐植物种类特点、耐盐机制以及目前研究存在的问题和解决方法,为黄河三角洲地区耐盐植物的研发及盐碱地植物改良提供理论支持.

Sheepgrass (Leymus chinensis (Trin.) Tzvel) is an important forage grass in the Eurasian steppe. However, little information is available concerning its seed morphological features and germination characteristics during seed development and after-ripening among different germplasm. To clarify the appropriate seed harvest time and the effects of germplasm, seed development and after-ripening on seed germination, 20 germplasm of sheepgrass were selected. Moreover, the seed morphological and physical changes as well as the seed germination and dormancy characteristics of sheepgrass during seed development stages were analyzed using a seven—d gradient of day after pollination (DAP). The results indicated that the seed water content decreased significantly during 35–42 DAP and that the highest seed germination rate of most germplasm was observed at 35–42 DAP. Thus, 35–42 DAP may be the best time to harvest sheepgrass to obtain the maximum seed germination rate and avoid seed shattering. Furthermore, our results indicated that there were six types of germination patterns, including germplasm with increasing germination rates in the developing seed, such as S19 and S13, and germplasm that maintained a consistently low germination rate, such as S10. Moreover, we compared the seed germination rate of eight germplasm during seed development in both 2016 and 2017, and the results indicated that the seed germination patterns of the eight germplasm were highly consistent between the two consecutive years, suggesting that germplasm rather than year is the major factor in determining germination during seed development. The effect of after-ripening on seed germination was different among the germplasm where four types of germination patterns were revealed for 10 germplasm and resulted in various dormancy features. A two-factor ANOVA analysis suggested that the germplasm of the sheepgrass has a large influence on seed germination, whether during seed development or after-ripening. Thus, these findings lay the foundation for future studies on seed dormancy and germination and may guide the breeding of new cultivars of sheepgrass with better germination performance.

Sheepgrass (Leymus chinensis (Trin.) Tzvel.) is an economically and ecologically important forage in the grass family. Self-incompatibility (SI) limits its seed production due to the low seed-setting rate after self-pollination. However, investigations into the molecular mechanisms of sheepgrass SI are lacking. Therefore, microscopic observation of pollen germination and pollen tube growth, as well as transcriptomic analyses of pistils after self- and cross-pollination, were performed. The results indicated that pollen tube growth was rapidly inhibited from 10 to 30 min after self-pollination and subsequently stopped but preceded normally after cross-pollination. Time course comparative transcriptomics revealed different transcriptome dynamics between self- and cross-pollination. A pool of SI-related signaling genes and pathways was generated, including genes related to calcium (Ca2+) signaling, protein phosphorylation, plant hormone, reactive oxygen species (ROS), nitric oxide (NO), cytoskeleton, and programmed cell death (PCD). A putative SI response molecular model in sheepgrass was presented. The model shows that SI may trigger a comprehensive calcium- and phytohormone-dominated signaling cascade and activate PCD, which may explain the rapid inhibition of self-pollen tube growth as observed by cytological analyses. These results provided new insight into the molecular mechanisms of sheepgrass (grass family) SI.

中国是一个草原和草种资源大国,在气候变化和社会经济发展过程中如何以全球视野保护和开发草种资源？如何提高资源的研发和利用效率？带着这些问题,本文作者参加了2019年在美国奥兰多举办的“国际牧草与草坪草育种会议”,获得了大量动态信息.本文从现代育种与遗传工具、表型组学技术、育种与遗传资源、分子工具在育种上的应用、内生真菌研究等方面对大会主要内容进行了综述,并指出基于智能化表型数据的育种方法成为热点,正在迅速突破,基于基因组的育种技术趋于成熟.

中科1号羊草(Leymus chinensis“Zhongke No.1”)是由中国科学院植物研究所选育的国审育成品种,该品种市场需求大,种源远远不能满足需求.陕西省佳县是国贫县,根据其土壤气候资源,适合开展羊草种子繁殖,在收获良种的同时,饲草可用于饲喂牲畜,发展草畜加产业链.因此,本文采用三年引种试验数据评价了中科1号羊草品种引种到榆林佳县的适应性.结果 表明:该品种田间发芽率56％,保苗率95％以上;第二年越冬率保持在98％以上,完成了从播种到新种子形成的有性生活史.进入生殖期的群体,抽穗率65.51％,结实率76.63％,千粒重2.34g,发芽率76.29％,种子产量426kg/hm2;第一茬鲜草和干草产量分别为15 100 kg/hm2和5 301 kg/hm2.综上所述,中科1号羊革新品种适宜在佳县及同类地区种植,具有建设我国“黄土高原羊草种子繁殖基地”的巨大潜力,为我国农牧交错带和草原区生态修复提供乡土草种种源.

In recent years, sea rice research has aroused widespread concern in society. Leymus chinensis as a salt-tolerant native grass species resource, there is no experimental report on the tolerance of Leymus chinensis to seawater. In this paper, two sheep grass germplasms, S19 and S11, were selected to study the effects of different seawater concentrations on seed germination characteristics. The following results were obtained: The germination rate of Leymus chinensis seeds decreased with the increase of seawater concentration, and the germination rate was significantly negatively correlated with seawater concentration. S19 is more resistant to seawater inhibition than S11. The length of radicle and the length of the first true leaf of Leymus chinensis were significantly inhibited with the increase of seawater concentration, and the inhibition of coleoptile was less. These results have important reference value for seawater evaluation and new variety cultivation of Leymus chinensis germplasm resources.

Sheepgrass (Leymus chinensis ((Trin.) Tzvel)) is an important perennial forage grass that is widely distributed in the Eurasia steppe. The seed germination percentage show significant variation among the different germplasm in sheepgrass. However, the underlying molecular mechanisms of distinct germination during seed development are still mostly unknown. Here, we performed comparative transcriptomic analyses of high seed germination percentage (H) and low seed germination percentage (L) at 14, 28, and 42 days after pollination. After comparing 3 consecutive development stages, 9255, 5366, and 4306 genes were found to be significantly differently expressed between H and L. Pathway analysis indicated that transcripts related to starch and sucrose metabolism, phenylpropanoid biosynthesis, plant hormone signal transduction, amino sugar and nucleotide sugar metabolism, and photosynthesis were significantly changed between the two germplasm at three stages. ABA and GA metabolism- and signaling transduction-related genes were differentially expressed between two germplasm at development stages, suggesting that the reduced signaling of GA and ABA is likely to be related to seed germination and dormancy in sheepgrass. We also identified 81 transcription factor (TF) families, and some TFs genes such as NAC48, NAC78, WRKY80, ZnFP, C3H14 and ILR3 were significantly differential expressed in two germplasm. Our results provide insights into seed development, germination and dormancy in sheepgrass at the transcriptional level.

LcbHLH92, a pleiotropic gene from sheepgrass, negatively regulates anthocyanins/proanthocyandins and reduces seed dormancy in transgenic Arabidopsis.

BACKGROUND:Drought is one of the most serious factors limiting plant growth and production. Sheepgrass can adapt well to various adverse conditions, including drought. However, during germination, sheepgrass young seedlings are sensitive to these adverse conditions. Therefore, the adaptability of seedlings is very important for plant survival, especially in plants that inhabit grasslands or the construction of artificial grassland.RESULTS:In this study, we found a sheepgrass MYB-related transcription factor, LcMYB2 that is up-regulated by drought stress and returns to a basal level after rewatering. The expression of LcMYB2 was mainly induced by osmotic stress and was localized to the nucleus. Furthermore, we demonstrate that LcMYB2 promoted seed germination and root growth under drought and ABA treatments. Additionally, we confirmed that LcMYB2 can regulate LcDREB2 expression in sheepgrass by binding to its promoter, and it activates the expression of the osmotic stress marker genes AtDREB2A, AtLEA14 and AtP5CS1 by directly binding to their promoters in transgenic Arabidopsis.CONCLUSIONS:Based on these results, we propose that LcMYB2 improves plant drought stress tolerance by increasing the accumulation of osmoprotectants and promoting root growth. Therefore, LcMYB2 plays pivotal roles in plant responses to drought stress and is an important candidate for genetic manipulation to create drought-resistant crops, especially during seed germination.