Table of Content

20 July 2024, Volume 44 Issue 4

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Review



Roles of Superoxide Dismutase in Plant Response to Drought, Salinity and Cold Stress

Jianan GUO, Yipeng ZHAO, Yuanzhi YANG, Qingjie GUAN

2024, 44(4):  481-490.  doi:10.7525/j.issn.1673-5102.2024.04.001

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Superoxide dismutase（SOD） widely presents in plants and can be mainly classified into three categories： Mn-SOD， Fe-SOD and Cu/Zn-SOD. They play different defense roles in cells and enhance plant tolerance. Additionally， Ni-SOD in blue cells and marine organisms remains to be explored. In this paper， the physicochemical properties and mechanisms of action of SOD were analyzed according to the different metal ions contained in SOD， and the role of SOD in plants under stress conditions such as drought， salinity and cold were elucidated， and the role of SOD in plant growth and development in future was prospected， and a reference for studying the mechanisms of plant growth and development under adverse environments was provided.

Taxonomy



Taxonomic Status of Paragymnopteris in Pteridaceae and Its Relationship with Pellaea

Yue YIN, Wenli YANG, Hongyu HU, Gangmin ZHANG

2024, 44(4):  491-501.  doi:10.7525/j.issn.1673-5102.2024.04.002

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The taxonomy of Cheilanthoid ferns is difficult due to morphological convergence， and there are only five species in Paragymnopteris， the taxonomy of this genus is still controversial with its members assigned to several different genera by different scholars. In this paper， the phylogenetic relationships between Paragymnopteris and other cheilanthoid fernsbased on the datasets of seven tandem chloroplast gene segments， the chloroplast genome， and the ribosomal DNA were investigated， respectively. The results showed that these three genera formed a well-supported monophyletic clade and constituted the pellaeoid group. The five species of Paragymnopteris formed two clades and each clustered with members of Pellaea. Based on the above results， this study suggested that the Pellaea should be redefined and incorporated with the Paragymnopteris into the same genus.



Complementary Description of a New Recorded Species and Two Endemic Species of Corydalis from Shaanxi

Zhechao XU, Yong ZHANG, Weidong FAN, Ying YANG, Jialong LIU, Haofei ZHOU, Zhongyun ZHANG, Rui JI

2024, 44(4):  502-509.  doi:10.7525/j.issn.1673-5102.2024.04.003

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A species named Corydalis bulbilligera C.Y.Wu of sect. Elatae Fedde，from Shaanxi Province is newly recorded. Complementary description on the morphology， especially fruit characteristics， of C. nanwutaishanensis Z.Y.Su & Lidén and C. virginea Lidén & Z.Y.Su， which were endemic to Shaanxi province， was provided. The morphological comparison of the above mentioned three species was made， and the key table of species classification of sect. Elatae in Shaanxi Province was also compiled.



Supplementary Description of Primula lithophila and Two New Recorded Species of Primula in Guizhou Province

Xiao WANG, Guili YANG, Kang LUO, Xinxiang BAI

2024, 44(4):  510-516.  doi:10.7525/j.issn.1673-5102.2024.04.004

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Primula lithophila was an early species published on plant specimens， and curremt literature of its phenological period and many biological characteristics were incorrectly described， which made it difficult to define the species. This study adopted methods such as field investigation， literature review， specimen collection， and morphological feature comparison in the type locality， the supplementary description of its phenological period and biological characteristics was provided. The results indicated that： the petioles of P. lithophila did not have wings， and color was pink with few white， scape 10-25 cm length， pedicel 15-30 mm length， corolla tube about 16 mm and limb diameter 10-15 mm respectively. Capsule tubular， about 3 mm long， approximately half long of the persistent calyx. The flowering period was from September to February， and the fruiting period was from March to June. In addition， two new recorded species： P. pelargoniifolia G.Hao， C.M.Hu & Z.Y.Liu and P. tardiflora（C.M.Hu） C.M.Hu， were reported.

Systematic and Evolutionary



Foliar Epidermal Micromorphology of Eleven Species and One Variety of Simple-Leaved Sorbus

Xueyan WEI, Baomei TAN, Chi ZHANG, Jiabao LI, Xin CHEN

2024, 44(4):  517-527.  doi:10.7525/j.issn.1673-5102.2024.04.005

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To evaluate the taxonomic significance of leaf epidermal micromorphological characteristics， 11 species and one variety of simple-leaved Sorbus from sect. Aria and sect. Micromeles native to China were investigated using light microscopy（LM）and scanning electron microscopy（SEM）. The results showed that the shapes of epidermal cells wereirregular or polygonal-irregular. Anticlinal wall of polygonal cells was straight or arched， and anticlinal wall of irregular cells was arched or wavy. The area of epidermal cells varied significantly among taxa， and the size of the upper epidermal cells was larger than the lower epidermal cells. Cuticular ornaments such as ridges， striations， wrinkles， secondary thickening， thickened areas， and epicuticular waxy ornamented with crusts， granules， threads， and platelets were observed by scanning electron microscopy. Leaves were glabrous or with trichomes， and the position， color， density， and type of trichomes were important characters for the segregation of the taxa. Stomatal apparatuses were anomocytic and distributed in areole of abaxial epidermis. Guard cells had annular outer edges， with or without T-piece at stomatal pole. The cell size， length， width， area， density， and index of stomata varied significantly among taxa. Therefore， foliar epidermal micromorphology proved to be valuable for simple-leaved Sorbus taxa definition and identification.



Relationship Between the Differences in Leaves Morphology and Structure and Epiphyllous Bud Development of Tropical Water Lily before and after Leaf Expansion

Yuanyuan SUN, Tianqi YANG, Xingmei AI, Haoran LI, Caibao ZHAO, Xuan ZHANG

2024, 44(4):  528-539.  doi:10.7525/j.issn.1673-5102.2024.04.006

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To explore the relationship between leaf morphological characteristics and epiphyllous bud development of tropical water lilies， the viviparous and non-viviparous leaves of Nymphaea ‘Ruby’and N. ‘Blue Bird’ were used as materials， and the non-viviparous leaf of N. ‘Colorata’ was as control. The leaf morphological parameters of three cultivars were measured and compared， and the leaf anatomical structure during the leaf-rolling stage and leaf-expansion stage was observed using paraffin section. The results showed that all three cultivars had typical characteristics of tropical water lilies， the viviparous leaves of N. ‘Ruby’ and N. ‘Blue Bird’， except for the epiphyllous bud， their leaf length， leaf width， and leaf area were slightly lower than non-viviparous leaves， but there were no significant differences（P>0.05）， while the anatomical structural parameters of the leaves changed with the leaf development. Although the upper and lower epidermis， sponge tissue of the leaves of viviparous N. ‘Ruby’and N. ‘Blue Bird’ were thinner at the leaf-expansion stage， both were higher than that of non-viviparous leaves. However， the palisade tissue and the ratio of palisade to sponge increased at the leaf-expansion stage， and were lower than that of non-viviparous leaves， indicating that the development of the viviparous buds resulted in a decrease in the structural compactness of the palisade tissue， while the looseness of sponge tissue structure increased， but it was not related to the leaf thickness. The ratio of palisade to sponge and cell structure compactness of the non-viviparous variety N. ‘Colorata’ were significantly higher than those of the viviparous variety N. ‘Ruby’. In addition， the plasticity variation of each indicator was relatively high， and there was a certain correlation and an obvious co-evolution. Principal component analysis showed that the thickness of the upper and lower epidermis， spongy tissue， palisade tissue， the ratio of palisade to spongy， and the compactness and looseness of the leaf tissue structure might be regarded as the main indicators to reflect the anatomical structure characteristics of the viviparous leaves of water lilies. Viviparous leaves responded to epiphyllous bud development by changing the structure of mesophyll tissue.

Genetic and Breeding



Phenotypic Diversity Analysis of Saxifraga stolonifera

Shimei TANG, Anqi HUANG, Zhilin CHEN, Jialin LUO, Xin LI, Yuxuan JIN, Daike TIAN

2024, 44(4):  540-553.  doi:10.7525/j.issn.1673-5102.2024.04.007

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In order to better understand the intraspecific diversity of Saxifraga stolonifera and to explore the possibility of its classification， and to provide reference for the resource protection and innovative utilization of S. stolonifera germplasms， 33 traits from 43 populations of S. stolonifera in China were investigated， and the diversity of phenotypic traits was analyzed by numerical trait variation analysis， qualitative trait genetic diversity analysis， correlation analysis， principal component analysis and cluster analysis. The results showed that： （1）The coefficient of variation of numerical traits was 0.05-0.67， and the diversity index of qualitative traits was 0.19-1.39， and the distribution pattern of maculation and leaf color diversity were high among populations， and the branch number and the ratio of leaf length to width of stolon were the most unstable and the most stable traits， respectively. （2）The coefficient of variation of numerical and derived traits， and the diversity index of quality traits were generally high， and the contribution rates of each principal component were relatively scattered， so it was unsuitable to classify the species into different taxa only by morphological traits. （3）There were differences in the correlation of different personality traits among populations of S. stolonifera， and significant correlations included leaf length and width， length of long lower petal and length of short lower petal， width of long lower petal and width of short lower petal， respectively. （4）Based on the results of morphological clustering， S. stolonifera in China could be divided into three branches， which exhibited certain regional character. ClusterⅠ was composed of eight Southwest populations， two East China populations， and three Northwest populations； ClusterⅡ consisted of four populations from East China， four populations from Central China， four populations from Southwest China， and one population from Northwest China， so Cluster Ⅱ was widely distributed； Cluster Ⅲ consisted of ten Central China populations， six Southwest populations， and one East China population.



Coupling Evaluation of Growth and Wood Properties of Pinus koraiensis Half-sib Families

Xuelai WANG, Xiaoting LIU, Liran WANG, Shitong LI, Taijin ZHANG, Jiafeng ZHANG, Jinghua XU, Guanzheng QU, Xiyang ZHAO

2024, 44(4):  554-564.  doi:10.7525/j.issn.1673-5102.2024.04.008

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Pinus koraiensis is an important tree species used as fruit in northeast China， but due to its long growth cycle， its genetic improvement progress is slow. In order to evaluate and screen the elite P. koraiensis germplasm resources， 36 half-sib families of 20-year-old P. koraiensis from Xiyang forest seed orchard in Jilin Province were used as materials， and the growth traits and wood properties of different families were investigated. The results of variance analysis showed that the differences of each trait among families reached extremely significant level（P<0.01）， and the phenotypic variation coefficients of different investigated traits was 5.89%~45.21%. Except trait straightness（0.46）， the family heritabilities of other traits exceeded 0.5， which all belonged to high heritability. Correlation analysis results showed that the growth traits such as tree height and diameter at breast height had significantly positive correlations（r>0.663）. The contents of hemicellulose， cellulose and holocellulose were significantly correlated with each other among wood traits， while only cellulose and holocellulose were negatively correlated with some growth traits among growth traits and wood properties. The results of principal component analysis showed that 14 traits constituted five principal components， and the cumulative contribution rate was 79.24%. The comprehensive evaluation method was used to evaluate 36 half-sib families， with an admission rate of 10%， three elite families（PK61， PK29 and PK22） were selected according to their growth traits， and the genetic gain of each growth trait ranged from 6.41%- 33.91%. According to wood properties， three elite families（PK16， PK78 and PK10） were preliminarily screened， and the genetic gain of each wood trait ranged from 1.08%-6.72%. Combined with growth and wood properties， three excellent families（PK61， PK29 and PK44） were selected， and the genetic gain of each index ranged from 0.27%-37.28%. The elite families selected in this study can provide the basis for the selection of improved varieties of P. koraiensis.

Physiology and Ecology



Analysis of the Alleviating Mechanism of Selenium on Cadmium Stress in Astragalus membranaceus

Hongzheng WANG, Shaolian YU, Yuehua MA, Lingyun REN, Hongwei NI

2024, 44(4):  565-575.  doi:10.7525/j.issn.1673-5102.2024.04.009

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In order to reveal the mechanism of selenium alleviating the cadmium stress in Astragalus membranaceus， the traditional medicinal plant A. membranaceus was used as materials， and the roles of ion antagonism， antioxidant enzyme system， heavy metal chelates and isoflavones in alleviating the Cd stress by Se were clarified comprehensively using hydroponic cultivation method. The results showed that 10 μmol·L^-1 Se significantly improved the growth of A. membranaceus seedlings under 50 μmol·L^-1 Cd stress， and reduced the accumulation of reactive oxygen species and membrane lipid peroxidation levels. The addition of Se significantly reduced the Cd content in all parts of A. membranaceus under Cd treatment. Meanwhile， the addition of Cd also reduced the Se content， indicating that it has a significant antagonistic effect on the absorption of Se and Cd. Se reduced the activities of POD， SOD， APX， CAT and GR in all parts of A. membranaceus under Cd stress. Correlation analysis showed that various antioxidant enzymes activities were significantly positively correlated with {\mathrm{O}}_{\mathrm{2}}^{?-} content， suggesting that the changes of antioxidant enzyme activity were more adapted to the level of reactive oxygen species in the plants. In addition， the addition of Se also reduced the content of non-protein sulfhydryl groups and metallothionein in all parts of A. membranaceus exposed to Cd treatment， and the contents showed a good positive correlation with the Cd content in corresponding part， indicating that the content of heavy metal chelates was regulated by the Cd content in various parts. Unlike antioxidant enzymes and metallothionein， the contents of three isoflavone components were significantly increased by Se addition in the roots of A. membranaceus seedlings under Cd stress. Furthermore， the expression levels of key enzyme genes in the isoflavone synthesis pathway， including CHS， IFS， I3'H， IOMT and UCGT， were significantly upregulated by Se under Cd stress. In summary， Se decreased the content of Cd in A. membranaceus seedlings under Cd treatment by antagonizing Cd during the absorption process， and reduced the degree of plant stress. At the same time， Se improved the tolerance of plant to Cd stress by upregulating the synthesis of secondary metabolites such as isoflavones.



Characteristics of Temperature Stratification on Germination Physiology and Metabolism of Acanthopanax senticosus Seeds at Different Stages

Yanjun REN, Xiaorui GUO, Zixuan YU, Kexin WU, Yu SUN, Ning CHEN, Qiaomu YOU, Kaixin XING

2024, 44(4):  576-589.  doi:10.7525/j.issn.1673-5102.2024.04.010

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To investigate the dormancy type and physiological and metabolic characteristics of Acanthopanax senticosus seeds during germination， the seeds from northeast China were treated with sand accumulation for 140 days under different temperature conditions（20 ℃， 4 ℃， 20 ℃/4 ℃） respectively. Five distinct stages were identified based on embryo phenotypic changes，and the dynamic changes in endogenous hormones， main nutrient substances and their hydrolases， antioxidant system， and metabolomics during these five stages were examined respectively. The results revealed that： （1）A. senticosus seeds exhibited good water absorption； while the constant temperature of 20 ℃ only promoted embryo elongation， but not germination. There was no increase in embryo rate at 4 ℃， and the embryo rate increased and the seeds germinated only when the temperature was maintained at 20 ℃ for 0-110 d and 4 ℃ for 110-140 d. （2）As the embryo growth rate increased， gibberellic acid content increased while abscisic acid content decreased. The levels of indoleacetic acid， indolebutyric acid， and naphthenic acetic acid all decreased. Fat content decreased while soluble sugar content increased. Fat content showed a significant negative correlation with lipohydrolase activity as well as a highly significant negative correlation with soluble sugar content. （3）A total of 92 differential metabolites were screened， and the carbon metabolism， energy metabolism， and antioxidant metabolism were the major differential metabolic pathways. Additionally， there were difference in sesquiterpene and triterpene biosynthesis， fatty acid biosynthesis and glyceride metabolism. In conclusion， seeds of A. senticosus were morphological and physiological dormancy， and variable temperature stratification was a necessary condition to break seed dormancy， and endogenous hormones might regulate seed dormancy and germination. Macromolecular nutrients such as fat were decomposed by hydrolases to provide material and energy for seed germination， which was also one of the necessary conditions for seed germination. This study provided theoretical guidance for identifying seed dormancy types and artificial propagation of A. senticosus.



The Responses of Rhizosphere Soil of Caragana korshinskii under Soil Sterilization, AM Fungi Inoculation and N Addition

Yixue LI, Dongmei YE, Longfei HAO, Tingyan LIU, Jiajing DUAN, Zhengying NIE

2024, 44(4):  590-601.  doi:10.7525/j.issn.1673-5102.2024.04.011

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Based on the fact that soil microorganisms can enhance the adaptability of plants to global change， the effects of soil microorganisms on the ecological stoichiometric characteristics of rhizosphere soil microorganisms were studied under the background of nitrogen deposition， and then the regulation of changes in ecological stoichiometric characteristics on the soil microbial nutrient limitation was explored. Under the premise of soil sterilization treatment（sterilized soil（+S） and non-sterilized soil（-S））， one-year-old potted seedlings of Caragana korshinskii were inoculated in two ways（inoculation（+M） and without inoculation（-M））， and nitrogen addition treatments（no nitrogen application（CK）， low nitrogen（LN， 3 g·m^-2·a^-1）， high nitrogen（HN， 6 g·m^-2·a^-1）） were set up. Compared with the original microbial community composition in non-sterilized soil without fungus inoculation， the correlation between ecological stoichiometric characteristics of microhabitat and microbial nutrient limitation under different treatments was explored.Results were as follows： （1）In sterilized soil treatment， the relative abundance of fungi in the rhizosphere soil of C. korshinskii mycorrhizal seedlings was significantly increased by 82.20%， 25.00% and 59.84% under CK， LN and HN treatments than that of non-mycorrhizal seedlings， respectively. （2）In the treatment of non-sterilized soil， the microbial biomass carbon-to-phosphorus ratio in the rhizosphere soil of non-mycorrhizal C. korshinskii seedlings under LN treatment was lower by 46.28% compared to CK treatment（P<0.05）， while that of mycorrhizal seedlings was 56.76% higher compared to CK treatment（P<0.05）. （3）Under the nitrogen addition treatments， stoichiometry of carbon and nitrogen-related soil enzyme activity， stoichiometry of carbon and phosphorus-related soil enzyme activity， and vector length in the rhizosphere soil of C. korshinskii non-mycorrhizal seedlings under sterilized soil treatment were significantly lower than those of mycorrhizal seedlings（P<0.05）. （4）PLS-PM path analysis showed that the total effect coefficient of microbial regulation on microbial nutrient limitation was greater than that of nitrogen addition treatment. In summary， soil indigenous microorganisms and mycorrhizal fungi synergistically regulated the enzymatic stoichiometric ratio of rhizosphere soil， and enhanced the adaptation of soil microbial nutrient limitation to nitrogen addition.



Functional Components and Antioxidant Activity of Aralia elata Leaves at Different Harvesting Periods

Meixin TANG, Zejia DUAN, Yun GUO, Ye ZHANG, Jiaotong LI, Hengtian ZHAO, Zhonghua TANG

2024, 44(4):  602-611.  doi:10.7525/j.issn.1673-5102.2024.04.012

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To provide a theoretical basis for the timely harvesting of Aralia elata， the cultivated A.elata was used as experimental materials， and the biomass， photosynthetic pigment content， total phenolic content， total flavonoid content， and antioxidant capacity of A. elata leaves in different harvesting periods（S1 period， April 10th， 2023； S2 period， April 30th， 2023； S3 period， May 20th， 2023； S4 period， June 9th， 2023） were analyzed respectively. Meanwhile， the high-performance liquid chromatographic（HPLC） method was established to determine the contents of araloside X， araloside V， and araloside A. Based on high-performance liquid chromatography-mass spectrometry metabolomics technology， the differences in secondary metabolites of A. elata at different harvesting periods were compared and analyzed. The results showed that： （1）The fresh weight， dry weight， and photosynthetic pigment content of A. elata leaves increased with growth， and reached the maximum value in the S4 period. （2）The contents of total phenol and total flavone reached the maximum value in the S1 period（1.36 mg·g^-1， 29.38 mg·g^-1）. （3）The scavenging ability of DPPH radical was the strongest in the S1 period（IC₅₀ of 0.262 g·L^-1） and the scavenging ability of ABTS radical was the strongest in the S2 period （IC₅₀ of 0.511 g·L^-1）. （4）The content of araloside A reached a maximum of 12.90 mg·g^-1 in the S4 period. The contents of araloside V and X in the S2 period were significantly higher than those in other periods， which were 1.53 and 3.30 mg·g^-1 respectively. （5）A total of 24 phenolic metabolites were identified， and the total amount of phenolic compounds in the four periods were 64.84， 119.31， 101.95 and 89.32 mg·g^-1， respectively. Among the total phenolic compounds， the C6C1 backbone compounds （protocatechuic acid and gentisic acid）， the C6C3C6 backbone compounds （rutin）， and the C6C3 backbone compounds （caffeic acid） were significantly accumulated in the S2 period. In conclusion， considering the content of functional components， antioxidant activity， and edibility， the S2 period is the most suitable time for harvesting.



Ecological Adaptability of Three Native Tree Species after Artificial Cultivation in Desert Area of Hetao Plain

Yaowen SUN, Yingmei MA, Xiaomin REN, Feng HAN, Xin CHEN, Lang ZUO

2024, 44(4):  612-624.  doi:10.7525/j.issn.1673-5102.2024.04.013

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The establishment of shelter forests in the northeastern region of Ulan Buh Desert is a crucial ecological barrier to protect agricultural productivity within the eastern Hetao Plain. However， the lack of attention towards scientific research on artificial afforestation has resulted in a decline tendency in many shelter forest systems. The investigation of ecological adaptability of indigenous tree species after artificial cultivation was a crucial approach to guide the establishment and sustainable management of plantations. In order to further investigate the ecological adaptability of native tree species in Ulan Buh Desert after artificial cultivation， three native tree species： Ammopiptathus mongolicus， Zygophyllum xanthoxylon and Prunus mongolica were used as materials. By measuring the epidermal morphology， anatomical structure， and physiological indices of functional leaves， in conjunction with local meteorological data， the adaptive mechanisms of these plants to arid desert environments were clarified. The results showed that each of three plants exhibited distinct adaptations to arid desert environment in different ways. A. mongolicus enhanced light exposure and photosynthetic efficiency by augmenting leaf area， strengthened leaf mechanical defenses through dense epidermal hairs and well-developed cuticle， reduced light-induced damage and water transpiration， and maintained cellular water balance to minimize lipid peroxidation. The leaves of P. mongolica were clustered， by increasing number of leaves， the light receiving area was increased and the photosynthetic efficiency was improved， and by curling the leaves to avoid strong light burns， the water transpiration was reduced and the cell water balance was maintained by specializing the stomatal position（all the stomata were distributed on the lower surface of the leaves）， developed vascular bundles and rich mucous cells and crystal structures， and reduced cell membrane lipid peroxidation. The leaves of Z. xanthoxylon showed a cylindrical strip structure. By reducing the wind resistance， the probability of wind-sand flow damage to the leaves was reduced. The antioxidant enzyme activity and osmotic adjustment substance content in leaves was enhanced by physiological metabolic regulation， and the balance of cell water and reactive oxygen species metabolism was maintained. These findings suggested the different adaptation strategies adopted by the three plants in response to the desert environment， and provided the new ideas for introduction and domestication of native tree species in the northeastern Ulan Buh Desert.

Molecular biology



Cloning and Expression Activity Analysis of Rubisco Small Subunit Gene Promoter in Populus × xiaohei

Jiayu CAO, Lina CAO, Qiaoyi ZHANG, Shuang ZHANG, Zhibao HU, Tangrui ZHAO, Zhiru XU, Chunming LI, Xiankui QUAN, Guanjun LIU

2024, 44(4):  625-633.  doi:10.7525/j.issn.1673-5102.2024.04.014

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Ribulose-1，5-diphosphate carboxylase/oxygenase（Rubisco） is a key enzyme in photosynthesis， in which small subunits（rbcS） are encoded by nuclear genes and mainly expressed in leaves. In this study， the Rubisco small subunit genes PxrbcS1 and PxrbcS2， which are highly expressed in Populus × xiaohei’s leaves， were determined by RT-qPCR technology， and their upstream promoters of 2 240 and 2 174 bp were cloned respectively. The results of promoter element analysis showed that the promoters of PxrbcS1 and PxrbcS2 had multiple elements related to light induced expression， including G-box， MRE and Box4 elements. Plant expression vectors of pBI-121-pPxrbcS1：：GUS and pBI-121-pPxrbcS2：：GUS were constructed and genetically transformed into 84K poplar（P. alba×P. glandulosa）. GUS histochemical staining and qPCR expression analysis showed that the promoters of PxrbcS1 and PxrbcS2 could drive the GUS gene to express in 84K poplar leaves with high specificity. In conclusion， the above results showed that PxrbcS1 and PxrbcS2 promoters with high leaf expression activity were successfully cloned from P.×xiaohei， and the promoters might be applied to the study of gene functions related to plant photosynthesis and genetic operations to improve photosynthesis in plants， including poplars.



Composition of the Genome Repeat Sequences of Psathyrostachys juncea and Its Distribution on the Chromosomes in Leymus Species

Ying YANG, Yuan LI, Jie CHEN, Bo LIU, Quanwen DOU

2024, 44(4):  634-640.  doi:10.7525/j.issn.1673-5102.2024.04.015

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Psathyrostachys juncea was considered an important ancestral species of Leymus. The genomic Cot-1 DNA library with highly repeat sequences of Psa. juncea was constructed， and sequenced and characterized， and the results showed that the library could be classified into six types： retrotransposons， transposons， satellite DNA， LZ-NBS-LRR， uncharacterized sequences， and retrotransposon LTR mixed LTR/Copia， and the proportions were 49.5%， 1.0%， 28.7%， 5.9%， 13.9% and 1.0% of the Cot-1 DNA， respectively. Furthermore， two satellite DNAs and five retrotransposon sequences were used as probes， and chromosomes in Psa. juncea， Leymus secalinus and L. racemosus were detected by florescence in situ hybridization （FISH）. The results showed that the hybridization signals of satellite DNA sequences TaiI-family and pSc250-family were mainly distributed at the ends of chromosomes， and the number of TaiI-family hybridization signals were 20， 16， 7， and 18 in Psa. juncea， L. secalinus， L. racemosus （PI 531811） and L. racemosus （PI 531812）， respectively， and the number of pSc250-family hybridization signals were 17 and 24 in Psa. juncea and L. secalinus， respectively， but no signal was detected in two L. racemosus samples. The distribution of retrotransposon sequences on the chromosomes of three detected species was basically dispersed， and the distribution of chromosome sequences in Leymus species showed a tendency of homogenity. Especially， clone sequences pPj-44 and pPj-28 showed significant differences in signal distribution between Psa. juncea and Leymus species， suggesting sequence expansion and contraction， respectively， during allopolyploidization， and clone sequence pPj-77 only differentiated the hybridization intensity of 10 chromosomes from the rest of the chromosomes in one L. racemosus（PI 531812）. The results suggested the repeats of Psa. juncea evolved rapidly and had homogenous diffusion during the polypoid formation of Leymus species and the repeat composition might be significant different among different Leymus species.