A preliminary review on population parameters and genetic diversity in Oreochromis mossambicus:meta-regression and haplotype diversity

Assessment of population parameters and genetic diversity is critical for the economic and threatened species,including Oreochromis mossambicus.The morphometric and population parameters data for O.mossambicus were extracted based on the available literature from various countries.Phylogenetic and genetic diversity were analyzed based on cytochrome c oxidaseⅠ(COⅠ)sequences of the mitochondrial DNA(mtDNA)gene.The population parameters(asymptotic length(L_(∞)),growth constant(K),growth performance index(Ø),approximate maximum age(t_(max)),standard length(L),and weight(W))results revealed a variation among the populations studied.The result categorized the population into two groups:South African populations located close to Zimbabwe,Mozambique,Namibia,Australia,and China,as GroupⅠ,and the Indian population placed close to Thailand,the Philippines,Indonesia,America,and Mexico as GroupⅡ.The meta-regression results reveal that temperature strongly correlated with weight.In contrast,other population factors showed no significant differences.The haplotype analysis based on COI of mtDNA displayed 21 haplotypes,which revealed low nucleotide(π=0.025)diversity.Haplotype diversity(HD)was 0.65.The haplotype analysis showed that Tajima(D)was negative(-0.82)and Fu’s Fs was positive(2.2),and both tests were not significant(P>0.05),whereas the overall F-statistic(F_(st))value was 0.40(P<0.001).In conclusion,population parameters,and genetic analysis indices a high variation among the O.mossambicus from different locations.Additionally,the population parameters for O.mossambicus in America,Asia,and Australia were more influenced by ecological factors.At the same time,the population parameters in the African continent were influenced more by genetic factors.

Genome-wide SNP markers provided insights into the reproductive strategy and genetic diversity of the green tide causative species Ulva prolifera in China

Ulva prolifera is the causative species of the annually occurring large-scale green tides in China since 2007.Its specific biological features on reproductivity strategies,as well as intra-species genetic diversity,are still largely unknown,especially at the genome level,despite their importance in understanding the formation and outbreak of massive green tides.In the present study,the restriction site-associated DNA genotyping approach(2b-RAD)was adopted to identify the genome-wide single-nucleotide polymorphisms(SNPs)of 54 individual thalli including samples collected from Subei Shoal in 2019 and Qingdao coast from 2019 to 2021.SNPs genotype results revealed that most of the thalli in 2019 and 2020 were haploid gametophytes,while only half of the thalli were gametophytes in 2021,indicating flexibility in the reproductive strategies for the formation of the green tides among different years and the dominance of asexual and vegetative reproductive mode for the floating period.Besides,population analysis was conducted,and it revealed a very low genetic diversity among samples from Subei Shoal and the Qingdao coast in the same year and a higher divergence among samples in different years.The results showed the efficiency of 2b-RAD in the exploration of SNPs in U.prolifera and provided the first genome-wide scale evidence for the origin of the large-scale green tides on the Qingdao coast.This study improved our understanding of the reproductive strategy and genetic diversity of the green tide causative species and will help further reveal the biological causes of the green tide in China.

Epidemiological Surveillance: Genetic Diversity of Rotavirus Group A in the Pearl River Delta, Guangdong, China in 2019

Objective This study aimed to understand the epidemic status and phylogenetic relationships of rotavirus group A(RVA)in the Pearl River Delta region of Guangdong Province,China.Methods This study included individuals aged 28 days–85 years.A total of 706 stool samples from patients with acute gastroenteritis collected between January 2019 and January 2020 were analyzed for 17 causative pathogens,including RVA,using a Gastrointestinal Pathogen Panel,followed by genotyping,virus isolation,and complete sequencing to assess the genetic diversity of RVA.Results The overall RVA infection rate was 14.59%(103/706),with an irregular epidemiological pattern.The proportion of co-infection with RVA and other pathogens was 39.81%(41/103).Acute gastroenteritis is highly prevalent in young children aged 0–1 year,and RVA is the key pathogen circulating in patients 6–10 months of age with diarrhea.G9P[8](58.25%,60/103)was found to be the predominant genotype in the RVA strains,and the 41 RVA-positive strains that were successfully sequenced belonged to three different RVA genotypes in the phylogenetic analysis.Recombination analysis showed that gene reassortment events,selection pressure,codon usage bias,gene polymorphism,and post-translational modifications(PTMs)occurred in the G9P[8]and G3P[8]strains.Conclusion This study provides molecular evidence of RVA prevalence in the Pearl River Delta region of China,further enriching the existing information on its genetics and evolutionary characteristics and suggesting the emergence of genetic diversity.Strengthening the surveillance of genotypic changes and gene reassortment in RVA strains is essential for further research and a better understanding of strain variations for further vaccine development.

Genetic diversity of the S-type small subunit ribosomal RNA gene of Plasmodium knowlesi isolates from Sabah,Malaysian Borneo and Peninsular Malaysia

Objective:To determine the genetic diversity of Plasmodium(P.)knowlesi isolates from Sabah,Malaysian Borneo and Peninsular Malaysia,targeting the S-type SSU rRNA gene and including aspects of natural selection and haplotype.Methods:Thirty-nine blood samples infected with P.knowlesi were collected in Sabah,Malaysian Borneo and Peninsular Malaysia.The S-type SSU rRNA gene was amplified using polymerase chain reaction,cloned into a vector,and sequenced.The natural selection and haplotype of the S-type SSU rRNA gene sequences were determined using DnaSP v6 and illustrated using NETWORK v10.This study's 39 S-type SSU rRNA sequences and eight sequences from the Genbank database were subjected to phylogenetic analysis using MEGA 11.Results:Overall,the phylogenetic analysis showed no evidence of a geographical cluster of P.knowlesi isolates from different areas in Malaysia based on the S-type SSU rRNA gene sequences.The S-type SSU rRNA gene sequences were relatively conserved and with a purifying effect.Haplotype sharing of the S-type SSU rRNA gene was observed between the P.knowlesi isolates in Sabah,Malaysian Borneo,but not between Sabah,Malaysian Borneo and Peninsular Malaysia.Conclusions:This study suggests that the S-type SSU rRNA gene of P.knowlesi isolates in Sabah,Malaysian Borneo,and Peninsular Malaysia has fewer polymorphic sites,representing the conservation of the gene.These features make the S-type SSU rRNA gene suitable for comparative studies,such as determining the evolutionary relationships and common ancestry among P.knowlesi species.

Genetic Diversity and Combining Ability of Developed Maize Lines to Realize Heterotic and High Yielding Hybrids for Arid Conditions

Developing high-yield maize hybrids is critical for sustaining maize production,especially in the face of rapid climate changes and the growing global population.Exploring the genetic diversity and combining ability in parental inbreds is needed for developing such high-yielding hybrids.Consequently,this study aimed at evaluating parental genetic diversity employing simple sequence repeats(SSR)markers,estimating effects of general(GCA)and specific(SCA)combining abilities for grain yield and yield contributing characters,identifying high yielding hybrids,and evaluating the association of SCA effects and performance of hybrids with genetic distance.Half-diallel mating scheme was utilized to develop 21 F_(1) hybrids from seven diverse maize inbred lines.The F_(1) hybrids along with check hybrid(SC-10),were investigated in a field trial over two growing seasons under arid conditions.The assessed F_(1) hybrids displayed significant genetic variations across all recorded traits.The inbreds P_(1) and P_(3) were detected as effective combiners to develop early maturing hybrids.Additionally,P_(3) and P_(4) were recognized as better combiners for improving grain yield and yield attributed characters.The hybrids P_(1)×P_(5) and P_(4)×P_(7) displayed significant SCA effects coupled with favorable agronomic performance.These hybrids are recommended for further evaluation and release as variety for arid environments to increase total maize production and contribute to food security.The alleles per locus differed between 2 and 5,with average of 3.5 alleles/locus.The polymorphic information content(PIC)altered between 0.21 to 0.74,with a mean of 0.56.Unweighted neighbor-joining tree grouped the inbred lines into three clusters,providing a valuable tool to decrease the crosses needed to be assessed in the trial field.Parental genetic distance varied from 0.63 to 0.90,averaging 0.79.The relationship between genetic diversity assessed through SSR markers and SCA effects was insignificant for all considered traits.Otherwise,SCA demonstrated a significant correlation with hybrid performance,suggesting that SCA serves as a reliable predictor for hybrid performance.The assessed maize inbred lines and developed hybrids revealed substantial genetic variability,offering valuable resources for enhancing maize productivity under arid conditions.The identified promising inbred lines(P_(1),P_(3),and P_(4))might be regarded as effective combiners for developing early-maturing genotypes and excellent combiners for enhancing yield attributes.Notably,the developed hybrids P_(1)×P_(5) and P_(4)×P_(7) possessed significant SCA alongside superior yield traits.SCA demonstrated a significant correlation with hybrid performance,suggesting its potential as a reliable predictor for the performance of developed hybrids.

Genetic Diversity of Jute Mallow (Corchorus spp.) Accessions Based on ISSR Markers

Jute mallow is a nutritious leafy vegetable. The leaves are rich in proteins, vitamins and essential amino acids. Molecular characterization of Jute mallow with focus on improvement of leaf yield is scarcely reported. In the present study, inter sequence simple repeats (ISSR) molecular markers were employed to assess genetic diversity and relationships of 83 accessions of Jute mallow from different parts of Africa and Asia conserved at the World Vegetable Center East and Southern Africa. A total of 89 bands were amplified by 8 ISSR primers. Number of polymorphic bands per primer ranged from 2 to 6 with an average of 2.75 bands per primer. Polymorphic information content (PIC) values ranged from 0.390 to 0.760 with average of 0.53. Average Nei’s gene diversity (h) and Shannon’s information index (I) were 0.335 and 0.494 respectively. The highest pairwise genetic distance was 0.431 observed in a population from East Africa accessions. PC1 and PC2 axis explained 21.69% and 11.66% of the total variation respectively. UPGMA cluster analysis grouped the accessions into six main clusters at genetic similarity coefficient of 0.53 as standard value for classification. These results have important implications for jute mallow breeding and conservation.

Genetic diversity and occult hepatitis B infection in Africa: A comprehensive review

BACKGROUND Occult hepatitis B infection(OBI)is a globally prevalent infection,with its frequency being influenced by the prevalence of hepatitis B virus(HBV)infection in a particular geographic region,including Africa.OBI can be transmitted th-rough blood transfusions and organ transplants and has been linked to the development of hepatocellular carcinoma(HCC).The associated HBV genotype influences the infection.AIM To highlight the genetic diversity and prevalence of OBI in Africa.METHODS This systematic review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and involved a comprehensive search on PubMed,Google Scholar,Science Direct,and African Journals Online for published studies on the prevalence and genetic diversity of OBI in Africa.RESULTS The synthesis included 83 articles,revealing that the prevalence of OBI varied between countries and population groups,with the highest prevalence being 90.9%in patients with hepatitis C virus infection and 38%in blood donors,indicating an increased risk of HBV transmission through blood transfusions.Cases of OBI reactivation have been reported following chemotherapy.Genotype D is the predominant,followed by genotypes A and E.CONCLUSION This review highlights the prevalence of OBI in Africa,which varies across countries and population groups.The study also demonstrates that genotype D is the most prevalent.

Impact of Genetic Diversity of Uropathogenic Escherichia coli and Klebsiella pneumoniae Strains on the Dissemination of Extended Spectrum Beta-Lactam Resistance Genes in Côte d’Ivoire

The increase and spread of bacterial resistance to extended-spectrum beta-lactam antibiotics are reported in many infections and are a real public health problem worldwide. Drug pressure is a factor that favors the emergence of a population of better adapted bacteria. However, there is no literature highlighting the genetic diversity and evolutionary structure of E. coli and K. pneumoniae in an environment with high selection pressure in Côte d’Ivoire. The objective of this study was to evaluate the genetic diversity of E. coli and K. pneumoniae strains circulating at the HKB Hospital in Abobo and at the Daloa Regional Hospital and its impact on the dissemination of extended spectrum beta-lactam resistance genes. A total of 39 strains isolated from the urinary tract of infected patients, including 30 strains of E. coli and 9 strains of K. pneumoniae were studied. A total of 39 strains isolated from the urinary tract of infected patients, including 30 strains of E. coli and 9 strains of K. pneumoniae were studied. From genomic DNA extracts, ESBL resistance genes were amplified by PCR and sequenced, in addition to genetic typing by ERIC-PCR. The data obtained were submitted to genetic and bioinformatics analyses. The results have shown a genetic diversity important in E. coli and K. pneumoniae with diversity indexs (SID) ranging from 0.5 to 0.77. The genetic structure of the bacterial species studied has shown a clonal distribution of strains with clones expressing TEM-9 and CTX-M-15 variants. Also, this clonal structure was correlated with the spread of resistance genes in E. coli and K. pneumoniae. The spread of resistant clones is a factor that might limit the fight against antibiotic resistance.

Genetic Diversity in Cowpea (Vigna unguiculata (L.) Walp) under Two Growing Conditions*

This study explores the use of genetic variability for advancing the genetic improvement of Cowpea (Vigna unguiculata (L.) Walp), particularly in response to insect infestation stress. Over a period spanning 2015 to 2017, forty accessions of cowpeas were evaluated to determine their variability under both insecticide spray and no insecticide spray conditions at the Teachings and Research Farms, Federal University of Agriculture, Abeokuta. The experimental design was a randomized complete block design in three replicates. The accessions were evaluated for plant height, leaf length, leaf width, number of days of 50% flowering, number of pods per plant, pod length, number of seeds per plant, 100-seed weight, and seed yield. Data collected were subjected to principal component and single linkage cluster analyses. Principal axis I (PCA1) accounted for 39% and 35% under insecticide spray and no insecticide spray respectively to the total variation in the accessions. Plant height with a factor score of 0.38, leaf length (0.41), number of leaves (0.37), and 100-seed, weight (0.30) was related to PCAI under insecticide spray while leaf width (0.32). Pod length (0.37) and number of seeds/plant (0.38) were significant to PCA1 under no insecticide spray. Notably, accessions such as SAMPEA6, SAMPEA10, IFE-Brown, and IFE-BPE exhibited consistent performance across both conditions, while others displayed condition-specific attributes. For instance, NGB1063, NGB1152, and NGB1093 demonstrated distinct traits under insecticide spray, while NGB1146 and NGB1124 exhibited notable characteristics under no insecticide spray conditions. Therefore, identifying these forty accessions with desirable traits hold promise for future genetic improvement efforts of cowpea cultivation in Nigeria and beyond.

Investigating the genetic diversity of several varieties of Iranian tomato (Solanum lycopersicum) using RAPD and ISSR molecular markers

Background:Numerous studies have demonstrated the existence of approximately 7,500 genetic tomato varieties worldwide.Hence,it is crucial to assess the genetic diversity among tomato cultivars.This study aimed to investigate the genetic diversity of selected Iranian tomato cultivars(Solanum lycopersicum)using RAPD and ISSR molecular markers.Method:Ten RAPD primers and ten ISSR primers were employed to assess the genetic diversity among 10 tomato cultivars:Matin,RFT 112,Hirad,Golsar,Raha,Hengam,Hedah,Fasa,JS12,and Emerald.Data analysis involved the UPGMA algorithm and NTYSYSpc software.Results:RAPD analysis revealed close genetic proximity between Fasa and JS12,as well as between Raha and Hadieh.Conversely,the RFT 112,Hengam,Hirad,and Emerald cultivars exhibited significant genetic diversity within this group.ISSR primer analysis identified Hengam as the most diverse variety,while Matin,Emerald,and Vibrid,as well as Raha and JS12,displayed genetic similarities with minimal observed diversity.Furthermore,the overall analysis of the cultivars using RAPD and ISSR markers indicated that Hengam exhibited the highest diversity among all the varieties.Notably,Raha and JS12 demonstrated limited diversity in this analysis.Conclusion:This research demonstrates substantial genetic diversity among the investigated tomato varieties,with Hengam displaying the highest diversity within this group.Furthermore,ISSR markers proved more effective in determining genetic diversity in tomato plants.

Genetic Diversity of Volatile Components in Xinjiang Wild Apple (Malus sieversii)

To evaluate genetic relationships using qualitative and/or quantitative differentiation of volatile components in Xinjiang Wild Apple （Malus sieversii （Lebed.） Roem.） and to acquire basic data for the conservation and utilization of the species, aroma components in ripe fruit of M. sieversii obtained from 30 seedlings at Mohe, Gongliu County, Xinjiang Autonomic Region, China, and in ripe fruit of 4 M. purnila cultivars （＇Rails＇, ＇Delicious＇, ＇Golden Delicious＇, and ＇Fuji＇） were analyzed using head space-solid phase microextraction and gas chromatography-mass spectrometry. The results indicated that the values of similarity coefficient concerning volatile types between the two species were in accordance with the evolution of M. pumila cultivars （forms）, and that M. sieversii seedlings showed considerable genetic variations in these aspects： the total content of volatile components, the classes and contents of each compound classes, the segregation ratio, and content of main components. The results showed significant difference among seedlings and wide genetic diversity within the populations. Comparison of the volatile components in M. sieversii with those in M. pumila cultivars showed that the common compounds whose number were larger than five with the contents over 0.04 mg/L simultaneously between M. sieversii and M. pumila cultivars belonged to esters, alcohols, aldehydes or ketones. This suggests fundamental identity in main volatile components of M. sieversii and M. pumila cultivars. The results above sustained the conclusion ＂M. sieversii is probably the ancestor ofM. purnila＂. However, there were 48 compounds present in M. puraila that were not detected in M. sieversii, including 6 character impact components （i.e., propyl acetate, （Z）-3-hexenal, 2-methyl-l-butanol acetate, pentyl acetate, 3-furanmethanol, and benzene acetaldehyde）. This suggested that in the domestication of M. pumila, introgression of other apple species, except for M. sieversii, by interspecies hybridization was possible. There were 177 compounds in total belonging to 11 classes detected in 30 M. sieversii seedlings, including esters, alcohols, ketones, aldehydes, acids, benzene ramifications, terpenes, heterocycles, hydrocarbon derivates, acetals, and lactones. Among them, acetals and lactones were not detected in M. pumila cultivars, 90 compounds were unique to M. sieversii, and 7 components （l-butanol, ethyl hutanoate, 1-hexanol, ethyl hexanoate, 3-octen-1-ol, ethyl octanoate, and damascenone） belonged to character impact odors. Thus, the potential of M. sieversii in ＂utilization conservation＂ is enormous as a rate germplasm on genetic improvement of M. pumila cultivars.

Assessment of Genetic Diversity of Yunnan,Tibetan,and Xinjiang Wheat Using SSR Markers

A total of 206 SSR （Simple Sequence Repeats） primer pairs were used to detect genetic diversity in 52 accessions of three unique wheat varieties of western China. A total of 488, 472, and 308 allelic variants were detected in 31 Yunnan, 15 Tibetan and 6 Xinjiang wheat accessions with an average of PIC values 0.2764, 0.3082, and 0.1944, respectively. Substantial differences in allelic polymorphisms were detected by SSR markers in all the 21 chromosomes, the 7 homoeologous groups, and the three genomes （A, B, and D） in Yunnan, Tibetan, and Xinjiang wheat. The highest and lowest allelic polymorphisms in all the 21 chromosomes were observed in 3B and 1D chromosomes, respectively. The lowest and highest allelic polymorphisms among the seven homoeologous groups was observed in 6 and 3 homoeologous groups, respectively. Among the three genomes, B genome showed the highest, A the intermediate, and D the lowest allelic polymorphism. The genetic distance （GD） indexes within Yunnan, Tibetan, and Xinjiang wheat, and between different wheat types were calculated. The GD value was found to be much higher within Yunnan and Tibetan wheat than within Xinjiang wheat, but the GD value between Yunnan and Tibetan wheat was lower than those between Yunnan and Xinjiang wheat, and between Tibetan and Xinjiang wheat. The cluster analysis indicated a closer relationship between Yunnan and Tibetan wheat than that between Yunnan and Xinjiang wheat or between Tibetan and Xinjiang wheat.

Comparative Assessment of Genetic Diversity of Peanut (Arachis hypogaea L.)Genotypes with Various Levels of Resistance to Bacterial Wilt Through SSR and AFLP Analyses

Bacterial wilt （BW） caused by Ralstonia solanacearum is an important constraint to peanut （Arachis hypogaea L.） production in several Asian and African countries, and planting BW-resistant cultivars is the most feasible method for controlling the disease. Although several BW-resistant peanut germplasm accessions have been identified, the genetic diversity among these has not been properly investigated, which has impeded efficient utilization. In this study, the genetic relationships of 31 peanut genotypes with various levels of resistance to BW were assessed based on SSR and AFLP analyses. Twenty-nine of 78 SSR primers and 32 of 126 AFLP primer combinations employed in this study were polymorphic amongst the peanut genotypes tested. The SSR primers amplified 91 polymorphic loci in total with an average of 3.14 alleles per primer, and the AFLP primers amplified 72 polymorphic loci in total with an average of 2.25 alleles per primer. Four SSR primers （14H06, 7G02, 3A8, 16C6） and one AFLP primer （P1M62） were found to be most efficient in detecting diversity. The genetic distance between pairs of genotypes ranged from 0.12 to 0.94 with an average of 0.53 in the SSR data and from 0.06 to 0.57 with an average of 0.25 in the AFLP data. The SSR-based estimates of the genetic distance were generally larger than that based on the AFLP data. The genotypes belonging to subsp, fastigiata possessed wider diversity than that of subsp, hypogaea. The clustering of genotypes based on the SSR and AFLP data were similar but the SSR clustering was more consistent with morphological classification ofA. hypogaea. Optimum diverse genotypes of both subsp, hypogaea and subsp.fastigiata can be recommended based on this analysis for developing mapping populations and breeding for high yielding and resistant cultivars.

Population Genetic Diversity in Chinese Pomegranate (Punica granatum L.) Cultivars Revealed by Fluorescent-AFLP Markers

Eighty-five pomegranate （Punica granatum L.） cultivars from six geographical populations located at Shandong, Anhui, Shaanxi, Henan, Yunnan, and Xinjiang Provinces were studied for its population genetic diversity by means of fluorescent-AFLP markers. The results indicated that 135-185 polymorphic loci were amplified by eight pairs of primers at species level. An average of 158.25 polymorphic loci was amplified for each primer combination. The polymorphism percentage ranged from 62.5% to 86.11%, and the average polymorphism percentage was 73.26%. This indicated that there was plentiful genetic diversity in pomegranate cultivars. The genetic diversity at the species level was higher than that at the population level. The order of the genetic diversity was Henan population 〉 Xinjiang population 〉 Shaanxi population 〉 Anhui population 〉 Shandong population 〉 Yunnan population. Variance analysis showed that there was significant difference between populations in genetic diversity. The genetic differentiation coefficient between populations （Gsr） was 0.2018, which indicated that gene differentiation was mainly within the population, and between populations, it accounted for 20.18% of the total variation. Gene flow （Nm） between the populations measured was 1.9027 based on the genetic differentiation coefficient between populations, indicating that there was mild gene flow between populations. The UPGMA cluster analysis showed that most accessions from the same population were clustered together, but there was partly gene exchange. All genetic parameters indicated that there was plentiful genetic diversity in pomegranate cultivars in China, of which Henan population was significantly higher than the other populations, and it had wide application foreground in pomegranate breeding in China.

The Application of RAPD Markers in Diversity Detection and Variety Identification of Porphyra

RAPD (random amplified polymorphic DNA) markers were generated from filaments of 15 Porphyra lines representing four important groups, P. yezoensis, P. haitanensis, P. katadai var. hemiphylla and P. oligospermatangia . Among the total 69 fragments generated by 6 selected primers (among 50 primers), 67 appeared to be polymorphic (97.1%). Cluster analysis based on the RAPD results was performed. The 15 Porphyra lines were divided into 3 groups. This result was consistent with that from taxonomy analysis. A DNA fingerprinting based on 8 bands amplified with OPN_02 and OPJ_18 was constructed and might be used in Porphyra variety identification. Five specific RAPD fragments of 5 Porphyra lines were isolated and cloned into pGEM_T easy vector. These five RAPD fragments may be useful in germplasm identification and property protection of Porphyra .

Genetic Diversity of Gli-1, Gli-2 and Glu-1 Alleles in Sichuan Wheat Landraces

Genetic diversity at Gli_1, Gli_2 and Glu_1 loci was investigated in 89 Sichuan wheat (Triticum aestivum L.) landraces by using acid polyacrylamide gel electrophoresis (APAGE) and SDS_PAGE. In these landraces, a total of 32 gliadin and 3 high_molecular_weight (HMW) glutenin patterns were observed. In total, 14, 15 and 5 alleles were identified at Gli_1, Gli_2 and Glu_1, respectively. At each locus, the alleles in higher frequency were Gli_A1a (89%), Gli_B1h (46%), Gli_D1a (65%), Gli_A2a (64%), Gli_B2j (45%), Gli_D2a (48%), Glu_A1c (99%), Glu_B1b (99%) and Glu_D1a (100%). The Nei's genetic variation index (H) of Sichuan wheat landraces was 0.370?6, varying from 0 to 0.708?7. The highest genetic diversity was found at Gli_B2 locus, while the lowest was found at Glu_D1. The genetic diversity at Gli loci was higher than that of Glu_1 loci among these landraces, but it was much lower than that of modern wheat cultivars. These results indicated a narrow genetic base of Sichuan wheat landraces. In this study, “Chengdu_guangtou” had the identical gliadin and HMW_glutenin patterns with “Chinese Spring”, further supporting the proposal that “Chinese Spring” is a strain of “Chengdu_guangtou”.

Genetic Diversity of Gli-1,Gli-2 and Glu-1 Alleles Among Chinese Endemic Wheats

Genetic diversity at Gli_1, Gli_2 and Glu_1 loci was investigated in 32 accessions of Chinese endemic wheat by using acid polyacrylamide gel electrophoresis (APAGE) and sodium dodecyl sulfate (SDS)_PAGE. There were 8 gliadin and 3 high_molecular_weight (HMW)_glutenin patterns in 14 Yunnan hulled wheat ( Triticum aestivum ssp. yunnanese King) accessions, 9 gliadin and 4 HMW_glutenin patterns in 9 Tibetan weedrace ( T. aestivum ssp. tibetanum Shao ) accessions, and 9 gliadin and 5 HMW_glutenin patterns in 9 Xinjiang rice wheat ( T. petropavlovskyi Udacz. et Migusch.) accessions. One accession (i.e. Daomai 2) carried new subunits 2.1+10.1 encoded by Glu_D1. Among the three Chinese endemic wheat groups, a total of 10, 14 and 11 alleles at Gli_1 locus; 11, 14 and 12 alleles at Gli_2 locus; and 5, 6 and 8 alleles at Glu_1 locus were identified, respectively. Among Yunnan hulled wheat, Tibetan weedrace and Xinjiang rice wheat, the Nei's genetic variation indexes were 0.3798, 0.5625 and 0.5693, respectively. These results suggested that Tibetan weedrace and Xinjiang rice wheat had higher genetic diversity than Yunnan hulled wheat.

RAPD analysis of genetic diversity of nine strains of Auricularia auricular cultivated in Heilongjiang Province

Polymorphism of nine strains （CF05, CF09, 29, 916, AU9, Chang10, Chang7, 8808 and AU. Japanese） of A. auricular cultivated in Heilongjiang Province were analyzed by RAPD （Random Amplication polymorphic DNA）. Thirteen primers were selected from forty PCR primers with 10bp long random primer. The results showed that nine strains of A. auricular have a high level of genetic diversity and the percentage of DNA polymorphic was 96.05. The genotypes of 9 strains of Auricularia auricular were identified by the fingerprints from primer 27 and primer 46 by RAPD analysis. The results are helpful for quickly identifying strains of A. auricular in its early breeding time, and also provides a powerful theoretic basis to differentiate strains （Auricularia auricular） whose morphology is very similar in breeding programs of edible fungus.

Genetic Diversity of Cephalotaxus mannii, a Rare and Endangered Plant

Using RAPD technique, the DNA diversity of Cephalotaxus mannii Hook. f., its genetic diversity pattern, the reasons for its endangered position and conservative approaches were studied. The results show that: 1. The genetic diversity of C. mannii collected from five localities in Hainan is low, and its adaptability to environmental change is weak. 2. The differences of genetic diversity between intra- and inter-populations are great, and the major variation distributes within the population (DNA diversity is 85.1%). 3. The excessive lumbering, man-made destruction, violent typhoon, edible value of the seeds and genetic drift were the main reasons for the low-level genetic diversity of C. mannii and its endangered position. 4. The difference of the micro-environment and other random factors affecting the population should also be taken into full consideration in the study and in protection of such occasionally scattered plants. 5. Enforced measures should be taken to protect the present population, enlarge the population and lower the loss rate of its gene. Mt. Limulin should be chosen as a conservative spot because of its high genetic diversity and less destruction of the forest. Meanwhile, the protection of other populations should be enforced. 6. The differences within and between the populations are great based on different primers used. The change of proportions in polymorphic loci between the populations is more than that between the primers.

Genetic Diversity in Cultivated Groundnut Based on SSR Markers

Peanut （Arachis hypogaea L.） is an important source crop for edible oil and protein. It is important to identify the genetic diversity of peanut genetic resources for cultivar development and evaluation of peanut accessions. Thirty-four SSR markers were used to assess the genetic variation of four sets of twenty-four accessions each from the four botanical varieties of the cultivated peanut. Among the tested accessions, ten to sixteen pairs of SSR primers showed polymorphisms. The maximum differentiation index, which was defined as the degree of genetic differentiation, was as high as 0.992 in the tested accessions. Each accession could be discriminated by a specific set of polymorphic SSR primers, and the intra-variety genetic distance was determined among accessions, with an average of 0.59 in var. fastigiata, 0.46 in var. hypogaea, 0.38 in var. vulgaris, and 0.17 in var. hirsuta. Dendrogrames based on genetic distances were constructed for the four botanical varieties, which revealed the existence of different clusters. It was concluded that there was abundant intra-variety SSR polymorphism, and with more and more SSR markers being developed, the intrinsic genetic diversity would be detected and the development of genetic map and marker-assisted selection for cultivated peanut would be feasible.