Molecular Identification and Cultivar Fingerprints of Prunus persica （L.） Batsch Germplasms

[Objective] The aim was to study the molecular identification and cultivar fingerprints of Prunus persica （L.） Batsch germplasms.[Method] Sixty peach genotypes,representing China common local cultivars and European samples were screened by microsatellites （simple sequence repeats,SSRs） and Inter-Simple Sequence Repeat （ISSR） markers.[Result] 26 reproducible bands were amplified by Nine SSR primers,and 24 of which were polymorphic; 236 bands were amplified by 30 ISSR primers,and 113 of which were polymorphic.31 genotypes were discriminated with 1-3 distinct polymorphic bands generated from the primers ISSR and SSR.Seven cultivar-specific ISSR fragments and two SSR unique alleles obtained from this study were available to be converted into Sequence Characterized Amplified Region （SCAR） markers.The genetic similarity coefficient （GS） estimated from these molecular data averaged were 0.939 （ranged from 0.856 to 0.983） for ISSR and 0.646 （ranged from 0.240 to 1.000） for SSR,respectively.The combined grouping association indicated that most local Chinese peach cultivars and exotic accessions were clustered together.This could be related to the mode of introduction and maintenance of the peach cultivars involving limited foundation germplasm,exchange of cultivars between plantations,and periodic development of new recombinant cultivars following sexual reproduction.[Conclusion] The results obtained in this work would help to improve the conservation,molecular identification and management of peach germplasm in breeding.     

Molecular Related Indexes Assessment and Traits Correlation Analysis of Turbot（Scophthalmus maximus L.） by Using SSR Marker Correlation Coefficient in Turbot

Five molecular related indexes： MOL, SIM, d2, H0and PIC of 15 turbot parent pairs were estimated by using 10 SSR loci, which were used in correlation analysis with growth traits, DIL and DIW, of family filial from those 15 parent pairs.DIL and DIW were regressed on the MOL, SIM, d2, H0and PIC. Results showed MOL of five SSR loci（12, 17, 24, 81 and 85） and SIM of five loci（17, 21, 24, 81and 85） all shared significant positive correlation with DIL（r=0.482, P=0.035 and r=0.479, P=0.035, respectively）; H0of six SSR loci（11, 17, 21, 24, 26 and 85） had significant positive correlation with DIW（r=0.551, P=0.017）; PIC of two SSR loci（9and 26） had significant positive（r=0.519, P=0.024） correlation with DIL, while that and of four loci（17, 24, 27 and 85） had significant negative correlation（r=-0.519,P=0.024）, with DIL. This present study suggested that filial growth expression could be predicted by using molecular related indexes in turbot breeding practice, and the accuracy of prediction depends on more SSR loci, especially associated with QTL.     

Identification of Molecular Markers Linked to the Wilt Resistance Gene FuJ7（t） in Flax

A cross between wilt resistant flax variety Jinya7 and susceptible variety Jinyal was made for mapping wilt resistance gene(s). The inoculation test of F1 and F2 progeny proved that the resistance of Jinya7 to wilt is controlled by two dominant genes. With 48 EcoRⅠ /MseⅠ primer combinations, amplified fragment length polymorphisms (AFLP) analysis was performed on two parents and their F2 resistance and susceptibility bulks. A total of about 3 300 distinguishable bands were amplified, of which three bands had stable differences. The genetic linkage analysis of the three polymorphic DNA fragments with the resistance gene(s) was made in the F2 segregating population derived from the cross between Jinya7 and Jinyal. The DNA fragment AG/CAG was found closely linked to one of the wilt-resistant genes, which with a genetic distance of 5.2cm, was tentatively named FuJ7(t). The cloned fragment AG/CAG was sequenced and then converted successfully to a sequence characterized amplified region (SCAR) marker, which can be used more conveniently in the identification and marker-assisted selection for the wilt resistance gene FuJ7(t) to flax wilt.     

Identiifcation and Molecular Mapping of the RsDmR Locus Conferring Resistance to Downy Mildew at Seedling Stage in Radish （Raphanus sativus L.）

Downy mildew （DM）, caused by the fungus Peronospora parasitica, is a destructive disease of radish （Raphanus sativus L.） worldwide. Host resistance has been considered as an attractive and environmentally friendly approach to control the disease. However, the genetic mechanisms of resistance in radish to the pathogen remain unknown. To determine the inheritance of resistance to DM, F1, F2 and BC1F1 populations derived from reciprocal crosses between a resistant line NAU-dhp08 and a susceptible line NAU-qtbjq-06 were evaluated for their responses to DM at seedling stage. All F1 hybrid plants showed high resistance to DM and maternal effect was not detected. The segregation for resistant to susceptible individuals statistically iftted a 3：1 ratio in two F2 populations （F2（SR） and F2（RS））, and 1：1 ratio in two BC1F1 populations, indicating that resistance to DM at seedling stage in radish was controlled by a single dominant locus designated as RsDmR. A total of 1 972 primer pairs （1 036 SRAP, 628 RAPD, 126 RGA, 110 EST-SSR and 72 ISSR） were screened, and 36 were polymorphic between the resistant and susceptible bulks, and consequently used for genotyping individuals in the F2 population. Three markers （Em9/ga24370, NAUISSR826700 and Me7/em10400） linked to the RsDmR locus within a 10.0 cM distance were identiifed using bulked segregant analysis （BSA）. The SRAP marker Em9/ga24370 was the most tightly linked one with a distance of 2.3 cM to RsDmR. These markers tightly linked to the RsDmR locus would facilitate marker-assisted selection and resistance gene pyramiding in radish breeding programs.     

Analysis of Genetic Diversity in Natural Populations of huashanica Keng Using Microsatellite （SSR） Markers

Psathyrostachys huashanica Keng is endemic to China and only distributed in Huashan Mountain in Shaanxi Province, China. In this study, 15 P. huashanica populations consisting of 450 individuals sampled across their main distribution were investigated by using the simple sequence repeats （SSRs） markers. A total of 184 alleles were detected on 24 SSR loci, and the number of alleles on each locus ranged from 2 to15, with an average of 7.667. The total gene diversity （HT= 0.683） and the coefficient of population differentiation （GST = 0.125） showed that P. huashanica had a relatively high level of genetic variation, and the genetic variation was mainly distributed within the populations. The gene flow among the populations of P. huashanica （Nm = 1.750） was much less than that of the common anemophytes （Nm = 5.24）. Correlation analysis demonstrated that the number of alleles as well as genetic diversity of the five populations of Huangpu valley decreased along with the increase of altitudes, but the correlation was not significant. Implications of these results for future P. huashanica collection, evaluation and conservation were discussed.     

Genetic Analysis and Preliminary Mapping of a Highly Male-Sterile Gene in Foxtail Millet（Setaria italica L.Beauv.） Using SSR Markers

Breeding of male-sterile lines has become the mainstream for the heterosis utilization in foxtail millet,but the genetic basis of most male-sterile lines used for the hybrid is still an area to be elucidated.In this study,a highly male-sterile line Gao146A was investigated.Genetic analysis indicated that the highly male-sterile phenotype was controlled by a single recessive gene a single recessive gene.Using F 2 population derived from cross Gao146A/K103,one gene controlling the highly male- sterility,tentatively named as ms1,which linked to SSR marker b234 with genetic distance of 16.7 cM,was mapped on the chromosome VI.These results not only laid the foundation for fine mapping of this highly male-sterile gene,but also helped to accelerate the improvement of highly male-sterile lines by using molecular marker assisted breeding method.     

Application of Molecular Markers Linking to Cytoplasmic Male Sterile Loci to Assist Maintainer Line Selection and Their Selection Efficiency in Welsh Onion （Allium fistulosum L.）

Cytoplasmic male sterility exists widely in most natural populations of welsh onion （Alliumfistulosum L.）, which makes it possible to breed out many male sterile lines for heterosis utilization. Unfortunately, the breeding of cytoplasmic male sterility in welsh onion has a little progress due to the limitation of its biological characteristic and traditional selection approach. To study the feasibility and the efficiency of utilizing marker assisted selection for male sterile lines in welsh onion, one SCAR marker, SCS13, and one RAPD marker, S2002400, which could distinguish between N and S cytoplasm in several welsh onion cultivars, were identified. The two markers were then confirmed by Southern blotting, and used to screen the N or S cytoplasm of individual plants in seven welsh onion cultivars in this study. Male sterile and fertile plants were evaluated by aceto-carmine dying. The frequency of N-cytoplasmic plants and maintainer genotype was calculated in the seven open populations of welsh onion. The minimum number of plants needed to identify a maintainer was evaluated to be 95% reliable. Results showed that 20 to 80% decrease of crosses and self-crosses for identifying a maintainer genotype could be achieved by the marker-assisted selection compared with traditional selection method. It was proved that the molecular markers could precisely identify cytoplasmic types individually, performed by one generation of cross and two generations of testcrosses and self-crosses. Finally, several maintainer genotype plants were selected with the help of the two markers in the seven cultivars. The screened markers could assist and accelerate sterile and maintainer lines selection with less labor and cost.     

An Integrated QTL Map of Fungal Disease Resistance in Soybean （G/ycine max L. Merr）： A Method of Meta-Analysis for Mining R Genes

Diseases caused by fungal pathogens account for approximately 50% of all soybean disease losses around the world. Conflicting results of fungal disease resistance QTLs from different populations often occurred. The objectives of this study were to： （i） evaluate evidence for reported fungal disease resistance QTLs associations in soybean and （ii） extract relatively reliable and useful information from the ＂real＂ QTLs and mine putative genes in soybean. An integrated map of fungal disease resistance QTLs in soybean was established with soymap 2 published in 2004 as a reference map. QTLs of fungal disease resistance developed from each of separate populations in recent 10 years were integrated into a combinative map for gene cloning and marker assisted selection in soybean. 107 QTLs from different maps were integrated and projected to the reference map with the software BioMercator 2.1. A method of meta-analysis was used to narrow down the confidence interval, and 23 ＂real＂ QTLs and their corresponding markers were obtained from 12 linkage groups （LG）, respectively. Two published R genes were found in these ＂real＂ QTLs intervals. Sequences in the ＂real＂ QTLs intervals were predicted by GENSCAN, and these predicted genes were annotated in Goblet. 228 resistance gene analogs （RGAs） in 12 different terms were mined. The results will lay the foundation for a bioinformatics platform combining abundant QTLs, and offer the basis for marker assisted selection and gene cloning in soybean.     

The Susceptibilities of Oxya chinensis （Orthoptera： Acridoidea） to Malathion and Comparison of the Esterase Properties from Three Collected Populations in Tianjin Area,China

The susceptibilities of Oxya chinensis to malathion were studied in three populations collected from outskirt of Tianjin, China, using bioassays and biochemical analysis. Populations were chosen to represent different exposure to insecticides： BDG （Beidagang; low exposure）, BD （Baodi; high exposure previously but low exposure now）, and JN （Jinnan; high exposure）. The results showed that the LD50 values of BD and JN populations were 3.95- and 12.02-fold and 3.64- and 10.07- fold higher than that of BDG population in females and males, respectively. The LD50 values in females were higher than those in males. The results of biochemical analysis indicated that the esterase （EST） activities in JN population were higher than those in BD and BDG populations. They showed that when α-NA, α-NB, and α-NA were used as substrates, females＇ EST activities of JN population were 1.11-, 1.30-, and 1.14-fold and 1.39-, 1.59-, and 1.54-fold higher than those of BD and BDG populations, respectively. When α-NA, α-NB, and β-NA were used as substrates, males＇ EST activities of JN population were 1.13-, 1.12-, and 1,00-fold and 1.20-, 1.14-, and 1.07-fold higher than those of BD and BDG populations, respectively. The results also showed that the specific activities of the females were higher than those of the males in the BD and JN populations, whereas the specific activities of the males were higher than those of the females in the BDG population. The results of bioassay were consistent with those of biochemical analysis. Thus, it was inferred that the elevated ESTs activities might play an important role in conferring the differences of susceptibility of O. chinensis to malathion in the three collected populations. Enzyme kinetic studies indicated that the Km and Vmax values were different among the three collected populations and between the females and the males. The observed changes in the kinetic parameters might be explained by differential expression patterns of isozymes so that the insect esterases have different affinities and maximum velocities toward the same substrate.