Genetic Differentiation of Different Geographical Populations of Bemisia tabaci （Gennadius） Complex

Bemisia tabaci （Gennadius） is a species complex, which includes different geographical populations with genetic differentiation. The recent progress on the genetic differentiation of various geographical populations of B. tabaci complex was introduced. The genetic differentiation was further analyzed on the basis of the sequences of mtDNA COI and rDNA ITS1 recorded in the world＇s GenBank. Five groups are defined on the basis of mtDNA COI and rDNA ITS1, including the Asia group, America group, Africa group, Australia group, and Biotype B/Mediterranean/Middle East/ Northern Africa/Biotype Ms group. There are several ungrouped geographical classifications, such as the Uganda population, Ivory Coast population, and Taiwan population. Geographical isolation may be the most important factor that contributed to the genetic differentiation of various geographical populations of B. tabaci. Many populations with biological advantages invaded new regions and caused severe economic losses within human activity. It is necessary to strengthen the research of B. tabaci biotype to prevent the spread of invaded populations and the invasion of potentially dangerous populations.     

Sequence Analysis of mtDNA COIGene and Molecular Phylogeny of Different Geographical Populations of Bemisia tabaci （Gennadius）

Bemisia tabaci(Gennadius) is a serious pest in many cropping systems worldwide and occurs in different biotypes. The mtDNA COIgene of the 12 Bemisia tabaci (Gennadius) populations from different regions and countries were analyzed. Based on mtDNA COI sequences, their biotypes were characterized and phylogenetic relationships among these populations were established with the method of UPGMA. The results indicated the genetic similarity between those populations from Beijing, Zhengzhou, Zaozhuang, Nanjing, Shanghai, Haikou, and the B-biotype populations from California, Texas, Arizona reached 99.8-100%, which meant the nation-wide infested populations of B.tabaci in China in recent years were B-biotypes. Another population collected from Kunming of Yunnan Province showed very high similarity with Q-biotype B.tabaci from Spain and Morocco, which meant the Kunming population was Q-biotype. This is the first report on the invasion of Q-biotype into China.     

Genetic Diversity Analysis of Balsam Pear （Momordica charantia L.） by ISSR Marker

[Objective] The aim was to explore the relationship between the classification and regional distribution of balsam pear.[Method] In the research,30 varieties of balsam pear were analyzed by ISSR marker.[Result] The research showed that 172 bands were amplified by 18 primers,in which,132 bands were polymorphism and the polymorphic proportion was 76.7％.All of the samples can be divided into four categories by UPGMA analysis.[Conclusion] The results indicated that the classification of balsam pear is similar as varieties＇ regional distribution,which will be useful for genetic relationships analysis and parents selection in hybridization breeding.     

Comparative Morphology and Morphometry of Six Biotypes of Bemisia tabaci （Hemiptera： Aleyrodidae） from China

Morphology and morphometry of six biotypes(B,Q,Cv,ZHJ-1,ZHJ-2 and ZHJ-3) of Bemisia tabaci(Gennadius) from China on cotton plants were studied by using microscopes.Nymphal body sizes and characters were measured and observed,especially on the 4th instar(pupal case),including the vasiform orifice,operculum,lingula,length and thickness of anterior and posterior wax margins,width of thoracic tracheal combs.Adult characters of both sexes were investigated including the body size,compound eyes,antennal segments,vasiform orifice,hind tarsi and genitals.The results indicated that differences of some morphological characters or morphometrics were significant among the six biotypes of B.tabaci in China:(1) Pupal sizes of the exotic biotypes(B and Q) were significantly larger than the indigenous biotypes with the following order as B>Q>ZHJ-1>Cv>ZHJ-3>ZHJ-2;(2) for both male and female adults,sizes of all characters investigated in the invading biotypes(B and Q),especially B,were much larger than those of the indigenous ones.     

ISSR Analysis on Genetic Diversity of Local Varieties of Chinese Hu mulberry（Morus L.）

[Objective] The aim was to study on the genetic diversity of local varieties of Chinese Hu mulberry （Morus L.）. [Method] The genetic diversity of 141 copies of Hu mulberry varieties was analyzed by ISSR molecular markers. [Result] 12 ISSR primers had amplified a total of 90 amplified,of which 57 bands were polymorphic,and the polymorphic rate was 63.33%. The genetic similarity coefficients of 141 Hu mulberry germplasm resources varied from 0.633 3 to 1.000 0 with the average of 0.483 35,indicating that there was difference on genetic diversity among different varieties of Hu mulberries. A dendrogram of all 141 Hu mulberry varieties based on the genetic similarity coefficients using ISSR molecular markers was generated by UPGMA cluster method. Clustering of the 141 Hu mulberry varieties did not correspond with the conventional classification involving differences in style,leaf,branch,fruit and other morphological or agronomical characters. [Conclusion] Four subgroups clearly represented the genetic relationships in the 141 accessions which were benefit for the variety improvement and germplasm resource conservation.     

Toxicity of selected insecticides against nymph of whitefly （Bemisia tabaci Gennadius）

Bemisia tabaci is one of serious insect pests attacking vegetables and has been difficult to control using conventional insecticides. In the past 10 years, new insecticides have been introduced that provide a diversity of novel modes of action and routes of activity to effectively control whitefly. Consequently, intensive used of insecticides in vegetable cultivation has resulted in reduced susceptibility and develops resistance in agriculture industry. In controlling B. tabaci population, insecticides are the common method used by farmers. This study aimed to determine the most effective insecticide against B tabaci by using LC5o value. This study was conducted at the Crop Protection Laboratory, Faculty of Applied Science, Universiti Teknologi MARA Malaysia with the controlled room temperature of 24.33 ± 0.14℃ with dark and light ratio of 1：1 （12 hours： 12 hours） is an ideal condition for rearing the insect. The hypothesis of the study is to test if insecticides can control the nymph of whitefly. A total of 50 two-day-old nymphs were treated with insecticides using leaf-dip bioassay procedure. This experiment was replicated three times. The survival rates of the nymphs were analyzed using analysis of variance （ANOVA）. Data on toxicity was analyzed by a special Probit Programme-Single Line Analysis based on Finney （1971）. There was a significant difference （df = 8, F = 85.84, P = 0.000） in survival rate of nymph ofB. tabaci to eight insecticides tested. Among the insecticides tested, dimethoate, chlorpyrifos ＋ cypermethrin and diafenthiuron showed significantly higher survival rate of nymph compared to other treatments. When LC50 values were compared for diafenthiuron which is less potent （LCs0 ---- 2.44）, abamectin was found to be 3.44 times more potent than diafenthiuron, followed by esfenvalerate,acetamiprid, profenofos, chlorpyrifos ＋ cypermethrin and dimethoate, and the least potent was deltamethrin. The toxicity of eight insecticides tested against nymphs was in the following     

A Genetic Linkage Map of Kenaf （Hibiscus cannabinus L.） Based on SRAP,ISSR and RAPD Markers

Kenaf (Hibiscus cannabinus L.) is one of the most economically important crops for non-wood fiber production. The objective of this study was to establish a genetic linkage map of kenaf with higher density of molecular markers. A semi-wild variety Ga42 and a cultivar Alain kenaf were used as parents to construct an F₂ population consisting of 155 plants. The genetic linkage map comprising 134 marker loci was constructed, including 65 sequence-related amplified polymorphism (SRAP), 56 inter-simple sequence repeat (ISSR), and 13 randomly amplified polymorphic DNA (RAPD) markers. This map spans 2 108.9 cM and contains 20 linkage groups with an average marker density of 15.7 cM between the adjacent markers.     

Genetic Diversity Analysis of Faba Bean （Vicia faba L.） Based on EST-SSR Markers

Faba bean (Viciafaba L.), one of the most important legumes in the world, evolved different types of cultivars due to its partial cross-pollination. The development of simple sequence repeat (SSR) markers from expressed sequence tags (EST) provided a useful tool for investigation of its genetic diversity. The purpose of the present study was to investigate the genetic diversity of faba bean from China and Europe using EST-SSR markers. 5 031 faba bean ESTs from the NCBI database were downloaded and assembled into 1148 unigenes. A total of 107 microsatellites in 96 unigenes were identified, indicating that merely 8.36% of sequences contained SSRs. The most abundant SSR within faba bean was tri-nucleotide repeat motif, and among all the tri-nucleotide repeats, the motif AAG/CTT was the most abundant type. Based on these results, 11 EST-SSR markers were used to assess the genetic diversity of 29 faba bean cultivars from China and Europe with two to three alleles per locus. The polymorphism information content value ranged from 0.0644 to 0.4278 with an average of 0.2919. Principal coordinate analysis (PCA) and phylogenetic clustering based on these 11 EST-SSR markers distinguished these cultivars into different groups. The results indicated that faba bean in China had a narrow genetic basis, and the additional sources of genetic cultivars/accessions should be introduced to enhance the genetic variability. The results of this study proved that the EST-SSR marker is very effective in evaluation of faba bean germplasm.     

Density and Seasonal Dynamics of Bemisia tabaci （Gennadius） Mediterranean on Common Crops and Weeds Around Cotton Fields in Northern China

The density seasonal dynamics of Bemisia tabaci MED were evaluated over two years in a cotton-growing area in Langfang, Hebei Province, northern China on cotton （Gossypium hirsutum L.） and six other co-occurring common plants, common ragweed （Ambrosia artemisiifolia L.）, piemarker （Abutilon theophrasti Medicus）, sunflower （Helianthus annuus L.）, sweet potato （Ipomoea batatas L.）, soybean （Glycine max L.）, and maize （Zea mays L.）. The whitefly species identity was repeatedly tested and confirmed; seasonal dynamics on the various host plants were standardized by the quartile method. B. tabaci MED appeared on weeds （the common ragweed and piemarker） about 10 days earlier than on cotton, or the other cultivated plants. The peak population densities were observed over a span of 2 to 3 weeks on cotton, starting in early （2010） or mid-August （2011）. The common ragweed growing adjacent to cotton supported the highest B. tabaci densities （no. on 100 cm2 leaf surface）, 12-22 fold higher than on cotton itself. Sunflower supported more B. tabaci than the other plants, and about 1.5-2 fold higher than cotton did, Our results indicate that weeds （esp. the common ragweed） around cotton fields could increase the population density of B. tabaci MED on cotton, while sunflower could act as a trap crop for decreasing pest pressure on cotton.     

烟粉虱B型和Q型群体遗传结构的ISSR比较分析

【目的】对烟粉虱复合种中2种入侵性较强的生物型烟粉虱B型和Q型的群体遗传结构进行比较研究,揭示其入侵机制并对其管理提供依据。【方法】采用简单序列重复区间扩增（ISSR）标记,以温室白粉虱以及浙江非B/Q型为对照种群,对世界各地16个烟粉虱B型种群和4个烟粉虱Q型种群的遗传结构进行分析。【结果】遗传多样性分析结果表明,烟粉虱Q型种群的Nei氏基因多样性指数、Shannon信息指数及多态性位点百分比等各项遗传多样性指数均高于烟粉虱B型的相应指数。聚类分析结果提示,ISSR标记能够区分烟粉虱不同生物型,但可能不适用于生物型之间的系统发育分析。【结论】烟粉虱B型种群遗传多样性高于Q型种群。     

A Comparative Analysis of B Chromosomes and Genetic Diversity in Maize （Zea mays L.） Landraces from Southwest China

The number of B chromosomes （Bs） in 54 maize landraces from Southwest China was tested by means of cytological observations. Nine landraces with Bs were observed. A map, showing the geographic distribution of the landraces with Bs, was plotted. It was found that southeastern Sichuan Province in China was the main distribution area of the landraces with Bs in Southwest China. In order to obtain information on relationships between Bs and genetic variation, genetic diversity both among and within 11 landraces was evaluated. For each SSR marker, the number of alleles ranged from 3 to 12 with an average of 7.86, which revealed a high level of genetic diversity among maize landraces in Southwest China. Based on SSRs data, higher genetic variation was found in the landraces with 2B, and the genetic distance between the landraces with and without Bs was higher. The results together with the principal component analysis （PCA） supported the hypothesis that maize landraces in Southwest China were first introduced to the middle part of southwest Sichuan, China. At the same time, the effect of Bs on genetic variation was discussed.     

Genetic Diversity Analysis Among Populations of Mink from China by Inter-simple Sequence Repeat （ISSR） Markers

Inter-simple Sequence Repeat （ISSR） analysis was applied to assess the genetic diversity within and among five populations of mink from Liaoning Province. A total of 20 primers were screened, five selected primers produced 35 discernible bands, with 30 （85.71%） being polymorphic, indicating high genetic diversity at the species level. The highest genetic diversity was observed in the brown mink population, whereas the lowest diversity was found in the standard-pitchy mink population. Based on genetic distance （1972）, a dendrogram was constructed by using UPGMA algorithm, and five populations were divided into two major groups. Group I consisted of only the standard-pitchy mink population, and Group II included other four populations, in Group II, sapphire mink was close to brown mink population. The results of genetic differentiation indicated that the genetic differentiation degree between populations was lower and the genetic variation primarily came from within populations. This paper showed that ISSR technique was a reliable tool that could be used to study genetic diversity in the mink.     

Enhancement of Phenylalanine Ammonia Lyase,Polyphenoloxidase, and Peroxidase in Cucumber Seedlings by Bemisia tabaci（Gennadius） （Hemiptera： Aleyrodidae） Infestation

In this study, the activities of phenylalanine ammonia lyase （PAL）, polyphenoloxidase （PPO）, and peroxidase （POD） were assayed in cucumber seedlings （Cucumis sativus L.） at 0, 6, 12, 24, 48, 72, and 96 h after they were infested by Bemisia tabaci （Gennadius） using spectrophotometric analysis. The results indicated that herbivore infestation increased the activities of PAL, PPO, and POD. The enzymes showed different activity levels at different times after the infestation. The PAL activity reached the first high peak by 23.1% at 6 h and the highest peak by 29.1% at 48 h compared to the control. The PPO activity reached the first high peak by 22.7% at 6 h and the highest peak by 52.6% at 24 h, and the POD activity reached the highest peak by 213.2% at 6 h and another higher peak value by 135.2% at 96 h. The results suggest that the enhanced activities of the enzymes may contribute to bioprotection of cucumber plants against B. tabaci infestation.     

Genetic Differences of Mitten Crabs Based on RFLP Analysis on Mitochondrial Cytochrome Oxidase Subunit I （CO I） Gene

The genetic differences of 15 mitten crab populations from 6 river systems in mainland China and 1 population from Russia were studied based on RFLP analysis of mitochondrial cytochrome oxidase subunit I （CO I）. The results showed that Tas I-RFLP pattern could be used as a genetic marker to distinguish Eriocheir hepuensis from Eriocheir sinensis, Eriocheirjaponica and Eriocheir leptognathus; genetic distances among 13 populations of Eriocheir sinensis range from 0 to 0.015, indicating that they were different geographic strains; the subspecies status of Eriocheir sinensis and Eriocheir hepuensis （population from Nanliujiang） were considered owning to their genetic distances of 0.02-0.044, indicating that genetic divergence between them was low; Eriocheir leptognathus （population from Nanpaihe, Tianjin） was the most distant taxon with genetic distances value of 0.147-0.195, which could be defined as genetic distances between species in genus Eriocheir.     

Construction of Genetic Linkage Map Based on SSR Markers in Peanut （Arachis hypogaea L.）

Molecular genetic maps of crop species can be used in a variety of ways in breeding and genomic research such as identification and mapping of genes and quantitative trait loci （QTLs） for morphological, physiological and economic traits of crop species. However, a comprehensive genetic linkage map for cultivated peanut has not yet been developed due to the extremely low frequency of DNA polymorphism in cultivated peanut. In this study, 142 recombinant inbred lines （RILs） derived from a cross between Yueyou 13 and Zhenzhuhei were used as mapping population in peanut （Arachis hypogaea L.）. A total 652 pairs of genomic-SSR primer and 392 pairs of EST-SSR primer were used to detect the polymorphisms between the two parents. 141 SSR primer pairs, 127 genomic-SSR and 14 EST-SSR ones, which can be used to detect polymorphisms between the two parents, were selected to analyze the RILs population. Thus, a linkage genetic map which consists of 131 SSR loci in 20 linkage groups, with a coverage of 679 cM and an average of 6.12 cM of inter-maker distance was constructed. The putative functions of 12 EST-SSR markers located on the map were analyzed. Eleven showed homology to gene sequences deposited in GenBank. This is the first report of construction of a comprehensive genetic map with SSR markers in peanut （Arachis hypogaea L.）. The map presented here will provide a genetic framework for mapping the qualitative and quantitative trait in peanut.     

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.     

Analysis of Genetic Effects for Heterosis of Erucic Acid and Glucosinolate Contents in Rapeseed （Brassica napus L.）

The embryo,cytoplasmic,and maternal heterosis for erucic acid content (EAC) and glucosinolate content (GLS) of rapeseed (Brassica napus L.) were studied by using the genetic models for quantitative traits of seeds in diploid crops.Eight parents were included in a diallel mating design in two years.It was found that the heterosis of EAC and GLS was simultaneously controlled by genetic main effects and genotype×environment (GE) interaction effects.The general heterosis of most crosses for EAC was significantly positive,while it was not for GLS.The general heterosis was more important for two quality traits of rapeseed because of the low GE interaction heterosis in both years,especially for GLS.Among different genetic systems,significant positive embryo general heterosis and the negative maternal general heterosis were found for EAC and GLS in most hybrid crosses.Some hybrids with significant negative interaction heterosis were detected for either of EAC or GLS.In general,maternal general and interaction heterosis was more important for reducing EAC and GLS of rapeseed.