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Start Over Creator Li, Zheng-Xi

1. Distribution and diversity of Wolbachia in different populations of the wheat aphid Sitobion miscanthi (Hemiptera: Aphididae) in China

Creator:
Wang, Zhe, Shen, Zuo-Rui, Song, Yue, Liu, Hong-Yue, and Li, Zheng-Xi
Type:
article, model:article, and TEXT
Subject:
Cytoplasmic symbiont, wheat aphid, Wolbachia, Sitobion miscanthi, distribution, diversity, China, and 16s rDNA gene
Language:
English
Description:
Wolbachia is a widely distributed intracellular symbiont in the reproductive tissues of arthropods. The wheat aphid Sitobion miscanthi (Takahashi) is an important agricultural pest worldwide. Wolbachia was detected in different populations of S. miscanthi in China using 16s rDNA and wsp-specific primers. Of eighteen populations eleven were infected with Wolbachia. Several strains of Wolbachia infected these S. miscanthi populations. Of the eleven infected populations, four were infected with only one Wolbachia strain and seven with double infections. This is the most systematic survey of the distribution of Wolbachia in the wheat aphid.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public

2. Molecular differentiation of the four most commonly occurring Trichogramma (Hymenoptera: Trichogrammatidae) species in China

Creator:
Li, Zheng-Xi
Type:
article, model:article, and TEXT
Subject:
Trichogrammatidae, Trichogramma, molecular identification, species-specific primers, restriction fragment length polymorphism, and random amplified polymorphic DNA
Language:
English
Description:
Trichogramma dendrolimi, T. ostriniae, T. confusum and T. evanescens are the four most commonly occurring Trichogramma species with overlapping distribution in China. They are the most frequently used egg parasitoids for biological control of lepidopterous crop pests in China. It is difficult to differentiate Trichogramma species because of their small size and lack of differences in morphological characters. Different molecular markers were employed to molecularly characterize and differentiate these species, including direct amplification of the internally transcribed spacer 2 (ITS2) of ribosomal DNA by polymerase chain reaction (PCR), restriction fragment length polymorphism (RFLP), random amplified polymorphic DNA (RAPD) and species-specific primers. The results showed that direct amplification of ITS2 could not clearly discriminate these species, but they could be differentiated using RFLP pattern obtained with endonucleases EcoRI and HindIII. The banding pattern produced by RAPD is irreproducible so it is not a suitable way to identify Trichogramma species. Finally, the species-specific primers designed based on ITS2 sequences could unequivocally distinguish the four species. The species-specific primer-based protocol proved to be the most convenient and time saving method for the identification of Trichogramma species by creating a unique PCR product, which can be used in surveying natural populations of Trichogramma species. This is the first report of the prompt identification of the four most commonly occurring Trichogramma species in China.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public

3. Screening for stable internal reference genes for quantitative PCR analysis of Wolbachia-host interactions in whitefly Bemisia tabaci (Homoptera: Aleyrodidae)

Creator:
Liu, Xin-Chao and Li, Zheng-Xi
Format:
počítač and online zdroj
Type:
model:article and TEXT
Subject:
Homoptera, Aleyrodidae, Bemisia tabaci, reference gene, quantitative PCR, and Wolbachia transfection
Language:
English
Description:
Stable reference genes (RGs) determine the reliability of quantitative polymerase chain reaction (qPCR) analyses and it is recommended that different reference genes are used for different types of DNA and tissues. The present study aimed to screen for stable RGs for the qPCR analysis of the immune responses of the whitefly Bemisia tabaci to the Wolbachia wMel strain from Drosophila melanogaster. A total of eight candidate RGs were evaluated using five different methods, i.e., Coefficient of Variation analysis, GeNorm, NormFinder, BestKeeper and ΔCt. The stability of these RGs was assessed for both genomic DNA (gDNA) and complementary DNA (cDNA). The results indicate that β-actin (Actin) and elongation factor 1 alpha (EF-1α) were the most stable RGs for gDNA, whereas 18S rRNA (18S) and glyceraldehyde phosphate dehydrogenase (GAPDH) were the least stable; in contrast, Actin and GAPDH were the most stable for cDNA, whereas RPL29 and ATPase were the least stable. The effectiveness of the most stable RGs was then validated against the least stable using qPCR analysis of the titre of wMel (gDNA) and the transcriptional responses of the antimicrobial peptide Alo-3-like and the phosphatidylinositol-bisphosphate 3-kinase catalytic subunit delta isoform (cDNA) to wMel transfection. The results support the notion that reliable RGs are essential for a qPCR analysis of samples of both gDNA and cDNA.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public

4. Using internally transcribed spacer 2 sequences to re-examine the taxonomic status of several cryptic species of Trichogramma (Hymenoptera: Trichogrammatidae)

Creator:
Li, Zheng-Xi, Zheng, Li, and Shen, Zou-Rui
Type:
article, model:article, and TEXT
Subject:
Internally transcribed spacer 2, ITS2, cryptic species, molecular taxonomy, Trichogramma chilonis, T. confusum, T. brassicae, T. maidis, and T. evanescens
Language:
English
Description:
Mass releases of Trichogramma confusum Viggiani and T. maidis Pintureau & Voegele are widely used to control lepidopterous pests. They have long been considered to be the subspecies of T. chilonis Ishii and T. brassicae Bezdenko, respectively. To re-examine the taxonomic status of these closely related Trichogramma species, the internally transcribed spacer 2 (ITS2) of ribosomal DNA was used as a molecular marker to detect between-species differences. The ITS2 regions of 7 different Trichogramma species collected from China, Germany and France were sequenced and the inter-species distances were calculated. To quantify within-species sequence variation, the ITS2 regions of 6 geographical populations of T. dendrolimi Matsumura collected from across China were sequenced and compared. The results show that the ITS2 sequences of T. confusum and T. maidis are sufficiently different from those of T. chilonis and T. brassicae, respectively, that it is difficult to group them as cryptic species, whereas there are only minor differences between the T. dendrolimi populations. The ITS2 sequences identified in this study, coupled with 67 ITS2 sequences from a wide geographical distribution retrieved from GenBank, were then used for phylogenetic analyses. The results support previous records of minor within-species ITS2 sequence divergence and distinct interspecies differences. The cladograms show the T. maidis sequence clustered within T. evanescens Westwood, while the ITS2 sequences of T. confusum and T. chilonis are clustered in different branches. Taken together, these data suggest that T. maidis is not T. brassicae, but a cryptic or sibling species of T. evanescens; T. confusum and T. chilonis are not cryptic species but two closely related sister species.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public