Huang Yongping

A comparison of genetic variation among wild and cultivated Morus Species (Moraceae: Morus) as revealed by ISSR and SSR markers

In this study, inter-simple sequence repeats (ISSR) ans simple sequence repeat (SSR) markers were used to investigate genetic diversity of 27 mulberry accessions including 19 cultivated accessions (six M. multicaulis, three M. alba, two M. atropurpurea, two M. bombycis, one M. australis, two M. rotundiloba, one M. alba var. pendula, one M. alba var. macrophylla, and one M. alba var. venose) and 8 wild accessions (two M. cathayana, two M. laevigata, two M. wittiorum, one M. nigra and one M. mongolica). ISSRs and SSRs were compared in terms of their informativeness and efficiency in a study of genetic diversity and relationships among 27 mulberry genotypes. SSRs presented a higher level of polymorphism and greater information content. All index values of genetic diversity both markers analyzed using Popgene 32 software indicated that within wild species had higher genetic diversity than within cultivated species. Cultivation may caused the lose of genetic diversity of mulberry compared with wild species revealed by ISSR and SSR markers. The mean genetic similarity coefficients among all mulberry genotypes ascribed by ISSR and SSR matrices were 0.7677 and 0.6131, respectively. For all markers a high similarity in dendrogram topologies was obtained although some differences were observed. Cluster analysis of ISSR and SSR using UPGMA method revealed that the wild species are genetically distant from the domesticated species studied here. The correlation coefficients of similarity were statistically significant for both marker systems used. Principal coordinates analysis (PCA) for ISSR and SSR data also supports their UPGMA clustering. These results have an important implication for mulberry germplasm characterization, improvement, molecular systematics and conservation.

Genetic relatedness among cultivated and wild mulberry (Moraceae: Morus) as revealed by inter-simple sequence repeat analysis in China

The genetic diversity of 27 mulberry (Morus spp.) genotypes mainly from China was investigated using inter-simple sequence repeat (ISSR) markers to assist in addressing breeding objectives and conserving existing genetic resources. Of the 22 primers screened, 15 produced highly reproducible ISSR bands. Using these 15 primers, 138 discernible DNA fragments were generated with 126 (91.3%) being polymorphic, indicating considerable genetic variation among the mulberry genotypes studied. Genetic similarity ranged from 0.6014 between Yu 2 and Yu 711 to 0.9493 between Cuizhisang and Dejiang 10. The phenetic dendrogram based on ISSR data generated by the unweighed pair group method with arithmetical averages (UPGMA) method grouped the 27 accessions into two major clusters: cluster I, cultivated mulberry species (M. multicaulis Perr., M. alba Linn., M. atropurpurea oxb., M. bombycis Kiodz., M. australis Poir., M. rotundiloba Kiodz., M. alba var. pendula Dipp., M. alba var. macrophylla Loud., and M. alba var. veno...

[Mapping of non-lepis wing gene nlw in silkworm (Bombyx mori) using SSR and STS markers].

The non-lepis wing of silkworm (Bombyx mori) is controlled by the recessive gene, nlw. Owning to lack of crossing over in females, the reciprocal backcrossed F(1) (BC(1)) progenies were used for linkage analysis and mapping of nlw based on the SSR linkage map and STS markers using the wild type (+(nlw)/+(nlw)) silkworm strain P50 and U06 with scaleless wing (nlw/nlw). The nlw gene was linked to eight SSR markers and one STS marker. All the individuals with the wild type in the BC1F (Using F(1) as female to backcross to the recessive parent, that is (U06xP50)xU06) showed heterozygous profile of (U06xP50) F(1), and the ones with non-lepis wing in BC1F exhibited the homozygous profile of the strain U06. Using a reciprocal BC1M (Using F1 as male to backcross to the recessive parent, that is U06x(U06xP50))cross, we constructed a linkage map of 125.6 cM, and the distance between nlw and the nearest marker cash2p was 11.4 cM.

Genome Editing Technologies and Its Application in Insects

Genome editing technologies are important for functional genomics study and application. Zinc finger nucleases (ZFNs), transcription activitor-like effector nucleases (TALENs) and clustered regularly interspaced short palindromic repeats/CRISPR associated protein (CRISPR/Cas) system are three major genome editing technologies established in recent years. Mutagenesis induced by these three techniques is mainly through making double strand break (DSB) at a specific site and followed by DSB repair process. ZFNs is the first established genome editing technology which could be used to operate site-specific knock out and knock in. However, the ZFNs technology suffers from construction complexity, high cost and other problems. The TALENs technology, which was developed based on the ZFNs technology, is much better than ZFNs technology for higher flexibility and lower cost. The CRISPR/Cas system is different from ZFNs and TALENs technologies for its unique targeting mechanism which makes this technology more suitable for multiplexed targeting. Until now, all these technologies have been successfully tested in a number of organisms, e.g., mouse, zebrafish, fruit fly, nematode, silkworm. These genome editing tools will play important roles in future functional genomics study in the post genome era.

Genetic Regulation of Insect Populations

Genetic regulation of insect populations is a powerful system. It is set up based on the integration of regulation of species specific target gene and sexual specified control elements through genetic transformation. The offsprings produced in the system will have normal males bringing female lethal or abnormal genes. With advantages of species specificity, eco-friendliness and high efficiency, genetic regulation technique (GRT) established with the insect sterile technique becomes a better choice for insect population control. So far, GRT has evolved into the new generation called ‘Release of Insect with Dominant Lethal (RIDL) from the primitive radiation caused sterility and succeeded in several insects. In this review, we introduce the history of GRT and related theories and methods, including the specific regulating elements, lethal or defect genes and the transgenic system. Some successful cases, such as mosquitos, silkworm and cotton bollworm are also listed. Finally, we discuss potential problems and the future of GRT.