Characterization and comparative sequence analysis of the DNA mismatch repair MSH2 and MSH7 genes from tomato

DNA mismatch repair proteins play an essential role in maintaining genomic integrity during replication and genetic recombination. We successfully isolated a full length MSH2 and partial MSH7 cDNAs from tomato, based on sequence similarity between MutS and plant MSH homologues. Semi-quantitative RT-PCR reveals higher levels of mRNA expression of both genes in young leaves and floral buds. Genetic mapping placed MSH2 and MSH7 on chromosomes 6 and 7, respectively, and indicates that these genes exist as single copies in the tomato genome. Analysis of protein sequences and phylogeny of the plant MSH gene family show that these proteins are evolutionarily conserved, and follow the classical model of asymmetric protein evolution. Genetic manipulation of the expression of these MSH genes in tomato will provide a potentially useful tool for modifying genetic recombination and hybrid fertility between wide crosses

Transferability of Microsatellite Markers from Cucumber (Cucumis sativus) to Seven Cultivated Cucurbit Crops

Plant breeding relies heavily on genetic resources with high genetic diversity presence in nature. Lack of genomic resources can slow down molecular characterization of any plant species. Transferability of SSR markers is when SSRs developed in one species can cross amplify in other species. Cucumber is an economically important fruit crop in the family Cucurbitaceae with many already developed Simple Sequence Repeat (SSR). We evaluated 515 cucumber-derived SSR markers in seven less studied cucurbit crops consisting of fifty one accessions. The transferability rate was 6.94% in pumpkin, 17.09% in wax gourd, 19.81% in bottle gourd, 13.27% in luffa, 45.05% in melon, 18.55% in watermelon and 8.76% in bitter gourd. Genetic diversity analysis classified tested plant species into five clades corresponding to four tribes. The result indicated that cucumber derived genetic tools are applicable to decipher genetic information in other cucurbit species

Genetic Diversity of Saccostrea forskali Rock Oyster in the Gulf of Thailand

Located in the tropical region, many oysters are widely distributed near-shore in the shallow water along the Gulf of Thailand. Rock oyster, Saccostrea forskali, is commonly found attached to the rocks along the beach. In order to fully utilize them as bioindicators of aquatic pollution, in this study, the genetic diversity and distribution of S. forskali was assessed by using microsatellite markers. A total of 240 S. forskali oyster samples were collected from eight locations in seven provinces along the Gulf of Thailand including Trat, Chanthaburi, Rayong, Chon Buri, Phetchaburi, Prachuap Khiri Khan (two locations) and Chumphon, and were analyzed based on eleven microsatellite loci developed from oyster species. The average number of amplified DNA bands per locus varied between one to four bands. The observed heterozygosity of oyster populations ranged from 0.365 to 0.523 while the expected heterozygosity ranged from 0.537 and 0.597. The genetic differentiation between populations was high, suggestive of isolated populations with very low gene flow. By regular monitoring of the genetic diversities of these S. forskali populations, emerging environment threats could be efficiently detected before more catastrophic damages would occur

A multiplex PCR assay for the identification of five commercially important Portunid crabs: <i>Portunus pelagicus</i>, <i>P. gladiator</i>, <i>P. sanguinolentus</i>, <i>Charybdis natator</i>, and <i>C. feriatus</i>

<p>Portunid crabs of the genus <i>Portunus: P. pelagicus, P. gladiator</i> and <i>P. sanguinolentus</i> and the genus <i>Charybdis: C. natator</i> and <i>C. feriatus</i> are economically important species for many tropical countries. An ongoing problem in the crab industry is involved with food labelling or food fraud in which many food manufacturers may have substituted the cheaper crabmeat for the more expensive ones due to the difficulty of species identification after many steps of food processing. To solve this problem, a convenient and accurate multiplex PCR assay using a species-specific primer set KUGEN_PORTspec was developed based on the nucleotide variation of <i>cytochrome b</i> and 28S ribosomal RNA. The primer set specifically amplified fragments of 286, 348, 418, 124 and 481 bp in <i>P. pelagicus, P. gladiator, P. sanguinolentus, C. natator</i> and <i>C. feriatus</i>, respectively, as well as a 220 bp positive control fragment. Specificity and sensitivity tests showed consistency in product sizes and absence of cross-species amplification with 0.1 ng DNA template limit of detection. Validation of the multiplex PCR assay on crabmeat prepared by steaming, mixing, freezing and canning was done and visualized by either agarose gel electrophoresis or automated capillary electrophoresis. The results indicated that the multiplex PCR assay using KUGEN_PORTspec is an effective tool for portunid species identification from both high- and low-quality DNA obtained from processed food. This newly developed primer set is an effective tool for crabmeat species identification to be used in future food industry and consumer protection programs.</p