[Show abstract][Hide abstract] ABSTRACT: Nong-Han Lake, Thailand, sustains the whisker sheatfish (Micronema bleekeri Günther, 1864), which is a rare species of freshwater catfish. Wild-caught whisker sheatfish has been intensively harvested to meet market demand; yet, genetic information about this species remains unknown. To assist with the in situ conservation of whisker sheatfish populations in Nong-Han Lake, 35 and 34 individuals from the middle (MN) and lower (LN) areas of the lake, respectively, were studied using 7 microsatellite loci. Low genetic variation was detected in the MN (HO = 0.338, AR = 2.710) and LN (HO = 0.394, AR = 2.714) populations. Genetic differentiation between the 2 populations was significant (FST = 0.063, P < 0.05). The size of recent populations (NE < 50) was found to be 9- to 29-times smaller compared to the estimated historical populations, even though no bottleneck signal was observed. Low genetic diversity was observed, implying that the populations are at risk of being lost from this site. Of note, migration among the populations inhabiting the middle and lower parts of the lake exhibited opposing trends in changes to the genetic structure. This phenomenon might be due to the operation of a regional irrigation gate over the last decade. The information collected here indicates that the whisker sheatfish populations in Nong-Han Lake require consistent fisheries monitoring and management. Further research about the whisker sheatfish populations from the Mekong and Chao Phraya River basins is required to assist national-scale conservation efforts.
[Show abstract][Hide abstract] ABSTRACT: Shells of certain freshwater mussel (Unionoida) species are highly demanded and serve as raw material for a range of decorative and pharmaceutical products. In Thailand, most animals for this purpose are currently harvested from wild populations, with unionoid culture still being in its infancy. Whilst reliable species identification is a prerequisite for developing a large-scale industry, identification by morphological means is hampered by extensive phenotypic plasticity and poor knowledge of species delimitations. To facilitate alternative molecular identification, we developed species-specific markers for the three Thai unionoids with considerable economic potential (CEP): that is, Chamberlainia hainesiana, Hyriopsis desowitzi and Hyriopsis myersiana. For this purpose, amplified fragment length polymorphism (AFLP) fingerprints using 24 specific primer pairs were generated for eight samples of each CEP species and four samples of the closely related, non-CEP species Contradens contradens. Cloning and sequencing of 13 CEP species-specific AFLP bands revealed fragment collision at three occasions. In total, 16 species-specific primer pairs were designed and tested on 92 Thai specimens spanning seven species and four genera. Thereby, specificity of (1) three primers to C. hainesiana, (2) one primer to H. desowitzi + Hyriopsis bialata, (3) one primer to H. myersiana + H. bialata and (4) four primers to all three Hyriopsis species tested was confirmed. Respective multiplex PCR protocols are provided. The developed primers enable cheap, quick and reliable identification of the Thai CEP species by one to three PCRs and offer a tool for a range of additional applications within mussel culture and ecological and evolutionary research on these important organisms.
[Show abstract][Hide abstract] ABSTRACT: Genetic analysis of 56 samples of Jatropha curcas L. collected from Thailand and other countries was performed using the methylation-sensitive amplification polymorphism (MSAP) technique. Nine primer combinations were used to generate MSAP fingerprints. When the data were interpreted as amplified fragment length polymorphism (AFLP) markers, 471 markers were scored. All 56 samples were classified into three major groups: γ-irradiated, non-toxic and toxic accessions. Genetic similarity among the samples was extremely high, ranging from 0.95 to 1.00, which indicated very low genetic diversity in this species. The MSAP fingerprint was further analyzed for DNA methylation polymorphisms. The results revealed differences in the DNA methylation level among the samples. However, the samples collected from saline areas and some species hybrids showed specific DNA methylation patterns. AFLP data were used, together with methylation-sensitive AFLP (MS-AFLP) data, to construct a phylogenetic tree, resulting in higher efficiency to distinguish the samples. This combined analysis separated samples previously grouped in the AFLP analysis. This analysis also distinguished some hybrids. Principal component analysis was also performed; the results confirmed the separation in the phylogenetic tree. Some polymorphic bands, involving both nucleotide and DNA methylation polymorphism, that differed between toxic and non-toxic samples were identified, cloned and sequenced. BLAST analysis of these fragments revealed differences in DNA methylation in some known genes and nucleotide polymorphism in chloroplast DNA. We conclude that MSAP is a powerful technique for the study of genetic diversity for organisms that have a narrow genetic base.
[Show abstract][Hide abstract] ABSTRACT: We describe the isolation and characterization of eight microsatellite loci from whisker sheatfish (Micronema bleekeri Günther, 1864). Genetic variability was assessed using 35 individuals. The number of alleles per locus ranged from two to
four. The observed heterozygosity (H
o) ranged from 0.072 to 0.637, whereas the expected heterozygosity (H
e) ranged from 0.174 to 0.725. All loci conformed to the Hardy–Weinberg expectation (HWE). Linkage disequilibrium was not significant
for any pair of loci. These loci should prove useful for population genetic studies of whisker sheatfish and other siluriforme
KeywordsWhisker sheatfish–Microsatellite marker–Genetic conservation
[Show abstract][Hide abstract] ABSTRACT: Temperature is a crucial factor affecting the quality and safety of food products during both distribution and storage. The difficulty in controlling and monitoring the temperature history of food products makes it difficult to precisely predict shelf life. Time–temperature indicators (TTIs) provide a visual summary of a product’s accumulated chill-chain history, recording the effects of both time and temperature. Attempts have been made to develop a prototype of a time–temperature indicator based on the diffusion of lactic acid, which is temperature-dependent. Four lactic acid-based TTIs were made in different substrate concentrations. Color changes associated with the diffusion of lactic acid were monitored. In the vapor diffusion of lactic acid, an irreversible color change of a chemical chromatic indicator (from green to red) clearly and progressively occurred due to the pH reduction. The temperature dependence of these TTIs kinetics was characterized isothermally in the range of 4–45 °C, yielding activation energy (Ea) of, approximately, 50 kJ mol−1. The mathematical models of each TTI were established according to the relationships between color changes and time and temperature. The differences between the Ea values of the TTIs and the Ea associated with food quality losses – including enzymatic loss, hydrolysis, lipid oxidation, nutrient loss and microbial growth – were less than 40 kJ mol−1, and therefore these TTIs could be considered as good candidates to monitor food quality losses. Although these TTIs do not cover the whole range of food quality losses, they could be applied to show the time–temperature history of some foods, especially fruits and vegetables, and to indicate food quality associated with time–temperature exposure.
[Show abstract][Hide abstract] ABSTRACT: A commercial variety of soybean, Chiangmai 60, which is susceptible to field weathering and two field weathering resistant varieties, GC 10848 and Kalitur, were grown and hybridized in the greenhouse at the Department of Agronomy, Kasetsart University. The F 1 hybrid seeds and their parental varieties were planted in the greenhouse to produce F 2 seeds. Parental varieties, F 1 hybrids and F 2 progenies were grown in an experimental field during the 2008 dry season at the National Corn and Sorghum Research Center, Pakchong District, Nakhon Ratchasima province. Individual plots were 3×3 m 2 , with six rows, composed of two rows of parents and four rows of F 1 hybrids or F 2 progenies for each cross. The spacing between rows was 50 cm and between hills was 25 cm. At physiological maturity, soybean pods were harvested, threshed and subjected to tests for accelerated aging (AA) and electrical conductivity (EC), and the seed coat percentage was measured. Field weathering resistance of the parental plants, F 1 hybrids and F 2 progenies was evaluated using germination percentages after AA testing and EC values of seed leachate and seed coat percentages. Dominance percentages of F 1 hybrids and the frequency distribution of F 2 progenies for the germination percentages after AA testing and EC values of seed leachate and seed coat percentages of the two soybean crosses revealed that field weathering resistance was controlled by a polygene with partial dominance.
[Show abstract][Hide abstract] ABSTRACT: Five waterlily cultivars, with good pod setting and completely formed flowers, from the subgenus Nymphaea (hardy waterlily) were used as pod (female) parent. Waterlilies from subgenera Anecphya (2 entities) and Brachyceras (20 entities), specifically the blue-flowered ones, were used as pollen (male) parent for transferring blue-flowered characteristic to the hardy waterlily. Hybridization of subgenus Nymphaea with subgenus Anecphya was unsuccessful. A successful crossing was obtained between the subgenera Nymphaea and Brachyceras, yielding one pod with 244 seeds, from which only 39 seeds germinated and yielded 20 good intersubgeneric hybrid plants. The characteristics of the hybrids were categorized by their flower colors into two groups, a pink-flowered group with 17 hybrids and a blue-flowered group with 3 hybrids. In the blue-flowered group, there was a prominent one with beautiful blue-purple flower, which was determined by PCR-RFLP markers to be a hybrid between Nymphaea and Brachyceras subgenera, as well as inherited some plant characteristics, for example, ovary carpel, leaf (pad), rootstock, position of flower at flowering from the parent. The blue-purple flowered hybrid had important characteristics inherited from the hardy waterlily (subgenus Nymphaea); therefore, the hybrid has been named Nymphaea ‘Siam Blue Hardy’ to honor the birth place and its distinct flower color.
Scientia Horticulturae 05/2010; DOI:10.1016/j.scienta.2010.01.024 · 1.37 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: This paper presents the karyotype and the idiogram of known sex plants for five species of Cycas (Cycadaceae) and seven species of Zamia (Zamiaceae). All five species of the genus Cycas had the same chromosome number (2n = 2x = 22) but their karyotype formulae varied into three groups: 10m+10sm+2st, 12m+8sm+2st and 14m+8sm. The karyotype of male and female Cycas plants could be clearly distinguished by the satellite chromosomes. All seven species of the genus Zamia varied in both chromosome numbers (2n = 2x = 16 up to 2n = 2x = 24) and karyotype formulae. It was difficult to differentiate between the male and female plants of the Zamia spp. by karyotyping because of the lack of satellite chromosomes in both sexes.
[Show abstract][Hide abstract] ABSTRACT: Pyricularia grisea is the most destructive and cosmopolitan fungal pathogen of rice and it can also cause disease on other agriculturally important cereals. We determined the number, location and interaction of quantitative trait loci (QTL) associated with resistance to P. grisea isolates obtained from rice (THL142 and THL222) and barley (TH16 and THL80) grown in Thailand. The isolates showed a spectrum of virulence when used to inoculate a series of differentials. We used a reference blast resistance mapping population of rice (IR64 × Azucena). IR64 was highly resistant, and Azucena was highly susceptible, to all four isolates. The numbers of resistant vs. susceptible progeny suggest that the resistance of IR64 is determined by two or three genes with additive effects. The correlation coefficients for all pairwise comparisons of disease severity were high and highest between barley isolates and between rice isolates. Four QTL were detected, one on each of the following chromosomes 2, 8, 9 and 10. IR64 contributed resistance alleles at three of the QTL (chromosomes 2, 8 and 9). Azucena contributed the resistance allele at the QTL on chromosome 10 in response to inoculation with isolate THL142. The results of the QTL analysis support interpretation of the phenotypic frequency distributions regarding the number of genes determining resistance to the four isolates in this population. Our results are novel in adding blast isolates from barley to the catalogue of pathogen specificities to which a gene, or genes, from IR64 confer resistance.
[Show abstract][Hide abstract] ABSTRACT: Karyotype and idiogram of three species of Cycas and Zamia from Nong Nooch Tropical Botanical Garden were obtained. All the three species of both Cycas and Zamia have an equal chromosome number in each species, namely 2n = 2x = 22 in Cycas and 2n = 2x = 16 in Zamia. The karyotype formulae of Cycas varied into 3 groups: 12 M + 8 SM + 2 A, 10 M + 8 SM + 2 A and 12 M + 8 SM + 2 T and of Zamia was 12 M + 4 SM. Of all three Cycas species studied, the karyotype of female and male plants could be distinguished. The Zamia evidence was complicated even all three species had the same chromosome number and karyotype pattern as well. Only Z. pumila could be differentiated between male and female plants.
[Show abstract][Hide abstract] ABSTRACT: Sixty-four accessions (960 individuals) of landraces collected from five former regions of Ethiopia and Eritrea covering different agro-ecologies were characterized for growth habit, ear shape, grain shape, grain surface, grain color and pericarp persistence. The objective was to study the pattern and phenotypic diversity of some characters in finger millet. The experiment was laid down in a randomized complete block design (RCBD) with three replications. The percentage frequencies of the phenotypic classes of each character were calculated. The Shanon-Weaver diversity index (H′) was used to estimate the magnitude of diversity. One way analysis of variance of the non-normalized H using regions was under taken for individual characters. All the character considered showed marked differences in their distribution and variation. In no cases monomorphic classes were observed. Regional wise, Gojam and Welega revealed the highest diversity (H′=0.84) while Eritrea showed the lowest (H′=0.67). There was an increasing trend of diversity from north to south. Overall characters revealed intermediate to high diversity ranging from 0.60 for pericarp persistence to 0.99 for grain surface. Ear shape (P≤0.01), grain shape (Pd≤0.05) and grain surface (Pd≤0.01) showed different levels of diversity among regions as opposed to growth habit, grain color and pericarp persistence whose variations were attributed to among accessions. The overall mean diversity estimate was high (H′=0.82). Generally, the result revealed the existence of a vast range of diversity in the indigenous finger millet germplasm.
[Show abstract][Hide abstract] ABSTRACT: The use of vetiver (Vetiveria zizanoides) anther for basic scientific research has not been well documented. This study was undertaken to identify cytologically the different developmental stages of vetiver anther to correlate them with previous karyomorphological study of vetiver germplasm in Thailand. Meiotic division in vetiver studied seemed to be normal only a few showed abnormality.
[Show abstract][Hide abstract] ABSTRACT: Sixty-six accessions of finger millet comprising of two standard varieties and 64 landraces collected from five former regions of Ethiopia and Eritrea were assessed to study the genetic affinity within the germplasm in order to provide the basis for selection of parents for hybridization. The study was conducted at Aresi-Negele Research Sub-Center in Ethiopia during the main season of 2004. The experiment was laid down in randomized complete block design (RCBD) with three replications. Data on 15 morpho-agronomic characters were recorded and two multivariate methods, cluster and principal component analyses were employed. The cluster analysis grouped the sixty-six accessions into five major clusters. The number of accessions in each cluster varied from 5 (cluster III) to 24 (cluster IV). Maximum inter-cluster divergence occurred between cluster I and III (D2=81.47) and the minimum was between cluster IV and V (D2=11.30). The principal component analysis indicated that days to heading, culm thickness, leaf number per main tiller, leaf blade width and finger width contributed most towards the genetic divergence. The most divergent populations with complementary characters could be used as parents in the improvement program of finger millet through hybridization.
[Show abstract][Hide abstract] ABSTRACT: Genetic diversity among 126 rice accessions, including 110 Thai landraces and 16 varieties used as subspecies reference, were evaluated by three types of DNA markers, InDel (Insertion/Deletion), inter-simple sequence repeat (ISSR) and simple sequence repeat (SSR) markers. Twelve InDel primer pairs, based on DNA sequence polymorphism between '93-11' (indica) and 'Nipponbare' (japonica), were used to identify subspecies of landraces. Most of the local rice samples had either '93-11' alleles or 'Nipponbare' alleles. The scatter plotting of the principal component analysis (PCA) and dendrogram results based on InDel data could clearly classify landraces into two groups, indica and japonica. InDel and SSR markers showed the average polymorphic information content (PIC) values of 0.3707 and 0.6367, respectively. The dendrogram, based on combining InDel, ISSR and SSR data, could classify rice samples into five clusters at a cut-off genetic similarity value of about 0.70. The genetic similarity within landraces was low, indicating that Thai local rice samples have a great genetic diversity. The results of this experiment provide helpful data for rice germplasm management in breeding program. Key word: Rice, genetic diversity, DNA markers, simple sequence repeat (SSR), inter-simple sequence repeat (ISSR), insertion/deletion (InDel).
[Show abstract][Hide abstract] ABSTRACT: Forty-eight soybean varieties/lines along with resistance and susceptibility checks were grown at the National Corn and Sorghum Research Center, Nakhon Ratchasima province, Thailand in a randomized complete block design with three replications. At physiological maturity, soybean pods were harvested and subjected to incubator weathering, controlled deterioration and electrical conductivity tests to evaluate the seed quality. Soybean seed physical characteristics, including seed coat percentage, seed weight and seed coat color were also investigated. Two sequence characterized amplified region (SCAR) primers, Eaag/Mcac-233 and Eact/Mctt-157, previously reported to link with a quantitative trait locus (QTL) that controlled field weathering resistance, were used to amplify the DNA of the 50 soybean varieties/lines. The results revealed that 48 soybean varieties/lines were significantly different in seed quality and seed physical characteristics. They were classified into four groups: resistant, moderately resistant, moderately susceptible and susceptible to field weathering, according to the average germination percentage after incubator weathering and controlled deterioration. The overall field weathering resistance was found to correlate with seed quality and seed physical characteristics. The two highest correlation coefficients were found between field weathering resistance and germination percentage after incubator weathering (r = 0.898**) and controlled deterioration (r = 0.888**). The two SCAR primers were able to differentiate between resistance and susceptibility checks but were unable to classify field weathering resistance in 48 soybean varieties/lines. It was concluded that the two markers were not appropriate for evaluating field weathering resistance in the soybean varieties/lines.