Genetic diversity studies of coarse and fine rice using RAPD markers

The availability of a genetically diverse gene pool is vitally important in varietal development. Molecular markers are being extensively utilized to explore the genetic diversity among native and exotic germplasm. This study was designed to reveal the genetic diversity and patterns of relationships among the 20 accessions/genotypes representative of basmati and non-basmati rice from the existing rice gene pool using RAPD markers. Employing RAPD, 17 decamer oligonucleotide primers directed the amplification of 116 fragments, out of which 101 were polymorphic (87.06%) while 15 fragments were monomorphic (12.93%). Similarity coefficients had ranged from 0.47 to 0.90. The average genetic similarity was calculated 0.68 (68%). In this study, the coarse rice genotypes showed more polymorphism (85.84%) than the fine rice genotypes (61.76%). Genotypes were clustered into 8 distinct groups: A, B, C, D, E, F, G, and H but two genotypes, i.e., Shadab and Kangni-27 showed divergence from all the genotypes of the groups. Therefore, these diverse genotypes may be included in future breeding programmes.     

Impact of calcium chloride concentrations and storage duration on quality attributes of peach (<Emphasis Type="Italic">Prunus persica</Emphasis>)

To investigate the impact of CaCl₂ concentrations and storage duration on quality of peach (Prunus persica), a research was conducted at postharvest Laboratory, Department of Horticulture, The University of Agriculture, Peshawar, Pakistan during 2012–2013. The experiment was laid out in Completely Randomized Design (CRD) with factorial arrangement repeated three times. The peach fruits (cv. Texas A 69) were harvested at physiological maturity stage from peach orchard, Horticulture Farm. The fruits were dipped in 0, 2 and 4% CaCl₂ solution for 10 min and transferred to cold storage having ±8–10°C with relative humidity of 80–85%. The application of CaCl₂ solution and storage duration significantly influenced the fruit quality of peach fruit. However, the application of CaCl₂ solution significantly reduced weight loss (4.98%), disease incidence (2.08%), total sugars (5.31%), TSS-Acid ratio (16.27), TSS(7.38⁰Brix) and increased the fruit firmness (2.21 kg cm^–2) titratable acidity (0.47%) and Ascorbic acid (5.35 mg/100 g) of peach fruits. The storage duration of peach fruit also significantly affected the fruit quality attributes during storage. The peach fruit stored for 30 days showed less fruit firmness (0.74 kg cm^–2) and titratable acidity (0.31%), Ascorbic acid (4.45 mg/100 g) and increased weight loss (19.74%), disease incidence (16.11%), total sugars (6.07%), TSSAcid ratio (27.62) and TSS(8.54⁰Brix) of peach fruit. Based on the findings of this study, it is concluded that the peach fruit should be treated with 4% CaCl₂ solution to retain the quality attributes for 30 days storage.     

Finding heterosis for fiber traits in intervarietal crosses of cotton, <Emphasis Type="Italic">Gossypium hirsutum</Emphasis> L.

Raising yield and fiber quality of cotton through heterosis (hybrid vigor) has been an objective of plant breeders and scientists. Heterosis over mid parent for fiber-related traits was calculated in three crosses of cotton (Gossypium hirsutum L.) involving five cotton varieties, viz., CIM 506, CIM 702, CIM 443, FH 1000 and CIM 1100 being commercially grown in Pakistan. Heterosis was observed for all four characters. The cross CIM 443 × CIM 1100 showed maximum positive heterosis (8.57%) for ginning outturn (GOT) (%) followed by fineness (7.81%) and staple length (1.01%). Therefore, the cross CIM 506 × CIM 1100 appeared to be promising for providing potential breeding materials for further commercial exploitation of heterosis in Pakistan, and heterosis breeding has a great potential for increasing stagnant cotton yields around the world.     

Aflatoxins and ochratoxin A contamination in rice,corn and corn products from Punjab,Pakistan

In present study, a total of 275 retail cereal samples including rice, corn and corn products was analyzed for the presence of aflatoxins and ochratoxin A (OTA) using HPLC equipped with a fluorescence detector. The data has shown that 38 out of 68 samples of rice, 37/105 of corn and 43/102 samples of corn products have been found contaminated with AFs, average level of AFB₁ and total AFs, 8.23 and 19.54, 7.90 and 12.08, and 5.47 and 7.85 μg/kg, respectively. Furthermore, 34, 28 and 26 numbers of rice, corn and corn product samples were found to be contaminated with OTA with an average level of 12.94, 5.29 and 3.69 μg/kg, respectively. The samples of rice, corn and corn products found above the permissible European Union (EU) limit for AFB₁ and total AFs were 18, 13 and 14 and 28, 14 and 20%, respectively; however, the samples of rice, corn and corn products above the EU limit were 40, 14 and 15%, respectively.     

Identification of Aspergillus flavus and aflatoxin in home mix layer poultry feed in relation to seasons in Karachi,Pakistan

Fungal toxins in feed are leading issue in poultry industry causing a detrimental effect on the performance and health of poultry. The study was carried out to determine the incidence and concentration of the aflatoxins and their major producer Aspergillus flavus in home mix layer poultry feed in respect of seasonal variation throughout the year. A total of (n?= 204) home mix poultry layer feed samples were analyzed for the isolation of fungi. The isolates were initially screened through colony morphology and microscopic examination. However, aflatoxin concentration was determined by ELISA. Revealed results indicated that, the highest percentage of A. flavus was found during the months of June to August 50/54 (92.5%) followed by September to November 43/65 (66.1%), March to May 21/40 (52.5%), and December to February 18/45 (40%). As a whole, the incidence was recorded 132/204 (64.7%). Moreover, of the 132 samples, 41 (31%) were exceeded in respect of aflatoxin contamination from the legal limit (20 μg/kg) imposed by Food Drug Association (FDA). Statistically, the growth of A. flavus and aflatoxin production was found significantly different in respect of seasonal variation. As highest total viable fungal count (9.9?×?10⁴ CFU/g) and aflatoxin level (72.27 μg/kg) were recorded during the months of June to August and lowest in December to February. Consequently, instantaneous essential control measures are demanded regarding appropriate storage and adequate drying in post-harvesting season. Along with surveillance plans and austere regulations for monitoring the aflatoxin contents for the wellbeing of consumers.

     

A fine-scale chimpanzee genetic map from population sequencing

To study the evolution of recombination rates in apes, we developed methodology to construct a fine-scale genetic map from high-throughput sequence data from 10 Western chimpanzees, Pan troglodytes verus. Compared to the human genetic map, broad-scale recombination rates tend to be conserved, but with exceptions, particularly in regions of chromosomal rearrangements and around the site of ancestral fusion in human chromosome 2. At fine scales, chimpanzee recombination is dominated by hotspots, which show no overlap with those of humans even though rates are similarly elevated around CpG islands and decreased within genes. The hotspot-specifying protein PRDM9 shows extensive variation among Western chimpanzees, and there is little evidence that any sequence motifs are enriched in hotspots. The contrasting locations of hotspots provide a natural experiment, which demonstrates the impact of recombination on base composition.