Genetic diversity and marker trait association for yellow mosaic virus disease in green gram, Vigna radiata (L.) Wilczek

Yellow mosaic virus (YMV) disease is known to cause severe damage in green gram in terms of yield loss. As the resistance is often governed by recessive genes, introgression of such resistance faces some difficulty. DNA molecular markers are reported to be effective in this process. However, validation of such markers is important. Here, we have made an attempt to validate DNA markers associated with YMV disease resistance gene from a diverse group of 26 green gram genotypes. A total of 19 molecular markers were used to assess the susceptibility or resistance against YMV disease. Results show that among the amplified 31 alleles, 21 were polymorphic, with a mean of 1.1.0 per locus. The polymorphism information content (PIC) values ranged from 0.32 to 0.80. Only five markers exhibited higher PIC value (>6.0) and were revealed to be polymorphic, suggesting its utility in marker assisted selection for breeding YMV resistant genotypes in greengram. Dice dissimilarity coefficient among the genotypes exhibited a range of 0.07 to 1.0 which show a wide genetic variation among the genotypes for YMV tolerance. Neighbor-joining cluster analysis has grouped 26 green gram genotypes into 4 main clusters which revealed the existence of genetic dissimilarities among the genotypes. The genotypes AUGG 6, VBN (Gg) 2 and CO (Gg) 8 carried the positive alleles for YMV disease resistance and the allele for susceptibility were found in the genotypes AUGG 12, AUGG 15, AUGG 17 and AUGG 19. Single marker analysis indicated that there was correlation between the markers and the disease reaction in the field with exceptions. The findings revealed that the SSR markers CEDG180 and YR4 could be used to screen germplasm in order to discriminate the YMV resistant genotypes from the susceptible genotypes in marker assisted selection.

Screening for seedling stage salinity tolerance and comparative transcriptome analysis in Rice (Oryza sativa L.)

Soil salinity is one of the major abiotic stresses which affect crop productivity including rice, Oryza sativa L. Developing salt tolerant varieties gained considerable attention accordingly. Here, we studied salinity tolerance in rice crop. We screened ten rice genotypes for saline tolerance at different concentrations of 0 dSm-1, 2 dSm-1, 4 dSm-1, 6 dSm-1, 8 dSm-1,10 dSm-1, 12 dSm-1 and 14 dSm-1, respectively. Among the ten genotypes studied, CARIDhan-7 tolerated salt stress up to 6dSm-1 of irrigated water. Comparative transcriptome analysis was done with the genotypes by treating with saline water at 0dSm-1 and 6 dSm-1. A total of 1013 genes were differentially expressed under simulated stress conditions. Out of which, 551 genes were upregulated and 462 genes were downregulated. Based on the metabolic pathway analysis, the MAPK signaling pathway, along with the other 9 pathways were found to be enriched in the stressed sample. Nine ion transporter genes, 1potassium channel, 1 protein phosphatase gene, IAA homologs OsIAA9, two ROS scavenging-related genes, and 4 stress regulated genes identified were found to be significantly up-regulated along with some functional proteins previously reported under salt stress. An AP2-like ethylene-responsive transcription factor PLETHORA 2 was found to be downregulated. The results suggested that the CARIDhan-7 genotype undergoes various saline tolerant mechanisms and pathways in response to the stress imposed when compared to non-stressed seedlings.

Determination of Water Requirements of Main crops in the Tank Irrigation Command area using CROPWAT 8.0.

A study was carried out to determine the water requirement of main crops in the perumal tank irrigation command area in Cuddalore district. The main crops include rice, groundnut, and sugarcane. The crop water requirements were determined using 15 year climatic data using CROPWAT 8.0. The seven crop growth stages (nursery,nursery/land preparation,land prepearation,initial,development,mid season,late season) and three decades (I,II,III) were considered for all crops. Crops were planted during 2012 kuruvai season and the crop coefficient was determined for each crop. Reference Crop Evapotranspiration (ETo) was determined using the FAO Penman Monteith method and the effective rainfall was calculated using USDA S.C. Method. The study shows that for the study area, reference evapotranspiration (ETo) varied from 3.67 to 6.42 mm/day and the effective rainfall varied from 12.8 to 166.8 mm. Crop evapotranspiration (ETo) and the crop water requirement for Rice varied from 0.74 mm/day to 6.23 mm/day and 0.0 mm/dec to 244 mm/dec, for groundnut 2.4 mm/day to 5.03 mm/day and 0.0 mm/dec to 29.2 mm/dec, for Rice (Navarai) 0.45 mm/day to 6.49 mm/day and 0.0 mm/dec to 152.5 mm/dec, for Groundnut (Navarai) 1.78 mm/day to 5.79 mm/day and 4.1 mm/dec to 54.8 mm/dec and for Sugarcane 2.07 mm/day to 6.57 mm/day and 0.0 mm/dec to 63.9 mm/dec respectively. The peak water requirement was 1.11 l/s/ha or 9.6 mm/day with an application efficiency of 70%.

Mosquito larvicidal properties of various extract of leaves and fixed oil from the seeds of Caesalpinia bonduc (L) Roxb.

A Preliminary laboratory trial was undertaken to determine the efficacies of petroleum ether, ethanolic, aqueous extracts of dried leaves and fixed oil from the seeds of Caesalpinia bonduc (L). Roxb (Family: Caesalpiniaceae) at various concentrations against the fourth instar larvae of Culex quinquefasciatus by following the WHO guidelines. Hundred per cent mortality was observed in 1% concentration of petroleum ether and ethanolic extract of leaf, whereas it was 55% in 2.5% concentration of aqueous extract and 92.6% in 2.5% concentration of fixed oil. The active constituent responsible for the mortality is to be isolated to come up with a promising larvicidal agent, which will be economic, non pollutant and ecofriendly.

Computerized tomography detects pulmonary lesions in children with normal radiographs diagnosed to have tuberculosis.

This report is based on observations during the conduct of a larger study to develop diagnostic criteria for childhood tuberculosis (TB). Of 201 children confirmed to have pulmonary or lymph node TB, 84 had normal chest radiographs. Computerized tomography (CT) of the chest was performed in nine of them, seven of whom had normal chest radiographs while two had visible calcification. Eight of the nine children had definitive lesions detected by computerized tomography of the chest. While five children had primarily hilar lymph node enlargement, three had pulmonary parenchymal lesions. The use of more sensitive diagnostic tests like computed tomography helps to detect tuberculosis lesions not otherwise visualized on chest radiographs. This report highlights the difficulty in excluding active tuberculosis in children. More studies are required on the role of CT scans in the diagnosis of tuberculosis in children.

Evaluation of secondary poisoning of difethialone, a new second-generation anticoagulant rodenticide to barn owl, Tyto alba Hartert under captivity.

Secondary toxcity of difethialone to Barn owl (Tyto alba) has been investigated. Difethialone was fed to owls for successive periods of 1 (phase 1), 3 (phase 2) and 6 (phase 3) days via-rodenticide dosed rats. The owls survived after the treament of rodenticide on phase 1 and phase 2 experiments but they died during phase 3 experiment. The results suggest that the difethialone could cause more secondary toxicity to owls.

Toxicity of Nerium indicum Miller seed extract on bandicoot rat, Bandicota bengalensis Gray.

Crude extract (12.5 ml/kg) of N. indicum seed gave 100% mortality of B. bengalensis. Humanness assessment study revealed that this plant orgin chemical caused low pain and sufferings to the target pests.

Field evaluation of difethialone, a new second generation anticoagulant rodenticide in the rice fields.

A new second generation anticoagulant rodenticide, difethialone (0.0025%), was evaluated in the rice fields at three different cropping stages, viz. Milky, Panicle formation and Panicle maturation, during Kuruvai and Thaladi seasons. The difethailone (0.0025%) yielded satisfactory control success suggesting a great potential as a rodenticide especially in the early stages of rice.