Abstract: Rice (Oryza sativa L.) is the staple food for most people in Asia and is major caloric dietary source. As population and economy expand, the demand for consumption of rice will increase. To meet this growing demand it is required to increase the productivity levels of rice by combating biotic and abiotic stresses and other constraints. Early duration Recombinant Inbred Lines, 41 in total, developed using deep-rooted (Moroberekan) and high-yielding (IR50) parents were validated with 15 trait-specific SSR markers. These genotypes were validated by 4 candidate genes. Single marker analysis was done to study the association of markers with traits using the Student’s t-test. RM242 and RM282 were associated with plant height, RM302 with days to 50% flowering, RM242 with number of tillers per plant, while RM257 was associated with seed weight per plant. Among the four candidate genes, Ext1L/1R, coding for extensin protein/leucine-rich repeats protein, was associated with days to maturity and MAPK for transcriptional control of stress response was associated with number of panicles.
Abstract: Rice is one of the most important food crops drastically affected by drought in the rice ecosystem. Among grain crops, rice is the single biggest user of water, requiring 2 to 3 times more water per unit of grain produced. Recognizing the water constraints to rice yield, an alternative method of rice production using available water is necessary. One such method is aerobic cultivation which requires about 50% of water as puddle cultivation. To generate new varieties suitable to aerobic cultivation, 41 early duration recombinant inbred lines developed using high-yielding (IR50) and deep-rooted (Moroberekan) parents, were evaluated for drought and yield traits under aerobic conditions. Among these, IM 65, IM71, IM84, IM108, IM122, IM151 and IM181 showed superior field traits. Furthermore, the genomic regions of IM65 (drought tolerant) and IM84 (drought susceptible) were graphically genotyped with the help of 45 SSR markers. Identification of DNA fragments responsible for drought tolerance may further help in developing introgression lines with an IR50 background and with Moroberekan-like drought tolerance.
Abstract: A field experiment was conducted during wet season 2009 to study the response of rice genotypes under aerobic conditions. Variance studies revealed significant differences among the genotypes for the traits, days to flowering, plant height, harvest index, grain yield, panicle number, straw yield, panicle length, test weight and biomass. Higher values of heritability and genetic advance were observed for plant height and days to flowering. Grain yield per plot showed positive association with harvest index and total biomass. Correlation and path analysis revealed an ideal plant type of genotype under aerobic conditions should have high harvest index and biomass. Eight rice genotypes with increased yield advantage over checks have been identified as suitable entries for aerobic cultivation. Results also suggested that all rice genotypes are not suitable for aerobic method of cultivation and the genotypes which are able to acclimatize to the non-puddled aerobic conditions should be identified and released.
Abstract: Seventeen across species functional primers were used for the first time to amplify forty three mulberry varieties/species to reveal cross transferability. About 94% cross amplification was observed with 11.7% polymorphic loci and 88.3% monomorphic loci. Marker developed from bZIP factor, which is responsible for ABA-induced transcription (ABA-Abscisic acid) mediating plant responses to environmental stress, such as high salinity, drought, low temperature and mechanical wounding generated two specific bands for Weeping and Okinowa varieties. These specific markers can be effectively utilized in marker assisted selection of mulberry for developing drought resistant varieties and also has potential ‘identification markers’ for protection, documentation and registration mulberry accessions. The amplification for the various functional loci shows the presence cross amplification for abiotic stress related marker sequences in mulberry and such across species markers along with other genetic markers can be utilized for characterization, genome mapping and marker assisted selection in mulberry.Seventeen across species functional primers were used for the first time to amplify forty three mulberry varieties/species to reveal cross transferability. About 94% cross amplification was observed with 11.7% polymorphic loci and 88.3% monomorphic loci. Marker developed from bZIP factor, which is responsible for ABA-induced transcription (ABA-Abscisic acid) mediating plant responses to environmental stress, such as high salinity, drought, low temperature and mechanical wounding generated two specific bands for Weeping and Okinowa varieties. These specific markers can be effectively utilized in marker assisted selection of mulberry for developing drought resistant varieties and also has potential ‘identification markers’ for protection, documentation and registration mulberry accessions. The amplification for the various functional loci shows the presence cross amplification for abiotic stress related marker sequences in mulberry and such across species markers along with other genetic markers can be utilized for characterization, genome mapping and marker assisted selection in mulberry.
Abstract: Genetic variability analysis and heritability of different yield contributing characters were studied in 26 genotypes of mulberry. Variance analysis for characters revealed significant differences among the accessions. Phenotypic coefficient of variation (PCV %) was found higher than the genotypic coefficient of variation (GCV %) for all the characters studied. High genetic advance coupled with heritability was observed in the characters namely, number of branches per plant, leaf yield per plant, leaf-shoot ratio, hundred leaf weight and total shoot length. Significant positive correlations to leaf yield/plant were observed for the characters, number of branches/plant (0.835**), longest shoot length (0.823**) and total shoot length (0.707**). Leaf yield/plant is an important agronomic character induced by many associated traits and hence characters like number of branches/plant, longest shoot length and total shoot length should be considered crucial parameters for selection in mulberry breeding programme.
Abstract: Germplasm evaluation is essential in any crop improvement program and genetic characterization at
morphological and molecular level is very vital for breeding programs to be successful. Twenty six cultivated and local genotypes of mulberry were subjected to diversity analysis with RAPD markers. Among the total 31 RAPD primers studied, 24 were polymorphic and 7 were monomorphic. Of the total 197 loci obtained from 24 polymorphic primers, 110 loci (55.83%) were polymorphic and 87 (44.16%) were monomorphic. A clear grouping was seen among the cultivated genotypes based on yield with varieties like S36, V1, S54 and M5 showing proximity to each other and sharing a close similarity. Local genotypes are rich reservoirs of resistant gene sources and are well acclimatized to the prevailing environmental conditions.Utilization of these along with other high yielding varieties will produce various combinations of resistance sources which can be incorporated into high yielding varieties.
Abstract: Eighty three cowpea genotypes were analyzed with 15 micro satellite markers to test the genetic variation. Among the total 15 SSR primers used, 12 primers were polymorphic and 3 primers were monomorphic. A total of 15 markers were obtained, among which 80% were polymorphic and 20% were monomorphic. Genotype specific markers were identified for some genotypes. The clusters constructed based on SSR marker data revealed significant genetic variation among the genotypes. The marker detected significant polymorphism among the local landraces as compared to the cultivated varieties. Genotypes with resistance to rust disease and nutritionally superior ones grouped together in separate clusters. The results using SSR markers indicated that micro satellites successfully unraveled the genetic variation existing in selected cowpea genotypes.
Abstract: The uzifly, Exorista sorbillans (=E. bombycis) a tachinid endoparasitoid of silkworm, Bombyx mori L., known to cause considerable damage to the silk industry. Earlier studies on various aspects of the uzifly indicated for possible presence of a number of cryptic species. Though the fly entered into South India 25 years ago, the basis for the existence of cryptic species was not known. To ascertain whether the genome of this parasitoid is differentiating into discrete gene pools in contrasting eco and geo-climatic conditions, an attempt has been made in the present study the molecular profiling of 8 populations (Chitoor, Kuppam, Erode, Bangarapete, Sira, Mandya, Chitradurga, and Kanakapura) from south India with 16 RAPD primers and also to explore the possibility of its endosymbiont Wolbachia as a causative agent as it known to cause cytoplasmic incompatibility in its host uzifly. The hierarchical clustering done on the basis of RAPD data and the Euclidean distance matrix put Chitradurga populations at the maximum distance from other south Indian populations studied and reveals the occurrence of spectacular region-wise pairing with separate clusters. Further, when we have crossed within and between selected populations for the Wolbachia induced reproductive isolation, the results showed the lower level (28–32%) of reproductive isolation within and between populations. The RAPD and crossing data clearly indicates the micro-level divergence in the uzifly, E. sorbillans. The significance of this study with a tachinid fly pest is discussed in the context of understanding the diversification of uzifly and also establishing this pest as a relevant biological material for studying microevolution in nature.
Abstract: The Random Amplified Polymorphic DNA (RAPD) technique was used to study DNA profiling of 5 multivoltine silkworm genotypes. The silkworm Bombyx mori. L, (Lepidoptera; Bombycidae) were analyzed using 30 random primers among which 18 polymorphic primers gave 73 amplified products and of which 38.3% were polymorphic. The dendrogram generated using an unweighted pair grouped method with arithmetic averages revealed the pattern of relatedness of 5 genotypes. Genetic similarity co-efficient and cluster analysis were performed by a hierarchical clustering technique. The genetic distances between the clusters and within the clusters estimated 6% variability between the 4 races and Nistari. The results of our study indicate that RAPDs are very efficient in the estimation of genetic diversity in populations that are closely related and acclimatized to local environmental conditions. The polymorphic data obtained from the study can be further utilized for MV genome mapping research and finally to assign function to sequences through biometrical tools. Modern breeding tools like molecular markers which show easily detectable differences among different races of a species offer a wide range of applications for silkworm breeding programs. India is being a country with diverse environmental conditions, the local races are rich reservoirs of many resistant genes, and molecular markers are inevitable tools to study inheritance of such complex genes.
