Frequency and fertility restoration efficiency of Rf3 and Rf4 genes in Indian rice

Identification of new parental lines is crucial for developing ecology‐specific hybrids with ideal agronomic performance. We screened a total of 570 different ecology‐specific Indian rice varieties for the presence of fertility restorer genes, Rf3 and Rf4 using tightly linked markers DRRM Rf3‐10 and RM6100, respectively. Among these varieties, 13% carried Rf3Rf3/Rf4Rf4, 31% carried rf3rf3/rf4rf4, 6% carried Rf3Rf3/rf4rf4 and remaining 50% carried Rf4Rf4/rf3rf3 allelic combinations. A mini set of 40 varieties with variable allelic combinations of fertility restorer genes were testcrossed with WA and Kalinga‐based CMS lines. All the 80 F₁s were evaluated for spikelet fertility and fertility restoration ability. Rf3Rf3/rf4rf4 genotypes mostly behaved as partial maintainers or partial restorers. In contrast, rf3rf3/Rf4Rf4 genotypes were partial or effective restorers. However, double dominant genotypes showed better fertility restoration than the genotypes containing Rf3 or Rf4 individually. Some of the genotypes showed unexpected restoration pattern implying occurrence of other fertility restorer(s) apart from Rf3 and Rf4. The perfect restorers and maintainers identified in this study can be directly used in hybrid rice breeding.     

Interspecific hybridization inBrassica juncea × Brassica hirta using embryo rescue

Summary Interspecific hybrids have been obtained in an otherwise incompatible cross betweenBrassica juncea × Brassica hirta through the in vitro culture of hybrid ovules and ovaries. The best response was observed from ovules and ovaries cultured 10–15 and 5–7 days after pollination respectively on a basal medium supplemented with indoleacetic acid, kinetin and casein hydrolysate. In some cases the basal cut end of the ovaries proliferated to form callus and shoots. The in vitro-derived hybrid seeds varied in their colour, size and shape, and the F₁ plants in the field showed a large diversity in their morphological traits. The hybrids were sterile, and had an intermediate number of chromosomes (2n=30).     

Identification of a diverse mini‐core panel of Indian rice germplasm based on genotyping using microsatellite markers

Identification of a small core germplasm set representing the available genetic diversity is essential for its proper evaluation and subsequent utilization in rice improvement programmes. For constituting a small diverse mini‐core panel of Indian rice germplasm, a representative set of 6912 accessions drawn based on their geographic origin from the whole rice germplasm collection available in the National Gene Bank was genotyped using 36 microsatellite markers. Automated fragment analysis of amplicons yielded a total of 435 alleles, with an average 12.4 and range of 3–29 alleles per locus. Polymorphism information content (PIC) ranged from 0.08 (RGNMS190) to 0.86 (RM552) with an average of 0.528. Based on genotyping data, a mini‐core consisting of 98 genotypes was identified. Ninety‐four per cent of the alleles present in the core set were present in the mini‐core. The identified small but diverse panel will be useful for further intensive trait‐specific evaluation and utilization in allele mining.     

Molecular mapping of a locus controlling resistance to Albugo candida in Indian mustard

Brassica juncea (L.) Czern & Coss is widely grown as an oilseed crop in the Indian subcontinent. White rust disease caused by Albugo candida (Pers.) Kuntze is a serious disease of this crop causing considerable yield loss every year. The present study was undertaken to identify molecular markers for the locus controlling white rust resistance in a mustard accession, BEC‐144, using a set of 94 recombinant inbred lines (RILs). The screening of individual RILs using an isolate highly virulent on the popular Indian cultivar ‘Varuna’ revealed the presence of a major locus for rust resistance in BEC‐144. Based on screening of 186 decamer primers employing bulked segregant analysis (BSA), 11 random amplified polymorphic DNA markers were identified, which distinguished the parental lines and the bulks. Five of these markers showed linkage with the rust resistance locus. Two markers, OPN0_l000 and OPB06₁₀₀₀, were linked in coupling and repulsion phases at 9.9 cM and 5.5 cM, respectively, on either side of the locus. The presence of only two double recombinants in a population of 94 RILs suggested that the simultaneous use of both markers would ensure efficient transfer of the target gene in mustard breeding programmes.     

Suitability of mapped sequence tagged microsatellite site markers for establishing distinctness, uniformity and stability in aromatic rice

At present, testing for distinctness, uniformity and stability (DUS) of crop varieties relies on a set of morphological characters. These characters suffer fromthe limitations of number, interaction with the environment in which the variety grows and subjectivity in decision-making. The potential of DNA-based markers such as sequence tagged microsatellite site (STMS), for establishing DUS merits investigation. In the present study, a set of 55 mapped STMS markers, selected from 12 linkage groups of rice genome, was used to examine distinctness of 23 aromatic rice genotypes including the commercially important Basmati varieties. Forty-one of these markers (74.5%) showed polymorphism between the varieties. The number of alleles per locus ranged from 2–4 with an average of 2.3. The polymorphism information content (PIC) of the markers varied from 0.083 to 0.665 with an average of 0.338. All the varieties could be differentiated from each other at a low probability (0.07×10^-13) of identical match by chance. The marker-based clustering of the varieties corresponded with the known phenotypic classification, thereby providing confidence in the distinctness established by the mapped STMS markers. The utility of these markers to study uniformity and stability was analysed using a commercially important crossbred Basmati rice variety Pusa Basmati 1(IET-10364) that contributes about 40–50% of Basmati rice export from India. Genotyping of twenty individual plants, grown from the nucleus, breeder, foundation, certified and farmer's saved seed samples using all the 55 markers revealed no variation among the plants. These observations suggested that the set of mapped markers employed in this study could be further used for establishing distinctness of aromatic rice varieties and for studying DUS of the important commercial variety Pusa Basmati 1. This revised version was published online in July 2006 with corrections to the Cover Date.     

Evaluation of selected metal nanoparticles on hatching and survival of larvae and fry of Indian major carp,rohu (Labeo rohita)

Different laboratory synthesized metal nanoparticles viz. Copper oxide (CuO), Zinc oxide (ZnO) and silver doped titanium dioxide (Ag‐TiO₂) were studied for their effect on hatching and survival of larvae and fry of Indian major carp, rohu, Labeo rohita both in direct application in tank water & coated onto tanks. Among these nanoparticles, CuO and ZnO nanoparticles exhibited highest percentage of hatching in both direct addition (78.0 ± 3.1% and 78.05 ± 4.2%, respectively) and coating onto tanks (58.6 ± 2.1% and 61.2 ± 2.7%, respectively) at 1 mg mL^?1 while least percentage of hatching was recorded in Ag‐TiO₂ nanoparticles irrespective of its concentration & mode of supplementation. Highest survival of L. rohita fry (50.13 ± 2.2%) was observed after 15 days post hatching in CuO coated tanks followed by ZnO coated tanks (38.6 ± 2.8%) while least was recorded in Ag‐TiO₂ coated tanks (22.53 ± 3.0%). However in control tanks coated with Poly‐Urethane base with hardener and uncoated control tanks, the survival was 42.4 ± 1.2% and 41.36 ± 1.8% respectively. Further, significantly lower microbial load of water was recorded in CuO nanoparticles coated tanks (1.5 × 10¹⁰ CFU L^?1) as compared to uncoated control tanks (1.1 × 10¹⁶ CFU L^?1) without affecting water quality parameters. On the other hand, in Ag‐TiO₂ coated tanks, significantly lower microbial load (1.0 × 10⁶ CFU L^?1) as compared to uncoated control tanks at 15 days post hatching was recorded. However, Ag‐TiO₂ was toxic to L. rohita larvae & fry both in direct application and coating onto tanks. Considering the beneficial effects of CuO nanoparticle application, it has the scope of being used in a more eco‐friendly way in hatchery operations.     

Immunomodulating potency of lipopolysaccharides (LPS) derived from smooth type of bacterial pathogens in Indian major carp

Lipopolysaccharides (LPS), the outer membrane of the Gram-negative bacteria, are reported to stimulate the immunity of different vertebrates including fish. However, their potency and spectrum of actions often differ among different bacteria. In this study, effect of crude LPS, derived from three species of smooth Gram-negative bacterial fish pathogens viz. Edwardsiella tarda, Escherichia coli, and Pseudomonas fluorescens, on certain innate immune parameters of Indian major carp, Labeo rohita was studied. L. rohita yearlings, when injected intraperitoneally with crude LPS extracted from these bacteria showed little variations in different innate immune parameters. Furthermore, LPS injected fish were protected against a virulent E. tarda challenge. Although, no significant difference (p>0.05) in most of the immune parameters were found with LPS of different bacteria, the E. coli LPS injected fish elucidated high resistivity during challenge study. Hence, there could be some variations in LPS with respect to the bacterial type which needs to be further explored.     

Antibody response to sheep erythrocytes in Indian native vis-à-vis imported breeds of chickens.

1. A total of 433 birds (7 weeks old) of both sexes belonging to Indian native breeds, including, Aseel, Kadakanath, Naked Neck and Frizzle fowl along with the imported breeds Dahlem Red, White Leghorn, Synthetic dam line broiler (SDL) and Naked Neck broiler were utilised to test the primary antibody response to sheep erythrocytes by haemagglutination test. The effect of genotype (breed), sex and their interactions on antibody response were also studied. 2. The results revealed the presence of natural antibodies in all groups under study. 3. All groups except broilers showed the highest HA titre on day 5 post immunisation, which gradually declined until the end of the experiment (19th day post immunisation). In broilers, the peak HA titre was observed on day 12. 4. Dahlem Red showed the highest response throughout. The lowest antibody response was recorded for broilers except on day 19 post immunisation when it exceeded the White Leghorn value. 5. Amongst the native Indian breeds, the Naked neck had the highest titre on day 5 post immunisation but the Aseel titre was highest on days 12 and 19. 6. Males tended to have higher titres than females in Aseel, Kadakanath, Naked Neck, White Leghorn and Naked Neck broilers whereas Frizzle, Dahlem Red and SDL broilers showed the converse. 7. Statistical analysis revealed significant variation in HA response among the various genetic groups on different days post immunisation. The apparent differences between sexes were not significant. However, interactions between breed and sex were significant on day 5 and 19 post immunisation.     

Haemato-immunology and histo-architectural changes in <Emphasis Type="Italic">Labeo rohita</Emphasis> fingerlings: effect of dietary aflatoxin and mould inhibitor

A feeding trail of 60 days was conducted for delineating the effect of dietary aflatoxin (AFB1) with or without supplementation of a mixture of mould inhibitor (0.25% clove oil + 0.32% sodium propionate) on haematology, respiratory burst activity and histology of Labeo rohita fingerlings. Three hundred and sixty fishes (avg. wt. 1.48–1.54 g) were randomly distributed into eight treatment groups. Eight experimental diets with four different levels of aflatoxin (0, 10, 20 and 40 ppb) with or without mould inhibitor were prepared. Haematological parameters like total serum protein, albumin, globulin and A:G ratio were significantly (P < 0.05) reduced with increasing levels of aflatoxin in the diet. However, supplementation of mould inhibitor showed enhanced values when compared to non-supplemented counter parts suggesting ameliorating effects of mould inhibitor on aflatoxin. Total leucocyte count was higher in aflatoxin-treated groups. Histological observations were complementary to haematological parameters. Respiratory burst activity was significantly (P < 0.05) decreased in higher aflatoxin-treated groups but not affected significantly (P > 0.05) due to inclusion of inhibitor alone and/or interaction of aflatoxin level and inhibitor in the diet. From this study, it was concluded that up to 20 ppb aflatoxin level in the diet the haemato-immunological parameters are protected.