Effect of jaggery on the quality and intake levels of maize silage

Silage, which is anaerobically fermented green fodder, is valued throughout the world as a source of animal feed during lean months. Several farms in India use carbohydrate sources like jaggery or molasses at 2% for preparation of silage, and this increases cost of production. The present study was undertaken to assess the effect of jaggery on quality and intake of maize silage, with an objective to find out whether additional carbohydrate source is essential in preparation of silage using green maize. Three silage types, one without jaggery (A), the second with 1% jaggery (B), and the third with 2% jaggery (C) were prepared in cylindrical bins under similar conditions. They were compared for colour, pH, lactic acid bacteria count, lactic acid content, proximate composition and silage intake by sheep. Silage type C with 2% jaggery was significantly different from the other two types with values of 3.98 and 805.66 g for pH and mean silage intake, respectively. Even though the values of pH and dry matter intake for all three silage types were within normal levels, silage type C was significantly superior in terms of fermentation and palatability. The method of preparation followed could be ideal for small holder farmers requiring less quantity of silage.     

Gametophytic selection for wilt resistance and its impact on the segregation of wilt resistance alleles in chickpea (Cicer arietinum L.)

In the present study, the effect of gametophytic selection on the segregation of molecular markers linked and unlinked to wilt resistance loci was investigated. A homozygous resistant genotype WR315 (h₁h₁ h₂h₂) was crossed to two susceptible lines, Karikadle (H₁H₁ H₂H₂) and BG256 (h₁h₁ H₂H₂), to generate two different F₁ populations. Three F₁ plants from each cross were subjected to gametophytic selection by spraying a pathotoxin at flower bud initiation stage, while the remaining F₁ plants in each cross were treated as control by spraying them with water. Both control and treated F₁ plants were selfed to generate respective F₂ populations. The seeds of control and selected F₂ populations of both crosses were sown to raise the plants. The DNA from 60 to 70 plants in each treatment group were isolated and tested for presence of the markers linked and unlinked to wilt resistance loci. Both the linked and unlinked markers showed expected monogenic ratio of 3:1 individually in control population. In the selected F₂ population the markers CS 27₇₀₀ linked to H₁ locus, A07C₄₁₇ and H₄G₁₁ linked to H₂ locus of wilt resistance exhibited significant deviations for monogenic and digenic ratios. The unlinked markers NCPGR93 and NCPGR48 showed expected monogenic ratios in the selected F₂ population. The results demonstrated that the gametophytic selection for wilt resistance increase the frequency of resistance alleles and resistant plants in the progeny. Deviation from the expected segregation ratio of the marker closely linked to resistance loci suggests the presence of linkage drag in gametophytic selection for resistance. The significant deviation from monogenic ratio was also observed for the linked marker A07C₄₁₇ in the selected F₂ population of second cross BG256 × WR315. On the contrary, the segregation of markers in a different linkage not linked to resistance loci was not affected. Thus demonstrating the utility of gamete selection for resistance is increasing the frequency of resistant plant in the progeny independent of the parental genotype. Gametophytic selection can be applied in plant breeding programmes to develop wilt resistant genotypes in a short period.     

Clinical protection, sub-clinical infection and persistence following vaccination with extinction payloads of O1 Manisa Foot-and-Mouth Disease monovalent vaccine and challenge in goats and comparison with sheep

Small ruminants play an important role in the epidemiology of Foot-and-Mouth Disease (FMD). Small ruminants are vaccinated with one-half or one-third of cattle dose of oil-based or aqueous vaccines respectively. The extinction antigen payload in vaccine for protection in small ruminants is poorly studied. FMD seronegative Nellore sheep (n=30) and Osmanabadi goats (n=30) were vaccinated with different payloads of O(1) Manisa vaccine (0.45-5 μg). Vaccinated and sero-negative unvaccinated sheep (n=6) and goats (n=6) were challenged intradermally into the coronary band with O(1) Manisa virus. The sheep and goats were monitored for signs of FMD and samples were collected for measuring viraemia and virus associated with nasal swabs and probang samples. Clotted blood was collected for serology. Vaccines containing antigen payload up to 0.94 μg protected sheep and goats against challenge. Sheep and goats vaccinated with 0.45 μg antigen payload were poorly protected against challenge. An antigen payload of 0.94 μg was sufficient to offer complete protection and also absence of carrier status. Sheep and goats with no vaccination or with poor sero conversion to vaccination showed sub-clinical infection and became carriers. The results of the study suggest that vaccination offers protection from clinical disease even at a low payload of 0.94 μg and hence one-half of cattle dose of the oil-based vaccine formulations is sufficient to induce protective immune response in sheep and goats. Since no live virus could be isolated after 5 days post challenge from the nasal swab or probang samples even though viral RNA was detected, the risk of these animals transmitting disease was probably very low.     

Determination of bovine rotavirus G serotype by polymerase chain reaction

A total of 113 diarrheic samples comprising of 68 buffalo calves and 45 cow calves were screened by RNA-PAGE for the detection of presence of rotavirus. RNA-PAGE analysis of these samples revealed 11 (9.73%) was found positive for rotavirus. Out of 68 faecal samples of buffalo calves tested for viral gastroenteritis, 8 (11.76%) were found positive for rotavirus. Similarly, out of 45 faecal samples of cattle calves tested for viral gastroenteritis, 3 (6.66%) was found positive for rotavirus. Rotavirus-positive samples represented long electropherotype. All RNA-PAGE-positive faecal samples for rotavirus subjected to RT-PCR for VP7 gene, ten samples yielded a specific product of 1,013 bp of VP7 gene. All the PCR-positive samples of the present study were subjected to genotyping with primers for G6, G8 and G10 genotype. All positive samples showed G10 genotype. This indicates that G10 may be predominant genotype among bovine calves in Mumbai region in India.     

Cotton Marker Database (CMD) as an Enhanced Resource for Cotton Research Community

Recently,thousands of SSR and now SNP markers have been discovered in cotton.Each of these markers provides a valuable molecular tool applying genetic and genomic research to cotton improvement.Cotton DNA marker database (CMD) continues to serve as a molecular marker resource for the cotton research community (http://www.cottonrnarker,org).The current collection of cotton SSR markers oublicly available through CMD is 8,915 and the number continues to grow.     

Conventional and contemporary approaches for drought tolerance rice breeding: Progress and prospects

Drought is becoming a major threat to rice farming across the globe owing to the depletion of water tables in rice-growing belts. Drought affects rice plants at multiple stages, causing damage at morphological and physio-biochemical levels, leading to severe losses that exceed losses from all other stresses. The amalgamation of conventional breeding methods with modern molecular biology tools and biometrical methods could help accelerate the genetic gain for drought tolerance in rice. Many drought-tolerance traits with genetic determinants have been identified and exploited for tolerance rice variety breeding. The integration of genome-wide association study and genomic selection tools with speed breeding shortened the breeding cycle and aided in rapid improvement of genetic gain. In this review, we emphasized the progress made through classical breeding as well as the limitations and usefulness of current genomic methods in improving drought tolerance. We briefly addressed methods for identifying genetic determinants for drought tolerance and deploying them through genomics-assisted breeding programmes to develop high-yielding drought-tolerant rice cultivars.     

Genetic Dissection of Grain Size Traits Through Genome-Wide Association Study Based on Genic Markers in Rice

Grain size plays a significant role in rice, starting from affecting yield to consumer preference, which is the driving force for deep investigation and improvement of grain size characters. Quantitative inheritance makes these traits complex to breed on account of several alleles contributing to the complete trait expression. We employed genome-wide association study in an association panel of 88 rice genotypes using 142 new candidate gene based SSR (cgSSR) markers, derived from yield-related candidate genes, with the efficient mixed-model association coupled mixed linear model for dissecting complete genetic control of grain size traits. A total of 10 significant associations were identified for four grain size-related characters (grain weight, grain length, grain width, and length-width ratio). Among the identified associations, seven marker trait associations explain more than 10% of the phenotypic variation, indicating major putative QTLs for respective traits. The allelic variations at genes OsBC1L4, SHO1 and OsD2 showed association between 1000-grain weight and grain width, 1000-grain weight and grain length, and grain width and length-width ratio, respectively. The cgSSR markers, associated with corresponding traits, can be utilized for direct allelic selection, while other significantly associated cgSSRs may be utilized for allelic accumulation in the breeding programs or grain size improvement. The new cgSSR markers associated with grain size related characters have a significant impact on practical plant breeding to increase the number of causative alleles for these traits through marker aided rice breeding programs.