Breeding for disease resilience: opportunities to manage polymicrobial challenge and improve commercial performance in the pig industry

Disease resilience, defined as an animal’s ability to maintain productive performance in the face of infection, provides opportunities to manage the polymicrobial challenge common in pig production. Disease resilience can deliver a number of benefits, including more sustainable production as well as improved animal health and the potential for reduced antimicrobial use. However, little progress has been made to date in the application of disease resilience in breeding programs due to a number of factors, including (1) confusion around definitions of disease resilience and its component traits disease resistance and tolerance, and (2) the difficulty in characterizing such a complex trait consisting of multiple biological functions and dynamic elements of rates of response and recovery from infection. Accordingly, this review refines the definitions of disease resistance, tolerance, and resilience based on previous studies to help improve the understanding and application of these breeding goals and traits under different scenarios. We also describe and summarize results from a “natural disease challenge model” designed to provide inputs for selection of disease resilience. The next steps for managing polymicrobial challenges faced by the pig industry will include the development of large-scale multi-omics data, new phenotyping technologies, and mathematical and statistical methods adapted to these data. Genome editing to produce pigs resistant to major diseases may complement selection for disease resilience along with continued efforts in the more traditional areas of biosecurity, vaccination and treatment. Altogether genomic approaches provide exciting opportunities for the pig industry to overcome the challenges provided by hard-to-manage diseases as well as new environmental challenges associated with climate change.

Genetic Variability and G×E Interactions in a Diverse Set of Groundnut Accessions

Background: Knowledge of the genetic diversity for various agronomic traits and their interaction with the environment and subsequent classification of genotypes will be beneficial for identification of divergent and stable sources of agronomic traits. Methods: A set of 96 groundnut germplasm accessions belonging to four botanical groups were evaluated for three years (2017 to 2019) for pod yield and component traits using AMMI analysis and subsequently accessions were classified based Euclidean cluster analysis. Result: Among different botanical groups, Virginia genotypes matured late and possessed high SPAD chlorophyll meter readings (SCMR) and pod yield compared to Spanish types. The component traits of pod maturity like days to flowering (first and 50%) showed low heritability and high genotype × environment interaction (GEI) and significant negatively affected sound mature kernel (SMK) and shelling per centage (SP). The cumulative contribution of environment and GEI component to the total variance was the highest in the expression of SP (67%) followed by days to maturity (54%) and days to 50% flowering (52%). Euclidean distance-based cluster analysis grouped the 96 accessions into five major clusters. Cluster I had accessions with higher pod yield, whereas cluster V contained accessions with low SLA, high SCMR and moderate pod yield. High yielding as well as stable accessions identified based on AMMI stability value (ASV) are NRCG 17332, 10076, 17268, 17197, 17108, 10106, 10089 and 17165. Trait specific as well as stable accessions identified in the present study can be useful donors for groundnut breeding programme.

Estimation of Gene Action for Seed Yield and Component Traits using Generation Mean Analysis in Pigeonpea [Cajanus cajan (L.) Millspaugh]

Background: For improvement of quantitative traits the information on nature of gene action is an important asset for plant breeders. However, the information on gene action for yield and its attributes is scanty in pigeonpea crop. Methods: The present experiment was carried out during kharif 2018-2020 at GBPUAT, Pantnagar, Uttarakhand. The experimental material consisted of six generations of three crosses viz., PADT-16 × PUSA 992, PADT-16 × UPAS 120 and PADT-16 × PAU 881. The observations were recorded on nine morphological characters. The gene action was estimated by three parameters model of Jinks and Jones if scaling tests were non significant and six parameters model of Hayman if scaling tests were significant. Result: For majority of traits in all three crosses, epistatic gene action was present as scaling tests were found to be significant. However, for traits number of primary branches, number of secondary branches and number of seeds per pod in cross PADT-16 × UPAS 120 a simple additive/dominance model was found to be adequate. In general, magnitude of dominance was found to be higher as compared to corresponding additive gene action. The high magnitude of dominance indicated that heterosis breeding is rewarding in these characters.

​Studies on Heterotic Trends in Blackgram [Vigna mungo (L.) Hepper] for Yield and Earliness

Background: As blackgram cultivation is majorly spread in rain fed areas, breeding short duration and high yielding blackgram varieties is of profound importance to tackle terminal moisture stress and reap impressive yields by breaking the yield plateau. Hence, the present study was aimed to identify highly heterotic cross combinations for yield and earliness. Methods: Six parents along with 15 F1s were evaluated (rabi, 2019) for seed yield and its component traits along with earliness to estimate the magnitude of heterosis. Result: The cross LBG-752 × TBG-104 exhibited heterosis estimates in desirable direction for yield and earliness. The next best crosses were LBG-752 × PU-31, TU-40 × TBG-104, LBG-752 × TU-40 and IPU-2-43 × TBG-104. Because of its autogamous genetic architecture and biological constraints in large scale economic hybrid seed production, heterosis could be exploited only by isolating the early maturing and high yielding segregants followed by bi-parental or recurrent selection in early segregating generations and single plant selection in subsequent generations that would result in short duration and high yielding blackgram variety that fits well into different ecological niches.

Analysis of combining ability and gene action studies for grain yield and its component traits in bread wheat utilizing line x tester mating design

The present research investigation was conducted in order to analyze combining ability and nature of gene actions in 33 F1s of bread wheat (Triticum aestivum L. em. Thell) developed by crossing eleven lines with three testers in a line x tester mating design in terms of grain yield and associated traits. The hybrids along with the parental lines and two check varieties were planted in a randomized block design in three replications. Variance ratio between general and specific combining ability was found to be less than unity which indicated the prevalence of non-additive gene actions involved in the inheritance of these characters. Parental lines QLD 75 (3.164), followed by SOKOLL (2.888) and QLD 65 (2.819) exhibited significant GCA for grain yield, while another line PRL/2*PASTOR*2//FH6-1-7/3/KINGBIRD#1//… was observed to be the better general combiner for most other traits including maturity. Among the hybrids cross combination NAC/TH.AC//3*PVN/3/MIRLO/BUC/4/2*PASTOR/5/…x HD 3237 showed significant higher positive SCA for grain yield and biological yield per plant, whereas, F1 QLD 75 x HI 1621was a good specific combiner for harvest index (%) and number of grains per spike. The cross combination VORB/4/D67.2/PARANA66.270 x PBW 725 was observed with significant higher positive SCA for days to 75% heading, days to maturity and plant height, and another hybrid VORB/4/D67.2/PARANA 66.270 x HI 1621 exhibited significant positive SCA for 1000 grain weight and spike length.

Multivariate analysis on blackgram genotypes for bruchine (Callosobruchus maculatus F.) resistance towards selection of parental lines

Black gram (Vigna mungo (L.) Hepper) is one of the most important pulse crops in daily diets. However, black gram production and post-harvest preservation are still tedious due to the losses caused by the storage pest bruchine, Callosobruchus maculatus (F.), both quantitatively and qualitatively. Hence, the present study involves the utilization of the multivariate analysis by effectively understanding variation among the genotypes based on their level of bruchine infestation. The multivariate studies indicated that the traits viz., the total number of adult emergence (AE), seed damage % (SD) and seed weight loss % (SWL) had more variation and with more significant correlation among them. Also, these traits are the most influential principal component traits governing 88% of the variation among genotypes. The divergence analysis showed that the genotype TU 68 found in cluster II would have the potential to create the variation for bruchine infestation among the black gram genotypes involved in the study. As it has scored lesser adult emergence (AE) (7 adults), seed damage % (SD) (14 %) and seed weight loss % (SWL) (17.79 %) than the other genotypes. It shows the resistant nature of the genotype against bruchine beetles. Hence, TU 68 could be utilized in the future hybridization programme as a donor for bruchine resistance.

Phenotyping of boro rice (Oryza sativa L.) cultivars in Assam based on its potential yield and variable component traits

The current environmental scenario and increased average yield rate has marked boro rice cultivars as a potent rice cultivar during rabi season. It serves to be an alternative to traditional sali rice and an escape to flood problems. The selection and development of potent boro rice cultivar among its diverse types has been an issue. In this study, 117 traditionally grown boro rice cultivars in different low-lying areas and newly developed irrigated areas of Assam were analyzed. The cultivars were analyzed based on yield and related component traits as per the standard evaluation system for rice. Grain yield and its related component traits showed a significant relationship among the cultivars. All the traits analyzed showed positive relationship with grain yield and harvest index except to time taken for flowering and maturity. Based on total yield, principal component and cluster analysis, Bahurupi, PSB 68, Mandhya Vijaya, Bahunipi, Pathariya showed to be best performing cultivars, with high yield and higher component traits performance. This study marks the significant association of grain yield with its component traits and further provides an insight to the selection of rice cultivars for breeding programmes.