Phenotypic diversity and identification of wild Arachis accessions with useful agronomic and nutritional traits

Wild relatives harbor novel sources of variation, which can be used to enhance the genetic base of a cultivar gene pool. A total of 269 accessions from 20 wild Arachis species belonging to six sections were evaluated for 41 morpho-agronomic traits and 89 selected accessions for oil, protein and total sugar content. Six plants from each accession were grown in an open Arachis house in largecylindrical concrete structures during the 2004–2005 season at Patancheru, India. REML analysis showed significant differences between species and accessions for most of the traits studied. Hierarchical cluster analysis, based on the first five principal component scores accounted for 82.5% variation, resulting in four clusters. Variation in genome relationships and ploidy levels had no bearing on the clustering pattern which was predominated by life forms: clusters 1 and 2, contained mostly annuals and clusters 3 and 4 perennials. A large range of variations were noticed among species for some of the agronomic traits: days to flowering, pod and seed characteristics, specific leaf area (SLA) and for SPAD chlorophyll meter reading (SCMR). Arachis duranensis showed the maximum intraspecific variation as revealed by a high diversity index for 23 of the 41 traits which included: days to flowering, primary branches, plant width, pod length, pod width, SCMR and SLA. The other species with desirable traits were A. pusilla (earliest flowering) and A. villosa (high SCMR at 60 and 80 days after sowing). The latter species is cross compatible with cultivated groundnut, thus, is a good source to enhance the trait value in the cultigen’s gene pool. The best 20 accessions with superior agronomic, nutritional quality and drought related trait combinations have been identified for their use in introgression of diverse and unique alleles from wild Arachis species into A. hypogaea

Variability and Stability Analysis for Nutritional Traits in the Mini Core Collection of Peanut

The nutritional quality of peanut (Arachis hypogaea L.) products depends on the protein content, oil content, and composition of oil. Low genetic variability has been a major bottleneck in genetic enhancement of these nutritional traits in commercial cultivars. The present study was conducted to identify stable genotypes with better nutritional traits and good agronomic performance for use in future breeding programs. The 184 mini core accessions and four control cultivars were evaluated for nutritional traits for two seasons at two locations and for agronomic traits at one location. Significant genotypic and genotype × environment interactions were observed for all the nutritional and agronomic traits in the entire mini core collection and within each A. hypogaea ubspecies of fastigiata Waldron and hypogaea. Eighteen accessions with higher nutritional traits such as protein content, oil content, oleic acid, and oleic to linoleic acid ratio with superior agronomic traits were identified and their stability analysis resulted in identification of a high oleic acid content (>73%) ccession (ICG 2381). On the basis of higher nutritional and agronomic traits 11 subsp. fastigiata and 10 subsp. hypogaea diverse accessions were identified with more than two trait combinations for use in peanut breeding programs for genetic nhancement of nutritional trait

Combining ability studies for yield and its components in groundnut

Nine lines were mated to three testers in a line x tester design. Among the lines, ICGV-86125 proved to be a good general combiner for pod and kernel yield and unit pod weight. Majority of the best specific combinations for different characters resulted from the crosses among the parents with high x low or low x low gca effects. Non-additive effects were predominant for pod and kernel yield and shelling outturn, but appreciable additive/effects were noted for pod number, pod weight, and primary branches. The breeding method which can exploit both nonadditive as well as additive types of gene action is suggested for groundnut improvement

Diversity in soybean (Glycine max) accessions based on morphological characterization and seed longevity characteristics

Soybean (Glycine max (L.) Merrill) is a significant and cheap source of protein (40%) and soy vegetable oil (20%) is another important product of processing the soybean crop for both human consumption and industrial application. Present study was conducted with the objectives to study the genetic diversity for various morphological traits and seed longevity in 225 accessions of soybean. Clustering pattern of 225 genotypes was grouped into 8 clusters and 6 clusters with 62 genotypes in concern to seed longevity. High range of intra clusters (0-314.62) and inter clusters (324.61-3514.91) distances showed high diversity among the genotypes for various characters. Seed yield per hectare contributed maximum of (23.6%) towards total genetic divergence. Cluster V showed minimum days to maturity with high test weight (13.98g) and cluster VI found to be included genotypes with high oil (19.20%) and seed yield per hectare (4294.44kg). The cluster VIII involved highest number of pods per plant (71.52) with high seed yield per hectare with less reduction in germination (24.19%) in other words with high seed longevity

Genetic diversity analysis based on nutritional, oil quality and yield component traits in mini core collection of groundnut (Arachis hypogaea L.)

Groundnut (Arachis hypogaea L.) is an annual legume, grown primarily for high quality edible oil and easily digestible protein in its seeds. It is cultivated in 109 countries, in tropical, subtropical, and warm temperate regions of the world. In India during 2010-11 it was grown on 4.93 million ha with an estimated total production of 5.64 million tonnes (groundnuts in shell) and an average productivity of 1144 kg/ ha (FAO 2011)..

Genetic analysis for yield, nutritional and oil quality traits in RIL population of groundnut (Arachis hypogaea L.)

A total of 268 recombinant inbred lines (RILs) were evaluated for genetic variability for yield, nutritional and oil quality traits under two consecutive seasons at two locations. Analysis showed that variability exists in the population for the nutritional and oil quality as well as for yield component traits. Majority of the yield components and oil quality traits were governed by additive effects. The nutritional and oil quality traits were not affected by environmental factors and simple phenotypic selection ensures increased performance of the genotypes. Yield components showed moderate to high heritability but with great influence of environment

Analysis of a mutant population in groundnut

Fifty three mutants derived from Dharwad Early Runner (DER), a true breeding variant from a cross between two Valencia varieties of groundnut were evaluated for taxonomic, productivity and quality traits for assessing its suitability to ascertain marker-trait association. Mutants were confirmed for subspecific changes. Sixteen independent mutants shared common taxonomic shift from DER type to that of ssp. hypogaea var. hypogaea. Seventeen and nine mutants showed taxonomic shift to ssp. fastigiata var. fastigiata and ssp. fastigiata var. vulgaris, respectively. Four mutants had a shift from var. fastigiata to var. vulgaris. Significant shifts both in positive and negative direction were observed for most of the productivity and quality traits along with resistance to late leaf spot and rust. Since these mutants are derived from a common source (Dharwad Early Runner), those contrasting for any trait are expected to differ for a small genomic region. Role of transposons being significant in groundnut mutations, genotyping such mutants with transposon-specific markers might reveal marker-trait associations useful for groundnut improvement

Phenotypic and molecular dissection of ICRISAT mini core collection of peanut (Arachis hypogaea L.) for high oleic acid

High oleic acid (O) and low linoleic acid (L) make peanut oil ideal for longer storage and better human health. Among the ICRISAT mini core collection accessions, oleic acid ranged from 33.60% to 73.54%. Accessions belonging to ssp. hypogaea had higher oleic acid (54.16%) compared with those of ssp. fastigiata (45.70%). An O : L ratio up to 6.93 was found among ssp. hypogaea. Additional varieties, mutants, germplasm lines and breeding lines had oleic acid within the range of mini core accessions. Mutations in ahFAD2A, which along with its homologous gene, ahFAD2B code for delta-12-desaturase, resulted in higher oleic acid and O : L ratio. ahFAD2A mutant allele was found in 49.5% of the accessions, and its frequency was higher in ssp. hypogaea (84.52%) than in ssp. fastigiata (19.39%). ahFAD2A mutation had a maximum contribution of 18.82, 12.98 and 10.52 towards the phenotypic variance of O, L and O : L ratio, respectively. Genotypes with high oleic acid levels could not reveal ‘A’ insertion mutation in ahFAD2B. Accessions with high oleic acid could be employed for improving peanut oil quality

Foliar fungal disease-resistant introgression lines of groundnut (Arachis hypogaea L.) record higher pod and haulm yield in multilocation testing

Introgression lines (ILs) of groundnut with enhanced resistance to rust and late leaf spot (LLS) recorded increased pod and haulm yield in multilocation testing. Marker-assisted backcrossing (MABC) approach was used to introgress a genomic region containing a major QTL that explains >80% of phenotypic variance (PV) for rust resistance and 67.98% PV for LLS resistance. ILs in the genetic background of TAG 24, ICGV 91114 and JL 24 were evaluated for two seasons to select 20 best ILs based on resistance, productivity parameters and maturity duration. Multilocation evaluation of the selected ILs was conducted in three locations including disease hot spots. Background genotype, environment and genotype × environment interactions are important for expression of resistance governed by the QTL region. Six best ILs namely ICGV 13192, ICGV 13193, ICGV 13200, ICGV 13206, ICGV 13228 and ICGV 13229 were selected with 39–79% higher mean pod yield and 25–89% higher mean haulm yield over their respective recurrent parents. Pod yield increase was contributed by increase in seed mass and number of pods per plant