Inheritance of high oleic acid content in new sources of groundnut (Arachis hypogaea L.)

Not AvailableIn view of growing importance of oil quality, an understanding of the inheritance of high oleic acid is essential to breed for high oleate groundnuts. Hence an investigation was undertaken to infer genes governing the high oleic acid in newly identified sources of groundnut. Number of crosses studied were one with low × medium (TAG 24 × TPG 41), two with low × high (TAG 24 × ICG 2381 and TAG 24 × 104 P51) and with one medium × high oleic acid (TPG 41 × 104 P 56) cross combinations during post rainy season of 2010 at Main Agricultural Research Station of University of Agricultural Sciences, Dharwad, India. Individuals in F2 generation segregated in the ratio 3:1 in the crosses of low × medium and medium × high crosses and 15:1 in low × high cross combinations suggesting duplicative recessive genes governing the high oleate trait.Not Availabl

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Not AvailableGroundnut is an important oilseed legume and oil quality mainly depends on its fatty acid composition. In present study,backcross populations of the cross between GPBD 4 × GM 4-3 (using GPBD 4 as recurrent parent) were evaluated for two generations in augmented randomized block design at experimental plots of University of Agricultural Sciences, Dharwad.Frequency distribution and mean values of both generations showed considerable variability for oleic acid, linoleic acid,O/L ratio and iodine value. Both Oleic acid and linoleic acid are associated strongly with linoleic acid and iodine value in both backcross generations. Moderate heritability of oleic acid and high heritability of O/L ratio and also negative correlation between O/L ratio and linoleic acid suggests the scope for selection of oleic acid and O/L ratio to improve oil quality in groundnut.Not Availabl

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Not AvailableGroundnut is major rain fed oilseed crop and its production is mainly affected by biotic stresses (rust andlate leaf spot).Two backcross population were evaluated for yield and foliar diseases. ANOVA indicated significant differences for yield component traits and reaction to rust and LLS incidence. In both generations (BC1F3 and BC2F2) days to 50 per cent flowering and days to maturity exhibited low estimates of PCV and GCV values, whereas pod yield per plant and Spodoptera litura damage exhibited higher PCV and GCV estimates. High heritability coupled with high genetic advance as per cent of mean was observed for plant height, primary branches per plant, Spodoptera litura damage and pod yield per plant in both generations, indicates the additive gene control and scope for simple selection for improving these traits. Phenotypic correlations coefficients among characters indicated differences between BC1F3 and BC2F2generations. Lower incidence of LLS incidence at 90 days and spodopteralitura damage in BC2F2 generation as compared to BC1F3 generation as reveled by lower magnitudes of correlation coefficients and non-significant correlationNot Availabl

Quantitative trait locus analysis and construction of consensus genetic map for foliar disease resistance based on two recombinant inbred line populations in cultivated groundnut (Arachis hypogaea L.)

Late leaf spot (LLS) and rust have the greatest impact on yield losses worldwide in groundnut (Arachis hypogaea L.). With the objective of identifying tightly linked markers to these diseases, a total of 3,097 simple sequence repeats (SSRs) were screened on the parents of two recombinant inbred line (RIL) populations, namely TAG 24 × GPBD 4 (RIL-4) and TG 26 × GPBD 4 (RIL-5), and segregation data were obtained for 209 marker loci for each of the mapping populations. Linkage map analysis of the 209 loci resulted in the mapping of 188 and 181 loci in RIL-4 and RIL-5 respectively. Using 143 markers common to the two maps, a consensus map with 225 SSR loci and total map distance of 1,152.9 cM was developed. Comprehensive quantitative trait locus (QTL) analysis detected a total of 28 QTL for LLS and 15 QTL for rust. A major QTL for LLS, namely QTLLLS01 (GM1573/GM1009-pPGPseq8D09), with 10.27–62.34% phenotypic variance explained (PVE) was detected in all the six environments in the RIL-4 population. In the case of rust resistance, in addition to marker IPAHM103 identified earlier, four new markers (GM2009, GM1536, GM2301 and GM2079) showed significant association with the major QTL (82.96% PVE). Localization of 42 QTL for LLS and rust on the consensus map identified two candidate genomic regions conferring resistance to LLS and rust. One region present on linkage group AhXV contained three QTL each for LLS (up to 67.98% PVE) and rust (up to 82.96% PVE). The second candidate genomic region contained the major QTL with up to 62.34% PVE for LLS. Molecular markers associated with the major QTL for resistance to LLS and rust can be deployed in molecular breeding for developing groundnut varieties with enhanced resistance to foliar diseases

Foliar fungal disease-resistant introgression lines of groundnut (Arachis hypogaeaL.) 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

Validation of markers linked to late leaf spot and rust resistance, and selection of superior genotypes among diverse recombinant inbred lines and backcross lines in peanut (Arachis hypogaea L.)

Recombinant inbred lines (RILs) from four populations involving cultivated varieties, and backcross lines from three populations involving cultivated varieties and synthetic tetraploids (developed from wild diploids) were employed for validating late leaf spot (LLS) and rust resistance-linked markers and identifying superior genotypes in peanut. GM2009, GM2301, GM2079, GM1536, GM1954 and IPAHM103 markers showed significant association with rust resistance. They were successfully validated in a new RIL (TG 19 × GPBD 4) and two backcross (DH 86 × ISATGR 278-18 and DH 86 × ISATGR 5) populations. GM1954, GM1009 and GM1573 markers showed significant association with LLS resistance. TAG 19 × GPBD 4 and ICGS 76 × ISATGR 278-18 populations showed strong co-segregation of LLS-linked markers with the phenotype. From these genetic resources, six superior genotypes were identified. RIL 78-1 was resistant to LLS and rust, and recorded 30 % more pod yield than GPBD 4 (control). It also had higher kernel yield and oil yield along with higher oleate and linoleate content over GPBD 4. These genetic and genomic resources could be useful in breeding for LLS and rust resistance in peanut

Development of NILs from heterogeneous inbred families for validating the rust resistance QTL in peanut (Arachis hypogaeaL.)

Heterogeneous inbred families segregating for rust resistance were identified from the two crosses involving susceptible (TAG 24 and TG 26) and resistant (GPBD 4) varieties of peanut. Rust-resistant (less than score 5) and rust-susceptible (more than score 5) plants were identified in each HIF and evaluated under rust epiphytotic conditions. The set of plants belonging to the same HIF, but differing significantly in rust resistance, not in other morphological and productivity traits, was regarded as near-isogenic lines (NILs). Largely, rust-resistant NILs had GPBD 4-type allele, and susceptible NILs carried either TAG 24 or TG 26-type allele at the three SSR loci (IPAHM103, GM1536 and GM2301) linked to a major genomic region governing rust resistance. Comparison of the remaining genomic regions between the NILs originating from each of the HIFs using transposon markers indicated a considerably high similarity of 86.4% and 83.1% in TAG 24 × GPPBD 4 and TG 26 × GPBD 4, respectively. These NILs are useful for fine mapping and expression analysis of rust resistance

Genomewide association studies for 50 agronomic traits in peanut using the ‘Reference Set’ comprising 300 genotypes from 48 countries of the Semi-Arid Tropics of the World

Peanut is an important and nutritious agricultural commodity and a livelihood of many small-holder farmers in the semi-arid tropics (SAT) of world which are facing serious production threats. Integration of genomics tools with on-going genetic improvement approaches is expected to facilitate accelerated development of improved cultivars. Therefore, high-resolution genotyping and multiple season phenotyping data for 50 important agronomic, disease and quality traits were generated on the ‘reference set’ of peanut. This study reports comprehensive analyses of allelic diversity, population structure, linkage disequilibrium (LD) decay and marker-trait association (MTA) in peanut. Distinctness of all the genotypes can be established by using either an unique allele detected by a single SSR or a combination of unique alleles by two or more than two SSR markers. As expected, DArT features (2.0 alleles/locus, 0.125 PIC) showed lower allele frequency and polymorphic information content (PIC) than SSRs (22.21 alleles /locus, 0.715 PIC). Both marker types clearly differentiated the genotypes of diploids from tetraploids. Multi-allelic SSRs identified three sub-groups (K = 3) while the LD simulation trend line based on squared-allele frequency correlations (r2) predicted LD decay of 15–20 cM in peanut genome. Detailed analysis identified a total of 524 highly significant MTAs (pvalue >2.1×10–6) with wide phenotypic variance (PV) range (5.81–90.09%) for 36 traits. These MTAs after validation may be deployed in improving biotic resistance, oil/ seed/ nutritional quality, drought tolerance related traits, and yield/ yield components

Correction to: Identification of main effect and epistatic quantitative trait loci for morphological and yield-related traits in peanut (Arachis hypogaea L.)

The published online version of this article unfortunately missed to capture Rajeev K. Varshney as co-corresponding author. There should have been two corresponding authors for this paper (Rajeev K. Varshney and Ramesh S. Bhat). The correct declaration is shown below

Molecular breeding tools improved drought tolerant groundnut variety for resistance to foliar fungal diseases

A largely rainfed crop in India, drought tolerance, particularly mid- and end-season tolerance, is a key trait in groundnut varieties. A combination of both empirical and trait-based approaches was used in breeding programs of ICAR and ICRISAT, resulting in release of few tolerant varieties that have superior pod yield under drought stress and/or have enhanced water-use-efficiency. There is a need to breed varieties with drought tolerance, disease resistance and quality traits that suit different production ecologies as well as meet the needs of the farmers, consumers and industries. ICRISAT has released an early-maturing (90-95 d) and drought- tolerant variety ICGV 91114 for the drought-prone Ananthapur district of Andhra Pradesh, India, where about 0.7 m ha area is under groundnut cultivation and has low (300 mm) and erratic (30-40 rainy days) rainfall. On-farm studies conducted with ICGV 91114 during 2008-10 showed 30% reduction in yield variability over the years. Following screening in hot-spots of both rust and LLS disease during 2014 rainy season, a total of 27 introgression lines derived from ICGV 91114 were selected and advanced for evaluation in multi-location trials at six locations in 2015 under rainfed conditions. Based on the pod yield under rainfed conditions and disease resistance, three superior introgression lines (ICGV 14410, ICGV 13189, ICGV 14421) were proposed for the first-ever NILs trial (near-isogenic lines trial) along with eight others conducted under All India Coordinated Research Project on Groundnut (AICRP-G) at national level