Genetic approaches for assessment of phosphorus use efficiency in groundnut (Arachis hypogaea L.)

Production of phosphorus efficient genotypes can reduce environmental pollution. Identification of P-efficient groundnut genotypes is a need of the hour to sustain in P-deficient soils. The pot experiment showed significant differences between genotypes (G) and treatments (T) for all the traits and G × T interaction for majority of traits. The G × T × Y interaction effects were also significant for all the traits except leaf P% (LP%), leaf acid phosphatase (LAP) and root dry weight (RDW). In lysimeter experiment, the effect of G, T and G × T were significant for leaf dry weight (LDW), stem dry weight (SDW), total transpiration (TT) and transpiration efficiency (TE). For traits, LDW, SDW, TT, TE, ICGV 00351 and ICGS 76; for SDW, TT, ICGV 02266 are best performers under both P-sufficient and deficient conditions. Based on P-efficiency indices and surrogate traits of P-uptake, ICGV’s 02266, 05155, 00308, 06040 and 06146 were considered as efficient P-responding genotypes. From GGE biplot, ICGV 06146 under P-deficient and TAG 24 under both P-sufficient and deficient conditions are portrayed as best performer. ICGV 06146 was identified as stable pod yielder and a promising genotype for P-deficient soils. The genotypes identified in this study can be used as a parent in developing mapping population to decipher the genetics and to devleop groundnut breeding lines suitable to P-deficient soils

Fine mapping and expression analysis of thermosensitive genic male sterility gene (tms) in rice (Oryza sativa L.)

Thermosensitive genic male sterility (TGMS) is a most comfortable type of male sterility for the production of two-line hybrids in rice. In TGMS system, genes responsible for male sterility and its reversibility is of great importance to create a new pathway for development of new male sterile lines in rice. In this study, genetic analysis based on F2 population derived from a cross between TNAU 60S and IET 21009 revealed that a single recessive gene controls male sterility in TNAU 60S. Marker analysis combined with bulked segregant analysis (BSA) was used and located the target gene on chromosome 2. Fine mapping with 86 SSR markers on chromosome 2 between 20.0 cM and 27.0 cM revealed that tms gene is located at 24.3 cM between two SSR markers RM12713 and RM12722. Among the six genes, two genes LOC_Os02g12420 and LOC_Os02g12680 which encodes receptor like kinase and cytochrome P450 respectively were considered as candidate genes for thermosensitive gene male sterility in TNAU 60S because of very high differential expression between sterile and fertile samples. •The inheritance pattern of TGMS gene in TNAU 60S was identified to be under the control of single recessive gene based on χ2 test.•Through bulked segregant analysis, tms gene was located on chromosome 2 and Composite interval mapping using 11 polymorphic markers between bulks from 20 to 27 cM with 126 F2 individuals from cross TNAU 60S/ IET 21009 revealed that tms gene is located at 24.3 cM on short arm of chromosome 2.•The qPCR with six genes revealed differential expression of all the genes, however two genes LOC_Os02g12420 and LOC_Os02g12680 which encodes receptor like kinase and P450 respectively were considered as candidate genes for TGMS in TNAU 60S because of very high differential expression between sterile and fertile samples

Variability and Trait Association Studies for Late Leaf Spot Resistance in a Groundnut MAGIC Population

Globally, late leaf spot (LLS), a foliar fungal disease is one of the most important biotic constraint in groundnut production. Multi-Parent Advanced Generation Inter Cross (MAGIC) groundnut population was developed in a convergent crossing scheme using eight founder parents to develop a mapping population for multiple traits includes LLS. The experiments conducted in light chamber using detached leaf assay, and disease field screening nurseries at two locations (ICRISAT and ARS, Kasbe Digraj) showed significant variability for LLS resistance and component of resistance traits. Total 10 MAGIC lines with longer incubation (>11.0 days) and two MAGIC lines with longer latent period (>27 days) than the resistant parent, GPBD 4 were identified. The MAGIC lines, ICGR 171413, and ICGR 171443 with a lesion diameter of <1 mm and 4.10–5.67% of leaf area damage can be valuable sources for the alleles limiting the pathogen severity. A total of 20 MAGIC lines recorded significantly superior for disease score at 105 DAP_I (5.60–6.89) compared to resistant check, GPDB 4 (6.89). Further studies to determine the type and number of genes controlling the LLS component traits in groundnut will be useful for improvement of resistance to LLS. Genomic selection approach can be valuable in groundnut breeding to harness the minor alleles contributing to the component traits of LLS resistance

Influence of elevated CO2 on growth, yield, haulm, and kernel quality of groundnut (Arachis hypogaea L.)

A study was conducted to evaluate the effect of elevated CO2 on groundnut growth, yield, kernel and haulm nutritional quality in the Open Top Chambers (OTC). Three regimes of CO2, ambient (380 ppm) and two elevated CO2 levels (550 and 700 ppm) are maintained in three different OTCs. Compared to the ambient CO2 conditions, the kernel yield per plant declined by 32.28% and 28.40% at 550 and 700 ppm, respectively, although the pod yield remained unaffected under elevated CO2. Under elevated CO2, plant height, specific leaf area, root area and root volume are reduced, while specific leaf weight increased because of leaf thickening. Root dry weight increased due to allocation of extra fixed carbon to roots for greater support to growth under CO2 enriched conditions. Haulm quality is reduced under elevated CO2, observed as reduced metabolizing energy and in-vitro organic matter digestibility at 550 ppm, and low ash and nitrogen content at 700 ppm. Kernel oil (6.54% and 2.98%) and protein content (7.07% and 4.56%) declined at 550 and 700 ppm as compared to ambient conditions, while fatty acid content remained unaffected. Among minerals, kernel iron and manganese content remained unaffected, while copper (13.93% and 26.19%) and calcium (24.33% and 8.20%) content declined at both elevated CO2 levels. The genotype by trait biplot analysis revealed ICGV 03043 as the best performing genotype with a superior trait profile alongside high kernel yield and oil content across three CO2 levels, making it a candidate for future studies to understand the insensitivity to elevated CO2