Advanced backcross QTL analysis for disease resistance, oil quality and yield component traits revealed genetic imprints of domestication in groundnut (Arachis hypogaea L.)

Authors: KHERA, PAWAN - International Crops Research Institute For Semi-Arid Tropics (ICRISAT) - India; PANDEY, MANISH - International Crops Research Institute For Semi-Arid Tropics (ICRISAT) - India; MALLIKARJUNA, NALINI - International Crops Research Institute For Semi-Arid Tropics (ICRISAT) - India; SRISWATHI, MANDA - International Crops Research Institute For Semi-Arid Tropics (ICRISAT) - India; ROORKIWAL, M - International Crops Research Institute For Semi-Arid Tropics (ICRISAT) - India; JANILA, PASUPULETI - International Crops Research Institute For Semi-Arid Tropics (ICRISAT) - India; SHARMA, S - International Crops Research Institute For Semi-Arid Tropics (ICRISAT) - India; SHILPA, K - International Crops Research Institute For Semi-Arid Tropics (ICRISAT) - India; SUDINI, HARIKISHAN - International Crops Research Institute For Semi-Arid Tropics (ICRISAT) - India; Guo, Baozhu; VARSHNEY, RAJEEV - International Crops Research Institute For Semi-Arid Tropics (ICRISAT) - India

Submitted to: Molecular Genetics and Genomics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/8/2018
Publication Date: 11/22/2018
Citation: Khera, P., Pandey, M.K., Mallikarjuna, N., Sriswathi, M., Roorkiwal, M., Janila, P., Sharma, S., Shilpa, K., Sudini, H., Guo, B., Varshney, R.K. 2018. Advanced backcross QTL analysis for disease resistance, oil quality and yield component traits revealed genetic imprints of domestication in groundnut (Arachis hypogaea L.). Molecular Genetics and Genomics. 294:365-378.

Interpretive Summary: The efforts of using wild peanut toward diversifying the domestic peanut gene pool resulted in the development of interspecific peanut germplasm. These interspecific peanut genotypes were developed through crossing between wild species to develop diploid hybrids and subsequently treating the diploid hybrid pollen with colchicine to develop synthetic tetraploid peanut plants, which will be used to cross to cultivated peanut. This study is important in the direction of developing advanced-backcross (AB) populations using the wild synthetic populations for construction of genetic maps and identification of markers linked to traits of interest. Two synthetic populations were used to generate two advanced backcross-quantitative trait loci (AB-QTL) populations. Genetic maps were constructed and quantitative trait loci (QTL) markers were identified for disease resistance, oil quality, and yield components. The highest QTL contributed to 50.9% for late leaf spot and 67.8% for yield traits. The AB-QTL approach facilitated simultaneous identification of QTLs and introgression of wild genes associated with traits of interest into the cultivated gene pool of peanut. These introgression lines will be useful resource for further genetic studies and breeding introgression/selection of lines with traits of interest. It was interesting to note that majority of the favorable alleles for disease resistances were contributed by the synthetic wild parents. This indicated that peanut wild relatives may serve as a good source for improving disease resistance under different environments.

Technical Abstract: Ploidy difference between wild Arachis species and cultivated genotypes hinder transfer of useful alleles for agronomical important traits. To overcome this genetic barrier, two synthetic amphidiploids viz., ISATGR 1212 (A. duranensis ICG 8123 × A. ipaensis ICG 8206) and ISATGR 265-5A (A. kempff-mercadoi ICG 8164 × A. hoehnei ICG 8190) were used to generate two advanced backcross-quantitative trait loci (AB-QTL) populations. The AB-QTL populations namely AB-QTL1 (ICGV 91114 × ISATGR 1212) and AB-QTL2 (ICGV 87846 × ISATGR 265-5A) were genotyped with DArT and SSR markers. Genetic maps were constructed for AB-QTL1 and AB-QTL2 populations contained 258 loci (1,415.7 cM map length and map density of 5.5) and 1,043 loci (1,500.8 cM map length with map density of 1.4 cM), respectively. These populations were phenotyped for disease resistance (late leaf spot, rust and peanut bud necrosis), oil quality (oleic and linoleic acid ratio, saturated and unsaturated fatty acids), and yield components (pod yield, 100 seed weight, sound mature kernels and shelling percentage). QTL analysis using above mentioned genotyping and phenotyping data identified 15 QTLs with phenotypic variation (PV) 6.7-14.8% in AB-QTL1 population while 35 QTLs with PV 7.2-67.8% in AB-QTL2 population for disease resistance, oil quality and yield component traits. The AB-QTL approach facilitated simultaneous identification of QTLs and introgression of wild genomic regions associated with traits of interest into the cultivated gene pool of groundnut. These introgression lines will be very useful resource for further genetic studies and selection of lines with traits of interest.