Abstract
BackgroundPeanut smut is a disease caused by the fungus Thecaphora frezii Carranza & Lindquist to which most commercial cultivars in South America are highly susceptible. It is responsible for severely decreased yield and no effective chemical treatment is available to date. However, smut resistance has been identified in wild Arachis species and further transferred to peanut elite cultivars. To identify the genome regions conferring smut resistance within a tetraploid genetic background, this study evaluated a RIL population {susceptible Arachis hypogaea subsp. hypogaea (JS17304-7-B) × resistant synthetic amphidiploid (JS1806) [A. correntina (K 11905) × A. cardenasii (KSSc 36015)] × A. batizocoi (K 9484)4×} segregating for the trait.ResultsA SNP based genetic map arranged into 21 linkage groups belonging to the 20 peanut chromosomes was constructed with 1819 markers, spanning a genetic distance of 2531.81 cM. Two consistent quantitative trait loci (QTLs) were identified qSmIA08 and qSmIA02/B02, located on chromosome A08 and A02/B02, respectively. The QTL qSmIA08 at 15.20 cM/5.03 Mbp explained 17.53% of the phenotypic variance, while qSmIA02/B02 at 4.0 cM/3.56 Mbp explained 9.06% of the phenotypic variance. The combined genotypic effects of both QTLs reduced smut incidence by 57% and were stable over the 3 years of evaluation. The genome regions containing the QTLs are rich in genes encoding proteins involved in plant defense, providing new insights into the genetic architecture of peanut smut resistance.ConclusionsA major QTL and a minor QTL identified in this study provide new insights into the genetic architecture of peanut smut resistance that may aid in breeding new varieties resistant to peanut smut.
Highlights
Peanut smut is a disease caused by the fungus Thecaphora frezii Carranza & Lindquist to which most commercial cultivars in South America are highly susceptible
Because seeds of wild species collected in Bolivia, Brazil and Argentina were delivered to main germplasm banks of the world, peanut smut constitutes a threat to the peanut industry around the world
By developing a high-density Single nucleotide polymorphism (SNP) genetic map and phenotypic data measured on the Recombinant inbred line (RIL) population, we were able to detect one major Quantitative trait loci (QTLs) and a minor QTL for peanut smut resistance, one on linkage group (LG) A08 and other on LG A02/B02, with markers introgressed from the amphidiploid parent
Summary
Peanut smut is a disease caused by the fungus Thecaphora frezii Carranza & Lindquist to which most commercial cultivars in South America are highly susceptible. It is responsible for severely decreased yield and no effective chemical treatment is available to date. The cultivated peanut (Arachis hypogaea L.) is an important allotetraploid (AABB) originated in South America [1,2,3]. This legume crop is grown in more than 100. Because seeds of wild species collected in Bolivia, Brazil and Argentina were delivered to main germplasm banks of the world, peanut smut constitutes a threat to the peanut industry around the world
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