Abstract
Key message SSR-based QTL mapping provides useful information for map-based cloning of major QTLs and can be used to improve the agronomic and quality traits in cultivated peanut by marker-assisted selection. Cultivated peanut (Arachis hypogaea L.) is an allotetraploid species (AABB, 2n = 4× = 40), valued for its edible oil and digestible protein. Linkage mapping has been successfully conducted for most crops, and it has been applied to detect the quantitative trait loci (QTLs) of biotic and abiotic traits in peanut. However, the genetic basis of agronomic and quality-related traits remains unclear. In this study, high levels of phenotypic variation, broad-sense heritability and significant correlations were observed for agronomic and quality-related traits in an F 2:3 population. A genetic linkage map was constructed for cultivated peanut containing 470 simple sequence repeat (SSR) loci, with a total length of 1877.3 cM and average distance of 4.0 cM between flanking markers. For 10 agronomic traits, 24 QTLs were identified and each QTL explained 1.69–18.70 % of the phenotypic variance. For 8 quality-related traits, 12 QTLs were identified that explained 1.72–20.20 % of the phenotypic variance. Several QTLs for multiple traits were overlapped, reflecting the phenotypic correlation between these traits. The majority of QTLs exhibited obvious dominance or over-dominance effects on agronomic and quality traits, highlighting the importance of heterosis for breeding. A comparative analysis revealed genomic duplication and arrangement of peanut genome, which aids the assembly of scaffolds in genomic sequencing of Arachis hypogaea. Our QTL analysis results enabled us to clearly understand the genetic base of agronomic and quality traits in cultivated peanut, further accelerating the progress of map-based cloning of major QTLs and marker-assisted selection in future breeding.Electronic supplementary materialThe online version of this article (doi:10.1007/s00122-015-2493-1) contains supplementary material, which is available to authorized users.
Highlights
Cultivated peanut (Arachis hypogaea L.) is an allotetraploid (AABB, 2n = 4× = 40) species that may be the product of a single hybridization event between A. duranensis (AA, 2n = 2× = 20) and A. ipaënsis (BB, 2n = 2× = 20) followed by chromosome duplication (Kochert et al 1996)
In China, the field area of 4.7 Mha was harvested with a total peanut production of 16.1 Mt, which is the largest area of production worldwide but not the highest yield per hectare (3.4 t ha−1), suggesting that there is great potential to further enhance peanut production through the genetic improvement of high-yield varieties
We developed a molecular genetic map of peanut based on an F2 mapping population using published simple sequence repeat (SSR) markers
Summary
Peanut is cultivated in tropical and sub-tropical regions in more than 100 countries, with a global annual production of 38.6 Mt over an area of 21.8 Mha (http://faostat.fao.org/faostat/collections?su bset=agriculture 2011). Yield is one of the most important and complex traits in crops. Peanut yield is directly and indirectly influenced by agronomic traits, such as the height of the main stem and total branching number. Pod- and seedrelated traits, such as pod length, pod width, seed length and seed width directly influence peanut yield. More than 60 % of the total peanut production in China is crushed for edible oil. Fatty acid composition influences the quality and storage stability of the total oil. Oil content and fatty acid composition have become increasingly important trait objectives in the breeding of high-yield peanut varieties
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