Abstract
BackgroundTime-to-maturation (TTM) is an important trait contributing to adaptability, yield and quality in peanut (Arachis hypogaea L). Virginia market-type peanut belongs to the late-maturing A. hypogaea subspecies with considerable variation in TTM within this market type. Consequently, planting and harvesting schedule of peanut cultivars, including Virginia market-type, need to be optimized to maximize yield and grade. Little is known regarding the genetic control of TTM in peanut due to the challenge of phenotyping and limited DNA polymorphism. Here, we investigated the genetic control of TTM within the Virginia market-type peanut using a SNP-based high-density genetic map. A recombinant inbred line (RIL) population, derived from a cross between two Virginia-type cultivars ‘Hanoch’ and ‘Harari’ with contrasting TTM (12–15 days on multi-years observations), was phenotyped in the field for 2 years following a randomized complete block design. TTM was estimated by maturity index (MI). Other agronomic traits like harvest index (HI), branching habit (BH) and shelling percentage (SP) were recorded as well.ResultsMI was highly segregated in the population, with 13.3–70.9% and 28.4–80.2% in years 2018 and 2019. The constructed genetic map included 1833 SNP markers distributed on 24 linkage groups, covering a total map distance of 1773.5 cM corresponding to 20 chromosomes on the tetraploid peanut genome with 1.6 cM mean distance between the adjacent markers. Thirty QTL were identified for all measured traits. Among the four QTL regions for MI, two consistent QTL regions (qMIA04a,b and qMIB03a,b) were identified on chromosomes A04 (118680323–125,599,371; 6.9Mbp) and B03 (2839591–4,674,238; 1.8Mbp), with LOD values of 5.33–6.45 and 5–5.35 which explained phenotypic variation of 9.9–11.9% and 9.3–9.9%, respectively. QTL for HI were found to share the same loci as MI on chromosomes B03, B05, and B06, demonstrating the possible pleiotropic effect of HI on TTM. Significant but smaller effects on MI were detected for BH, pod yield and SP.ConclusionsThis study identified consistent QTL regions conditioning TTM for Virginia market-type peanut. The information and materials generated here can be used to further develop molecular markers to select peanut idiotypes suitable for diverse growth environments.
Highlights
Time-to-maturation (TTM) is an important trait contributing to adaptability, yield and quality in peanut (Arachis hypogaea L)
High-yielding but latematuring Runner- and Virginia- market-type peanuts are widely grown in the USA and the Middle East, where irrigation is available to most farming areas
Phenotyping of the parents and the recombinant inbred line (RIL) population A RIL population was developed from a cross between Hanoch and Harari cultivars (Fig. 1a)
Summary
Time-to-maturation (TTM) is an important trait contributing to adaptability, yield and quality in peanut (Arachis hypogaea L). Peanut (Arachis hypogaea L.) is an important grain legume and oilseed source for human nutrition It is grown in more than 100 countries and plays a significant role in global trade. Fastigiata is characterized by early fruit maturation, sequential flowering pattern, determinate shoot formation and erect growth habit, whereas ssp. Early-maturation (90 to 120 days post-planting) is necessary for drought avoidance in areas with a short rainy season For this reason, Spanish market-type peanuts are predominately grown in West Africa and India, where the drought stress level is high [5]. High-yielding but latematuring Runner- and Virginia- market-type peanuts are widely grown in the USA and the Middle East, where irrigation is available to most farming areas
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