Identification of QTL Associated with Agro-Morphological and Phosphorus Content Traits in Finger Millet under Differential Phosphorus Supply via Linkage Mapping

Finger millet (<i>Eleusine coracana</i> (L.) Gaertn.) is one of the most important cereal crops for people in Asia and Africa. It supplies energy and nutrients for all people, particularly poor people in these continents. Phosphorus (P) is an essential macronutrient for plant growth and grain quality, so an adequate amount of P is required for healthy plant life. There is considerable evidence that P deficiency affects the growths and yields of all cereals, including finger millet. The present study aimed at identifying the quantitative trait loci (QTL) for various agro-morphological and P-content traits under low P (LP) and high P (HP) conditions through linkage mapping. Two cultivars, IE-2606 (low-P-susceptible) and PR-202 (low-P-tolerant) were used to develop 100 recombinant inbred lines (RILs). In total, 55 QTL, associated with various agro-morphological (primary root length (PRL), shoot fresh weight (SFW), root fresh weight (RFW), shoot dry weight (SDW), root dry weight (RDW), and root hair density (RHD)) and P-content traits (inorganic phosphate content in shoots (PiS), inorganic phosphate content in roots (PiR), and total P content in shoots (TPS)) were detected under LP conditions. Similarly, 37 QTL for various agro-morphological (PRL, RFW, SDW, and root hair length (RHL)) and P-content traits (PiS, PiR, TPS, and total P content in roots (TPR)) were detected under HP conditions. Biotic and abiotic stress-responsive candidate genes linked to a few QTL were also identified. The identified QTL associated with agro-morphological and P-content traits in finger millet under P deficiency could be used in breeding programs to develop finger millet with better P use efficiency (PUE). Furthermore, improving finger millet growth and yield under LP soil will help to reduce Pi application and eutrophication, which may help to improve the lives of poor farmers and maintain sustainable environments in Asia and African countries.