Improving seed number per pod of soybean by molecular breeding based on <italic>Ln</italic> locus

Abstract

<p id="C3">Molecular design breeding is one of the important methods to combine molecular genetics with conventional breeding, and to breed a series soybean variety with excellent traits. Although this method can shorten the breeding process to a large extent, it is rarely used in the artificial breeding process. Increasing production is one of the most important goals in the process of soybean breeding. Soybean is a typical short-day bean plant, which provides more than a quarter of plant protein for human and animals in the world. In the process of soybean breeding, increasing the yield is one of the main breeding objectives, among which the number of seeds per pod is one of the key traits to determine the yield per plant. In soybean, the number of seeds per pod was positively correlated with leaf shape, which was controlled by an allele <italic>Ln</italic>/<italic>ln</italic>. The broad leaflet (<italic>Ln</italic>) usually linked with no 4-seed pod, and narrow leaflet (<italic>ln</italic>) associated with 4-seed pod. Although <italic>Ln</italic> was potentially important for soybean yield, whether this locus could be used in molecular breeding had not been reported. In this study, we found that the narrow leaflet variety was always in high latitude, and the broad leaflet variety in low latitude. To improve soybean yield in low latitude, we developed the molecular marker of <italic>Ln</italic>. <italic>ln</italic> was substituted into broad leaflet varieties Willams 82 and Huaxia 3 by backcrossing. Our data provide an important theoretical and practical basis for molecular design breeding to improve soybean yield.