Estimation of Genetic Parameters for the Alkalinity Tolerance Trait in Urechis Unicinctus

Abstract

The echiura worm Urechis unicinctus has high nutritional and medicinal values and has been identified as a Chinese featured aquatic germplasm resource. However, overfishing and social demands have made it difficult to fill this market gap. The vast area of saline-alkali water in China is still a huge unexploited resource owing to its harsh environmental conditions. In view of the lack of excellent germplasm resources for alkalinity tolerance of U. unicinctus in China, this study focused on the wild population in Qinhuangdao and conducted stress experiments using 15 full-sib families. The 72-h semi-lethal concentration of U. unicinctus was obtained to be 85.59 mM under alkalinity stress conditions. In this study, we estimated the genetic parameters of the alkalinity tolerance trait in U. unicinctus for the first time and calculated the heritability of the alkalinity tolerance trait as 0.14 ± 0.06 (P < 0.05), which belongs to a low level of heritability, indicating that it can be improved by population hybridization, molecular breeding, and family selection breeding. In addition, the genetic and phenotypic correlation coefficients between alkalinity tolerance trait and body weight were 0.97 ± 0.02 and 0.82 ± 0.02 (P < 0.01), respectively, with a Pearson correlation coefficient of 0.49 (P < 0.01), indicating a high correlation between alkalinity tolerance trait and body weight, which can be indirectly selected through body weight. The results of this study provide valuable insights for the selection breeding of superior varieties with alkalinity tolerance in U. unicinctus and have important value in promoting the utilization of saline-alkali water resources.

Keywords: Alkalinity tolerance, Genetic parameters, Selective breeding, Urechis unicinctus