Genetic diversity, phylogenetic structure and development of core collections in Melilotus accessions from a Chinese gene bank

Hongxiang Zhang,Jiyu Zhang,Fan Wu,Wenli Guo,Rong Bai,Jinxing Ma,Qi Yan,Zhuanzhuan Yan,Yufei Zhang

doi:10.1038/s41598-019-49355-y

Abstract

Melilotus is an important forage legume, with high values as feed and medicine, and widely used as green manure, honey plant, and wildlife habitat enhancer. The genetic diversity, structure and subdivision of this forage crop remain unclear, and plant genetic resources are the basis of biodiversity and ecosystem diversity and have attracted increasing attention. In this study, the whole collection of 573 accessions from the National Gene Bank of Forage Germplasm (NGBFG, China) and 48 accessions from the National Plant Germplasm System (NPGS, USA) in genus Melilotus were measured with respect to five seed characters: seed length, width, width-to-length ratio, circumference and 100-seed weight. Shannon’ genetic diversity index (H’) and phenotypic differentiation (Pst) were calculated to better describe the genetic diversity. The ITS and matK sequences were used to construct phylogenetic trees and study the genetic relationships within genus Melilotu. Based on seed morphology and molecular marker data, we preliminarily developed core collections and the sampling rates of M. albus and M. officinalis were determined to be 15% and 25%, respectively. The results obtained here provide preliminary sorting and supplemental information for the Melilotus collections in NGBFG, China, and establish a reference for further genetic breeding and other related projects.

Highlights

Melilotus is a forage legume of family, including 19 annual and biennial species, and three of the species have been cultivated: M. albus, M. officinalis, and M. indicus[1,2,3]
As a high-quality forage species, Melilotus has many advantages and grows widely in China, and nearly 600 accessions of Melilotus were collected in NGBFG, China
The results indicated that Melilotus had high genetic variation among species, and we further studied the genetic diversity and phylogenetic relationships of all Melilotus accessions in NGBFG, China

Summary

Discussion

Conservation of plant genetic diversity is essential for present and future human well-being. As a high-quality forage species, Melilotus has many advantages and grows widely in China, and nearly 600 accessions of Melilotus were collected in NGBFG, China. The results indicated that Melilotus had high genetic variation among species, and we further studied the genetic diversity and phylogenetic relationships of all Melilotus accessions in NGBFG, China. To better protect and utilize these resources, we analyzed the diversity of all accessions in NGBFG based on morphological and molecular data and developed core collections of two species. Morphological and molecular data can be analyzed separately or in combination to determine genetic diversity[37]. Based on seed morphological traits and the ITS and matK sequences of Melilotus, we analyzed the genetic diversity of this genus and developed core sets to conserve and utilize germplasm resources efficiently

Evaluation Parameters

Sampling Methods

Materials and Methods