Genetic Diversity and Molecular Evolution of Chinese Waxy Maize Germplasm

Hongjian Zheng,Yunbi Xu,Lijun Luo,Biao Shi,Hui Wang,Run Cai,Jinhong Wu,Hua Yang,Aizhong Wu,Giovanni G Vendramin

doi:10.1371/journal.pone.0066606

Abstract

Waxy maize (Zea mays L. var. certaina Kulesh), with many excellent characters in terms of starch composition and economic value, has grown in China for a long history and its production has increased dramatically in recent decades. However, the evolution and origin of waxy maize still remains unclear. We studied the genetic diversity of Chinese waxy maize including typical landraces and inbred lines by SSR analysis and the results showed a wide genetic diversity in the Chinese waxy maize germplasm. We analyzed the origin and evolution of waxy maize by sequencing 108 samples, and downloading 52 sequences from GenBank for the waxy locus in a number of accessions from genus Zea. A sharp reduction of nucleotide diversity and significant neutrality tests (Tajima’s D and Fu and Li’s F*) were observed at the waxy locus in Chinese waxy maize but not in nonglutinous maize. Phylogenetic analysis indicated that Chinese waxy maize originated from the cultivated flint maize and most of the modern waxy maize inbred lines showed a distinct independent origin and evolution process compared with the germplasm from Southwest China. The results indicated that an agronomic trait can be quickly improved to meet production demand by selection.

Highlights

Waxy maize (Zea mays L. var. certain Kulesh) is a special cultivated type of maize, and was first discovered in China in 1908 and in other Asian countries [1,2,3,4]
With simple sequence repeats (SSR) markers, comparative analysis of genetic diversity in landraces of waxy maize from Yunnan and Guizhou concluded that both Yunnan and Guizhou would be the center of diversity and origin for waxy maize [10]
We first used SSR markers to study the genetic diversity of Chinese waxy maize including landraces and inbred lines; we sampled waxy sequences from 108 maize accessions including 89 waxy and 19 nonglutinous ones and compared with data of waxy sequences downloaded from GenBank to study the systematic position of Chinese waxy maize in genus Zea, and investigate the origin and dynamics of population evolution for Chinese waxy maize

Summary

Introduction

Waxy maize (Zea mays L. var. certain Kulesh) is a special cultivated type of maize, and was first discovered in China in 1908 and in other Asian countries [1,2,3,4]. Several studies have suggested that Chinese waxy maize originated from Yunnan and Guangxi according to morphology, karotype, isozymes and DNA markers [3,10,12,13,14]. In the isozyme patterns of malic dehydrogenase, Chinese waxy maize has six bands as the same as that of Coix, suggesting that the origin of waxy maize might be related to Coix [6]. We first used SSR markers to study the genetic diversity of Chinese waxy maize including landraces and inbred lines; we sampled waxy sequences from 108 maize accessions including 89 waxy and 19 nonglutinous ones and compared with data of waxy sequences downloaded from GenBank to study the systematic position of Chinese waxy maize in genus Zea, and investigate the origin and dynamics of population evolution for Chinese waxy maize

Materials and Methods

Results

Discussion