Abstract

BackgroundThe overall genetic distribution and divergence of cloned genes among bread wheat varieties that have occurred during the breeding process over the past few decades in Ningxia Province, China, are poorly understood. Here, we report the genetic diversities of 44 important genes related to grain yield, quality, adaptation and resistance in 121 Ningxia and 86 introduced wheat cultivars and advanced lines.ResultsThe population structure indicated characteristics of genetic components of Ningxia wheat, including landraces of particular genetic resources, introduced varieties with rich genetic diversities and modern cultivars in different periods. Analysis of allele frequencies showed that the dwarfing alleles Rht-B1b at Rht-B1 and Rht-D1b at Rht-D1, 1BL/1RS translocation, Hap-1 at GW2-6B and Hap-H at Sus2-2B are very frequently present in modern Ningxia cultivars and in introduced varieties from other regions but absent in landraces. This indicates that the introduced wheat germplasm with numerous beneficial genes is vital for broadening the genetic diversity of Ningxia wheat varieties. Large population differentiation between modern cultivars and landraces has occurred in adaptation genes. Founder parents carry excellent allele combinations of important genes, with a higher number of favorable alleles than modern cultivars. Gene flow analysis showed that six founder parents have greatly contributed to breeding improvement in Ningxia Province, particularly Zhou 8425B, for yield-related genes.ConclusionsVarieties introduced from other regions with rich genetic diversity and landraces with well-adapted genetic resources have been applied to improve modern cultivars. Founder parents, particularly Zhou 8425B, for yield-related genes have contributed greatly to wheat breeding improvement in Ningxia Province. These findings will greatly benefit bread wheat breeding in Ningxia Province as well as other areas with similar ecological environments.

Highlights

  • The overall genetic distribution and divergence of cloned genes among bread wheat varieties that have occurred during the breeding process over the past few decades in Ningxia Province, China, are poorly understood

  • Since the 1950s, bread wheat varieties have experienced five replacements: the wheat germplasm ‘Quality’ introduced from Australia was widely grown in the 1950s and achieved the first variety update of Ningxia spring wheat; the ‘Abbondanza’ wheat resource from Italy was efficiently used in the 1960s and achieved the second variety update of Ningxia wheat breeding; breeding of milestone variety ‘Doudi 1’ is representative of the third variety update in the 1970s; ‘Ningchun 4’ was one of the most used spring wheat varieties in China, and its application and improvement in the 1980s was the fourth variety update of Ningxia wheat; the release of ‘Ningchun 50’ in the 2000s was the mark of the last variety update [2]

  • Kompetitive Allele Specific PCR (KASP) genotyping of functional genes Conventional functional markers were summarized based on 44 cloned wheat genes for grain yield, quality, adaptation and stress resistance [33]; these markers were converted into KASP assays [39] that have been widely exploited to characterize wheat germplasm resources [41,42,43,44]

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Summary

Introduction

The overall genetic distribution and divergence of cloned genes among bread wheat varieties that have occurred during the breeding process over the past few decades in Ningxia Province, China, are poorly understood. We report the genetic diversities of 44 important genes related to grain yield, quality, adaptation and resistance in 121 Ningxia and 86 introduced wheat cultivars and advanced lines. Introduced bread wheat germplasms, such as ‘Quality’ and ‘Cajeme F-71’, have driven studies on wheat production areas with northward expansion and farming system reforming in the Yellow River Ningxia Basin, as well as wheat breeding programmes in Ningxia. It is essential to dissect the genetic contributions to bread wheat improvement of landraces, introduced wheat varieties and specific founder parents at multiple gene levels in the past several decades to direct future wheat breeding in Ningxia

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