Mapping-by-Sequencing via MutMap Identifies a Mutation in ZmCLE7 Underlying Fasciation in a Newly Developed EMS Mutant Population in an Elite Tropical Maize Inbred.

Quan Hong Tran,Khuat Huu Trung,Son Lang Vi,Michael Lenhard,Tran Dang Khanh,Tran Dang Khanh,Christian Kappel,Thuy Thi Tran,Nga Thi Ngoc Dau,Ngoc Hong Bui,Loan Thi Nguyen

doi:10.3390/genes11030281

Abstract

Induced point mutations are important genetic resources for their ability to create hypo- and hypermorphic alleles that are useful for understanding gene functions and breeding. However, such mutant populations have only been developed for a few temperate maize varieties, mainly B73 and W22, yet no tropical maize inbred lines have been mutagenized and made available to the public to date. We developed a novel Ethyl Methanesulfonate (EMS) induced mutation resource in maize comprising 2050 independent M2 mutant families in the elite tropical maize inbred ML10. By phenotypic screening, we showed that this population is of comparable quality with other mutagenized populations in maize. To illustrate the usefulness of this population for gene discovery, we performed rapid mapping-by-sequencing to clone a fasciated-ear mutant and identify a causal promoter deletion in ZmCLE7 (CLE7). Our mapping procedure does not require crossing to an unrelated parent, thus is suitable for mapping subtle traits and ones affected by heterosis. This first EMS population in tropical maize is expected to be very useful for the maize research community. Also, the EMS mutagenesis and rapid mapping-by-sequencing pipeline described here illustrate the power of performing forward genetics in diverse maize germplasms of choice, which can lead to novel gene discovery due to divergent genetic backgrounds.

Highlights

Maize is an important staple crop worldwide used for food, feed and industrial products including biofuels [1]
We successfully mutagenized an exotic elite tropical maize inbred by Ethyl Methanesulfonate (EMS) treatment on pollen
Mutants in causal promoter deletion in ZmCLE7 (CLE7) had not been found in any EMS populations of standard inbreds, but were identified in our population

Summary

Introduction

Maize is an important staple crop worldwide used for food, feed and industrial products including biofuels [1]. The demand for maize has steadily risen in past decades and is expected to continue to increase, with maize demand predicted to double by 2050 [2,3]. Maize is of agronomic importance; it has been a very important model organism for genetic studies. Forward genetics in maize has been very fruitful and there are several mutant populations in maize; most of these are in standard inbred backgrounds. Most induced mutants in maize were created by two methods: pollen mutagenesis with Ethyl Methanesulfonate (EMS) or crossing with maize lines that carry highly active transposons [4].

Methods

Results

Conclusion