A Weak Allele of FASCIATED EAR 2 (FEA2) Increases Maize Kernel Row Number (KRN) and Yield in Elite Maize Hybrids

Khuat Huu Trung,Thuy Thi Tran,Son Lang Vi,Son Lang Vi,Duong Thi Thuy Quan,Diep Thi Ngoc Nguyen,Cuong Cao Dang,Bach Duong Vu,Tran Dang Khanh,Kong Quy Luu,Quan Hong Tran,Nga Thi Thu Tran,Tran Dang Khanh,Hien Thi Nguyen,Diep Thuy Nguyen,Bao Manh Tran,Son Lang Vi,Ngoc Hong Bui,Loan Thi Nguyen,Son Lang Vi

doi:10.3390/agronomy10111774

Abstract

Meristems are central to plant growth and development, yet evidence of directly manipulating this control to improve crop yield is scarce. Kernel row number (KRN) is an important agronomic trait that can directly affect maize (Zea mays L.) yield. However, this trait is difficult to select by phenotyping, since it is highly variable in the mixed genetic backgrounds in early selfing generations. This study sought to improve this trait by marker-assisted backcrossing (MABC) of a weak allele of FASCIATED EAR 2 that is known to affect inflorescence meristem size, but the effect of which on yield is unclear. All of the four introgressed tropical elite inbreds of different heterotic groups, which are homozygous for the fea2-1328 allele, had 2–5 more KRNs compared to their respective recurrent parents. Furthermore, one hybrid made from crosses between two introgressed parents also had KRN increases that resulted in up to 28% yield increase compared to the original hybrid across multiple yield trials. The novel negative effects of the pericentromeric fea2 and/or its linkage drag effect on plant height, seed weight, and ear length, which could prevent line improvement, were revealed in several genetic backgrounds. Integration of conventional phenotypic selection to overcome these undesirable effects was discussed. This is the first work to demonstrate the possibility to increase yield of maize varieties using a mutation in a meristem size regulator. The crossing, selection strategies, and recombinant lines in this work can be applied to other elite maize hybrids and provide a potentially straightforward, non-transgenic way to improve the yield of an existing variety by 8–28%.

Highlights

Maize (Zea mays L.) is one of the most important crops and is providing billions of dollars annually to agriculture, supplying over 30% of the calories consumed by humans [1]
We analyzed the linkage between the phenotype (KRN) and genotypes in the F2 generations of the crosses between fea-1328 and the recurrent parents (RPs)
We found a normal segregation in genotypes, i.e., 1:2:1 ratio, for ML10 and MVS36 (p-values in Chi-square test were 0.54 and 0.35, respectively) but a mild distorted segregation in BL10 and BVS (p-values in Chi-square test were 0.01 and 0.001, respectively)

Summary

Introduction

Maize (Zea mays L.) is one of the most important crops and is providing billions of dollars annually to agriculture, supplying over 30% of the calories consumed by humans [1]. In Vietnam, maize is the second biggest annual crop after rice in terms of harvested area and is consumed for animal feed in the livestock and poultry industry. This crop is cultivated in diverse environments of both rainfed upland and irrigated lowland areas in the northeast, northwest, central highlands, and southeast regions [6].

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Results

Conclusion