The retromer protein ZmVPS29 regulates maize kernel morphology likely through an auxin-dependent process(es).

Lin Chen,Tianyu Wang,Dengfeng Zhang,Yunsu Shi,Yong‐Xiang Li,Yu Li,Haiyang Wang,Yanchun Song,Chunhui Li

doi:10.1111/pbi.13267

Abstract

SummaryKernel size and morphology are two important yield‐determining traits in maize, but their molecular and genetic mechanisms are poorly characterized. Here, we identified a major QTL,qKM4.08, which explains approximately 24.20% of the kernel morphology variance in a recombinant population derived from two elite maize inbred lines, Huangzaosi (HZS, round kernel) and LV28 (slender kernel). Positional cloning and transgenic analysis revealed that qKM4.08 encodes ZmVPS29, a retromer complex component. Compared with the ZmVPS29 HZS allele, the ZmVPS29 LV28 allele showed higher expression in developing kernels. Overexpression of ZmVPS29 conferred a slender kernel morphology and increased the yield per plant in different maize genetic backgrounds. Sequence analysis revealed that ZmVPS29 has been under purifying selection during maize domestication. Association analyses identified two significant kernel morphology‐associated polymorphic sites in the ZmVPS29 promoter region that were significantly enriched in modern maize breeding lines. Further study showed that ZmVPS29 increased auxin accumulation during early kernel development by enhancing auxin biosynthesis and transport and reducing auxin degradation and thereby improved kernel development. Our results suggest that ZmVPS29 regulates kernel morphology, most likely through an auxin‐dependent process(es).

Highlights

Maize (Zea mays ssp. mays) is one of the most widely cultivated crops worldwide, and its current total grain production has topped that of any other crops
We showed that qKM4.08 encodes a retromer complex subunit, ZmVPS29, that mainly acts to regulate grain width likely through an auxindependent process(es)
To dissect the genetic basis of the maize kernel morphology (KM), we conducted a QTL analysis using an recombinant inbred line (RIL) population of Huangzaosi (HZS) and LV28 previously generated in our laboratory (Li et al, 2013)

Summary

Introduction

Maize (Zea mays ssp. mays) is one of the most widely cultivated crops worldwide, and its current total grain production has topped that of any other crops (http://www.fao.org/home/en/). The kernel size and shape are two major components of maize yield and have been extensively selected during maize domestication and breeding processes (Liu et al, 2017). During the maize breeding process, kernels of larger size are preferred by breeders due to the positive impact on grain yield (Doebley, 2004; Li et al, 2011). Based on the KM value, maize kernels can be divided into the following categories: large rounds, large flats, middle rounds, middle flats, small rounds and small flats (Pinnisch et al, 2012). Understanding the genetic basis of kernel development might aid further improvements in grain yield and its commodity in maize

Results

Discussion

Conclusion