Global transcriptional profiling between inbred parents and hybrids provides comprehensive insights into ear-length heterosis of maize (Zea mays)

Xiangge Zhang,Li Huang,Jingkuan Shao,Zhanyong Guo,Jihua Tang,Chenchen Ma,Weihua Li,Xiaoqing Wang,Mingbo Wu,Xuehai Zhang,Liang Yuan,Zhiyuan Fu

doi:10.1186/s12870-021-02890-1

Global transcriptional profiling between inbred parents and hybrids provides comprehensive insights into ear-length heterosis of maize (Zea mays)

Xiangge Zhang, Li Huang + Show 10 more

Open Access

https://doi.org/10.1186/s12870-021-02890-1

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Abstract

BackgroundMaize (Zea mays) ear length, which is an important yield component, exhibits strong heterosis. Understanding the potential molecular mechanisms of ear-length heterosis is critical for efficient yield-related breeding.ResultsHere, a joint netted pattern, including six parent-hybrid triplets, was designed on the basis of two maize lines harboring long (T121 line) and short (T126 line) ears. Global transcriptional profiling of young ears (containing meristem) was performed. Multiple comparative analyses revealed that 874 differentially expressed genes are mainly responsible for the ear-length variation between T121 and T126 lines. Among them, four key genes, Zm00001d049958, Zm00001d027359, Zm00001d048502 and Zm00001d052138, were identified as being related to meristem development, which corroborated their roles in the superior additive genetic effects on ear length in T121 line. Non-additive expression patterns were used to identify candidate genes related to ear-length heterosis. A non-additively expressed gene (Zm00001d050649) was associated with the timing of meristematic phase transition and was determined to be the homolog of tomato SELF PRUNING, which assists SINGLE FLOWER TRUSS in driving yield-related heterosis, indicating that Zm00001d050649 is a potential contributor to drive heterotic effect on ear length.ConclusionOur results suggest that inbred parents provide genetic and heterotic effects on the ear lengths of their corresponding F1 hybrids through two independent pathways. These findings provide comprehensive insights into the transcriptional regulation of ear length and improve the understanding of ear-length heterosis in maize.

Highlights

Maize (Zea mays) ear length, which is an important yield component, exhibits strong heterosis
These expression differences may be caused by allelespecific expression (ASE), which refers to the characteristic of preferentially expressing one parental allele in the hybrid owing to variations in regulatory sequences from the parental genome [25, 26]
The F1 hybrids generated by T121 crosses (T121 × PH4CV and T121 × PH6WC) had longer young ears than those generated by corresponding T126 crosses (T126 × PH4CV and T126 × PH6WC) (Table 1, Fig. 1a)

Summary

Introduction

Maize (Zea mays) ear length, which is an important yield component, exhibits strong heterosis. Several kinds of gene expression modes were observed in F1 hybrids: mid-parent (MP) (additivity), high and low parent (high and low parent dominance, respectively), above the high parent (over-dominance) and below the low parent (under-dominance) [21] These data revealed that in hybrids, some genes exhibit non-additive expression patterns (not the expected MP level), which suggested a potential association with heterosis [22,23,24]. These expression differences may be caused by allelespecific expression (ASE), which refers to the characteristic of preferentially expressing one parental allele in the hybrid owing to variations in regulatory sequences from the parental genome [25, 26]. Analyzing transcriptional regulation is a valuable strategy for untangling the molecular basis of heterosis

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