Hierarchical additive effects on heterosis in rice (Oryza sativa L.)

Zhiwu Dan,Jun Hu,Wei Zhou,Wenchao Huang,Yingguo Zhu,Guoxin Yao,Renshan Zhu

doi:10.3389/fpls.2015.00738

Abstract

Exploitation of heterosis in crops has contributed greatly to improvement in global food and energy production. In spite of the pervasive importance of heterosis, a complete understanding of its mechanisms has remained elusive. In this study, a small test-crossed rice population was constructed to investigate the formation mechanism of heterosis for 13 traits. The results of the relative mid-parent heterosis and modes of inheritance of all investigated traits demonstrated that additive effects were the foundation of heterosis for complex traits in a hierarchical structure, and multiplicative interactions among the component traits were the framework of heterosis in complex traits. Furthermore, new balances between unit traits and related component traits provided hybrids with the opportunity to achieve an optimal degree of heterosis for complex traits. This study dissected heterosis of both reproductive and vegetative traits from the perspective of hierarchical structure for the first time. Additive multiplicative interactions of component traits were proven to be the origin of heterosis in complex traits. Meanwhile, more attention should be paid to component traits, rather than complex traits, in the process of revealing the mechanism of heterosis.

Highlights

The world is currently facing the daunting task of addressing food and energy shortages
We found, based on a hierarchical structure, that additive effects composed the fundamental level of heterosis for compound traits
Plant Materials Eighteen inbred rice lines were used in this study (Supplementary Table S1), which were identified as indica or japonica with the InDel marker estimating method (Lu et al, 2009)

Summary

Introduction

The world is currently facing the daunting task of addressing food and energy shortages. One cause of these shortages is the growing population. China needs to increase grain production by ∼25% to satisfy the huge national consumption by 2020 (Qiu, 2008; Wang et al, 2013). Climate change could result in decreasing yields of staple food crops in most parts of the world from the 2030s onward (Challinor et al, 2014). Discovering the mechanism of heterosis is an urgent task

Methods

Results

Conclusion