Mitochondrial Dysfunction Causes Oxidative Stress and Tapetal Apoptosis in Chemical Hybridization Reagent-Induced Male Sterility in Wheat.

Junwei Wang,Lin Zhang,Zheng Chen,Yaqin Yao,Shoucai Ma,Shuping Wang,Gaisheng Zhang,Zhengwu Fang,Yingxin Zhang,Lili Zhang,Qilu Song,Yamin Zhang,Na Niu,Zanmin Hu

doi:10.3389/fpls.2017.02217

Abstract

Male sterility in plants has been strongly linked to mitochondrial dysfunction. Chemical hybridization agent (CHA)-induced male sterility is an important tool in crop heterosis. Therefore, it is important to better understand the relationship between mitochondria and CHA-induced male sterility in wheat. This study reports on the impairment of mitochondrial function duo to CHA-SQ-1, which occurs by decreasing cytochrome oxidase and adenosine triphosphate synthase protein levels and theirs activities, respiratory rate, and in turn results in the inhibition of the mitochondrial electron transport chain (ETC), excessive production of reactive oxygen species (ROS) and disruption of the alternative oxidase pathway. Subsequently, excessive ROS combined with MnSOD defects results in damage to the mitochondrial membrane, followed by ROS release into the cytoplasm. The microspores underwent severe oxidative stress during pollen development. Furthermore, chronic oxidative stress, together with the overexpression of type II metacaspase, triggered premature tapetal apoptosis, which resulted in pollen abortion. Accordingly, we propose a metabolic pathway for mitochondrial-mediated male sterility in wheat, which provides information on the molecular events underlying CHA-SQ-1-induced abortion of anthers and may serve as an additional guide to the practical application of hybrid breeding.

Highlights

Heterosis plays a major role in improving crop yields, and has been used in crop production for decades
Anthers were embedded in an optimal cutting temperature medium
Unlike the mature pollen of control plants, those of the Chemical hybridization agent (CHA)-SQ-1-treated plants did not show intense staining with iodine-potassium iodide (Wang et al, 2015a) and the pollen was not shed (Figure 1). These results indicated that CHA-SQ-1-treated plants were 100% pollen sterile

Summary

Introduction

Heterosis plays a major role in improving crop yields, and has been used in crop production for decades. CHA-SQ-1 Disrupts Mitochondrial Function in Anther a typically self-pollinating crop, using chemical hybridizing agent (CHA) to induce male sterility because female parentals generally do not undergo self-pollination are crucial for the commercial production of hybrid wheat seeds. SQ-1 is an ideal chemical hybridization agent which could induce male sterility by changing the cell microstructure (Wang et al, 2016), triggering programmed cell death (PCD) (Wang et al, 2015a, 2016), striking the oxidative/antioxidative balance (Wang et al, 2016) and increasing the cell membrane permeability (Song et al, 2015). Despite some progress toward understanding the mechanisms of male sterility has been made, such as reactive oxygen and aliphatic metabolism (Ba et al, 2013, 2014a), DNA methylation (Ba et al, 2014b), cell morphological (Wang et al, 2015a), transcriptome (Zhu et al, 2015) and proteomics (Song et al, 2015; Wang et al, 2015b), the mechanisms underlying male sterility in plants resulting from CHA treatment remain elusive

Methods

Results

Conclusion