Abnormal development of tapetum and microspores induced by chemical hybridization agent SQ-1 in wheat.

Randall P Niedz,Shuping Wang,Qilu Song,Zheng Li,Junwei Wang,Gaisheng Zhang,Jialin Guo,Na Niu,Yingxin Zhang,Shoucai Ma

doi:10.1371/journal.pone.0119557

Abstract

Chemical hybridization agent (CHA)-induced male sterility is an important tool in crop heterosis. To demonstrate that CHA-SQ-1-induced male sterility is associated with abnormal tapetal and microspore development, the cytology of CHA-SQ-1-treated plant anthers at various developmental stages was studied by light microscopy, scanning and transmission electron microscopy, in situ terminal deoxynucleotidyl transferasemediated dUTP nick end-labelling (TUNEL) assay and DAPI staining. The results indicated that the SQ-1-treated plants underwent premature tapetal programmed cell death (PCD), which was initiated at the early-uninucleate stage of microspore development and continued until the tapetal cells were completely degraded; the process of microspore development was then blocked. Microspores with low-viability (fluorescein diacetate staining) were aborted. The study suggests that premature tapetal PCD is the main cause of pollen abortion. Furthermore, it determines the starting period and a key factor in CHA-SQ-1-induced male sterility at the cell level, and provides cytological evidence to further study the mechanism between PCD and male sterility.

Highlights

Wheat hybrids have had a significant improvement on grain yield through improved cultivars and have led to better adaptation to adverse environments [1,2]
We investigated the characteristics of chemical hybridization agent (CHA)-SQ-1-induced male sterile in wheat plants, and compared the morphological changes between normal fertile anthers from control plants and male sterile anthers from CHA-SQ-1-treated plants at different developmental stages; comparisons were made using light microscopy, electron microscopy and the biochemical characteristics of nuclear DNA fragmentation using terminal deoxynucleotidyl transferase-mediated dUTP nick end-labelling (TUNEL) assay in situ
The CHA-SQ-1-treated plant anthers appeared normal at the tetrad stage (Fig. 1A,F)

Summary

Introduction

Wheat hybrids have had a significant improvement on grain yield through improved cultivars and have led to better adaptation to adverse environments [1,2]. A number of approaches have been proposed to avoid self-pollination for the commercial production of hybrid wheat seeds, which include genetic male sterility (GMS), cytoplasmic male sterility (CMS), photo-thermosensitive male sterility (PTMS) and chemical hybridizing agents (CHAs) [3,4,5,6]. Of these, CHAinduced male sterility can provide rapid, flexible and high performance seed-producing female parents for F1 hybrid production; they simultaneously avoid fluctuations of genotype and environmental factors in maintaining male-sterility and/or male-fertility restoration [7]. Anther Development in CHA-Induced Male Sterility in Wheat design, data collection and analysis, decision to publish, or preparation of the manuscript

Methods

Results

Conclusion