Production of reactive oxygen species by PuRBOHF is critical for stone cell development in pear fruit

Xiaoqian Wang,Xinyue Li,Deguo Lyu Deguo Lyu,Siqi Liu,Chunyan Liu,Huili Sun,Yang Liu,Guodong Du

doi:10.1038/s41438-021-00674-0

Abstract

The production of reactive oxygen species (ROS) by NADPH oxidase, which is also referred to as respiratory burst oxidase homolog (RBOH), affects several processes in plants. However, the role of RBOHs in cell wall lignification is not well understood. In this study, we show that PuRBOHF, an RBOH isoform, plays an important role in secondary wall formation in pear stone cells. ROS were closely associated with lignin deposition and stone cell formation according to microscopy data. In addition, according to the results of an in situ hybridization analysis, the stage-specific expression of PuRBOHF was higher in stone cells than in cells of other flesh tissues. Inhibitors of RBOH activity suppressed ROS accumulation and stone cell lignification in pear fruit. Moreover, transient overexpression of PuRBOHF caused significant changes in the amount of ROS and lignin that accumulated in pear fruit and flesh calli. We further showed that PuMYB169 regulates PuRBOHF expression, while PuRBOHF-derived ROS induces the transcription of PuPOD2 and PuLAC2. The findings of this study indicate that PuRBOHF-mediated ROS production, which is regulated by a lignin-related transcriptional network, is essential for monolignol polymerization and stone cell formation in pear fruit.

Highlights

Pear, which belongs to the Rosaceae family, is an important fruit tree species and is widely cultivated throughout temperate regions worldwide
We found that PuRBOHF preferentially accumulated in the stone cell zone and found a relatively weak signal in the parenchymal cells, suggesting that this gene is involved in stone cell formation (Fig. 4d)
The results showed that PuRBOHF was expressed at the highest levels in isolated stone cells (Fig. 4c), indicating that this gene is Transient expression of PuRBOHF in pear fruit To further elucidate the function of PuRBOHF in lignin biosynthesis, PuRBOHF overexpression or antisense constructs were transferred into Nanguo pear fruit at 40 days after full bloom (DAFB)

Summary

Introduction

Pear (a member of the Pyrus genus), which belongs to the Rosaceae family, is an important fruit tree species and is widely cultivated throughout temperate regions worldwide. Unlike the fruit of other Pyrus species, P. ussuriensis fruit has a relatively high stone cell content, which is a crucial factor affecting fruit quality[3]. The presence of stone cells contributes to the rough flesh texture of some pear fruit, thereby reducing their economic value[4]. It is essential to reduce the content of stone cells to improve pear quality. Pear stone cells are sclerenchyma cells formed by the secondary deposition of lignin within the primary walls of parenchyma cells[5]. The formation of stone cells is strongly associated with the synthesis, transfer, and deposition of

Methods

Results

Conclusion