PcDWF1, a pear brassinosteroid biosynthetic gene homologous to AtDWARF1, affected the vegetative and reproductive growth of plants

Xiaodong Zheng,Shaolan Yang,Yuxiong Xiao,Caihong Wang,Yike Tian

doi:10.1186/s12870-020-2323-8

Abstract

BackgroundThe steroidal hormones brassinosteroids (BRs) play important roles in plant growth and development. The pathway and genes involved in BR biosynthesis have been identified primarily in model plants like Arabidopsis, but little is known about BR biosynthesis in woody fruits such as pear.ResultsIn this study, we found that applying exogenous brassinolide (BL) could significantly increase the stem growth and rooting ability of Pyrus ussuriensis. PcDWF1, which had a significantly lower level of expression in the dwarf-type pear than in the standard-type pear, was cloned for further analysis. A phylogenetic analysis showed that PcDWF1 was a pear brassinosteroid biosynthetic gene that was homologous to AtDWARF1. The subcellular localization analysis indicated that PcDWF1 was located in the plasma membrane. Overexpression of PcDWF1 in tobacco (Nicotiana tabacum) or pear (Pyrus ussuriensis) plants promoted the growth of the stems, which was caused by a larger cell size and more developed xylem than those in the control plants, and the rooting ability was significantly enhanced. In addition to the change in vegetative growth, the tobacco plants overexpressing PcDWF1 also had a delayed flowering time and larger seed size than did the control tobacco plants. These phenotypes were considered to result from the higher BL contents in the transgenic lines than in the control tobacco and pear plants.ConclusionsTaken together, these results reveal that the pear BR biosynthetic gene PcDWF1 affected the vegetative and reproductive growth of Pyrus ussuriensis and Nicotiana tabacum and could be characterized as an important BR biosynthetic gene in perennial woody fruit plants.

Highlights

The steroidal hormones brassinosteroids (BRs) play important roles in plant growth and development
We overexpressed PcDWF1 in tobacco and pear and found that the overexpression of PcDWF1 affected the vegetative growth and the reproductive growth of the transgenic plants. These findings showed the positive role of PcDWF1 in BR biosynthesis and clarified the function of PcDWF1 in the vegetative and reproductive growth of woody plants
The results showed that the expression of PcDWF1, which is the homologous gene of AtDWF1, was significantly lower in dwarf-type pears than in standard-type pears in the roots, stems and leaves (Fig. 2)

Summary

Introduction

The steroidal hormones brassinosteroids (BRs) play important roles in plant growth and development. The pathway and genes involved in BR biosynthesis have been identified primarily in model plants like Arabidopsis, but little is known about BR biosynthesis in woody fruits such as pear. The plant steroidal hormones brassinosteroids (BRs) are ubiquitously distributed throughout the plant kingdom [1,2,3,4,5]. In the woody plant apple, the roles of BRs in plant growth were preliminarily reported. Ma et al (2016) reported that dwarfism resulted from the reduced expression of the BR biosynthesis gene MdDWF4 coupled with the high expression of BRI1 kinase inhibitor 1 (MdBKI1) and brassinosteroid insensitive 2 (MdBIN2) [23, 24]. The molecular genetic studies of BR function were mainly based on key genes in the BR biosynthetic pathway

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Conclusion