Transcriptome-Wide Identification and Expression Profiling of SPX Domain-Containing Members in Responses to Phosphorus Deprivation of Pinus massoniana

Conghui Wang,Zijing Zhou,Guijie Ding,Fuhua Fan,Xianwen Shang

doi:10.3390/f12121627

Abstract

The SPX domain-encoding proteins are believed to play important roles in phosphorus (Pi) homeostasis and signal transduction in plants. However, the overall information and responses of SPXs to phosphorus deficiency in pines, remain undefined. In this study, we screened the transcriptome data of Pinus massoniana in response to phosphorus deprivation. Ten SPX domain-containing genes were identified. Based on the conserved domains, the P. massoniana SPX genes were divided into four different subfamilies: SPX, SPX-MFS, SPX-EXS, and SPX-RING. RNA-seq analysis revealed that PmSPX genes were differentially expressed in response to phosphorus deprivation. Furthermore, real-time quantitative PCR (RT-qPCR) showed that PmSPX1 and PmSPX4 showed different expression patterns in different tissues under phosphorus stress. The promoter sequence of 2284 bp upstream of PmSPX1 was obtained by the genome walking method. A cis-element analysis indicated that there were several phosphorus stress response-related elements (e.g., two P1BS elements, a PHO element, and a W-box) in the promoter of PmSPX1. In addition, the previously obtained PmSPX2 promoter sequence contained a W-box, and it was shown that PmWRKY75 could directly bind to the PmSPX2 promoter using yeast one-hybrid analysis in this study. These results presented here revealed the foundational functions of PmSPXs in maintaining plant phosphorus homeostasis.

Highlights

Phosphorus (P) is one of the major nutrients required by plants, indispensable in plant growth and development [1]
Genes containing SPX domains were identified in the transcriptome of P. massoniana by gene models and CD-search program, and 10 SPX genes (PmSPXs) were confirmed in the transcriptome of P. massoniana (Table 1)
Based on the location of the green fluorescence signal, the results showed that PmSPX1 and PmSPX4 were localized in the nucleus (Figure 1)

Summary

Introduction

Phosphorus (P) is one of the major nutrients required by plants, indispensable in plant growth and development [1]. It is usually absorbed and utilized in the form of inorganic phosphate (Pi) [2]. In the natural environment, plants often encounter phosphorus deficiency in the soil and overcome this problem by applying large amounts of phosphorus fertilizer. This approach can cause overexploitation of phosphate ore and water eutrophication [4]. It is crucial to improve the adaptability of plants to a phosphorus-deficient environment

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Discussion

Conclusion