PaPTP1, a Gene Encoding Protein Tyrosine Phosphatase from Orchid, Phalaenopsis amabilis, is Regulated During Floral Development and Induced by Wounding

Abstract

Protein tyrosine phosphorylation is crucial in many cellular regulatory mechanisms, including development, stress management, and hormonal responses. However, the precise function of plant protein tyrosine phosphatase (PTP) has not been well elucidated. In this study, we report on the isolation and characterization of an orchid (Phalaenopsis amabilis) PTP gene, referred to as PaPTP1. The cloned PaPTP1 cDNA is 1,588 nucleotides long and the deduced protein sequence composed of 346 amino acid residues. The PaPTP1 gene encodes a classical plant PTP containing a catalytically active cysteine residue within the signature motif. Sequence homology analysis indicated that the predicted amino acid sequence is 57% identical to that of Arabidopsis AtPTP1. To our knowledge, the PaPTP1 is the first classical PTP identified in monocotyledon plant species. Southern blot analysis of genomic DNA revealed the presence of a single PaPTP1 gene in P. amabilis. Expression of PaPTP1 gene was examined in different organs of P. amabilis plants. The result showed that the PaPTP1 gene was abundantly expressed in labella and column of 24-month-old plants, but poorly in leaves. In addition, the PaPTP1 gene expression in response to wounding was investigated. The steady-state level of the PaPTP1 transcript increased significantly in wound-treated leaves. The identity as phosphatase was also demonstrated by characterizing the PaPTP1 expressed as a recombinant glutathione-Stransferase-fusion protein. The enzyme exhibited phosphatase activity towards a synthetic substrate, p-nitrophenolphosphate. Taken together, these results suggest that this PaPTP1 gene encodes a functional protein phosphatase, and its expression patterns are associated with the development of the orchid flowers and in response to wounding.

Poplar PdPTP1 Gene Negatively Regulates Salt Tolerance by Affecting Ion and ROS Homeostasis in Populus

“…In plants, PTP1 is involved in various stresses, such as salt, oxidative, osmotic, pathogen response, wounding, and ABA signaling [14,19,24,36,37]. Our results found that the transcript of PdPTP1 was induced by NaCl and oxidative treatment ( Figure 3B,C), and this finding is consistent with previous studies that the transcript of AtPTP1 was upregulated by high salinity and H 2 O 2 [14,38].…”

“…Moreover, the PdPTP1 harbors two conserved motifs which are present in all members of Tyr-specific PTPs but was not detectable in the sequence of any other DsPTPs family: KNRY motif necessary to permit the access of phosphotyrosine residues to the active site and WPD motif essential for the phosphotyrosine activity in all eukaryotes ( Figure S1) [35]. Another unique sequence signature for Tyr-specific PTPs in plants, IHNT motif, also appears in the amino acid sequence of PdPTP1 ( Figure 1B) [36]. Taken together, the presence of these motifs clearly places the PdPTP1 within the Tyr-specific PTPs family.…”

OsPFA-DSP1, a rice protein tyrosine phosphatase, negatively regulates drought stress responses in transgenic tobacco and rice plants

“…The recombinant AtPTP1 protein can be reversibly inactivated by hydrogen peroxide (H 2 O 2 ), suggesting that AtPTP1 may be a major target for oxidative stress in plants (Gupta and Luan 2003). In Phalaenopsis amabilis, the classical PTP gene, PaPTP1, was isolated and implicated to play a role in response to wounding (Fu et al 2011). In wheat, TMKP1 is induced in the sensitive durum wheat variety Mahmoudi and repressed in the tolerant variety Om Rabia3 under salt and osmotic stresses, suggesting that it may play an active role in modulating plant cell responses to these conditions (Zaidi et al 2010).…”

Functional characterization of DnSIZ1, a SIZ/PIAS-type SUMO E3 ligase from Dendrobium

“…To investigate temperature tolerance, normally cultured Dendrobium seedlings were placed at 4 °C for the cold treatment or 37 °C for the heat shock treatment for 3, 6, 12 or 24 h, while for the high temperature treatment seedlings were placed at 45 °C for 1, 2, 4 or 6 h. The wounding treatment involved slicing off the 1 cm leaf apex with a sterile razor blade: the area 1 cm from the excised site was defined as W1 and regions at sequential 1 cm intervals adjacent to W1 were defined as W2, W3, and W4, respectively. The wound-treated plants were placed in the growth chamber, and leaf samples were collected after 48 h [ 78 ]. After all treatments, plant materials were immediately frozen in liquid N 2 and stored at -80 °C until needed for RNA extraction.…”