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Kageyama H.,Meijo University | Tripathi K.,Banaras Hindu University | Rai A.K.,Banaras Hindu University | Cha-Um S.,Plant Physiology and Biochemistry Laboratory | And 2 more authors.
Applied and Environmental Microbiology

Alkaline phosphatases (APases) are important enzymes in organophosphate utilization. Three prokaryotic APase gene families, PhoA, PhoX, and PhoD, are known; however, their functional characterization in cyanobacteria largely remains to be clarified. In this study, we cloned the phoD gene from a halotolerant cyanobacterium, Aphanothece halophytica (phoD Ap). The deduced protein, PhoD Ap, contains Tat consensus motifs and a peptidase cleavage site at the N terminus. The PhoD Ap enzyme was activated by Ca 2+ and exhibited APase and phosphodiesterase (APDase) activities. Subcellular localization experiments revealed the secretion and processing of PhoD Ap in a transformed cyanobacterium. Expression of the phoD Ap gene in A. halophytica cells was upregulated not only by phosphorus (P) starvation but also under salt stress conditions. Our results suggest that A. halophytica cells possess a PhoD that participates in the assimilation of P under salinity stress. © 2011, American Society for Microbiology. Source

Tsutsumi K.,Meijo University | Yamada N.,Meijo University | Yamada N.,Plant Physiology and Biochemistry Laboratory | Cha-um S.,Plant Physiology and Biochemistry Laboratory | And 2 more authors.
Journal of Plant Physiology

Atriplex gmelini is a halophyte and possesses bladder hairs on the leaf surface. It is also known to accumulate the osmoprotectant glycinebetaine (GB). However, it remains unclear whether GB and its biosynthetic enzyme choline monooxygenase (CMO) accumulate in the bladder hairs. Microscopic observation of young leaves showed many bladder hairs on their surfaces, but their total number decreased along with leaf maturity. Sodium Green fluorescent approach revealed Na+ accumulation in bladder cells of young leaves when A. gmelini was grown at high salinity (250mM NaCl). Due to fewer bladder hairs in mature leaves, Na+ accumulation was mostly found in mesophyll cells of mature leaves under high salinity. GB accumulation was found at significant level in both bladder- and laminae-cells without any addition of NaCl and its content increased at high salinity. CMO was not found in bladder hairs or young leaf laminae. Instead, the CMO protein expression was observed in mature leaves and that showed increased accumulation with increasing concentration of NaCl. Furthermore, in situ hybridization experiments revealed the expression of a transporter gene for GB, AgBetT, in the bladder hairs. Based on these results, the synthesis and translocation of GB in A. gmelini were discussed. © 2014 Elsevier GmbH. Source

Yamada N.,Plant Physiology and Biochemistry Laboratory | Theerawitaya C.,Plant Physiology and Biochemistry Laboratory | Kageyama H.,Meijo University | Cha-um S.,Plant Physiology and Biochemistry Laboratory | Takabe T.,Meijo University

The cytoplasmic free Ca2+ could play an important role for salt tolerance in rice root (Oryza sativa L.). Here, we compared the expression profiles of two putative developmentally regulated plasma membrane polypeptides (DREPP1 and DREPP2) in rice roots of salt-tolerant cv. Pokkali and salt-sensitive cv. IR29. The messenger RNA (mRNA) for OsDREPP1 could be detected in all parts of root and did not change upon salt stress, whereas the mRNA for OsDREPP2 was detected only in root tips. The transcript level of OsDREPP2 first disappeared upon salt stress, then recovered in Pokkali, but not recovered in IR29. The gene-encoding OsDREPP2 was cloned from cv. Pokkali and expressed in Escherichia coli, and its biochemical properties were studied. It was found that OsDREPP2 is a Ca2+-binding protein and binds also to calmodulin (CaM) as well as microtubules. The mutation of Trp4 and Phe16 in OsDREPP2 to Ala decreased the binding of DREPP2 to Ca2+/CaM complex, indicating the N-terminal basic domain is involved for the binding. The binding of OsDREPP2 to microtubules was inhibited by Ca2+/CaM complex, while the binding of double-mutant OsDREPP2 protein to microtubules was not inhibited by Ca2+/CaM complex. We propose that CaM inhibits the binding of DREPP2 to cortical microtubules, causes the inhibition of microtubule depolymerization, and enhances the cell elongation. © 2015, Springer-Verlag Wien. Source

Yamada N.,Meijo University | Cha-Um S.,Plant Physiology and Biochemistry Laboratory | Kageyama H.,Meijo University | Promden W.,Meijo University | And 3 more authors.
Tree Physiology

Oil production from oil palm is adversely affected by drought and salt. Under drought and salt stress, proline content increases in oil palm; the mechanism for this is unknown. Here, an 8319-nucleotide sequence including cDNA, genomic DNA and the promoter region of proline transporter gene from oil palm Elaeis guineensis was determined. The transporter gene exhibited high similarity to Bet/ProT genes from several plants, but the highest homology was found with rice ProT1. The exon-intron structure of genomic DNA was unique, and numerous stress-response cis-elements were found in the promoter region. Expression of cDNA EgProT1 in Escherichia coli mutant exhibited uptake activities for glycinebetaine and choline as well as proline. Under salt-stressed conditions, exogenously applied glycinebetaine was taken up into the root more rapidly than the control. These data indicate that oil palm has a unique Pro/T1 gene. Nucleotide sequence data for the cDNA and genomic DNA of proline transporter gene from Elaeis guineensis are available in the DDJB database under accession numbers AB597035 and AB597036, respectively. © 2011 The Author. Source

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