Expression analysis of a novel pyridoxal kinase messenger RNA splice variant, PKL, in oil rape suffering abiotic stress and phytohormones

Authors

  • Shunwu Yu,

    1. Shanghai Agrobiological Gene Center, Shanghai Academy of Agricultural Sciences, Germsperm Resources Division (Shanghai), National Key Laboratory of Crop Genetic Improvement, Shanghai 201106, China
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  • Lijun Luo

    Corresponding author
    1. Shanghai Agrobiological Gene Center, Shanghai Academy of Agricultural Sciences, Germsperm Resources Division (Shanghai), National Key Laboratory of Crop Genetic Improvement, Shanghai 201106, China
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  • This work was supported by the grants from the Shanghai Rising-Star Program (No. 06QA14045) and the China National High-Tech Program (863) (No. 2006AA02Z115)

*Corresponding author: Tel, 86-21-52230526; Fax, 86-21-62204010; E-mail, lijun@sagc.org.cn

Abstract

Pyridoxal kinase is key enzyme for the biosynthesis of pyridoxa 15′-phosphate, the biologically active form of vitamin B6, in the salvage pathway. A pyridoxal kinase gene, BnPKL (GenBank accession No. DQ 463962), was isolated from oilseed rape (Brassica napus L.) following water stress through rapid amplification of complementary DNA (cDNA) ends. The results showed that the gene had two splice variants: PKL and PKL2.PKL, the long cDNA, encodes a 334 amino acid protein with a complete ATP-binding site, pyridoxal kinase-binding site and dimer interface site of a pyridoxal kinase, while PKL2, the short cDNA, lacked a partial domain. Southern blot showed that there were two copies in Brassica napus. The expression of BnPKL cDNA could rescue the mutant phenotype of Escherichia coli defective in pyridoxal kinase. Real-time reverse transcription-polymerase chain reaction revealed that the relative abundance of two transcripts are modulated by development and environmental stresses. Abscisic acid and NaCl were inclined to decrease PKL expression, but H2O2 and cold temperatures induced the PKL expression. In addition, the PKL expression could be transiently induced by jasmonate acid at an early stage, abscisic acid, salicylic acid and jasmonate acid enhanced the PKL expression in roots. Our results de monstrated that BnPKL was a pyridoxal kinase involved in responses to biotic and abiotic stresses.

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