biologia plantarum

Biologia plantarum 2016, 60:482-488 | DOI: 10.1007/s10535-016-0625-3

Molecular cloning, expression, and subcellular localization of a PAL gene from Citrus reticulata under iron deficiency

H. Y. Yang¹, T. Dong², J. F. Li³, M. Y. Wang^1,*

¹ Department of Horticulture, Huaqiao University, Xiamen, P.R. China

² Institute of Fruit Tree Research, Guangdong Academy of Agricultural Sciences, Guangzhou, P.R. China

³ School of Agriculture and Biology, Shanghai Jiaotong University, Shanghai, P.R. China

Phenylalanine ammonia lyase (PAL) is a specific branch point enzyme of primary and secondary metabolism. The Citrus reticulata Blanco PAL gene was cloned and designated as CrPAL1. The cDNA sequence of CrPAL1 was 2 166 bp, encoding 721 amino acid residues. Sequence alignment indicates that CrPAL1 shared a high identity with PAL genes found in other plants. Both the dominant and catalytic active sites of CrPAL1 were similar to PAL proteins observed in Petroselinum crispum. Phylogenetic tree analysis indicates that CrPAL1 was more closely related to PALs in Citrus clementina × C. reticulata and Poncirus trifoliata than to those from other plants. Subcellular localization reveals that CrPAL1-green fluorescent protein fusion protein was specifically localized in the plasma membrane. Activity of PAL as well as CrPAL1 expression increased under Fe deficiency. A similar result was noted for total phenolic content. The root exudates of C. reticulata strongly promoted reutilization of apoplastic Fe in roots. Furthermore, Fe was more desorbed from the cell wall under Fe deficiency than in sufficient Fe supply.

Keywords: phenolics; phenylalanine ammonia lyase; root exudation

Subjects: gene expression; subcellular localization; phenylalanineammonia lyase; iron deficiency; phenolics; root exudation; phylogenetic tree

Species: Citrus reticulate

Received: September 3, 2015; Revised: December 9, 2015; Accepted: December 14, 2015; Published: September 1, 2016Show citation