J Integr Plant Biol. ›› 2005, Vol. 47 ›› Issue (2): 243-250.DOI: 10.1111/j.1744-7909.2005.00047.x

• Research Articles • Previous Articles    

Expression of Brassica napus L. g-Glutamylcysteine Synthetase and Low- and High-Affinity Sulfate Transporters in Response to Excess Cadmium

Xin SUN, Xue-Mei SUN, Zhi-Min YANG, Shao-Qiong LI, Jin WANG and Song-Hua WANG   

  • Published:2005-02-01

Abstract: In both the roots and leaves of Brassica napus L. cv. Youyan No. 8 under treatment with 30 μmol/L Cd, massive production of non‐protein thiols (NPT; mainly containing glutathione (GSH) and phytochelatins (PCs)) was induced, together with an increase in γ‐glutamylcysteine synthetase (γ‐ECS) mRNA transcripts. Because γ‐ECS is the key enzyme catalyzing the first step in GSH biosynthesis, which, in turn, is converted to PCs, the Cd‐induced increase in γ‐ECS expression may be responsible for the observed increase in the production of NPT. Using a quantitative reverse transcription polymerase chain reaction (RT‐PCR) approach, the expression of genes encoding a putative low‐affinity sulfate transporter (LAST) and a putative high‐affinity sulfate transporter (HAST) was determined at the transcriptional level. The RT‐PCR analysis of relative transcript amounts indicates that the LAST gene in B. napus leaves showed a constitutive expression, which was hardly affected by Cd treatment. However, treatment with 30 μmol/L Cd for 2 or 3 d induced a marked increase in the expression of LAST in roots. Transcriptional expression of the HAST gene occurred in roots, but not in leaves. The expression of HAST only in the roots suggests that it has a specific function in sulfate uptake from soil and that the putative LAST may be responsible for the transport of sulfate from the roots to the shoots, as well as for the uptake of sulfate from soil. These results indicate that changes in transcriptional expression for sulfate transporters were required for the increased demand for sulfate during Cd stress.

Key words: Brassica napus L., cadmium, g-glutamylcysteine synthetase, non-protein thiol, sulfate transporters.

Editorial Office, Journal of Integrative Plant Biology, Institute of Botany, CAS
No. 20 Nanxincun, Xiangshan, Beijing 100093, China
Tel: +86 10 6283 6133 Fax: +86 10 8259 2636 E-mail: jipb@ibcas.ac.cn
Copyright © 2022 by the Institute of Botany, the Chinese Academy of Sciences
Online ISSN: 1744-7909 Print ISSN: 1672-9072 CN: 11-5067/Q