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The BIG gene is involved in regulation of sulfur deficiency‐responsive genes in Arabidopsis thaliana
Author(s) -
Kasajima Ichiro,
OhkamaOhtsu Naoko,
Ide Yoko,
Hayashi Hiroaki,
Yoneyama Tadakatsu,
Suzuki Yoshihito,
Naito Satoshi,
Fujiwara Toru
Publication year - 2007
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.2006.00814.x
Subject(s) - mutant , gene , biology , microbiology and biotechnology , arabidopsis thaliana , arabidopsis , green fluorescent protein , locus (genetics) , genetics , gene expression , nonsense mutation , mutation , missense mutation
The Arabidopsis thaliana mutants altered sulfur response 1‐1 ( asr1‐1 ) and asr1‐2 were isolated using the green fluorescent protein gene ( GFP ), as a marker, driven by a sulfur deficiency‐responsive promoter containing the β SR fragment, which is responsible for the induction of gene expression under sulfur deficiency. In the asr1 mutants, the expression of three sulfur deficiency‐responsive genes β SR ‐driven GFP , sulfate transporter 2;2 ( SULTR2;2 ) and adenosine‐5′‐phosphosulfate reductase 1 ( APR1 ) were induced in medium containing a normal sulfate concentration. The ASR1 locus was mapped to a 53‐kb region on the upper arm of chromosome III; this is also the region of the BIG gene, which encodes a calossin‐like protein necessary for the polar transport of auxin. The morphology of the asr1 mutants, i.e. reduced leaf size and inflorescence elongation, resembled that of big mutants. Using nucleotide sequence analysis of the BIG gene, we identified independent nonsense mutations in asr1‐1 and asr1‐2 . To confirm that ASR1 was BIG , we established lines of transgenic A. thaliana carrying a transfer DNA (T‐DNA) insertion in the BIG gene. In these T‐DNA insertion mutants, mRNA levels of β SR ‐driven GFP and APR1 were upregulated in normal sulfate medium. The F 1 plants from crosses between asr1‐1 and T‐DNA insertion lines exhibited reduced leaf size and inflorescence length, indicating that ASR1 was indeed BIG . Taken together, the present results established that BIG is involved in the regulation of β SR ‐driven GFP and APR1 mRNA level gene expression. Indole‐3‐acetic acid also upregulated β SR ‐driven GFP and APR1 together with SULTR2;2 mRNA level, suggesting that the big effect on β SR ‐driven GFP and APR1 is a pleiotropic aspect of the BIG gene.