Comparative genomics in salt tolerance between Arabidopsis and aRabidopsis-related halophyte salt cress using Arabidopsis microarray.
Salt cress (Thellungiella halophila), a halophyte, is a genetic model system with a small plant size, short life cycle, copious seed production, small genome size, and an efficient transformation. Its genes have a high sequence identity (90%-95% at cDNA level) to genes of its close relative, Arabidopsis. These qualities are advantageous not only in genetics but also in genomics, such as gene expression profiling using Arabidopsis cDNA microarrays. Although salt cress plants are salt tolerant and can grow in 500 mm NaCl medium, they do not have salt glands or other morphological alterations either before or after salt adaptation. This suggests that the salt tolerance in salt cress results from mechanisms that are similar to those operating in glycophytes. To elucidate the differences in the regulation of salt tolerance between salt cress and Arabidopsis, we analyzed the gene expression profiles in salt cress by using a full-length Arabidopsis cDNA microarray. In salt cress, only a few genes were induced by 250 mm NaCl stress in contrast to Arabidopsis. Notably a large number of known abiotic- and biotic-stress inducible genes, including Fe-SOD, P5CS, PDF1.2, AtNCED, P-protein, beta-glucosidase, and SOS1, were expressed in salt cress at high levels even in the absence of stress. Under normal growing conditions, salt cress accumulated Pro at much higher levels than did Arabidopsis, and this corresponded to a higher expression of AtP5CS in salt cress, a key enzyme of Pro biosynthesis. Furthermore, salt cress was more tolerant to oxidative stress than Arabidopsis. Stress tolerance of salt cress may be due to constitutive overexpression of many genes that function in stress tolerance and that are stress inducible in Arabidopsis.
Taji
Teruaki
T
Laboratory of Plant Molecular Biology, RIKEN Tsukuba Institute, Tsukuba, Ibaraki 305-0074, Japan.
Seki
Motoaki
M
Satou
Masakazu
M
Sakurai
Tetsuya
T
Kobayashi
Masatomo
M
Ishiyama
Kanako
K
Narusaka
Yoshihiro
Y
Narusaka
Mari
M
Zhu
Jian-Kang
JK
Shinozaki
Kazuo
K
D000040:Abscisic Acid / Q000378:metabolism; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics*; D029681:Arabidopsis Proteins / Q000235:genetics; D019607:Brassicaceae / Q000187:drug effects / Q000235:genetics*; D018506:Gene Expression Regulation, Plant / Q000235:genetics; D018745:Genome, Plant; D023281:Genomics; D018527:Hydroponics; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods; D010940:Plant Proteins / Q000235:genetics; D011392:Proline / Q000378:metabolism; D012964:Sodium / Q000378:metabolism; D012965:Sodium Chloride / Q000494:pharmacology*; D013045:Species Specificity
D029681:Arabidopsis Proteins; D010940:Plant Proteins; D012965:Sodium Chloride; D000040:Abscisic Acid; D011392:Proline; D012964:Sodium