title: Comparative genomics in salt tolerance between Arabidopsis and aRabidopsis-related halophyte salt cress using Arabidopsis microarray.
abstract: 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.
authors.affiliation: Laboratory of Plant Molecular Biology, RIKEN Tsukuba Institute, Tsukuba, Ibaraki 305-0074, Japan.
authors.forename: Teruaki
authors.initials: T
authors.lastname: Taji
authors.forename: Motoaki
authors.initials: M
authors.lastname: Seki
authors.forename: Masakazu
authors.initials: M
authors.lastname: Satou
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Sakurai
authors.forename: Masatomo
authors.initials: M
authors.lastname: Kobayashi
authors.forename: Kanako
authors.initials: K
authors.lastname: Ishiyama
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Narusaka
authors.forename: Mari
authors.initials: M
authors.lastname: Narusaka
authors.forename: Jian-Kang
authors.initials: JK
authors.lastname: Zhu
authors.forename: Kazuo
authors.initials: K
authors.lastname: Shinozaki
mesh_terms: 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
chemical_list: D029681:Arabidopsis Proteins; D010940:Plant Proteins; D012965:Sodium Chloride; D000040:Abscisic Acid; D011392:Proline; D012964:Sodium