ABSTRACT
Two Arabidopsis thaliana genes, psr9.2 and psr 9.4 appeared to be highly similar to a phosphate-starved induced gene, psr9, isolated from Brassica nigra suspension cells. Sequence analysis classified the encoded polypeptides as members of leucine-rich repeat [LRR] proteins superfamily. The sequence of psr9 proteins comprise a unique N-terminal region encompassing a coiled-coil structure proceeding eleven LRRs along the C-terminal. Expression pattern analysis showed the responsiveness of these genes to various environmental conditions. Although both psr9 genes, psr9.2 and psr9.4, are expressed throughout the plant, the expression of psr9.2 was higher in the root whereas psr9.4 expression was prominent in the shoot. The expression levels were increased proportional to the duration of phosphate deprivation treatment. Plants exposed to cold temperature expressed both genes at high levels in both roots and shoots. In contrast, heat shock increased the expression levels of both genes in the shoots while reducing it in roots. High-salt treatment upregulated the expression of psr9 genes only in the roots. These data may suggest distinct roles for psr9 genes during plant response to various environmental conditions