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Phosphate-induced-1 (PHI-1) and phosphate-induced-1-like family genes respond to plant hormones such as abscisic acid (ABA), BR (brassinosteroid) and ethylene. To date, very few researches have been done on abiotic stress for PHI-1 genes. In this work, we report 12 rice PHI-1 genes through genome-wide analysis. The 12 OsPHI-1 genes were tandemly arranged into two clusters and nine conserved motifs were found among their amino acid sequences. Microarray data indicated that all the OsPHI-1 genes exhibited identical expression level but different expression patterns: most OsPHI-1 genes were expressed intensively in panicle development and responded to IAA and BAP treatments; several OsPHI-1 genes responded to trans-zeatin (tZ) and dimethyl sulfoxide (DMSO) treatments; 11 OsPHI-1 genes showed response to abiotic stress. Furthermore, the promoter region analysis showed that all the OsPHI-1 genes contained cis-regulatory elements responding to abiotic stresses. Our study will be helpful to further investigate the biological functions of PHI-1 genes in rice.

To better understand the mechanisms of plant abiotic stress responses and identify novel stress-related genes in rice, we performed global expression analysis in indica rice Pei'ai 64S under multiple stresses. Among numerous genes, a gene named OsTHIC was selected, which was highly induced in leaves and panicles in response to all stresses at different developmental stages, especially at the booting stage under cold stress. OsTHIC contains an open reading frame (ORF) of 1920 bp and encodes a predicted protein with 639 amino acid residues. The molecular weight and isoelectric point were predicted to be about 71.31 kD and 6.41, respectively. The results of quantitative real-time polymerase chain reaction (qRT-PCR) analysis were almost identical to those from the GeneChip Rice Genome Array. The sequence alignment showed about 99% similarity to rice phosphate methylpyrimidine synthase. Promoter sequence analysis showed that various stress response-related cis-elements were contained in the promoter region. All the results suggested that OsTHIC may be involved in rice stress responses.

Cold has a major impact on rice, so rice can only grow in specific climate zones. TMP14 (thylakoid membrane protein of 14 kDa) is a nuclear genome-encoded chloroplast thylakoid membrane protein, which is involved in a wide range of abiotic stress responses. However, the knowledge of TMP14 roles in response to adverse stimuli is still very limited in rice. Based on the results of expression profiles, OsTMP14 (GenBank accession: BAF27084.1) was highly induced in both leaf and panicle at all the developmental stages of rice analyses under cold and drought stresses. Sequence analyses of OsTMP14 putative promoter regions identified nine cis-elements related to stress responses. Furthermore, transgenic rice plants with overexpression of OsTMP14 showed more tolerance to cold stress. Taken together, these results indicate that OsTMP14 is involved in stress tolerance in rice, which is useful in developing transgenic rice with enhancing tolerance to cold stress.