Os01g0919900

Gene Os01g0919900,namely OsSSI2,meaning fatty-acid desaturase gene, is involved in the negative regulation of defense responses in rice, as are itsArabidopsis and soybean counterparts.

Annotated Information

Function

Fatty acids and their derivatives play important signaling roles in plant defense responses. It has been shown that suppressing a gene for stearoyl acyl carrier protein fatty-acid desaturase (SACPD) enhances the resistance of Arabidopsis (SSI2) and soybean to multiple pathogens. we present functional analyses of a rice homolog of SSI2(OsSSI2) in disease resistance of rice plants.[1]

Expression

A transposon insertion mutation (Osssi2-Tos17) and RNAi-mediated knockdown of OsSSI2 (OsSSI2-kd) reduced the oleic acid (18:1) level and increased that of stearic acid (18:0), indicating that OsSSI2 is responsible for fatty-acid desaturase activity. These plants displayed spontaneous lesion formation in leaf blades, retarded growth, slight increase in endogenous free salicylic acid (SA) levels, and SA/benzothiadiazole (BTH)-specific inducible genes, includingWRKY45, a key regulator of SA/BTH-induced resistance, in rice. Moreover, the OsSSI2-kd plants showed markedly enhanced resistance to the blast fungus Magnaporthe grisea and leaf-blight bacteria Xanthomonas oryzae pv. oryzae. These results suggest that OsSSI2 is involved in the negative regulation of defense responses in rice, as are itsArabidopsis and soybean counterparts. [1]

Evolution

Microarray analyses identified 406 genes that were differentially expressed (≥2-fold) in OsSSI2-kd rice plants compared with wild-type rice and, of these, approximately 39% were BTH responsive. Taken together, our results suggest that induction of SA-responsive genes, including WRKY45, is likely responsible for enhanced disease resistance in OsSSI2-kd rice plants.[1]

Fig. 1. Phylogenetic tree of stearoyl acyl carrier protein (ACP) fatty-acid desaturase (SACPD) family proteins in rice, Arabidopsis, and soybean. The protein sequences were aligned with Clustal-X software and the tree was constructed using TreeView software. The Rice Annotation Project (RAP) codes and the Arabidopsis Genome Initiative (AGI) codes are shown in the figure. The GenBank accession numbers for soybean proteins are as follows: GmSACPD-A, AAX86050; GmSACPD-B, AAX86049; and GmSACPD-C, ABM45911.

Fig. 2. Growth phenotypes of the wild-type (WT), Osssi2-Tos17 (NF7039), and OsSSI2-knockdown (kd) plants. The plants were grown for 4 months in the greenhouse. The insets show spontaneous lesion formation on the leaf blades of Osssi2-Tos17 (NF7039) and OsSSI2-kd plants.

Fig. 3. RNA blot analysis. Transcripts of OsSSI2, two OsSSI2 homologs, WRKY45, and PR1b were analyzed in wild-type (WT) and OsSSI2 mutant plants. OsSSI2 transcripts were not detected in homozygous Osssi2-Tos17 (NF7039) and OsSSI2-knockdown (kd) plants, whereas the expression of the two closest homologs of OsSSI2 (i.e., Os04g0379900 and Os01g0880800) was unaffected in these plants. The arrow indicates a band of fusion transcripts encoding OsSSI2 with the Tos17 insertion. The salicylic acid/benzothiadiazole-induced gene WRKY45 and the pathogenesis-related gene OsPR1b were constitutively expressed in the NF7039 and OsSSI2-kd plants. Leaf blades from the fourth leaves of seedlings were used.

Fig. 4. Restoration of the expression of WRKY45 and PR1b after 18:1- application. Segments of leaf blades from seedlings of wild-type (WT), homozygous Osssi2-Tos17 (NF7039), and OsSSI2-knockdown (kd) plants were incubated in mock, solution containing 18:0, or solution containing 18:1 under light for 12 h at 30°C. Transcripts of WRKY45 and PR1b were analyzed by quantitative reverse-transcription polymerase chain reaction. Averages of three determinations relative to those of Rubq1 are shown with standard deviations (SD).

Fig. 5. Enhanced disease resistance in OsSSI2-knockdown (kd) plants. Wild-type (WT) and OsSSI2-kd plants were inoculated with A, the rice blast fungus Magnaporthe grisea and B, blight bacteria Xanthomonas oryzae pv. oryzae. Numbers on the y axes of the graph indicate A, the number of fungal blast lesions per 10-cm middle region of leaf blades and B, the lesion lengths of bacterial leaf blight. Each value represents the average of 15 to 20 plants. The bars indicate standard deviations (SD).

Fig. 6. Defense response induced by glycerol application. The seedlings of wild-type rice plants were sprayed with mock or glycerol (Gly). A, Induction of WRKY45 and PR1b expression by glycerol application. Transcript levels were analyzed by quantitative reverse-transcription polymerase chain reaction. Averages of three determinations relative to those of Rubq1 are shown with standard deviations (SD). B, Enhanced resistance to blast fungus Magnaporthe grisea (shown on left axis) and blight bacteria Xanthomonas oryzae pv. oryzae (shown on right axis) after glycerol application. The values on the y axes of the graph indicate A, the number of fungal blast lesions per 10-cm middle region of leaf blades and B, the lesion lengths of bacterial leaf blight. Each value represents the average of 15 to 20 plants.

Fig. 7. Proposed model for the functioning of OsSSI2 in the rice defense pathway. OsSSI2 negatively regulates the defense responses in rice partly through suppressing salicylic acid (SA)-responsive genes. OsSSI2 is also likely to regulate an SA-independent defense signaling pathway mediated by an unknown factor (X).

Table 1. Fatty acid (FA) composition in leavesa

Table 2. Salicylic acid contentsa

Table 3. Summary of microarray data for representative genes upregulated in OsSSI2-kd plantsa

Labs working on this gene

• Plant Disease Resistance Research Unit, Division of Plant Science, National Institute of Agrobiological Sciences,Kannondai 2-1-2, Tsukuba, 305-8602 Japan
• College of Agriculture, Ibaraki University, Ami 300-0393, Japan

References

Please input cited references here.

Structured Information

Gene Name	Os01g0919900
Description	Similar to Acyl-[acyl-carrier-protein] desaturase, chloroplast precursor (EC 1.14.19.2) (Stearoyl-ACP desaturase) (Delta(9) stearoyl-acyl carrier protein desaturase)
Version	NM_001051750.1 GI:115441870 GeneID:4327738
Length	3991 bp
Definition	Oryza sativa Japonica Group Os01g0919900, complete gene.
Source	Oryza sativa Japonica Group ORGANISM Oryza sativa Japonica Group Eukaryota; Viridiplantae; Streptophyta; Embryophyta; Tracheophyta; Spermatophyta; Magnoliophyta; Liliopsida; Poales; Poaceae; BEP clade; Ehrhartoideae; Oryzeae; Oryza.
Chromosome	Chromosome 1
Location	Chromosome 1:41902665..41906655
Sequence Coding Region	41902993..41903553,41903893..41904391,41906418..41906560
Expression	GEO Profiles:Os01g0919900
Genome Context	<gbrowseImage1> name=NC_008394:41902665..41906655 source=RiceChromosome01 preset=GeneLocation </gbrowseImage1>
Gene Structure	<gbrowseImage2> name=NC_008394:41902665..41906655 source=RiceChromosome01 preset=GeneLocation </gbrowseImage2>
Coding Sequence	<cdnaseq>atggcgtcgaggatggcgctccggcccaacgacgtcacgctccgcctcaccccgcccctcgccgccgccgcgcggcgcaaccgccgcgccgccgccggcggtgtcagggtctacgccgtcgcgtccggggccgtctccaccaaggttgagaacaagaagccatttgctcctccacgagaggtgcacgtccaggttacacattccatgccaccccagaagattgaaatattcaagtctcttgatgattgggccagagataatattttgtcccaccttaagcctgtcgagaaatgttggcaaccacaggattttcttcctgatccagcctcagatgggtttcatgatgaagtcaaagaacttagagaacgtgccaaggaaattcctgatgattattttgtttgtttggttggagacatgattacggaggaagctcttcctacgtaccagactatgcttaacactctcgatggtgtccgagatgaaacaggtgcaagccccactgcctgggctgtttggacaagggcatggactgctgaggagaacaggcatggtgacctcctgaacaaatatctctacctcactggtagggtggacatgagacaaattgagaagacaattcagtatcttattggctctggaatggaccctaggacagagaacaatccttatcttggattcatctacacctccttccaagagcgtgcgaccttcatctcacatgggaacactgctcgccatgccaaagactttggcgacctaaaacttgcacagatctgtggcatcatcgcctcagatgagaagcgtcatgagactgcatacaccaagattgttgagaagctgtttgagattgaccctgatggcactgtgcttgcttttgctgacatgatgaagaagaagatctcgatgcctgcccacctgatgttcgatggggaggatgataagctctttgagcacttctccatggttgcacagaggcttggtgtttacaccgccaaggactacgccgacatccttgagttcctcgttagcaggtggaagatatctgacctgactggcctatctagcgagggaaacaaggcgcaagactacctttgcacccttgctgctaggatcagaaggctggatgagagggcacaatcgagagccaagaaagctggtacattgcctttcagctgggtatatggtagggaagttcaactctga</cdnaseq>
Protein Sequence	<aaseq>MASRMALRPNDVTLRLTPPLAAAARRNRRAAAGGVRVYAVASGA VSTKVENKKPFAPPREVHVQVTHSMPPQKIEIFKSLDDWARDNILSHLKPVEKCWQPQ DFLPDPASDGFHDEVKELRERAKEIPDDYFVCLVGDMITEEALPTYQTMLNTLDGVRD ETGASPTAWAVWTRAWTAEENRHGDLLNKYLYLTGRVDMRQIEKTIQYLIGSGMDPRT ENNPYLGFIYTSFQERATFISHGNTARHAKDFGDLKLAQICGIIASDEKRHETAYTKI VEKLFEIDPDGTVLAFADMMKKKISMPAHLMFDGEDDKLFEHFSMVAQRLGVYTAKDY ADILEFLVSRWKISDLTGLSSEGNKAQDYLCTLAARIRRLDERAQSRAKKAGTLPFSW VYGREVQL</aaseq>
Gene Sequence	<dnaseqindica>3103..3663#2265..2763#96..238#acacccccatcccctctctccgcgcctcgcctcgccacccgcatcgccatctcgcaccgccacctcctccactctcggcggcgggggcctcatcgatggcgtcgaggatggcgctccggcccaacgacgtcacgctccgcctcaccccgcccctcgccgccgccgcgcggcgcaaccgccgcgccgccgccggcggtgtcagggtctacgccgtcgcgtccggggccgtctccaccaagtaagctcgcccccgctccgctcgccactctcctctaatccctctctatcgacctcgtcgcgttcgggattggttccccgtgtgttgggttgggttcgatgcatcggtttgctctgggcgacgcctcgccgccgctgcgtagggatttccggtgcacctgtccccggattggcgcggcgattcggggttcgtcgacgttgcggcatgaatgcgtgtctctcttacccaggattcggtttttcttctcttcgttttgcttgcctcgtctgggttttgtctcaaattctgcgccgtctccgttcctcgtcgccggctttggcaccggtgccaggaatcgtgagattcatcctcgtccgtgtcgcgcgctctccctacgcgcatggccgctgcatctcgccgctgcctcagatcaggctgcaaagatttgcagcttcgccgttcaatcattcgtgcagcatacagtaggtcggtttcactgtatgaactggcgacctgctccaccacggcttctccgttgcaagcaaagtgaagctactagctcgagttagtccctttcacattcatttttgacgccgcatttcaccggcattaaatttgctgggaccttcataccttcaagcttgtactctggaaccatactctccattaatatatcgctgtactgcacaaggaaaatcggtggtacacaacagtatcgatttgaagaacctctttaggggggcttccatggggactccaaggcgttcctatcgttgtcagcccgatttggtggcccgtggtccacagcatggtgatgttgctcgcagtgtcatggaatttaatttgatttgttcttcgcttgttagtaccactggactcctaggtagagatgctttatggcagctcagtgtcgctgacctgtttagttgacgggttctagagtcatttaatacagtatggcattggaaggaggttggttgtgtcctatcctaggcatggcactgaaatggaatcacctccatactccacccctgtcctgggtttcttgatcggattatttgctccatttctctataaaaatgtatttgctcggagtatttatttagtattgttccattttctgatatttacaaactgataccctggaaatcagattgtttttctgagagggtggatatcatagttactgcttaaaccttacccaaagttaaatttttctagttacttccagtagttaaactggcatgaatgcaagatggcagatttgactgcttggtccaattagttccacctggctgatcttatttctatttctgcacaccctgctgcagcaaaaattgtgttccccccagagatgctgcccatgcccagctacagtgatatgcagggcttccaggctaaaacgcgcaggaaagacatccttgctgtatatcaggatttctttagcctatgcattaatacgttcagtatggggagatcctcgcaccataatttatagagcatggcatgtgactgtagtgtggacaaggtcaatgatattagctagtagtactaacctaactgcattttcgctttgtctacctgatgaactctagagaggccaagaagctaaagcttattgcacacttcagttgttgtgcataatctaccgttttgtcaaaagaacagtccaaccataactgatttaattttaaccttaagggaaaaaaatattaggatgaccatcaaactagtacgattagtcttctttatcttgacaaagctgaatggaaaccgtacaggtcaccattctaagcatacctatacatatattttacaactcaggtgtaatctgtttcttttcttttctttgggagggtgttgcttttaacagtgtcccatcagtgtccctcttgtcaaagtttaaccttgtaaatttgtaaatactccctaaattaatgaaatttggccggcctagtctttggccagcctggcaaatgcctaaagctagaggtatattcatcatgtgtctggtagttgctgaaagtttgtttaatttttgtatcagggttgagaacaagaagccatttgctcctccacgagaggtgcacgtccaggttacacattccatgccaccccagaagattgaaatattcaagtctcttgatgattgggccagagataatattttgtcccaccttaagcctgtcgagaaatgttggcaaccacaggattttcttcctgatccagcctcagatgggtttcatgatgaagtcaaagaacttagagaacgtgccaaggaaattcctgatgattattttgtttgtttggttggagacatgattacggaggaagctcttcctacgtaccagactatgcttaacactctcgatggtgtccgagatgaaacaggtgcaagccccactgcctgggctgtttggacaagggcatggactgctgaggagaacaggcatggtgacctcctgaacaaatatctctacctcactggtagggtggacatgagacaaattgagaagacaattcagtatcttattggctctggaatggtaacagttttcttccgcttctttgctagcctagctatatttaactgattattttgaaattgtcattcatgagtttttccctcaagcaattgttttcctcactggctagcgtatattagcatgatgtttttgaaaaactcttttgagttttgaggaagctagtaactccactaactacatactttaggaataacttttacctggcattatcaattttctaattttttagtcttatgttcttttgctctgttctattctgttctgttcacattggactgtttaagtggcaattgagcagagaaatctgtagcacttactcttttgctgcatcatttccaggaccctaggacagagaacaatccttatcttggattcatctacacctccttccaagagcgtgcgaccttcatctcacatgggaacactgctcgccatgccaaagactttggcgacctaaaacttgcacagatctgtggcatcatcgcctcagatgagaagcgtcatgagactgcatacaccaagattgttgagaagctgtttgagattgaccctgatggcactgtgcttgcttttgctgacatgatgaagaagaagatctcgatgcctgcccacctgatgttcgatggggaggatgataagctctttgagcacttctccatggttgcacagaggcttggtgtttacaccgccaaggactacgccgacatccttgagttcctcgttagcaggtggaagatatctgacctgactggcctatctagcgagggaaacaaggcgcaagactacctttgcacccttgctgctaggatcagaaggctggatgagagggcacaatcgagagccaagaaagctggtacattgcctttcagctgggtatatggtagggaagttcaactctgagcatcagacgccattgcgacttcttcgagctccagtgttactactgtccgtgcttgtcgagacacattttgagaacaataccaggtgtgtcttgctacatagttcttcaggttgaccaaatgaactgagggcatatgttcgtggtatctttgcttagagtgatagagagatttgcgtctgtgttttagctctttttttcttttctgccttttcatgtacaacttctggccgtgtggattggacatgtactgaacgtgagtctgtcgttggccgtgtcaatctgctcgtgtgtttaaactggctgctgttcaggtctgaaaattttgtg</dnaseqindica>
External Link(s)	NCBI Gene:Os01g0919900, RefSeq:Os01g0919900