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| Title: The small interfering RNA production pathway is required for shoot meristem initiation in rice .
| | Author: Nagasaki H Itoh J Hayashi K Hibara K Satoh-Nagasawa N Nosaka M Mukouhata M Ashikari M Kitano H Matsuoka M Nagato Y Sato Y | | Journal: Proc Natl Acad Sci U S A Citation: V : 104 P : 14867-71 Year: 2007 | | Literature: oryza Field: abstract Doc ID: pub17804793 Accession (PMID): 17804793 | | Abstract: The shoot apical meristem ( SAM ) is a group of stem cells that are responsible for plant development .
Mutations in rice SHOOTLESS2 ( SHL2 ) , SHL4/SHOOT ORGANIZATION2 ( SHO2 ) , and SHO1 cause complete deletion or abnormal formation of the SAM .
In this study we showed that defects in SAM formation in shl mutants are associated with the loss of expression of the homeodomain-leucine zipper ( HD-ZIPIII ) family genes .
Rice SHL2 , SHL4/SHO2 , and SHO1 encoded orthologues of Arabidopsis RNA-dependent RNA polymerase 6 , ARGONAUTE ( AGO ) 7 , and DICER-like 4 , respectively , whose mutations affect leaf development through the trans-acting siRNA ( ta-siRNA ) pathway .
This suggested that the ta-siRNA pathway regulates the critical step of SAM formation during rice embryogenesis .
The gain-of-function experiment by the ectopic expression of SHL4 resulted in reduced accumulation of an microRNA , miR166 , and partial adaxialization of leaves , supporting a role for the ta-siRNA pathway in the maintenance of leaf polarity as previously reported in maize .
Analysis of the spatiotemporal expression patterns of HD-ZIPIII and miR166 in wild-type and shl mutant embryos suggested that the loss of HD-ZIPIII expression in the SAM region of the developing embryo is the result of ectopic expression of miR166 .
Our analysis of shl mutants demonstrated that HD-ZIPIII expression regulated by miR166 is sensitive to the ta-siRNA pathway during SAM formation in rice embryogenesis .
| Matching Sentences:
[ Sen. 2, subscore: 1.00 ]: Mutations in rice SHOOTLESS2 ( SHL2 ) , SHL4/SHOOT ORGANIZATION2 ( SHO2 ) , and SHO1 cause complete deletion or abnormal formation of the SAM .
[ Sen. 4, subscore: 1.00 ]: Rice SHL2 , SHL4/SHO2 , and SHO1 encoded orthologues of Arabidopsis RNA-dependent RNA polymerase 6 , ARGONAUTE ( AGO ) 7 , and DICER-like 4 , respectively , whose mutations affect leaf development through the trans-acting siRNA ( ta-siRNA ) pathway .
| | Supplemental links/files: reference in endnote online text related articles pubmed citation | |
Score: 1.00 |
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| Title: Shoot organization genes regulate shoot apical meristem organization and the pattern of leaf primordium initiation in rice .
| | Author: Itoh JI Kitano H Matsuoka M Nagato Y | | Journal: Plant Cell Citation: V : 12 ( 11 ) P : 2161-74 Year: 2000 | | Literature: oryza Field: abstract Doc ID: pub11090216 Accession (PMID): 11090216 | | Abstract: The mechanism regulating the pattern of leaf initiation was analyzed by using shoot organization ( sho ) mutants derived from three loci ( SHO1 , SHO2 , and SHO3 ) .
In the early vegetative phase , sho mutants show an increased rate of leaf production with random phyllotaxy .
The resulting leaves are malformed , threadlike , or short and narrow .
Their shoot apical meristems are relatively low and wide , that is , flat shaped , although their shape and size are highly variable among plants of the same genotype .
Statistical analysis reveals that the shape of the shoot meristem rather than its size is closely correlated with the variations of plastochron and phyllotaxy .
Rapid and random leaf production in sho mutants is correlated with the frequent and disorganized cell divisions in the shoot meristem and with a reduction of expression domain of a rice homeobox gene , OSH1 .
These changes in the organization and behavior of the shoot apical meristems suggest that sho mutants have fewer indeterminate cells and more determinate cells than wild type , with many cells acting as leaf founder cells .
Thus , the SHO genes have an important role in maintaining the proper organization of the shoot apical meristem , which is essential for the normal initiation pattern of leaf primordia . | Matching Sentences:
[ Sen. 1, subscore: 1.00 ]: The mechanism regulating the pattern of leaf initiation was analyzed by using shoot organization ( sho ) mutants derived from three loci ( SHO1 , SHO2 , and SHO3 ) .
| | Supplemental links/files: reference in endnote online text related articles pubmed citation | |
Score: 1.00 |
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| Title: WAVY LEAF1 , an ortholog of Arabidopsis HEN1 , regulates shoot development by maintaining MicroRNA and trans-acting small interfering RNA accumulation in rice .
| | Author: Abe M Yoshikawa T Nosaka M Sakakibara H Sato Y Nagato Y Itoh J | | Journal: Plant Physiol Citation: V : 154 P : 1335-46 Year: 2010 | | Literature: oryza Field: abstract Doc ID: pub20805329 Accession (PMID): 20805329 | | Abstract: In rice ( Oryza sativa ) , trans-acting small interfering RNA ( ta-siRNA ) is essential for shoot development , including shoot apical meristem ( SAM ) formation and leaf morphogenesis .
The rice wavy leaf1 ( waf1 ) mutant has been identified as an embryonic mutant resembling shoot organization1 ( sho1 ) and sho2 , homologs of a loss-of-function mutant of DICER-LIKE4 and a hypomorphic mutant of ARGONAUTE7 , respectively , which both act in the ta-siRNA production pathway .
About half of the waf1 mutants showed seedling lethality due to defects in SAM maintenance , but the rest survived to the reproductive phase and exhibited pleiotropic phenotypes in leaf morphology and floral development .
Map-based cloning of WAF1 revealed that it encodes an RNA methyltransferase , a homolog of Arabidopsis ( Arabidopsis thaliana ) HUA ENHANCER1 .
The reduced accumulation of small RNAs in waf1 indicated that the stability of the small RNA was decreased .
Despite the greatly reduced level of microRNAs and ta-siRNA , microarray and reverse transcription-polymerase chain reaction experiments revealed that the expression levels of their target genes were not always enhanced .
A double mutant between sho and waf1 showed an enhanced SAM defect , suggesting that the amount and/or quality of ta-siRNA is crucial for SAM maintenance .
Our results indicate that stabilization of small RNAs by WAF1 is indispensable for rice development , especially for SAM maintenance and leaf morphogenesis governed by the ta-siRNA pathway .
In addition , the inconsistent relationship between the amount of small RNAs and the level of the target mRNA in waf1 suggest that there is a complex regulatory mechanism that modifies the effects of microRNA/ta-siRNA on the expression of the target gene .
| Matching Sentences:
[ Sen. 2, subscore: 1.00 ]: The rice wavy leaf1 ( waf1 ) mutant has been identified as an embryonic mutant resembling shoot organization1 ( sho1 ) and sho2 , homologs of a loss-of-function mutant of DICER-LIKE4 and a hypomorphic mutant of ARGONAUTE7 , respectively , which both act in the ta-siRNA production pathway .
| | Supplemental links/files: reference in endnote online text related articles pubmed citation | |
Score: 1.00 |
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| Title: Multiple plant surface signals are sensed by different mechanisms in the rice blast fungus for appressorium formation .
| | Author: Liu W Zhou X Li G Li L Kong L Wang C Zhang H Xu JR | | Journal: PLoS Pathog Citation: V : 7 P : e1001261 Year: 2011 | | Literature: oryza Field: abstract Doc ID: pub21283781 Accession (PMID): 21283781 | | Abstract: Surface recognition and penetration are among the most critical plant infection processes in foliar pathogens .
In Magnaporthe oryzae , the Pmk1 MAP kinase regulates appressorium formation and penetration .
Its orthologs also are known to be required for various plant infection processes in other phytopathogenic fungi .
Although a number of upstream components of this important pathway have been characterized , the upstream sensors for surface signals have not been well characterized .
Pmk1 is orthologous to Kss1 in yeast that functions downstream from Msb2 and Sho1 for filamentous growth .
Because of the conserved nature of the Pmk1 and Kss1 pathways and reduced expression of MoMSB2 in the pmk1 mutant , in this study we functionally characterized the MoMSB2 and MoSHO1 genes .
Whereas the Momsb2 mutant was significantly reduced in appressorium formation and virulence , the Mosho1 mutant was only slightly reduced .
The Mosho1 Momsb2 double mutant rarely formed appressoria on artificial hydrophobic surfaces , had a reduced Pmk1 phosphorylation level , and was nonresponsive to cutin monomers .
However , it still formed appressoria and caused rare , restricted lesions on rice leaves .
On artificial hydrophilic surfaces , leaf surface waxes and primary alcohols-but not paraffin waxes and alkanes stimulated appressorium formation in the Mosho1 Momsb2 mutant , but more efficiently in the Momsb2 mutant .
Furthermore , expression of a dominant active MST7 allele partially suppressed the defects of the Momsb2 mutant .
These results indicate that , besides surface hydrophobicity and cutin monomers , primary alcohols , a major component of epicuticular leaf waxes in grasses , are recognized by M oryzae as signals for appressorium formation .
Our data also suggest that MoMsb2 and MoSho1 may have overlapping functions in recognizing various surface signals for Pmk1 activation and appressorium formation .
While MoMsb2 is critical for sensing surface hydrophobicity and cutin monomers , MoSho1 may play a more important role in recognizing rice leaf waxes .
| Matching Sentences:
[ Sen. 5, subscore: 1.00 ]: Pmk1 is orthologous to Kss1 in yeast that functions downstream from Msb2 and Sho1 for filamentous growth .
| | Supplemental links/files: reference in endnote online text related articles pubmed citation | |
