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| | The rice ''semidwarf-1 (sd1)'' gene is well known as the "green revolution gene" and controls the plant height of rice. | | The rice ''semidwarf-1 (sd1)'' gene is well known as the "green revolution gene" and controls the plant height of rice. |
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| − | == Annotated Information ==
| + | tVkUNA <a href="http://gefjqcpoaonw.com/">gefjqcpoaonw</a>, [url=http://btgwfidexjik.com/]btgwfidexjik[/url], [link=http://dpmzzsndhbza.com/]dpmzzsndhbza[/link], http://hsxdyifatvig.com/ |
| − | === Function ===
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| − | [[File:Sd1-fig1.jpg|right|thumb|150px|''Semidwarf VS. normal-type rice plants at ripening (from reference <ref name="ref3" />).'']]
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| − | This gene is originally derived from the Chinese cultivar Dee-Geo-Woo-Gen (DGWG). It encodes an oxidase enzyme involved in the biosynthesis of gibberellin, which is a plant growth hormone. The rice genome carries at least two GA20ox genes (GA20ox-1 and GA20ox-2). SD1 corresponds to GA20ox-2. Mutation of SD1 will cause a semi-dwarf phenotype of rice without seed yield being affected <ref name="ref1" />. It is not surprising that a rice semidwarfing gene encodes GA20-ox since successful production of semidwarf plants using antisense or overexpressed GA20-ox genes has been reported in Arabidopsis, Solanum dulcamara, potato, and lettuce <ref name="ref3" />.
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| − | It is a key enzyme in the biosynthesis of gibberellin that catalyses the three steps GA53->GA44->GA19->GA20. Impaired GA 20-oxidase activity will cause elevated content of GA53, and reduced amount of G20<ref name="ref3" />. However, there is slight difference between different strains. The extent of GA1 is lower in Doongara (semi-dwarf rice strain) when compared with Kyeema (tall), while there is no significant difference between Calrose76 (semi-dwarf rice strain) and Calrose (tall). Calrose76 has lower contents of GA44 and of GA19 than Calrose, while there is no significant difference between Doongara (semi-dwarf rice strain) and Kyeema (tall) <ref name="ref3" />.
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| − | '''GO assignment(s):''' [http://amigo.geneontology.org/amigo/term/GO:0005506 GO:0005506], [http://amigo.geneontology.org/amigo/term/GO:0016216 GO:0016216], [http://amigo.geneontology.org/amigo/term/GO:0017000 GO:0017000]
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| − | === Mutation ===
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| − | 'Dee-Geo-Woo-Gen' (semi-dwarf rice strain): A 383-base-pair deletion from the genome (A 280-bp deletion within the coding region), which induces a frameshift that creates a stop codon in SD1, may be related with the semi-dwarf phenotype <ref name="ref1" /><ref name="ref2" />.
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| − | Calrose76 (semi-dwarf rice strain): The DNA sequence of Calrose76 is identical to Calrose (tall) except for a C to T transition at position 798 that resulted in a change of the predicted amino acid leucine (Leu-266) in Calrose to phenylalanine in Calrose76 <ref name="ref2" />.
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| − | It has been found that introgression of a chromosomal block containing the SD1 allele from tropical japonica is associated with a change in growth patterns in BHA1 (one weedy rice population) <ref name="ref7" />.
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| − | === Expression ===
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| − | This gene is strongly expressed in the leaf blade, stem and unopened flower, whereas GA20ox-1 is predominantly expressed in the unopened flower <ref name="ref1" />.
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| − | Among the DGWG-type sd-1 mutants, IR24 and Habataki have little transcript of this gene, while Milyang 23 expresses a normal or greater amount of truncated transcript. No significant difference is observed between Calrose and its single-nucleotide-substitution mutant Calrose 76 <ref name="ref3" />.
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| − | Analysis of the tissue- and stage-specificity of transcription of sd1 in Nipponbare revealed that this
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| − | gene was expressed within 48 hr after sowing, as well as in 10-day-old plants, 30-day-old leaves, and flowering panicles; no transcription is detected in 24-hr-old seedlings or in 14-day-old roots. Transcript accumulates predominantly in adult leaves <ref name="ref3" />.
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| − | {| class='wikitable' style="text-align:center"
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| − | ! | Primer
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| − | ! | Forward primer
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| − | ! | Reverse primer
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| − | | rowspan="3"|Gene amplication
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| − | | | 5'-CAACTCACTCCCGCTCAACACAGC-3'
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| − | | | 5'-TTTGAAATGCAATGTCGTCCACC-3' (used to amplify exon 1 <ref name="ref2" />)
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| − | |-
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| − | | | 5'-GCGCCAATGGGGTAATTAAAACG-3'
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| − | | | 5'-GGCATTCCATTGTTTGTGATTGG-3' (used to amplify exon 2 <ref name="ref2" />)
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| − | |-
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| − | | | 5'-GTTTGTCCTTGTCGCGTTGCTCAG-3'
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| − | | | 5'-TCTGTTCGTTCCGTTTCGTTCCG-3' (used to amplify exon 3 <ref name="ref2" />)
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| − | |-
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| − | | rowspan="2"|RT-PCR
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| − | | | 5'-CAACTCACTCCCGCTCAACACAGC-3'
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| − | | | 5'-GTTCGTTCCGTTTCGGTTCCG-3' <ref name="ref3" />
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| − | |-
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| − | | | 5'-AGCTGGACATGCCCGTGGTC-3'
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| − | | | 5'-TTGAGCTGCTGTCCGCGAAG-3' <ref name="ref3" />
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| − | |}
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| − | === Evolution ===
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| − | This gene is conserved in ''Arabidopsis'' (47% identity) and pea (50% identity). GA20ox-2 shows 47.8% identity to
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| − | GA20ox-1 in rice. There are at least three GA20-ox genes in Arabidopsis <ref name="ref1" /><ref name="ref2" />.
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| − | === Knowledge Extension ===
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| − | [[File:Gibberellin SD1 RHT Signal.PNG|right|thumb|500px|''Gibberellin signalling pathway (from reference <ref name="ref4" />).'']] | |
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| − | Except ''sd1'', another ‘green revolution’ gene named ''Rht1'', which encodes a GA signal suppressor DELLA protein. The deletion in the N-terminal region of the native RHT1 constitutively suppresses GA signaling, consequently resulting in a dominant semi-dwarf phenotype <ref name="ref5" />. Both sd1 and Rht1 are associated with GA pathway, indicating the importance of GA in the regulation of developmental processes and making it a prime target for improving crop yield <ref name="ref4" />.
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| − | The wheat green-revolution gene Rht (for ‘reduced height’) <ref name="ref5" /> is a gain-of-function allele caused by a mutation in a transcription factor that is associated with the gibberellin signalling pathway. As wheat has a hexaploid genome, it does not contain recessive alleles such as ''sd1'' in rice that might otherwise be used to produce a semi-dwarf strain of wheat. Although the genetic and biochemical functions of the rice SD1 and wheat RHT proteins are completely different (that is, recessive versus dominant, loss-of-function versus gain-offunction events, enzyme versus transcription factor, respectively), the products of both genes are linked with gibberellin malfunction <ref name="ref1" />.
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| − | In rice, ''Slr1'' gene encodes the DELLA protein. Three semi-dominant dwarf mutants (''Slr1-d1'', ''Slr1-d2'' and ''Slr1-d3'') associated with this gene have been identified, which were caused by gain-of-function mutations in the N-terminal region of SLR1. These three mutants are responsive to GA at a reduced rate, with later SLRl degradation, and showing reduced interaction activity with GID1 (GA receptor) comparing with wild type rice <ref name="ref6" />.
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| | == Labs working on this gene == | | == Labs working on this gene == |
