Gene Details:

• MSU gene ID: LOC_Os01g44220
• RAPdb gene ID: Os01g0633100
• Gene Symbol: OsAPL2 osagpl2-3 OsAGPL2 GIF2
• Genome: MSU7 ,  IRGSP-1.0
• Species: Oryza sativa

Functional Descriptions:

• A floury endosperm mutant, osagpl2-3, was isolated from the M2 generation of japonica rice cultivar Nipponbare following ethyl methane sulfonate mutagenesis.
• The osagpl2-3 mutant produced a white-core endosperm compared to the transparent endosperm of the wild type (WT).
• Phenotypic and Candidate Gene Analysis of a New Floury Endosperm Mutant (osagpl2-3) in Rice.
• The analysis for cooking and nutrition quality traits indicated that the values of gel consistency, gelatinization temperature, and rapid viscosity analysis profile of osagpl2-3 grains were lower than those of the WT.
• OsAPL3 was predominantly expressed in the middle phases of seed development, and OsAPS1, OsAPL1 and OsAPL2 were expressed later in seed development.
• The results from scanning electron microscope showed that the osagpl2-3 mutant grains comprised of round and loosely packed starch granules, some of which were compounded.
• Moreover, the expression of OsAGPL2 and its counterpart, OsAGPS2b, was highly coordinated in rice endosperm.
• Yeast two-hybrid and BiFC assays verified direct interactions between OsAGPL2 and OsAGPS2b as well as OsAGPL1 and OsAGPS1, supporting the model for spatiotemporal complex formation of AGPase isoforms in rice endosperm.
• Grains of GIF2 showed a slower filling rate and a significant lower final grain weight and yield compared to wild-type.
• All these results suggest that GIF2 plays important roles in the regulation of grain filling and starch biosynthesis during caryopsis development, and that it has been preserved during selection throughout domestication of modern rice.
• The starch content in GIF2 was noticeably decreased and its physicochemical properties were also altered.
• Transcript levels for granule-bound starch synthase, starch synthase, starch branching enzyme and starch debranching enzyme were distinctly elevated in GIF2 grains.
• Moreover, GIF2 endosperm cells showed obvious defects in compound granule formation.
• Positional cloning identified GIF2 to encode an ADP-glucose pyrophosphorylase (AGP) large subunit, AGPL2; consequently, AGP enzyme activity in GIF2 endosperms was remarkably decreased.
• This reflected the unanticipated expression of both OsAPL2 and OsAPS2b in the leaves, generating a complete ectopic AGPase in the leaf cytosol, and a corresponding decrease in the expression of the plastidial small subunit OsAPS2a that was only partially complemented by an increase in the expression of OsAPS1.
• The first committed step in the endosperm starch biosynthetic pathway is catalyzed by the cytosolic glucose-1-phosphate adenylyl transferase (AGPase) comprising large and small subunits encoded by the OsAPL2 and OsAPS2b genes, respectively.
• OsAPL2 is expressed solely in the endosperm so we hypothesized that mutating this gene would block starch biosynthesis in the endosperm without affecting the leaves.
• OsMADS14 and NF-YB1 cooperate in the direct activation of OsAGPL2 and Waxy during starch synthesis in rice endosperm.
• Transcriptomic profiling analyses revealed that the loss-of-function of OsMADS14 leads to significantly downregulated expression of many core starch synthesis genes, including OsAGPL2 and Waxy.

Function-related keywords:

• endosperm ,  temperature ,  seed-development ,  starch ,  grain ,  seed ,  domestication ,  yield ,  branching ,  grain-filling ,  grain-weight ,  starch-biosynthesis ,  pyrophosphorylase ,  leaf

Literature:

• Identification of the ADP-glucose pyrophosphorylase isoforms essential for starch synthesis in the leaf and seed endosperm of rice (Oryza sativa L.) .  DOI:  10.1007/s11103-007-9153-z ;  PMID:  17406793
• Phenotypic and Candidate Gene Analysis of a New Floury Endosperm Mutant (osagpl2-3) in Rice .  DOI:  10.1007/s11105-012-0435-5
• Compensation and interaction between RISBZ1 and RPBF during grain filling in rice .  DOI:  10.1111/j.1365-313X.2009.03925.x ;  PMID:  19473328
• SALT-RESPONSIVE ERF1 is a negative regulator of grain filling and gibberellin-mediated seedling establishment in rice .  DOI:  10.1093/mp/sst131 ;  PMID:  24046061
• Gene expression of ADP-glucose pyrophosphorylase and starch contents in rice cultured cells are cooperatively regulated by sucrose and ABA .  DOI:  10.1093/pcp/pci101 ;  PMID:  15821022
• ADP-glucose pyrophosphorylase large subunit 2 is essential for storage substance accumulation and subunit interactions in rice endosperm .  DOI:  10.1016/j.plantsci.2016.05.010 ;  PMID:  27297991
• ADP-glucose pyrophosphorylase large subunit 2 is essential for storage substance accumulation and subunit interactions in rice endosperm .  DOI:  10.1016/j.plantsci.2016.05.010 ;  PMID:  27297991
• GRAIN INCOMPLETE FILLING 2 regulates grain filling and starch synthesis during rice caryopsis development .  DOI:  10.1111/jipb.12510 ;  PMID:  27957808
• CRISPR/Cas9-induced monoallelic mutations in the cytosolic AGPase large subunit gene APL2 induce the ectopic expression of APL2 and the corresponding small subunit gene APS2b in rice leaves .  DOI:  10.1007/s11248-018-0089-7 ;  PMID:  30099722
• Bin-based genome-wide association studies reveal superior alleles for improvement of appearance quality using a 4-way MAGIC population in rice .  DOI:  10.1016/j.jare.2020.08.001 ;  PMID:  33364055
• OsMADS14 and NF-YB1 cooperate in the direct activation of OsAGPL2 and Waxy during starch synthesis in rice endosperm .  DOI:  10.1111/nph.17990 ;  PMID:  35067957

Related News:

Gene Resources:

• NCBI ID: AK071497
• UniProt accessions:

Sequences: