Gene Details:

• MSU gene ID: LOC_Os03g11600
• RAPdb gene ID: Os03g0215200
• Gene Symbol: DL
• Genome: MSU7 ,  IRGSP-1.0
• Species: Oryza sativa

Functional Descriptions:

• Here, we found that the genes DROOPING LEAF (DL) and OsETTIN2 (OsETT2) are involved in awn development in the awned indica strain Kasalath.
• Severe loss-of-function mutations of DL cause complete homeotic transformation of carpels into stamens.
• In this article, we report that carpel specification in the Oryza sativa (rice) flower is regulated by the floral homeotic gene DROOPING LEAF (DL) that is distinct from the well-known ABC genes.
• In addition, severe and weak DL alleles fail to form a midrib in the leaf.
• The phenotypic analysis of DL mutants, together with analyses of the spatial expression patterns and ectopic expression of DL, demonstrate that DL regulates midrib formation by promoting cell proliferation in the central region of the rice leaf.
• These results suggest that carpel specification is regulated by DL in rice flower development.
• Here, we report the interactions of rice (Oryza sativa) floral homeotic genes, OsMADS3 (a C-class gene), OsMADS13 (a D-class gene), and DROOPING LEAF (DL), in specifying floral organ identities and floral meristem determinacy.
• Strikingly, osmads3-4 DL-sup6 displayed a severe loss of floral meristem determinacy and produced supernumerary whorls of lodicule-like organs at the forth whorl, suggesting that OsMADS3 and DL synergistically terminate the floral meristem.
• These observations suggest that DL and OsMADS13 may function in the same pathway specifying the identity of carpel/ovule and floral meristem.
• Consistent with these functions, DL is initially expressed in the central region of the leaf primordia (presumptive midrib) and in the presumptive carpel primordia in the meristem.
• We also show that DL interacts antagonistically with class B genes and controls floral meristem determinacy.
• The awn is a long neeDLe-like appendage that, in some grass species, is formed on the lemma that encloses floral organs together with the palea.
• OsETT2 is expressed in the awn primordium in the awned indica floret, but not in the awnless japonica floret except in the provascular bunDLe.
• The DROOPING LEAF (DL) gene, a member of the YABBY gene family, promotes midrib formation in the leaf and carpel specification in the flower.
• 4kb, and introns 1 and 2, was shown to be sufficient to induce DL in the presumptive midrib, and to suppress it in other regions in the leaf primordia.
• We modified Oryza sativa (rice) plant architecture by expressing an activated version of DL (DL-VP16) in a precise manner using the DG1 sequence: the resulting transgenic plant produced a midrib in the distal region of the leaf blade, where there is no midrib in wild type, and formed more upright leaves compared with the wild type.
• The floral organ identity gene DROOPING LEAF (DL) was expressed ectopically in all defective organs of cfo1 flowers.
• In the weakest mutant, DL-2, most of the flowers are normal.
• The flower of the double mutant, spw1 DL-sup, produces incompletely differentiated organs indefinitely after palea-like organs are produced in the position where lodicules are formed in the wild-type flower.
• Genetic analyses and RNA-silencing experiments indicate that DL and OsETT2 act independently in awn formation, and that either gene alone is not sufficient for awn development.
• The YABBY gene DROOPING LEAF (DL) regulates midrib formation in the leaves and carpel specification in the flowers of rice (Oryza sativa L).
• By comparing the expression levels of DL and leaf phenotypes in the DL mutants with different severities, we confirmed our previous hypothesis that DL promotes cell proliferation in the central region of leaf primordia, and that this cell proliferation is critical for midrib formation in the mature leaves.
• Collectively, we propose a model to illustrate the role of OsMADS3, DL, and OsMADS13 in the specification of flower organ identity and meristem determinacy in rice.
• We analyzed recessive mutants of two homeotic genes in rice, SUPERWOMAN1 (SPW1) and DROOPING LEAF (DL).
• In contrast, two strong alleles of the DL locus, drooping leaf-superman1 (DL-sup1) and drooping leaf-superman2 (DL-sup2), cause the complete transformation of the gynoecium into stamens.
• Double mutant analysis revealed that loss of DL function mitigated some of the defects of floral organs in cfo1 flowers.
• We propose that the CFO1 gene plays a pivotal role in maintaining floral organ identity through negative regulation of DL expression.
• Furthermore, the defects of osmads13-3 DL-sup6 flowers appeared identical to those of DL-sup6, and the OsMADS13 expression was undetectable in DL-sup6 flowers.
• The intermediate allele DL-1 (T65), results in an increase in the number of stamens and stigmas, and carpels occasionally show staminoid characteristics.
• Based on genetic and molecular results, we postulate a model of stamen and carpel specification in rice, with DL as a novel gene controlling carpel identity and acting mutually and antagonistically to the class B gene, SPW1.
• We generated drooping leaf rice mutants by CRISPR/Cas and identified two novel alleles with specific editing that allow underpinning of the function of the DL protein domain towards midrib and carpel formations.
• The DROOPING LEAF (DL) gene plays an essential role in regulating midrib formation and carpel specification in rice and other grass species, but the specific function of DL protein domains in different developmental processes is unclear.
• These DL mutant alleles contribute to the DL gene functional analysis and to gain insights into possible modifications of leaf architecture of rice and other grass species.
• Here, we generated Nipponbare rice DL mutants using CRISPR/Cas gene editing and identified two novel DL alleles with different effects on midrib formation and carpel development.

Function-related keywords:

• leaf ,  stamen ,  flower ,  floral ,  floral-meristem ,  meristem ,  palea ,  vascular-bundle ,  awn ,  architecture ,  lemma ,  development

Literature:

• Genetic interaction of OsMADS3, DROOPING LEAF, and OsMADS13 in specifying rice floral organ identities and meristem determinacy .  DOI:  10.1104/pp.111.172080 ;  PMID:  21444646
• SUPERWOMAN1 and DROOPING LEAF genes control floral organ identity in rice .  DOI:  10.1242/dev.00294 ;  PMID:  12506001
• Temporal and spatial regulation of DROOPING LEAF gene expression that promotes midrib formation in rice .  DOI:  10.1111/j.1365-313X.2010.04404.x ;  PMID:  21175891
• The YABBY gene DROOPING LEAF regulates carpel specification and midrib development in Oryza sativa .  DOI:  10.1105/tpc.018044 ;  PMID:  14729915
• Rice MADS6 interacts with the floral homeotic genes SUPERWOMAN1, MADS3, MADS58, MADS13, and DROOPING LEAF in specifying floral organ identities and meristem fate .  DOI:  10.1105/tpc.111.087262 ;  PMID:  21784949
• A transposon, Ping, is integrated into intron 4 of the DROOPING LEAF gene of rice, weakly reducing its expression and causing a mild drooping leaf phenotype .  DOI:  10.1093/pcp/pcn093 ;  PMID:  18593744
• CHIMERIC FLORAL ORGANS1, encoding a monocot-specific MADS box protein, regulates floral organ identity in rice .  DOI:  10.1104/pp.112.200980 ;  PMID:  22891238
• The DROOPING LEAF and OsETTIN2 genes promote awn development in rice .  DOI:  10.1111/tpj.12411 ;  PMID:  24330191
• Effects of CRISPR/Cas9 generated drooping leaf (dl) alleles on midrib and carpel formations in Oryza sativa Nipponbare .  DOI:  10.1007/s00425-022-03973-5 ;  PMID:  35994211

Related News:

Gene Resources:

• NCBI ID: AB106554
• UniProt accessions:

Sequences: