Limits...
Two euAGAMOUS genes control C-function in Medicago truncatula.

Serwatowska J, Roque E, Gómez-Mena C, Constantin GD, Wen J, Mysore KS, Lund OS, Johansen E, Beltrán JP, Cañas LA - PLoS ONE (2014)

Bottom Line: This species is therefore a good experimental system to study the effects of gene duplication within the AG subfamily.Our results show that the M. truncatula euAG- and PLENA-like genes are an example of subfunctionalization as a result of a change in expression pattern.In contrast, MtSHP expression appears late during floral development suggesting it does not contribute significantly to the C-function.

View Article: PubMed Central - PubMed

Affiliation: Instituto de Biología Molecular y Celular de Plantas (CSIC-UPV). Ciudad Politécnica de la Innovación, Valencia, Spain.

ABSTRACT
C-function MADS-box transcription factors belong to the AGAMOUS (AG) lineage and specify both stamen and carpel identity and floral meristem determinacy. In core eudicots, the AG lineage is further divided into two branches, the euAG and PLE lineages. Functional analyses across flowering plants strongly support the idea that duplicated AG lineage genes have different degrees of subfunctionalization of the C-function. The legume Medicago truncatula contains three C-lineage genes in its genome: two euAG genes (MtAGa and MtAGb) and one PLENA-like gene (MtSHP). This species is therefore a good experimental system to study the effects of gene duplication within the AG subfamily. We have studied the respective functions of each euAG genes in M. truncatula employing expression analyses and reverse genetic approaches. Our results show that the M. truncatula euAG- and PLENA-like genes are an example of subfunctionalization as a result of a change in expression pattern. MtAGa and MtAGb are the only genes showing a full C-function activity, concomitant with their ancestral expression profile, early in the floral meristem, and in the third and fourth floral whorls during floral development. In contrast, MtSHP expression appears late during floral development suggesting it does not contribute significantly to the C-function. Furthermore, the redundant MtAGa and MtAGb paralogs have been retained which provides the overall dosage required to specify the C-function in M. truncatula.

Show MeSH

Related in: MedlinePlus

Floral phenotypes of M. truncatula mtagb and mtaga mutants and MtAGab-VIGS silenced plants.(A) Dissected wild-type M. truncatula flower showing the four floral whorls (W1 to W4). Floral phenotypes are similar in mtaga. (B) and mtagb (C) mutants. Mutant flowers (left) were opened to show the inner whorls. In W3 the staminal tubes are unfused and occasionally petaloid structures appear (arrow) replacing the anthers. Carpels in W4 present stigmatic protuberances (arrow) or multiple unfused carpels and exposed ovules (boxed). (D) MtAGab-VIGS flower with severe homeotic transformation of stamens into petals and carpels into sepaloid structures (arrows). Bars indicate 1 mm.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4126672&req=5

pone-0103770-g004: Floral phenotypes of M. truncatula mtagb and mtaga mutants and MtAGab-VIGS silenced plants.(A) Dissected wild-type M. truncatula flower showing the four floral whorls (W1 to W4). Floral phenotypes are similar in mtaga. (B) and mtagb (C) mutants. Mutant flowers (left) were opened to show the inner whorls. In W3 the staminal tubes are unfused and occasionally petaloid structures appear (arrow) replacing the anthers. Carpels in W4 present stigmatic protuberances (arrow) or multiple unfused carpels and exposed ovules (boxed). (D) MtAGab-VIGS flower with severe homeotic transformation of stamens into petals and carpels into sepaloid structures (arrows). Bars indicate 1 mm.

Mentions: To investigate the specific contribution of MtAGa and MtAGb genes in the M. truncatula floral development, we looked for retrotransposon insertion mutants [32]. These mutants were available for both genes, each containing a single Tnt1 element inserted in the N-terminal part of the gene (Figure 1A). mtagb Tnt1 insertion was identified as described in the experimental procedures and it was located in the first intron at 277 bp from the start codon (Figure 1A). mtaga (previously mtag-2), was isolated as a case study to demonstrate the utility of the reverse genetic platform in the model legume Medicago truncatula[32]. Using quantitative RT-PCR we have confirmed that MtAGa or MtAGb transcripts were nearly undetectable in the corresponding homozygous mutant plants without affecting the expression levels of the corresponding MtAG paralog (Figure S4). mtaga and mtagb mutants exhibit very similar floral phenotypes: flowers are wild-type in appearance, showing only mild developmental defects on the third and fourth-whorl organs (Figure 4). Incomplete fusion of the staminal tube was observed and occasionally, some petaloid prolongation in the anther tip (Figure 4B and 4C). Whorl 4 is frequently composed by multiple carpels (2-3) or by modified carpels with stigmatic protuberances and exposed ovules (Figure 4B and 4C). Flowers were generally sterile, although occasionally a few seeds were produced.


Two euAGAMOUS genes control C-function in Medicago truncatula.

Serwatowska J, Roque E, Gómez-Mena C, Constantin GD, Wen J, Mysore KS, Lund OS, Johansen E, Beltrán JP, Cañas LA - PLoS ONE (2014)

Floral phenotypes of M. truncatula mtagb and mtaga mutants and MtAGab-VIGS silenced plants.(A) Dissected wild-type M. truncatula flower showing the four floral whorls (W1 to W4). Floral phenotypes are similar in mtaga. (B) and mtagb (C) mutants. Mutant flowers (left) were opened to show the inner whorls. In W3 the staminal tubes are unfused and occasionally petaloid structures appear (arrow) replacing the anthers. Carpels in W4 present stigmatic protuberances (arrow) or multiple unfused carpels and exposed ovules (boxed). (D) MtAGab-VIGS flower with severe homeotic transformation of stamens into petals and carpels into sepaloid structures (arrows). Bars indicate 1 mm.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4126672&req=5

pone-0103770-g004: Floral phenotypes of M. truncatula mtagb and mtaga mutants and MtAGab-VIGS silenced plants.(A) Dissected wild-type M. truncatula flower showing the four floral whorls (W1 to W4). Floral phenotypes are similar in mtaga. (B) and mtagb (C) mutants. Mutant flowers (left) were opened to show the inner whorls. In W3 the staminal tubes are unfused and occasionally petaloid structures appear (arrow) replacing the anthers. Carpels in W4 present stigmatic protuberances (arrow) or multiple unfused carpels and exposed ovules (boxed). (D) MtAGab-VIGS flower with severe homeotic transformation of stamens into petals and carpels into sepaloid structures (arrows). Bars indicate 1 mm.
Mentions: To investigate the specific contribution of MtAGa and MtAGb genes in the M. truncatula floral development, we looked for retrotransposon insertion mutants [32]. These mutants were available for both genes, each containing a single Tnt1 element inserted in the N-terminal part of the gene (Figure 1A). mtagb Tnt1 insertion was identified as described in the experimental procedures and it was located in the first intron at 277 bp from the start codon (Figure 1A). mtaga (previously mtag-2), was isolated as a case study to demonstrate the utility of the reverse genetic platform in the model legume Medicago truncatula[32]. Using quantitative RT-PCR we have confirmed that MtAGa or MtAGb transcripts were nearly undetectable in the corresponding homozygous mutant plants without affecting the expression levels of the corresponding MtAG paralog (Figure S4). mtaga and mtagb mutants exhibit very similar floral phenotypes: flowers are wild-type in appearance, showing only mild developmental defects on the third and fourth-whorl organs (Figure 4). Incomplete fusion of the staminal tube was observed and occasionally, some petaloid prolongation in the anther tip (Figure 4B and 4C). Whorl 4 is frequently composed by multiple carpels (2-3) or by modified carpels with stigmatic protuberances and exposed ovules (Figure 4B and 4C). Flowers were generally sterile, although occasionally a few seeds were produced.

Bottom Line: This species is therefore a good experimental system to study the effects of gene duplication within the AG subfamily.Our results show that the M. truncatula euAG- and PLENA-like genes are an example of subfunctionalization as a result of a change in expression pattern.In contrast, MtSHP expression appears late during floral development suggesting it does not contribute significantly to the C-function.

View Article: PubMed Central - PubMed

Affiliation: Instituto de Biología Molecular y Celular de Plantas (CSIC-UPV). Ciudad Politécnica de la Innovación, Valencia, Spain.

ABSTRACT
C-function MADS-box transcription factors belong to the AGAMOUS (AG) lineage and specify both stamen and carpel identity and floral meristem determinacy. In core eudicots, the AG lineage is further divided into two branches, the euAG and PLE lineages. Functional analyses across flowering plants strongly support the idea that duplicated AG lineage genes have different degrees of subfunctionalization of the C-function. The legume Medicago truncatula contains three C-lineage genes in its genome: two euAG genes (MtAGa and MtAGb) and one PLENA-like gene (MtSHP). This species is therefore a good experimental system to study the effects of gene duplication within the AG subfamily. We have studied the respective functions of each euAG genes in M. truncatula employing expression analyses and reverse genetic approaches. Our results show that the M. truncatula euAG- and PLENA-like genes are an example of subfunctionalization as a result of a change in expression pattern. MtAGa and MtAGb are the only genes showing a full C-function activity, concomitant with their ancestral expression profile, early in the floral meristem, and in the third and fourth floral whorls during floral development. In contrast, MtSHP expression appears late during floral development suggesting it does not contribute significantly to the C-function. Furthermore, the redundant MtAGa and MtAGb paralogs have been retained which provides the overall dosage required to specify the C-function in M. truncatula.

Show MeSH
Related in: MedlinePlus