Floral development of the model legume Medicago truncatula: ontogeny studies as a tool to better characterize homeotic mutations

Benlloch, Reyes; Navarro, Cristina; Beltrán, José Pío; Cañas, Luis A.

doi:10.1007/s00497-002-0157-1

Cited by 65 publications

(68 citation statements)

References 38 publications

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“…Different from Arabidopsis's radially symmetric flowers, M. truncatula develops bilaterally symmetric ones (18). M. truncatula's flowers have four whorls of floral organs, including 5 sepals, 5 petals, and 10 stamens fusing into a staminal tube surrounding one carpel inside ( Fig.…”

Section: Identification Of the Mutants With Loss-of-c-function Floralmentioning

confidence: 99%

AGLF provides C-function in floral organ identity through transcriptional regulation of AGAMOUS in Medicago truncatula

Zhao

Liu

et al. 2019

Proc. Natl. Acad. Sci. U.S.A.

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Floral development is one of the model systems for investigating the mechanisms underlying organogenesis in plants. Floral organ identity is controlled by the well-known ABC model, which has been generalized to many flowering plants. Here, we report a previously uncharacterized MYB-like gene, AGAMOUS-LIKE FLOWER (AGLF), involved in flower development in the model legume Medicago truncatula. Loss-of-function of AGLF results in flowers with stamens and carpel transformed into extra whorls of petals and sepals. Compared with the loss-of-function mutant of the class C gene AGAMOUS (MtAG) in M. truncatula, the defects in floral organ identity are similar between aglf and mtag, but the floral indeterminacy is enhanced in the aglf mutant. Knockout of AGLF in the mutants of the class A gene MtAP1 or the class B gene MtPI leads to an addition of a loss-of-C-function phenotype, reflecting a conventional relationship of AGLF with the canonical A and B genes. Furthermore, we demonstrate that AGLF activates MtAG in transcriptional levels in control of floral organ identity. These data shed light on the conserved and diverged molecular mechanisms that control flower development and morphology among plant species.flower development | ABC model | AGAMOUS | Medicago truncatula O rgan differentiation is crucial in the development of living organisms, such as limb-bud growth in mammals, bodysegment development in insects, and flower-organ identity in plants. Most flowers of higher plants consist of four concentric whorls of floral organs: sepals, petals, stamens, and innermost carpel(s). Floral organs have distinct morphologies and functions. The outer sepals and petals provide protection to the reproductive organs inside, i.e., the stamens and carpels that produce gametophytes. The developmental process of four whorls of flower is controlled by the organ identity genes in the well-known ABC model (1-4). In Arabidopsis thaliana, sepals are controlled by the class A genes APETALA 1 (AP1) and AP2; petals are controlled by the class A genes and class B genes AP3 and PISTILLATA (PI); stamens are controlled by the class B gene and class C gene AGAMOUS (AG); and carpels are controlled by the class C gene only (5-9). In another model plant, Antirrhinum majus, similar genes have been identified, such as SQUAMOSA, LIPLESS1, and LIPLESS2 as class A genes, DEFICIENS and GLOBOSA as class B genes, and PLENA and FARINELLI as class C genes (10-12). All of the ABC genes except AP2 and its homologs belong to the MADS (MCM1, AGAMOUS, DEFICIENS A, and SERUM RESPONSE FAC-TOR) homeotic gene family (13). The knockout mutants of the ABC genes display homeotic transformation of the floral organs in corresponding whorls in Arabidopsis. The mutation of AP1 results in the transformation of sepals into carpels and petals into stamens, while the pi mutant causes petals and stamens to be transformed into sepals and carpels. The ag mutant develops indeterminate flowers with stamens and carpel transformed into numerous whorls of petals and sepals.The ABC model ha...

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Section: Identification Of the Mutants With Loss-of-c-function Floralmentioning

confidence: 99%

AGLF provides C-function in floral organ identity through transcriptional regulation of AGAMOUS in Medicago truncatula

Zhao

Liu

et al. 2019

Proc. Natl. Acad. Sci. U.S.A.

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“…Flowers of model dicot species, such as A. thaliana or A. majus , form the primordia of petals and stamens independently, but in some legumes, including Medicago truncatula , these organs derive from special structures called common primordia that probably represent an evolutionary specialization. These structures comprise four ephemeral meristems that develop between sepal and carpel primordia, and, upon division, each follows a characteristic pattern to produce the petal and stamen primordia (Ferrándiz et al ., ; Benlloch et al ., ; Tucker, ). B‐class genes have been suggested to contribute to control of the identity and determinacy of common primordia in legumes (Ferrándiz et al ., ; Taylor et al ., ; Berbel et al ., ), but experimental data are required to reinforce this hypothesis.…”

Section: Introductionmentioning

confidence: 99%

Functional specialization of duplicated AP3‐like genes in Medicago truncatula

et al. 2012

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SUMMARYThe B-class of MADS box genes has been studied in a wide range of plant species, but has remained largely uncharacterized in legumes. Here we investigate the evolutionary fate of the duplicated AP3-like genes of a legume species. To obtain insight into the extent to which B-class MADS box gene functions are conserved or have diversified in legumes, we isolated and characterized the two members of the AP3 lineage in Medicago truncatula: MtNMH7 and MtTM6 (euAP3 and paleoAP3 genes, respectively). A non-overlapping and complementary expression pattern of both genes was observed in petals and stamens. MtTM6 was expressed predominantly in the outer cell layers of both floral organs, and MtNMH7 in the inner cell layers of petals and stamens. Functional analyses by reverse genetics approaches (RNAi and Tnt1 mutagenesis) showed that the contribution of MtNMH7 to petal identity is more important than that of MtTM6, whereas MtTM6 plays a more important role in stamen identity than its paralog MtNMH7. Our results suggest that the M. truncatula AP3-like genes have undergone a functional specialization process associated with complete partitioning of gene expression patterns of the ancestral gene lineage. We provide information regarding the similarities and differences in petal and stamen development among core eudicots.

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“…The indeterminate pattern of the development of M. truncatula results from the presence on each axis of (1) an apical meristem from which leaves are initiated; (2) vegetative axillary meristems likely to produce branches; and (3) reproductive axillary meristems, from a varying node number, whose development gives rise to flowers (Benlloch et al 2003). As for pea (Ney & Turc 1993) and soybean (Munier-Jolain, Ney & Duthion 1993), the indeterminate development of M. truncatula is characterized by the sequential progression of flowering along each axis, from the first reproductive node (1RN) to the apex, and leads to a staggering of flowering during plant cycle.…”

Section: Introductionmentioning

confidence: 99%

A model‐based framework for the phenotypic characterization of the flowering of Medicago truncatula

Moreau

Salon

Munier-Jolain

2007

Plant Cell & Environment

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To facilitate the phenotypic characterization of Medicago truncatula, our aim was to provide a framework of analysis of flowering in response to environmental factors. The flowering of the line A17 was analysed in different conditions of temperature, duration of vernalization and photoperiod. Flowering was characterized using three descriptors at the axis level: the position of the first reproductive node (1RN), the date of beginning of flowering (DBF) and the florochron (RFa -1 ) corresponding to the reciprocal of the rate of progression of flowering along each axis. As for vegetative development, it was found that flowering could be analysed as a function of thermal time using a base temperature (Tb) of 5°C. Vernalization displayed a sound impact on the flowering. For all the studied axes, increasing the duration of vernalization lowered the 1RN and hastened the DBF. By contrast, for most of the studied axes, RFa -1 was only slightly affected by vernalization. For the branch B0, RFa -1 was a genotypic constant when thermal time was used. Considering B0 as a reference axis, an ecophysiological model was developed to simulate the impact of environmental factors on the three components of flowering. Concrete practical applications of the model-based framework presented herein are proposed for helping the genetic and genomic studies of M. truncatula.

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Floral development of the model legume Medicago truncatula: ontogeny studies as a tool to better characterize homeotic mutations

Cited by 65 publications

References 38 publications

AGLF provides C-function in floral organ identity through transcriptional regulation of AGAMOUS in Medicago truncatula

AGLF provides C-function in floral organ identity through transcriptional regulation of AGAMOUS in Medicago truncatula

Functional specialization of duplicated AP3‐like genes in Medicago truncatula

A model‐based framework for the phenotypic characterization of the flowering of Medicago truncatula

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