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Genetic control of inflorescence architecture in legumes.

Benlloch R, Berbel A, Ali L, Gohari G, Millán T, Madueño F - Front Plant Sci (2015)

Bottom Line: The architecture of the inflorescence, the shoot system that bears the flowers, is a main component of the huge diversity of forms found in flowering plants.In contrast, legumes represent a more complex inflorescence type, the compound inflorescence, where flowers are not directly borne in the main inflorescence axis but, instead, they are formed by secondary or higher order inflorescence meristems.Studies in model legumes such as pea (Pisum sativum) or Medicago truncatula have led to a rather good knowledge of the genetic control of the development of the legume compound inflorescence.

View Article: PubMed Central - PubMed

Affiliation: Molecular Genetics Department, Center for Research in Agricultural Genomics, Consortium CSIC-IRTA-UAB-UB, Parc de Recerca Universitat Autònoma de Barcelona Barcelona, Spain.

ABSTRACT
The architecture of the inflorescence, the shoot system that bears the flowers, is a main component of the huge diversity of forms found in flowering plants. Inflorescence architecture has also a strong impact on the production of fruits and seeds, and on crop management, two highly relevant agronomical traits. Elucidating the genetic networks that control inflorescence development, and how they vary between different species, is essential to understanding the evolution of plant form and to being able to breed key architectural traits in crop species. Inflorescence architecture depends on the identity and activity of the meristems in the inflorescence apex, which determines when flowers are formed, how many are produced and their relative position in the inflorescence axis. Arabidopsis thaliana, where the genetic control of inflorescence development is best known, has a simple inflorescence, where the primary inflorescence meristem directly produces the flowers, which are thus borne in the main inflorescence axis. In contrast, legumes represent a more complex inflorescence type, the compound inflorescence, where flowers are not directly borne in the main inflorescence axis but, instead, they are formed by secondary or higher order inflorescence meristems. Studies in model legumes such as pea (Pisum sativum) or Medicago truncatula have led to a rather good knowledge of the genetic control of the development of the legume compound inflorescence. In addition, the increasing availability of genetic and genomic tools for legumes is allowing to rapidly extending this knowledge to other grain legume crops. This review aims to describe the current knowledge of the genetic network controlling inflorescence development in legumes. It also discusses how the combination of this knowledge with the use of emerging genomic tools and resources may allow rapid advances in the breeding of grain legume crops.

No MeSH data available.


Meristem identity genes in Arabidopsis. (A) Images of wild-type (WT) and tfl1 mutant plants. While in the WT the main inflorescence and the lateral inflorescences (appearing in the axil of cauline leaves) show indeterminate growth, in the tfl1 mutant the main inflorescence ends into a terminal flower (a fruit in this image) and lateral branches are replaced by solitary flowers. (B) Inflorescence of an ap1 mutant. Individual flowers are replaced by branched structures. (C) Diagrams of meristem identity in the inflorescences of the wild-type and the tfl1 and ap1 mutants. In tfl1, the indeterminate inflorescence apex (I) is replaced by a terminal flower (F) while in ap1, the flowers are replaced by inflorescence-like structures. Arrowheads, indeterminate shoot; open circles, flowers, closed circles, abnormal flowers. (D) Model for specification of meristem identity in the simple inflorescence of Arabidopsis. In the Arabidopsis inflorescence apex, TFL1 expression in the inflorescence meristem (I) and AP1 and LFY expression in the floral meristem (F) are required for these meristems to acquire their identity. Expression of these genes in their correct domains is maintained by mutual repressive interactions.
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Figure 2: Meristem identity genes in Arabidopsis. (A) Images of wild-type (WT) and tfl1 mutant plants. While in the WT the main inflorescence and the lateral inflorescences (appearing in the axil of cauline leaves) show indeterminate growth, in the tfl1 mutant the main inflorescence ends into a terminal flower (a fruit in this image) and lateral branches are replaced by solitary flowers. (B) Inflorescence of an ap1 mutant. Individual flowers are replaced by branched structures. (C) Diagrams of meristem identity in the inflorescences of the wild-type and the tfl1 and ap1 mutants. In tfl1, the indeterminate inflorescence apex (I) is replaced by a terminal flower (F) while in ap1, the flowers are replaced by inflorescence-like structures. Arrowheads, indeterminate shoot; open circles, flowers, closed circles, abnormal flowers. (D) Model for specification of meristem identity in the simple inflorescence of Arabidopsis. In the Arabidopsis inflorescence apex, TFL1 expression in the inflorescence meristem (I) and AP1 and LFY expression in the floral meristem (F) are required for these meristems to acquire their identity. Expression of these genes in their correct domains is maintained by mutual repressive interactions.

Mentions: Arabidopsis thaliana is one of the best-known examples of simple indeterminate inflorescences. In Arabidopsis, upon floral transition, the vegetative meristem becomes an inflorescence meristem, which produces floral meristems laterally (Figures 1 and 2). The development of the Arabidopsis inflorescence can be mostly explained by the function and mutual regulation of three genes: TERMINAL FLOWER 1 (TFL1), LEAFY (LFY), and APETALA 1 (AP1) (Shannon and Meeks-Wagner, 1993; Liljegren et al., 1999; Blazquez et al., 2006). These three genes act as opposing forces maintaining the balance between inflorescence and floral meristem identity at the inflorescence apex (Ratcliffe et al., 1999; Blazquez et al., 2006).


Genetic control of inflorescence architecture in legumes.

Benlloch R, Berbel A, Ali L, Gohari G, Millán T, Madueño F - Front Plant Sci (2015)

Meristem identity genes in Arabidopsis. (A) Images of wild-type (WT) and tfl1 mutant plants. While in the WT the main inflorescence and the lateral inflorescences (appearing in the axil of cauline leaves) show indeterminate growth, in the tfl1 mutant the main inflorescence ends into a terminal flower (a fruit in this image) and lateral branches are replaced by solitary flowers. (B) Inflorescence of an ap1 mutant. Individual flowers are replaced by branched structures. (C) Diagrams of meristem identity in the inflorescences of the wild-type and the tfl1 and ap1 mutants. In tfl1, the indeterminate inflorescence apex (I) is replaced by a terminal flower (F) while in ap1, the flowers are replaced by inflorescence-like structures. Arrowheads, indeterminate shoot; open circles, flowers, closed circles, abnormal flowers. (D) Model for specification of meristem identity in the simple inflorescence of Arabidopsis. In the Arabidopsis inflorescence apex, TFL1 expression in the inflorescence meristem (I) and AP1 and LFY expression in the floral meristem (F) are required for these meristems to acquire their identity. Expression of these genes in their correct domains is maintained by mutual repressive interactions.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4508509&req=5

Figure 2: Meristem identity genes in Arabidopsis. (A) Images of wild-type (WT) and tfl1 mutant plants. While in the WT the main inflorescence and the lateral inflorescences (appearing in the axil of cauline leaves) show indeterminate growth, in the tfl1 mutant the main inflorescence ends into a terminal flower (a fruit in this image) and lateral branches are replaced by solitary flowers. (B) Inflorescence of an ap1 mutant. Individual flowers are replaced by branched structures. (C) Diagrams of meristem identity in the inflorescences of the wild-type and the tfl1 and ap1 mutants. In tfl1, the indeterminate inflorescence apex (I) is replaced by a terminal flower (F) while in ap1, the flowers are replaced by inflorescence-like structures. Arrowheads, indeterminate shoot; open circles, flowers, closed circles, abnormal flowers. (D) Model for specification of meristem identity in the simple inflorescence of Arabidopsis. In the Arabidopsis inflorescence apex, TFL1 expression in the inflorescence meristem (I) and AP1 and LFY expression in the floral meristem (F) are required for these meristems to acquire their identity. Expression of these genes in their correct domains is maintained by mutual repressive interactions.
Mentions: Arabidopsis thaliana is one of the best-known examples of simple indeterminate inflorescences. In Arabidopsis, upon floral transition, the vegetative meristem becomes an inflorescence meristem, which produces floral meristems laterally (Figures 1 and 2). The development of the Arabidopsis inflorescence can be mostly explained by the function and mutual regulation of three genes: TERMINAL FLOWER 1 (TFL1), LEAFY (LFY), and APETALA 1 (AP1) (Shannon and Meeks-Wagner, 1993; Liljegren et al., 1999; Blazquez et al., 2006). These three genes act as opposing forces maintaining the balance between inflorescence and floral meristem identity at the inflorescence apex (Ratcliffe et al., 1999; Blazquez et al., 2006).

Bottom Line: The architecture of the inflorescence, the shoot system that bears the flowers, is a main component of the huge diversity of forms found in flowering plants.In contrast, legumes represent a more complex inflorescence type, the compound inflorescence, where flowers are not directly borne in the main inflorescence axis but, instead, they are formed by secondary or higher order inflorescence meristems.Studies in model legumes such as pea (Pisum sativum) or Medicago truncatula have led to a rather good knowledge of the genetic control of the development of the legume compound inflorescence.

View Article: PubMed Central - PubMed

Affiliation: Molecular Genetics Department, Center for Research in Agricultural Genomics, Consortium CSIC-IRTA-UAB-UB, Parc de Recerca Universitat Autònoma de Barcelona Barcelona, Spain.

ABSTRACT
The architecture of the inflorescence, the shoot system that bears the flowers, is a main component of the huge diversity of forms found in flowering plants. Inflorescence architecture has also a strong impact on the production of fruits and seeds, and on crop management, two highly relevant agronomical traits. Elucidating the genetic networks that control inflorescence development, and how they vary between different species, is essential to understanding the evolution of plant form and to being able to breed key architectural traits in crop species. Inflorescence architecture depends on the identity and activity of the meristems in the inflorescence apex, which determines when flowers are formed, how many are produced and their relative position in the inflorescence axis. Arabidopsis thaliana, where the genetic control of inflorescence development is best known, has a simple inflorescence, where the primary inflorescence meristem directly produces the flowers, which are thus borne in the main inflorescence axis. In contrast, legumes represent a more complex inflorescence type, the compound inflorescence, where flowers are not directly borne in the main inflorescence axis but, instead, they are formed by secondary or higher order inflorescence meristems. Studies in model legumes such as pea (Pisum sativum) or Medicago truncatula have led to a rather good knowledge of the genetic control of the development of the legume compound inflorescence. In addition, the increasing availability of genetic and genomic tools for legumes is allowing to rapidly extending this knowledge to other grain legume crops. This review aims to describe the current knowledge of the genetic network controlling inflorescence development in legumes. It also discusses how the combination of this knowledge with the use of emerging genomic tools and resources may allow rapid advances in the breeding of grain legume crops.

No MeSH data available.