Background
Producing pure and stable plant lines that will be the future parents for a commercial hybrid is a necessary condition for generating homogenous and reproducible hybrid varieties expressing a high degree of heterosis. The production of pure lines involves self-fertilization in order to obtain uniformly homozygous lines, fixed for all the required characters of productivity, yield stability, quality traits or resistance to diseases. Equally important as being able to efficiently control self-pollination for inbreeding purposes, it is necessary to prevent self-pollination altogether when making crosses between parental lines in the creation of commercial hybrid seed.
A variety of genetic, chemical and mechanical strategies are currently used to direct self-pollination or suppress male flowers (create temporary male sterility), but are limited by factors such as cost, efficiency, persistence and phytotoxic effects.
To help in the controlled production of inbred lines and hybrids, there is therefore a need for a system which would enable the control of floral development, and to obtain a plant of a determined floral sexual type. Female plants are also associated with a yield increase, and when associated with mutations leading to parthenocarpy, can lead to female plants that produce seedless fruits.
Description of the innovation
Researchers of the French National Institute for Agricultural Research -INRA- led by Dr Abdelhafid Bendahmane, have analyzed the genetic determinants involved in the floral type of Cucumis melo (melon).
They have identified a pair of genetic elements A/a (“andromonoecious”) and G/g (“gynoecious”) controlling the floral development of Cucurbitaceae. These genes comprise a regulatory polynucleotide and a nucleic acid encoding the A/a protein (1-aminocyclopropane-1-carboxylic acid synthase, “CmACS-7”) or the G/g protein (CmWIP1 protein, “C. melo Zinc Finger Protein”). The dominant alleles A and G result in an increased production of their respective protein in plants when compared to the recessive alleles a and g.
Researchers have demonstrated that the combination of the A/a and G/g genetic elements fully control the floral development, potentially in a range of dicotyledonous species, resulting in the diversity of sexual phenotypes.
| Genotype |
Phenotype |
Flower type |
| monoecious |
(A / A or a) - (G / G or g) |
male and female |
| andromonoecious |
(a / a) - (G / G or g) |
male and bisexual |
| hermaphroditic |
(a / a) - (g / g) |
bisexual |
| gynoecious |
(A / A or a) - (g / g) |
female |
Industrial applications and technology transfer
This innovation deals with the selection of plant varieties, particularly the selection of the sex type of the flowers of dicotyledonous plants, preferably Cucurbitaceae, and provides to breeders new methods for:
Selection of plants of a determined sex phenotype via the detection of alleles A, a, G and g.
Production of plants with a modified floral type by chemical mutagenesis of the A/a and G/g control elements, resulting in the a/a - g/g genotype and hermaphroditic phenotype.
Production of transgenic plants having a determined floral type, notably but not exclusively the female or bisexual type, through the transformation with the desired combination of the required allele(s) of the “A/a” and/or “G/g” control elements.
These results are protected under two international patent applications (WO2010/012948; WO2007/125264) assigned to INRA, with INRA Transfert entitled to grant licenses for commercial applications.
Publications
- Martin A, Troadec C, Boualem A, Rajab M, Fernandez R, Morin H, Pitrat M, Dogimont C, Bendahmane A., A transposon-induced epigenetic change leads to sex determination in melon, Nature. 2009 Oct 22;461(7267):1135-8
- Boualem A, Troadec C, Kovalski I, Sari MA, Perl-Treves R, Bendahmane A., A conserved ethylene biosynthesis enzyme leads to andromonoecy in two cucumis species, PLoS One. 2009 Jul 3;4(7):e6144
- Boualem A, Fergany M, Fernandez R, Troadec C, Martin A, Morin H, Sari MA, Collin F, Flowers JM, Pitrat M, Purugganan MD, Dogimont C, Bendahmane A., A conserved mutation in an ethylene biosynthesis enzyme leads to andromonoecy in melons, Science. 2008 Aug 8;321(5890):836-8
A model for interactions between A (CmACS-7) and G (CmWIP1) genes, at the basis of sex determination and sexual organs development in melon.
- First, the G gene inhibits the expression of the A gene, allowing stamens to develop, and blocks carpel development. A male flower develops.
- Second, the non-expression of the G gene allows the A gene to express and to repress stamens development. A female flower develops.
- Third, if the A gene is expressed in a non-functional form, stamens can develop and a bisexual flower develop.
Scientific leader
Abdelhafid BENDAHMANE
Research unit
UMR1165 Génomique Végétale
INRA
2 rue Gaston Crémieux,
91057 EVRY,
France
Technology transfer officer
Claire LEMONTEY
INRA Transfert
28 rue du Docteur Finlay,
75015 Paris,
France
Phone: +33 (0) 1 55 35 26 38
Fax: +33 (0) 1 55 35 26 46
Email: claire.lemontey@paris.inra.fr
|
Topics
Species
Researchers have analyzed the genetic determinants involved in the floral type of Cucumis melo (melon). This innovation deals with the selection of plant varieties, particularly the selection of the sex type of the flowers of dicotyledonous plants, preferably Cucurbitaceae, and provides to breeders new methods for selection and production of plants.
