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Etude de l’évolution du développement reproductif dans le genre Oryza pour l’amélioration de riz cultivé moderne

Developing the plant of the future Microscopic (Gene/cell) Diversity/variability Evolution/domestication Protein/proteomic Rice
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Abstract

Food production and security will be a major issue for supplying an increasing world population. Rice is one of the major staple crops in the world, providing for the food needs of billions of people daily. A sustainable increase in productivity, especially in developing countries, requires plant material with improved yield potential that is more stress tolerant and more efficient in resource use. Panicle branching complexity, which shows inter- and intra-specific diversity, directly influences the number of grains produced per panicle and therefore yield potential. African rice (O. glaberrima) is a source of tolerance to abiotic and biotic stresses as well as ideal plant architecture. However, a strong post-zygotic reproductive barrier separates the Asian and African cultivated species, limiting significantly the use of the genetic potential of O. glaberrima for the improvement of Asian rice.

Goal

The broad aim of this project was to identity the evolutionary determinants of panicle architecture in African and Asian rice and of the reproductive barriers that exist between these species. The first objective was to characterize the cellular events underlying panicle development and reproductive barriers between Asian and African species. The second objective was to identify the molecular mechanisms leading to inter- and intra-specific variations of panicle architecture and to female sterility of F1 interspecific hybrids between O. glaberrima and O. sativa.

Results

• Diversity of panicle structure complexity between domesticated and wild-relatives is associated with differences in rachis meristem size and differential rates of axillary meristem establishment rather than heterochronic effects (ie. timing of acquisition of floral fate).
• A marked switch in expression profile is observed in the panicle between apical and axillary meristem types followed by more gradual changes during transitions in axillary meristem identity. Moreover, differential gene expression patterns were observed between crop and wild relatives with convergences and divergences between the Asian and African domestications.
• F1 interspecific hybrids between O. glaberrima and O. sativa are characterised by a defect in embryo sac differentiation and an alteration of expression of certain genes from the S1 locus.
• Several putative targets of the OsMADS13 protein controlling ovule development in rice were identified and functionally characterised.
• Genetic approaches using interspecific population (CSSL) and Genome-wide association studies (GWAS) on Asian and African populations allowed the identification of several QTLs associated with panicle morphological traits.

Perspectives

Beyond this project, the activities of the partnership will focus on the functional characterisation of the candidate genes identified via transcriptomic and genetic approaches and on the modelling of morphology and Gene Regulatory Networks governing panicle development and its diversity in order to identify the determinants of this vital plant structure.

Project Images

Project Number : 1201-004

Year : 2012

Type of funding : AAP

Project type : AAP CARIPLO

Start date :
02 Jan 2013

End date :
30 Jun 2016

Flagship project :
Non

Project leader :
Stephane Jouannic

Project leader's institution :
IRD

Project leader's RU :
DIADE

Budget allocated :
224999 €

Total budget allocated ( including co-financing) :
449998 €

Funding :
Labex