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Understanding genetic hubs in rice inflorescence architecture to increase grain yield

Periodic Reporting for period 1 - GainGrain (Understanding genetic hubs in rice inflorescence architecture to increase grain yield)

Reporting period: 2019-05-01 to 2021-04-30

Reproductive development, one of the most important stages in the plant life cycle, is essential for plant propagation, but also for crop yield. As a result, the molecular regulation of inflorescence architecture is an important research focus.
Domesticated rice (Oryza sativa L.) is a staple crop and by far the most convenient model cereal for research. Often, the knowledge and tools developed in rice can be transferred and validated in other common and ‘orphan’ cereals.
Rice has a complex inflorescence (panicle) whose architecture is established by iterations of branching, and is built by a group of undifferentiated, actively dividing cells forming the inflorescence meristem. The more branched is the inflorescence, the more grain it can produce. Therefore, if we could control inflorescence meristem activity to make more branched and/or longer inflorescence, with more room to set grain, we should be able to produce significant yield increases. Several genes that regulate rice inflorescence meristem activity have been already discovered, but only a very few of them could be used to make more productive plants. To fully exploit the potential of these genes for crop breeding, we need to advance our theoretical knowledge about how they work and are connected, which is the aim of this action, ‘GainGrain’.
GainGrain addresses grain production in rice, which is one of the most important cereals species, a major staple food, and the most important model plant for the wide phylogenetic group of monocots. It intends to dissect the regulatory mechanisms that control the branched inflorescence architecture of rice, aiming to both identify new functions and analyze the regulatory networks of conserved genes. This will eventually lead to improved rice inflorescence morphogenesis, facilitating breeding programs. Nevertheless, GainGrain is designed to transfer to other crops the knowledge and molecular tools obtained in rice. In collaboration with the group of prof. Dabing Zhang in Shanghai, we have clarified how some of these genes interact to regulate rice inflorescence architecture and complexity, and found several more candidate for future analysis. Moreover, our analysis on more species suggested that the molecular mechanisms that we have characterized in rice is quite conserved among plants, which is interesting for future applications in other crops. We are making public these findings by publications and dissemination at conferences and other events. We have participated to these events so far:

• The 7th International Symposium on Plant Reproductive Development (7th ISPRD). 5-8/07/2021 Shanghai Jiao Tong University, China. (Online participation)
• The XV Meeting of Plant Molecular Biology (online). 26-27/11/2020. Spain
• The 17th International Symposium of Rice Functional Genomics (ISRFG) 04-06/11/2019 Taipei, Taiwan.
• The 6th International Symposium on Plant Reproductive Development (6th ISPRD). 22-26/07/2019 Shanghai Jiao Tong University, China.
• Workshop on molecular mechanisms controlling flower development 2019. Presqu'île de Giens, Côte d'Azur, France, 18-22/06/2019.
The Marie Skłodowska-Curie Actions are terrific opportunities to support the early career of young scientists. This project is giving us excellent clues and data to establish our future field of research in rice reproduction. Although a process like this requires years, our ultimate goal is to exploit the genetic potential of rice to increase its productivity, and to provide new tools for breeders.
Example of rice accessions with different inflorescence architecture (bars = 2 cm).