ROLE OF THE ALOG GENE FAMILY IN THE INFLORESCENCE DEVELOPMENT OF ORYZA SATIVA AND ARABIDOPSIS THALIANA

Human population growth makes it of primary importance to find new ways to sustainably increase agricultural crop production to meet the increasing food demand. In this context, inflorescence architecture is one of the key agronomical traits which determines grain yield; thus, it has been a major target for crop domestication and improvement. For example, in rice an increased number of branches allows the panicle to bear more seeds, leading to a higher yield. To study the molecular genetic processes that lead to inflorescence architecture establishment, we used two model plant species: Oryza sativa, model plant for monocotyledons, and Arabidopsis thaliana, model plant for dicotyledons. In both Arabidopsis and rice, inflorescence architecture development depends on a complex gene regulatory network that controls the identity and activity of the reproductive meristems. A substantial number of genes involved in the pathways that lead to inflorescence architecture development have been identified, however, this complex developmental process is still far from understood. To identify new players involved in panicle development, reproductive meristems of Arabidopsis and rice were isolated by laser microdissection at different stages of development and used for RNA-seq analysis. The analysis of differentially expressed genes between the various stages of meristem development showed that several members of the ALOG (Arabidopsis LIGHT-DEPENDENT SHORT HYPOCOTYL 1 and Oryza G1) gene family showed the same expression pattern in meristematic tissues, suggesting a possible role in the determination of inflorescence architecture. These genes are OsG1L1, OsG1L2 and TAW1/OsG1L5 of rice; and AtLSH1, AtLSH3 and AtLSH4 of Arabidopsis. One member of the rice ALOG gene family, TAW1/OsG1L5, was already shown to be a fundamental regulator of inflorescence development in rice (Yoshida et al., 2013), further suggesting an important role for the ALOG gene family in reproductive development. My Ph.D. research project was focused on elucidating the role of the ALOG genes in inflorescence development in both Arabidopsis and rice. We generated single and multiple mutants in both species using CRISPR-Cas9. The molecular and morphological analysis of the mutants revealed that the knock-out of these genes determined defects in plant inflorescence architecture linked to the process of identity acquisition of the reproductive meristems.