ROLE OF ALOG FAMILY GENES IN INFLORESCENCE PATTERNING IN ORYZA SATIVA AND ARABIDOPSIS THALIANA

Inflorescence architecture is a key agronomical trait that determines fruit and seed yield. Understanding the genetic basis of inflorescence architecture will not only contribute to elucidate crop evolution/domestication mechanisms but also improve crop grain yield. Flowering plants develop different types of inflorescences, such as racemes in Arabidopsis and panicles in rice. The architecture is established during the early stages of reproductive development and it is determined by the activity of different meristem types and by the timing of the transition between indeterminate meristems to determinate ones. Inflorescence development is finely regulated by a genetic network that includes meristem identity genes and genes that regulate their expression; many genes are already known but others have still to be characterized to provide insight into how this complex process is controlled. Transcriptomic analysis performed in rice and in Arabidopsis through laser microdissection of different meristematic tissues highlighted differentially expressed genes belonging to the ALOG family suggesting their role in inflorescence patterning. We focus on G1L1, G1L2, and G1L5 of rice and on LSH1, LSH3, and LSH4 of Arabidopsis. G1L5 is already known to be a major regulator of inflorescence architecture, whereas LSH3 and LSH4 seem to have a role in meristem maintenance and organogenesis. Their expression profiles were analyzed by qRT-PCR and RNA in situ hybridization experiments using meristematic tissues from both species. We are also generating single and double/triple K.O mutants in different combinations by CRISPR-Cas9 genome editing technology to have a better understanding of their role in inflorescence patterning. The data so far obtained demonstrate the role of G1L1 and G1L2 in inflorescence branching and spikelet number determination and we also propose a role for G1L2 in root development. Furthermore, LSH1 seems to be involved in meristem maintenance and organ differentiation, and LSH3 in stem elongation. We propose the hypothesis that LSH1, LSH3, and LSH4 play a redundant function in inflorescence development.