58th Italian Society of Agricultural Genetics Annual Congress - Scientific Programme and Poster List

Plant response to drought is a complex trait involving well interconnected networks, of both developmental and epigenetic pathways, leading to rapid reprogramming of plant growth. Here we present a comprehensive description of the molecular networks activated in response to drought, focusing on three different developmental zones (proliferation, expansion, and mature cells) of young Brachypodium leaf. In fact, an in vivo drought assay has shown to cause a dramatic reduction in leaf size (over 45%), mostly due to a decrease in cell expansion, whereas cell division remains largely unaffected. In order to investigate the molecular network controlling leaf growth reduction, the third emerging leaf was dissected in the three developmental zones, and subjected to whole transcriptome and small RNAs profiling based on next generation sequencing. Small RNA-Seq data were analyzed using an in-house bioinformatics pipeline allowing the identification of 66 annotated miRNA genes and 122 new high confidence predictions, greatly expanding the number of known Brachypodium miRNAs. In addition, we identified a large number of small interfering RNA-producing loci that show characteristics suggesting that they may represent young miRNA genes. Our approach allowed to highlight that the expression profiles of both coding and non-coding genes, of different developmental leaf zones, respond differently to drought treatment. Differential expression analyses provide novel evidence for a regulatory network controlling cell division in both normal and stressed conditions. These results strongly suggest that drought triggers a genetic reprogramming of leaf growth where miRNAs and their targets genes are deeply involved