Exploring the genetic regulation of determinate root growth in Cactaceae

SHISHKOVA S; LAS PEÑAS, M. L.; MATVIENKO M.; CUEVAS-MOREIRA, A.; DUBROVSKY, J.

Foz de iguazu

Congreso; 11 th International congrest of plant molecular biology.; 2015

Plant Biology Europe 2014

Species of Cactaceae are well adapted to arid habitats. We have shown that most species from Cactoideae subfamily of the Cactaceae exhibit determinate growth of the primary root and that primary root growth in Cactoideae species matches their environment. Determinate root growth implies early root apical meristem (RAM) consumption and cell differentiation at the root tip. Our results also suggest that this type of growth became fixed after separation of the Cactiodeae/Opuntioideae and Maihuenioideae /Pereskioideae lineages (Shishkova et al., 2013). To characterize genes involved in the RAM maintenance and determinate root growth in cardón Pachycereus pringlei, we employed mRNA-seq and smallRNA-seq, and used CLC Genomic Workbench software for their analysis. mRNA-seq reads were de novo assembled and annotated by protein similarity. We analyzed differential gene expression in primary root tips in the initial growth phase (when RAM is still present), and in the terminal phase (when RAM is already exhausted). We also grouped and annotated small RNAs differentially expressed in the root tip. Besides conserved miRNAs, we identified hundreds of novel, species-specific smRNAs that show differential expression in the two growth phases. Significant conservation was revealed for the amino acid sequence and RNA expression patterns of various proteins of P. pringlei and other plant species. Our results highlight the importance of hormone homeostasis and signaling in P. pringlei root development and suggest that the primary root tip after meristem exhaustion performs functions similar to those of the differentiation zone of Arabidopsis root.