FUNCTIONAL CHARACTERIZATION OF TANDEM DUPLICATED sHSPS GENES IN TOMATO, POTATO AND ARABIDOPSIS GENOMES

CACCHIARELLI, PAOLO; ARCE, DÉBORA; TAPIA, ELIZABETH; PRATA, GUILLERMO R

Posadas, Misiones

Congreso; VIII Argentinian Bioinformatics and Computational Biology Congress; 2017

Asociación Argentina de Bioinformática y Biología Computacional

Small heat shock proteins (sHSPs, 12?40 kDa) have been associated with stress tolerance by preventing irreversible aggregation of misfolded proteins. Abiotic stress and developmental changes trigger sHSP gene expression and protein synthesis in Arabidopsis and Solanaceae plants, suggesting the existence of a complex chaperone-network to maintain cellular homeostasis. Previous analysis of sHSP gene family in the tomato genome, Solanum lycopersicum cv. Heinz 1706, identified two tandem duplicated sHSP genes (Solyc09g015000 and Solyc09g015020) mapping together in chromosome 09. Although both these genes are strongly induced during tomato heat stress, only one of them (Solyc09g015020) exhibits the characteristic presence of heat shock elements (HSEs) in its promoter region. Taking into account that Solyc09g015000 is also up-regulated during tomato abiotic stress and developmental changes, we wonder about the actual importance of HSEs for triggering the expression of sHSP genes. To shed light onto this issue, we evaluated the gene copy number and the presence of Solyc09g015000 and Solyc09g015020 orthologs across potato and Arabidopsis genomes. Comparison between tomato and potato indicates a numerical chromosome reorganization effect, while the comparison between tomato and Arabidopsis indicates a structural chromosome reorganization effect. Seven orthologs were found in S. tuberosum (PGSC v4.03), four of them were down-regulated after HS and showed the presence of HSEs. On the other hand, just one ortholog (AT3G46230) was found in Arabidopsis (Araport11); similarly to Solyc09g015020, AT3G46230 was up-regulated after HS and exhibits the presence of HSE. On the whole, these results suggest that absence of typical HSEs appears to be counterparted by the presence of a specific non-HSE (CTAGA) similar to that observed in the promoter region of MBF1c in Arabidopsis. MBF1c is a thermotolerance regulator up-regulated during heat shock in Arabidopsis and tomato. Furthermore, to uncover the functionality of target sHSP genes in these species, protein-protein interactions networks were built, suggesting that a conserved set of genes is associated to heat shock response in the three plant species, independently of duplications and polyploidy.