The importance of being duplicated in the tomato sHSP gene family

ARCE, DÉBORA P; SPETALE, FLAVIO; CACCHIARELLI, P; KRSTICEVIC, FLAVIA J; PONCE, SERGIO D; PRATTA, GUILLERMO; TAPIA, ELIZABETH

Cali

Conferencia; IV Congreso Colombiano de Bioinformática y Biología Computacional y la VIII Conferencia Iberoamericana de Bioinformática; 2017

Sociedad Iberoamericana de Bioinformática-Sociedad Colombiana de Bioinformática y Biología Computacional

In living organisms, small heat shock proteins (sHSPs) are triggered in response to stress situations. Evolutionary relationships in sHSP genes have been investigated in rice, potato and tomato genomes highlighting the importance of tandem duplication events for the expansion of sHSP gene family in plants. Additionally, transcriptomic studies have revealed complex patterns of expression for these genes during fruit ripening. This work aims to shed light on the way the expression patterns of sHSPs genes get affected by variations in their nearby promoter architecture by taking advantage of their redundant presence. HSEs indeed appeared in the regulatory region of most up-regulated sHSPs genes during tomato fruit ripening, however some striking exceptions are observed. Conversely, regulatory regions of down-regulated, not-differentially expressed or not-expressed sHSP genes are almost depleted of HSEs. Concerning the exceptions, we note Solyc09g015000, arising from tandem duplication event in chromosome 9. This uncharacterized sHSP gene is strongly up-regulated during fruit ripening (and heat shock) but is completely depleted from HSEs. Instead, a unique short CTAGA non-HSE motif, resembling a degenerated HSE sequence, is present as confirmed by similar results in orthologous promoters from S. tuberosum and S. pennelli. Preliminary results from  predicted protein-protein interactions involving the sHSP protein family and heat shock response (HSR) key factors (HSP70s, HSP90 and MBF1c) suggest that Solyc09g015000 could be mediating  the stress response through a regulatory network of the ring type involving four sHSP proteins, two of them of tandem origin, and one uncharacterized protein with an ATPase domain typical of the HSP100 family.