Elongacioni faktor translacije 1A kod krompira (Solanum tuberosum L.): karakterizacija izoformi, ekspresija i uloga u odgovoru biljaka na toplotni stres
Translation elongation factor 1A in potato (Solanum tuberosum L.): characterisation of isoforms, expression, and role in plant response to heat-stress
Doctoral thesis (Published version)
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Eukaryotic elongation factor 1A (eEF1A) is a cytosolic, multifunctional protein that plays a central role in the elongation phase of translation by delivering aa-tRNA complex to the A site of the ribosome. The eEF1A is also implicated in the nuclear export of aa-tRNA, organization of the cytoskeleton, participates in proteolysis, and possess chaperone activity. In this thesis, the effects of high temperatures on tuberization, growth, and development, as well as the expression and accumulation of eEF1A in shoots, leaves, and tubers, were investigated in different potato cultivars grown in a controlled environment and field. In addition, the characterization of eEF1A isoforms in leaves of different potato cultivars grown ex vitro or in the field was done. Also, in different potato cultivars, the number of eEF1A-coding genes, as well as the eEF1A genes' transcript expression under a high-temperature treatment, were investigated. Investigation of eEF1A accumulation in micro- and minitubers of heat-sensitive cultivar Désirée revealed a lower level of eEF1A under prolonged heat-stress, while in heat-tolerant cultivar Festival, a higher level of eEF1A in microtubers and older minitubers was found. Also, a significant positive correlation between eEF1A abundance in potato leaves and the potato productivity in the field was observed in two extremely hot years 2001. and 2012. These results indicate an important eEF1A role in mitigation of the adverse impacts of high temperature on the tuberization in potato. Results from ex vitro and field experiments have shown that potato eEF1A is a protein of 49.2 kDa with multiple isoforms (5-8). Increase in eEF1A abundance under high-temperature condition was mainly due to 2-3 basic polypeptides/isoforms. Genomic analysis indicated the existence of multiple genes encoding eEF1A in potato. Analysis of eEF1A genes' transcripts in minitubers of heat-sensitive cultivar Désirée revealed that expression of the most genes was sensitive to high temperature, and there was a significant reduction in number of eEF1A transcripts. On the other hand, in heat-tolerant cultivar Festival, high temperature had a milder effect on eEF1A gene-expression. The abundance of most eEF1A transcripts slightly increased or remained unchanged under high-temperature condition, with the exception of the eEF1A-12 transcript which was highly heat-inducible. Based on results obtained in this thesis, it can be concluded that eEF1A-12 gene expression mainly contributes to an observed increase in eEF1A abundance under high-temperature conditions in tubers of heat-tolerant cultivar Festival, which opens the possibility for its utilization in the development of new heat-tolerant potato varieties by classical breeding or genetic engineering.