Transcript profiling reveals that Cystein protease inhibitors are up-regulated in tuber sprouts after extended darkness

GRANDELLIS C; CERRUDO I; ULLOA RM; FANTINO E; SANTIN F; GIAMMARIA V; BACHMANN S

FUNCTIONAL & INTEGRATIVE GENOMICS

SPRINGER HEIDELBERG

Lugar: HEIDELBERG; Año: 2016 vol. 4 p. 399 - 418

1438-793X

Potato (Solanum tuberosum L.) tubers are an excellent staple food due to its high nutritional value. When the3 tuber reaches physiological competence, sprouting proceeds accompanied by changes at mRNA and protein4 levels. Potato tubers become a source of carbon and energy until sprouts are capable of independent growth.5 Transcript profiling of sprouts grown under continuous light or dark conditions was performed using the6 TIGR 10K EST Solanaceae microarray. The profiles analyzed show a core of highly expressed transcripts that7 are associated to the reactivation of growth. Under light conditions, the photosynthetic machinery was fully8 activated; the highest up-regulation was observed for the Rubisco activase (RCA), the glyceraldehyde-3-9 phosphate dehydrogenase (GAPDH) and the Photosystem II 22 kDa protein (CP22) genes, among others. On10 the other hand, sprouts exposed to continuous darkness elongate longer, and after extended darkness,11 synthesis of chloroplast components was repressed, the expression of proteases was reduced while genes12 encoding cystein protease inhibitors (CPIs) and metallocarboxypeptidase inhibitors (MPIs) were strongly13 induced. Northern blot and RT-PCR analysis confirmed that MPI levels correlated with the length of the dark14 period, however CPI expression was strong only after longer periods of darkness, suggesting a feedback-loop15 (regulation mechanism) in response to dark-induced senescence. Prevention of cystein protease activity in16 etiolated sprouts exposed to extended darkness could delay senescence until they emerge to light.