Dynamic expression of Kunitz protease inhibitors (KPI) in potato plants, sprouts and tubers exposed to light/dark conditions. Cloning of StKPI3.18520.

GITMAN, IVAN F.B.; ULLOA RITA M

Rosario

Congreso; RAFV 2023; 2023

SAFV

During sprouting, proteases break down the tuber storage proteins to provide free amino acids and small peptides which can contribute to the synthesis of structural and functional proteins of the developing sprout. Under continuous dark conditions plants are unable to obtain their resources from photosynthesis and undergo an autophagic process. During senescence, cellular components are degraded and remobilized to other parts of the plant. Plant proteolysis is the result of an interplay between plant proteases and protease inhibitors. We identified 142 protease inhibitors in the potato genome, 18 are clustered in tandem in chromosome 3 at 43 Mbp. According to public RNAseq data we observed that three of them, KPI 3.43.18520, KPI3.43.18580 and KPI3.43.18600, are upregulated in plants exposed to different stress treatments. RT-qPCR assays performed with specific primers against these genes showed that KPI3.43.18520 had the highest expression. Its expression pattern was further evaluated in dormant or sprouting tubers, in sprouts or in in vitro plants grown under 16:8 h photoperiod or under continuous darkness using degenerate primers that amplify a common region shared by KPI3.43.18580 and other closely related KPIs. We observed that KPI transcripts were high in dormant tubers, decreasing ≈ 4-fold in sprouting tubers, while increasing in the young sprout grown in the light. However, if the sprout was kept under dark conditions for long periods, we observed higher levels of expression. On the other hand, KPI transcripts were higher in plants grown under 16:8 photoperiod compared to those grown in the darkness. Overall, these data suggest that the expression of KPIs responds to the different nutritional requirements. To further understand the role of KPI3.18520 we cloned is coding region downstream to 35S promoter in pBI121 to obtain transgenic overexpressing plants.