Floração em cana-de-açúcar - desvendando o papel da HINT1 e Subtilase

Abstract

Flowering is a critical stage that promotes the transition of shoot apical meristem from the vegetative to reproductive stage. This transition is orchestrated by different signals (external and internal) that have been characterized in different models as Arabidopsis thaliana, Oryza sativa and Zea mays. For sugarcane this process is not well-known in molecular way. However, it has an important impact in yield. Considering this, the work presents here had the aim to characterize a sequence that had homology to HINT1 protein by different approaches. This sequence was previously identified using subtractive libraries from shoot apical meristem during different stages of sugarcane development. It was verified that HINT sequences were conserved in plants, and it was separate into two large branches: monocots and dicots. The data obtained from the 3D modeling showed that ScHINT may be a functional protein, as it presents the important binding sites for its catalytic activity. A second protein that was worked was ScSUBTILASE. This protein was characterized had been previously identified in a protein-protein assay using the two-hybrid methods. Here, it was attempted to understand the role of SUBTILASE and HINT1. It was verified that the ScSUBTILASE protein was also conserved in plants, and the modeling showed that it might also be functional due to the 3D structure and the presence of catalytic sites. In the twohybrid assays, a third protein was identified with homology to PHENYLALANINE AMMONIA-LYASE. The modeling was carried out and it was observed that this too must be functional. The other approached used was interactome using STRING. The results obtained for the proteins HINT, SUBTILASE and PHENYLALANINE AMMONIA-LYASE in the Arabidopsis model showed that these sequences are associated with the response of the production of ROS. Based on the results presented and on the literature data, it may be proposed that ScHINT and ScSUBTILASE may have the role of maintaining the level of ROS at the shoot apical meristematic during the transition process. The results obtained with transgenic Nicotiana tabacum plants containing over-expression cassettes in sense and antisense orientations for ScHINT1 reinforce the proposal idea that ScHINT may be associated with the flowering process.