Conclusion
Understanding the plant response to salinity and boron stresses is crucial in developing strategies to overcome these abiotic stresses with resilient cultivars. In our experiments, we observed that the combination of boron deficiency and high salinity has a different impact on plant growth than each stress alone, providing evidence that salinity is not the predominant stress in our conditions. Additionally, the fact that some fewer damaging effects were found under combinations leads us to think that the three stresses applied have strong impact on broccoli plant physiology, triggering adaptation mechanisms in different directions than individually. In this way, water pass, in relation to aquaporins, could be targeted as an avoidance strategy since mineral nutrients did not appear to change in an avoidance direction. Therefore, the broccoli plant appeared to modulate aquaporins expression towards allowing increase water uptake in case of salinity, for reducing B uptake in case of toxicity and for increasing B uptake in case of deficiency. However, the individual aquaporin involved in each treatment differed, pointing to a difficulty of identifying a marker aquaporin gene since each aquaporin expression changed depending on the individual or combination treatment, demonstrating the enormous complexity of aquaporins response.
As the results can be interpreted as a strategy to prevent the stresses applied, the fact that there are still several gaps in the knowledge constitute a challenge for further investigation. However, shutting down or upregulating the transcription of the gene seems not be enough, since the broccoli leave cells has to deal with trafficking of proteins in route to the plasma membrane and those already active in the plasma membrane. In this sense, the regulation of aquaporins in each membrane fraction need to be addressed, along with the functionality of the aquaporins according to the lipid and other proteins environment.