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.