Drought and nitrogen stress effects and tolerance mechanisms in tomato: a review

Being two of the most impactful crop-yield determinants, water and nitrogen (N) greatly affect plant performance, spanning from genes through the whole-plant level. Therefore, adequate water and N management is of utmost importance to face the global societal challenge of sustainably feeding the increasing world population while facing the constraints of climate change. Tomato is an emerging model system because of its economical importance, large genotypic variation, and its recently completely sequenced genome. Moreover, given that tomato plants have high water and N demands, this crop is very attractive for studying plant responses and tolerance mechanisms to deficits in these resources. This explains the huge amount of studies carried out on this topic in recent decades, but so far that valuable information has not yet been reviewed. In this chapter, we critically analyze the impact of drought and N deficiency on tomato at the morphological, physiological, biochemical, and molecular levels. Further, the reported tolerance mechanisms to drought and N deficit are outlined and the current knowledge gaps are summarized. More studies exploring the key genes controlling tolerance in tomato will be crucial to identify new important targets for breeding interventions, making agriculture more productive and sustainable.