Targeted effects of beneficial elements in plant photosynthetic process

Photosynthesis is the process that fuels the life on Earth. The proper functioning of this process is strictly connected to plant nutrition as well as the overall plant status. In addition to essential macro- and micronutrients, a set of other elements (metals, semi-metals, and non-metals) have been proposed as beneficial for plant performances in both optimal and stressful conditions. Following the definition of 'essentiality' proposed by Arnon and Stout in late 30s, those elements are not essential given that not necessary for plants to complete their life cycle. However, they also act as functional nutrients and promote plant performances including photosynthetic traits. In this review, we summarize the positive effect of 10 beneficial elements namely Ni, Mo, Cd, Al, Ti, La, Ce, Si, Se, and I for the photosynthesis of plants growing in optimal or stressful conditions. The purpose was to draw a clear picture of the role played by these elements in ameliorating the photosynthetic performances of different plant species and propose that those beneficial elements should be considered in the context of mineral nutrition, at least as functional nutrients.