Family Ties: Root-Root Communications Within and Outside the Family (Solanaceae to Fabaceae)

Earlier studies have shown that plants may use their root systems to communicate with other plants, this enables them to recognize and react to genetic relatedness and differentiate between self and non-self roots. Our ground-breaking study has shown that crops in the Solanaceae family, particularly bell pepper and tomatoes (cherry tomato and field tomato), can communicate through the root systems based on their degrees of relatedness (DOR). The study examined the effects of root-root communication on physiological and metabolic aspects in tomatoes and bell pepper plants, and the results showed that as DOR decreased, root growth and respiration increased in L-DOR plants with lower organic carbon and protein levels, suggesting that genetic relatedness plays a key role in root communication within the Solanaceae. Building on these findings, our objective was to know how plants respond differently to plants that are not genetically related or are outside their family. We examined the physiological and morphological changes in response to neighbor relatedness within the Solanaceae family (cherry tomato (C) and bell pepper (B)) and between the Solanaceae and Fabaceae family (pea (P)). Nine combinations were studied, examining self (C, B, P) and non-self-interactions (CC, CB, CP, BB, BP, PP). Two separate experiments were conducted; using rhizoslides, a paper-based growth system, and a pot experiment with a four-pot design with a split root system. The results demonstrated that cherry tomato increased plant height, stem diameter, chlorophyll content, photosynthesis, stomatal conductance, and root respiration parameters when paired with bell pepper. In contrast, when paired with cherry tomato, bell pepper exhibited decreases in all these parameters, indicating that bell peppers are beneficial neighbors to cherry tomato, whereas cherry tomato are costly neighbors to bell pepper. However, both cherry tomato and bell pepper performed better when grown with a neighbor from outside the family, pea. Pea showed an increase in all parameters when grown alone or with a Solanaceae neighbor but decreased when grown with a closely related neighbor. By understanding natural plant communication networks from both inside and outside of the Solanaceae family, root-to-root communication may result in improved agricultural techniques that increase crop resilience and yield.