Abstract

Phytochromes are involved in the expression of nutrient transporter genes and participate in signaling responses in plants under nutritional deficiency. This study investigated the reciprocal interaction between phytochrome B1 (phyB1) and N, P, and K deficiency responses, specifically focusing on shoot-root communication. For this purpose, we used grafting combinations of the control genotype (WT) with the tomato phyB1-deficient mutant (phyB1) under nutritional sufficiency and individual deficiencies of N, P, and K. In nutrient-sufficient conditions, shoot phyB1 stimulated N and P uptake in the roots and increased stomatal conductance, transpiration, and dry weight accumulation , whereas root phyB1 regulated the accumulation of chlorophyll in the shoot. With N deficiency, the WT/phyB1 combination attenuated the damage caused by N deficiency by increasing the dry weight of the entire plant. Under P deficiency, the absence of root phyB1 decreased N uptake and increased malondialdehyde (MDA) accumulation . However, the deficiency of phyB1 impaired the water-use efficiency of P-deficient plants. Under K deficiency, both shoot and root phyB1 modulated N and K uptake. Furthermore, shoot phyB1 influenced the oxidative status of leaf tissues, as indicated by variations in MDA content, and was associated with enhanced photosynthetic performance. These findings suggest that the phyB1-deficient mutant may have potential as a rootstock to attenuate damage caused by N deficiency in tomato. The results also demonstrate that phyB1 is involved in shoot-root communication for the control of nutritional, physiological, and growth responses in tomato, raising new roles of this photoreceptor and perspectives on the plant nutrition studies.