Ziv Spiegelman - Department of Plant Pathology and Weed Research, Agricultural Research Organization, The Volcani Center, 68 HaMaccabim Road, P.O. Box 15159, 7505101, Rishon LeZion, Israel.
Or Broshi - Department of Plant Pathology and Weed Research, Agricultural Research Organization, The Volcani Center, 68 HaMaccabim Road, P.O. Box 15159, 7505101, Rishon LeZion, Israel; The Robert H. Smith Faculty of Agriculture, Food and Environment, The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, 76100, Rehovot, Israel..
Amit Shahar - The Robert H. Smith Faculty of Agriculture, Food and Environment, The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, 76100, Rehovot, Israel.
Sumita Omer - The Robert H. Smith Faculty of Agriculture, Food and Environment, The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, 76100, Rehovot, Israel.
Hagit Hak - Department of Plant Pathology and Weed Research, Agricultural Research Organization, The Volcani Center, 68 HaMaccabim Road, P.O. Box 15159, 7505101, Rishon LeZion, Israel.
Shmuel Wolf - The Robert H. Smith Faculty of Agriculture, Food and Environment, The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, 76100, Rehovot, Israel.
The phloem-mobile protein SlCyp1 traffics to distant parts of the shoot to regulate its gravitropic response. In addition, SlCyp1 targets specific cells in the root to promote lateral root development. The tomato (Solanum lycopersicum) Cyclophilin 1 (SlCyp1) gene encodes a peptidyl-prolyl isomerase required for auxin response, lateral root development and gravitropic growth. The SlCyp1 protein is a phloem-mobile signal that moves from shoot to root to regulate lateral root development (Spiegelman et al., Plant J 83:853-863, 2015; J Exp Bot 68:953-964, 2017a). Here, we explored the mechanism of SlCyp1 movement by fusing it to the fluorescent protein mCherry. We found that, once trafficked to the root, SlCyp1 is unloaded from the phloem to the surrounding tissues, including the pericycle and lateral root primordia. Interestingly, SlCyp1 not only moves to the root system, but also to distant parts of the shoot. Grafting of the SlCyp1 mutant diageotropica (dgt) scions on VFN8 control rootstocks resulted in recovery of dgt shoot gravitropism, which was associated with the restoration of auxin-response capacity. Application of the cyclophilin inhibitor cyclosporine A suppressed gravitropic recovery, indicating that SlCyp1 must be active in the target tissue to affect the gravitropic response. These results provide new insights on the mechanism of SlCyp1 transport and functioning as a long-distance signal regulating shoot gravitropism.
Ziv Spiegelman - Department of Plant Pathology and Weed Research, Agricultural Research Organization, The Volcani Center, 68 HaMaccabim Road, P.O. Box 15159, 7505101, Rishon LeZion, Israel.
Or Broshi - Department of Plant Pathology and Weed Research, Agricultural Research Organization, The Volcani Center, 68 HaMaccabim Road, P.O. Box 15159, 7505101, Rishon LeZion, Israel; The Robert H. Smith Faculty of Agriculture, Food and Environment, The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, 76100, Rehovot, Israel..
Amit Shahar - The Robert H. Smith Faculty of Agriculture, Food and Environment, The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, 76100, Rehovot, Israel.
Sumita Omer - The Robert H. Smith Faculty of Agriculture, Food and Environment, The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, 76100, Rehovot, Israel.
Hagit Hak - Department of Plant Pathology and Weed Research, Agricultural Research Organization, The Volcani Center, 68 HaMaccabim Road, P.O. Box 15159, 7505101, Rishon LeZion, Israel.
Shmuel Wolf - The Robert H. Smith Faculty of Agriculture, Food and Environment, The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, 76100, Rehovot, Israel.
The phloem-mobile protein SlCyp1 traffics to distant parts of the shoot to regulate its gravitropic response. In addition, SlCyp1 targets specific cells in the root to promote lateral root development. The tomato (Solanum lycopersicum) Cyclophilin 1 (SlCyp1) gene encodes a peptidyl-prolyl isomerase required for auxin response, lateral root development and gravitropic growth. The SlCyp1 protein is a phloem-mobile signal that moves from shoot to root to regulate lateral root development (Spiegelman et al., Plant J 83:853-863, 2015; J Exp Bot 68:953-964, 2017a). Here, we explored the mechanism of SlCyp1 movement by fusing it to the fluorescent protein mCherry. We found that, once trafficked to the root, SlCyp1 is unloaded from the phloem to the surrounding tissues, including the pericycle and lateral root primordia. Interestingly, SlCyp1 not only moves to the root system, but also to distant parts of the shoot. Grafting of the SlCyp1 mutant diageotropica (dgt) scions on VFN8 control rootstocks resulted in recovery of dgt shoot gravitropism, which was associated with the restoration of auxin-response capacity. Application of the cyclophilin inhibitor cyclosporine A suppressed gravitropic recovery, indicating that SlCyp1 must be active in the target tissue to affect the gravitropic response. These results provide new insights on the mechanism of SlCyp1 transport and functioning as a long-distance signal regulating shoot gravitropism.