Table 1. Phloem-localized systemic signals.
| Mobile signal | Abbreviation | Species class | Developmental process | Plant species | References |
|---|---|---|---|---|---|
| Transition from vegetative to generative growth | |||||
| FLOWERING LOCUS T | FT | Protein | Flowering | Arabidopsis thaliana, Cucurbita moschata, Curcurbita maxima, Oryza sativa, Solanum lycopersicum, Zea mays, Glycine max, Nicotiana tabacum, Gossypium hirsutum, Solanum tuberosum | [77,78,82,83–94,95] |
| Nucleic acid (mRNA) | [37,96,97] | ||||
| CENTRORADIALIS | ATC | Protein | Flowering | Arabidopsis thaliana | [98] |
| Gibberellins | GA | Hormone | Flowering | Arabidopsis thaliana, Lolium temulentum | [41,42,99,100,99–110] |
| Cytokinins | CK | Hormone | Flowering | Arabidopsis thaliana, Elaeis guineensis | [41–44,100] |
| SINGLE FLOWER TRUSS | SFT | Protein | Flowering, leaf maturation, termination, and abscission | Solanum lycopersicum | [87,88,111] |
| Tuber development | |||||
| BEL1-RELATED HOMEOTIC PROTEIN 5 | BEL5 | Nucleic acid (mRNA) | Tuber development (promotion) | Solanum tuberosum | [112] |
| BEL1-RELATED HOMEOTIC PROTEIN 11 | BEL11 | Nucleic acid (mRNA) | Tuber development (inhibition) | Solanum tuberosum | [113] |
| BEL1-RELATED HOMEOTIC PROTEIN 29 | BEL29 | Nucleic acid (mRNA) | Tuber development (inhibition) | Solanum tuberosum | [113] |
| MicroRNA 156 | miR156 | Nucleic acid (miRNA) | Tuber development (promotion) | Solanum tuberosum | [114] |
| MicroRNA 172 | miR172 | Nucleic acid (miRNA) | Tuber development (promotion) | Solanum tuberosum | [115] |
| POTATO HOMEOBOX 1 | POTH1 | Nucleic acid (mRNA) | Tuber development (promotion) | Solanum tuberosum | [116] |
| SELF-PRUNING 6A | SP6A | Protein | Tuber development/photoperiod (promotion) | Solanum tuberosum | [95] |
| Nutrient status | |||||
| MicroRNA 399 | miR399 | Nucleic acid (miRNA) | Phosphate starvation | Arabidopsis thaliana, Brassica napus, Cucurbita maxima | [117,118] |
| C-TERMINALLY ENCODED PEPTIDE (CEP) DOWNSTREAM 1 | CEPD1 | Protein | Nitrogen acquisition | Arabidopsis thaliana | [119] |
| CEP DOWNSTREAM 2 | CEPD2 | Protein | Nitrogen acquisition | Arabidopsis thaliana | [119] |
| CEPD-LIKE 2 | CEPDL2 | Protein | Nitrogen acquisition | Arabidopsis thaliana | [120] |
| ELONGATED HYPOCOTYL 5 | HY5 | Protein | Nitrogen acquisition and carbon fixation | Arabidopsis thaliana | [121] |
| Root development | |||||
| CYCLOPHILIN 1 | CYP1 | protein | Photosynthetic status/light intensity, root morphology/nutrient acquisition | Solanum lycopersicum | [122,123] |
| INDOLE-3-ACETIC ACID 18 | IAA18 | Ncleic acid (mRNA) | Auxin signaling, lateral root formation | Arabidopsis thaliana | [124] |
| INDOLE-3-ACETIC ACID 28 | IAA28 | Nucleic acid (mRNA) | Auxin signaling, lateral root formation | Arabidopsis thaliana | [124] |
| Auxin | - | Hormone | Gravitropism/halotropism | Arabidopsis thaliana | [41,125,126] |
| MicroRNA 2111 | miR2111 | nucleic acid (miRNA) | Nodulation | Lotus japonicus | [127] |
| Cytokinins | CK | Hormone | Nodulation | Arabidopsis thaliana, Lotus japonicus | [41–44,128] |
| Biotic stress | |||||
| DEFECTIVE IN INDUCED RESISTANCE 1 | DIR1 | Protein | Biotic stress, pathogen defense | Arabidopsis thaliana, Cucumis sativus | [79,129] |
| Dehydroabietinal | DHA | Lipid | Biotic stress, pathogen defense | Arabidopsis thaliana | [12,130,131,132] |
| Azelaic acid | AZA | Lipid | Biotic stress, pathogen defense | Arabidopsis thaliana | [12,133,129,131,134,132] |
| glycerol-3-phosphate | G3P | Lipid | Biotic stress, pathogen defense | Arabidopsis thaliana | [12,135,133,131,132] |
| ACYL-COA BINDING PROTEIN 3 | ACBP3 | protein | Biotic stress, pathogen defense | Arabidopsis thaliana | [136,137] |
| ACYL-COA BINDING PROTEIN 6 | ACBP6 | protein | Biotic stress, pathogen defense | Arabidopsis thaliana, Cucurbita maxima, Oryza sativa | [138,136,137] |
| 12-oxo-phytodienoic acid | OPDA | Lipid | Wounding, pathogen defense | Arabidopsis thaliana | [12,139,140,132] |
| Jasmonic acid | JA | Hormone | Wounding, pathogen defense | Arabidopsis thaliana, Nicotiana attenuata, Solanum lycopersicum | [139–144] |
| Calcium | Ca2+ | Ion/electrical signal | Wounding, pathogen defense | Arabidopsis thaliana | [145] |
| Abiotic stress | |||||
| Abscisic acid | ABA | Hormone | Water status | Glycine max, Xanthium strumarium, Ricinus communis, Citrus sinensis x Poncirus trifoliata, Solanum lycopersicum, Arabidopsis thaliana | [146–152] |
| CLAVATA3/EMBRYO-SURROUNDING REGION-RELATED 25 | CLE25 | Protein | Water status | Arabidopsis thaliana | [153] |
| PHLOEM LIPID ASSOCIATED FAMILY PROTEIN | PLAFP | Protein | Water status | Arabidopsis thaliana, Brassica oleracea | [12,132,154,155] |
| Phosphatidic acid | PtdOH | Lipid | Water status | Arabidopsis thaliana | [12,132,154,155] |
Species and references highlight studies in which the relevant signal is phloem-mobile and functions in the associated developmental process.