Computational modeling and molecular physiology experiments reveal new insights into shoot branching in pea.
Bud outgrowth is regulated by the interplay of multiple hormones, including auxin, cytokinin, strigolactones, and an unidentified long-distance feedback signal that moves from shoot to root. The model of bud outgrowth regulation in pea (Pisum sativum) includes these signals and a network of five RAMOSUS (RMS) genes that operate in a shoot-root-shoot loop to regulate the synthesis of, and response to, strigolactones. The number of components in this network renders the integration of new and existing hypotheses both complex and cumbersome. A hypothesis-driven computational model was therefore developed to help understand regulation of shoot branching. The model evolved in parallel with stepwise laboratory research, helping to define and test key hypotheses. The computational model was used to verify new mechanisms involved in the regulation of shoot branching by confirming that the new hypotheses captured all relevant biological data sets. Based on cytokinin and RMS1 expression analyses, this model is extended to include subtle but important differences in the function of RMS3 and RMS4 genes in the shoot and rootstock. Additionally, this research indicates that a branch-derived signal upregulates RMS1 expression independent of the other feedback signal. Furthermore, we propose xylem-sap cytokinin promotes sustained bud outgrowth, rather than acting at the earlier stage of bud release.
Dun
Elizabeth A
EA
The University of Queensland, Australian Research Council Centre of Excellence for Integrative Legume Research and School of Biological Sciences, St. Lucia 4072, Australia.
Hanan
Jim
J
Beveridge
Christine A
CA
D000465:Algorithms; D000595:Amino Acid Sequence; D003198:Computer Simulation; D003583:Cytokinins / Q000235:genetics / Q000378:metabolism; D025461:Feedback, Physiological / Q000502:physiology; D018506:Gene Expression Regulation, Plant / Q000235:genetics*; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism; D055641:Mathematical Concepts; D008969:Molecular Sequence Data; D010105:Oxygenases / Q000235:genetics / Q000378:metabolism; D018532:Pisum sativum / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D018520:Plant Shoots / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D040901:Proteomics / Q000379:methods; D015398:Signal Transduction / Q000235:genetics
D003583:Cytokinins; D036341:Intercellular Signaling Peptides and Proteins; D010105:Oxygenases; C475747:RMS1 protein, pea