A new discrete dynamic model of ABA-induced stomatal closure predicts key feedback loops

• DOI: 10.1371/journal.pbio.2003451
• Publication Date: 2017-09-22T17:32:48Z
• Authors: Réka Albert; Biswa R. Acharya; Byeong Wook Jeon; Jorge G. T. Zañudo; Mengmeng Zhu; Karim Osman; Sarah M. Assmann
• Keywords: Closure (psychology); Negative feedback

Stomata, microscopic pores in leaf surfaces through which water loss and carbon dioxide uptake occur, are closed response to drought by the phytohormone abscisic acid (ABA). This process is vital for tolerance has been topic of extensive experimental investigation last decades. Although a core signaling chain elucidated consisting ABA binding receptors, alleviates negative regulation protein phosphatases 2C (PP2Cs) kinase OPEN STOMATA 1 (OST1) ultimately results activation anion channels, osmotic loss, stomatal closure, over 70 additional components have identified, yet their relationships with each other poorly elucidated. We integrated processed hundreds disparate observations regarding signal transduction responses underlying closure into network 84 nodes 156 edges and, as result, established those relationships, including identification 36-node, strongly connected (feedback-rich) component well its in- out-components. The network’s domination feedback-rich may reflect general feature rapid events. developed discrete dynamic model this effects plus knockout or constitutive activity 79 on both outcome system (closure) status all internal nodes. model, more than 1024 states, far from fully determined available data, agree existing experiments 82 cases disagree only 17 cases, validation rate 75%. Our reveal that could be engineered impact controlled fashion also provide 140 novel predictions data currently lacking. Noting paucity wet-bench combinatorial node activation, we experimentally confirmed several regard reactive oxygen species, cytosolic Ca2+ (Ca2+c), heterotrimeric G-protein signaling. analyzed dynamics-determining positive feedback loops, thereby elucidating attractor (dynamic behavior) repertoire groups determine attractor. Based analysis, predict likely presence previously unrecognized mechanism dependent Ca2+c. would agreement 10 observations, 85%. research underscores importance generating robust adaptable biological responses. high our illustrates advantages modeling complex, nonlinear systems common biology.