In vitro Reconstitution of an ABA Signaling Pathway

By Hiroaki Fujii, Viswanathan Chinnusamy, Américo Rodrigues, S. Rubio, Regina Antoni, Sang-Youl Park, Sean Cutler, Jen Sheen, P. L. Rodriguez, Jian‐Kang Zhu. Nature, 2009

789 citations recorded by the source corpus.

The phytohormone abscisic acid (ABA) regulates the expression of many genes in plants; it has critical functions in stress resistance and in growth and development. Several proteins have been reported to function as ABA receptors, and many more are known to be involved in ABA signalling. However, the identities of ABA receptors remain controversial and the mechanism of signalling from perception to downstream gene expression is unclear. Here we show that by combining the recently identified ABA receptor PYR1 with the type 2C protein phosphatase (PP2C) ABI1, the serine/threonine protein kinase SnRK2.6/OST1 and the transcription factor ABF2/AREB1, we can reconstitute ABA-triggered phosphorylation of the transcription factor in vitro. Introduction of these four components into plant protoplasts results in ABA-responsive gene expression. Protoplast and test-tube reconstitution assays were used to test the function of various members of the receptor, protein phosphatase and kinase families. Our results suggest that the default state of the SnRK2 kinases is an autophosphorylated, active state and that the SnRK2 kinases are kept inactive by the PP2Cs through physical interaction and dephosphorylation. We found that in the presence of ABA, the PYR/PYL (pyrabactin resistance 1/PYR1-like) receptor proteins can disrupt the interaction between the SnRK2s and PP2Cs, thus preventing the PP2C-mediated dephosphorylation of the SnRK2s and resulting in the activation of the SnRK2 kinases. Our results reveal new insights into ABA signalling mechanisms and define a minimal set of core components of a complete major ABA signalling pathway.

Subfields: Plant Science

View Paper: https://www.semanticscholar.org/paper/13481b15468ca7d6badb1d3c5b26da5f4b47796b

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In Plant Science

1. Jian‐Kang Zhu
2. Lizhong Xiong
3. R. Bressan
4. Yan Guo
5. Yongqing Yang
6. Huazhong Shi
7. Shahid Ali
8. Dai-Yin Chao

Citations in the corpus

• Plant abiotic stress response and nutrient use efficiency (2020, background): “The core ABA signaling pathway has been reconstituted in vitro and in yeast cells (Fujii et al., 2009; Ruschhaupt et al., 2019).”
• Implications of Abscisic Acid in the Drought Stress Tolerance of Plants (2020, background): “This modulates the stressresponsive genes’ expression [118], or gene encoding ion channels, such as SLAC1 (slow anion channel associated1), SLAH3 (SLAC1 homolog protein3) and QUAC1 (quick activating anion channel1), thereby regulating the stomatal movements [115,116,120,121].”
• Abscisic Acid and Abiotic Stress Tolerance in Crop Plants (2016, background): “The PYR/PYL/RCAR family in Arabidopsis (except PYL13) is capable of activating ABA signaling response, suggesting that nearly all members can function as ABA receptors (Fujii et al., 2009).”
• Abscisic acid dynamics, signaling and functions in plants. (2019, background): “The identity of the proteins of PYL/RCAR family was also demonstrated by in vitro reconstitution of the core ABA signaling pathway (Fujii et al. 2009), and later further confirmed by substantial genetic and structural evidence (Melcher et al.”
• Recent Advances in Hormonal Regulation and Cross-Talk during Non-Climacteric Fruit Development and Ripening (2019, background): “[80–82], and two essential ABA signaling pathways have been suggested: the ‘ABA-PYR/PYL/RCAR-PP2C-SnRK2’ [83], and the ‘ABA-ABAR-WRKY40-ABI5’ pathways [84].”