A chloroplast retrograde signal, 3'-phosphoadenosine 5'-phosphate, acts as a secondary messenger in abscisic acid signaling in stomatal closure and germination.
Organelle-nuclear retrograde signaling regulates gene expression, but its roles in specialized cells and integration with hormonal signaling remain enigmatic. Here we show that the SAL1-PAP (3'-phosphoadenosine 5'- phosphate) retrograde pathway interacts with abscisic acid (ABA) signaling to regulate stomatal closure and seed germination inArabidopsis. Genetically or exogenously manipulating PAP bypasses the canonical signaling components ABA Insensitive 1 (ABI1) and Open Stomata 1 (OST1); priming an alternative pathway that restores ABA-responsive gene expression, ROS bursts, ion channel function, stomatal closure and drought tolerance inost1-2. PAP also inhibits wild type andabi1-1 seed germination by enhancing ABA sensitivity. PAP-XRN signaling interacts with ABA, ROS and Ca2+; up-regulating multiple ABA signaling components, including lowly-expressed Calcium Dependent Protein Kinases (CDPKs) capable of activating the anion channel SLAC1. Thus, PAP exhibits many secondary messenger attributes and exemplifies how retrograde signals can have broader roles in hormone signaling, allowing chloroplasts to fine-tune physiological responses.
ARC Centre of Excellence in Plant Energy Biology, Research School of Biology, The Australian National University, Acton, Australia.|Department of Biochemistry, Faculty of Science, Kasetsart University, Bangkok, Thailand.
Wannarat
W
Pornsiriwong
ARC Centre of Excellence in Plant Energy Biology, Research School of Biology, The Australian National University, Acton, Australia.|CSIRO Agriculture and Food, Acton, Australia.
Gonzalo M
GM
Estavillo
ARC Centre of Excellence in Plant Energy Biology, Research School of Biology, The Australian National University, Acton, Australia.
Kai Xun
0000-0003-3554-7228
KX
Chan
ARC Centre of Excellence in Plant Energy Biology, Research School of Biology, The Australian National University, Acton, Australia.
Estee E
EE
Tee
ARC Centre of Excellence in Plant Energy Biology, Research School of Biology, The Australian National University, Acton, Australia.
Diep
D
Ganguly
ARC Centre of Excellence in Plant Energy Biology, Research School of Biology, The Australian National University, Acton, Australia.
Peter A
0000-0002-3655-0130
PA
Crisp
ARC Centre of Excellence in Plant Energy Biology, Research School of Biology, The Australian National University, Acton, Australia.
Su Yin
SY
Phua
School of Science and Health, Western Sydney University, Richmond, Australia.
Chenchen
C
Zhao
ARC Centre of Excellence in Plant Energy Biology, Department of Plant Science, School of Agriculture, Food and Wine, University of Adelaide, Glen Osmond, Australia.|Waite Research Institute, University of Adelaide, Glen Osmond, Australia.
Jiaen
J
Qiu
Division of Biological Sciences, Cell and Developmental Biology Section, University of California, San Diego, San Diego, United States.
Jiyoung
J
Park
School of Science and Health, Western Sydney University, Richmond, Australia.
Miing Tiem
MT
Yong
ARC Centre of Excellence in Plant Energy Biology, Research School of Biology, The Australian National University, Acton, Australia.
Nazia
N
Nisar
ARC Centre of Excellence in Plant Energy Biology, Research School of Biology, The Australian National University, Acton, Australia.
Arun Kumar
AK
Yadav
Research School of Biology, The Australian National University, Acton, Australia.
Benjamin
B
Schwessinger
Research School of Biology, The Australian National University, Acton, Australia.
John
J
Rathjen
ARC Centre of Excellence in Plant Energy Biology, Research School of Biology, The Australian National University, Acton, Australia.|Hawkesbury Institute for the Environment, Western Sydney University, Richmond, Australia.
Christopher I
CI
Cazzonelli
ARC Centre of Excellence in Plant Energy Biology, Research School of Biology, The Australian National University, Acton, Australia.
Philippa B
PB
Wilson
ARC Centre of Excellence in Plant Energy Biology, Department of Plant Science, School of Agriculture, Food and Wine, University of Adelaide, Glen Osmond, Australia.
Matthew
0000-0003-0666-3078
M
Gilliham
School of Science and Health, Western Sydney University, Richmond, Australia.|College of Agriculture and Biotechnology, Zhejiang University, Hangzhou, China.
Zhong-Hua
ZH
Chen
ARC Centre of Excellence in Plant Energy Biology, Research School of Biology, The Australian National University, Acton, Australia.
Barry J
0000-0003-1869-2423
BJ
Pogson
D000040:Abscisic Acid / Q000378:metabolism*; D000244:Adenosine Diphosphate / Q000378:metabolism*; D017360:Arabidopsis / Q000502:physiology*; D002736:Chloroplasts / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D018525:Germination; D010937:Plant Growth Regulators / Q000378:metabolism; D054046:Plant Stomata / Q000502:physiology*; D015398:Signal Transduction
D010937:Plant Growth Regulators; D000244:Adenosine Diphosphate; D000040:Abscisic Acid; C010840:adenosine 3'-phosphate-5'-phosphate
3'-phosphoadenosine 5'-phosphate; A. thaliana; ABA signaling; chloroplast; plant biology; retrograde signaling; seed germination; stomatal closure; xenopus