H2O2-triggered Retrograde Signaling from Chloroplasts to Nucleus Plays Specific Role in Response to Stress

Abstract

Background: Detailed insight into the role of chloroplastic H 2 O 2 in cell signaling is necessary. Results: A large change in gene expression occurred in response to chloroplastic H 2 O 2 , resulting in positive and negative effects on the response to stresses. Conclusion: Chloroplastic H 2 O 2 regulates abiotic and biotic stress response. Significance: We provided a new insight into the role of chloroplastic H 2 O 2 in stress response.

Molecular components of stress-responsive plastid retrograde signaling networks and their involvement in ammonium stress

“…45 The H 2 O 2 response is defective in guard-cell chloroplasts of the amos1 mutant, independent of external ammonium treatment and the absence or presence of ABA. 31 The expression of H 2 O 2 -responsive genes, such as small heat shock proteins (HSPs), 27,46 is induced greatly in wild-type Arabidopsis, but not in the amos1 mutant, upon exposure to excess ammonium. 31 These data indicate that a chloroplastic ROS signal is a highly plausible candidate for the AMOS1/EGY1-dependent ammonium-induced plastid retrograde signal.…”

“…29 Likewise, tAPX regulates the production of H 2 O 2 in chloroplasts. 27 As examples of the second type, plastid EX1 and EX2 proteins are required for the transfer of 1 O 2 -mediated plastid-to-nucleus signaling, although their detailed molecular function is unknown. 20,21 As an example of the third type, transcript profile analysis of flu and flu caa39 mutants revealed that topoisomerase VI (Topo VI) acts as a nuclear component of 1 O 2 -mediated plastid-to-nucleus signaling to directly regulate the expression of the AAA-ATPase and other 1 O 2 -responsive genes.…”

“…31 Further, the role chloroplastic H 2 O 2 plays in triggering retrograde signaling to regulate the expression of nuclear genes induced by abiotic and biotic stresses was established by the construction of silencing lines of thylakoid membrane-bound ascorbate peroxidase (tAPX), using RNAi. 27,28 The regulatory role of these molecular components in stressresponsive plastid retrograde signaling can be preliminarily divided into five functional types, based on their targets: regulation of the signal compound level, signal transfer, gene transcription in the nucleus, chloroplast homeostasis, and interaction with other signaling pathways. An example of the first type can be seen in chloroplastic SAL1, a phosphatase that regulates the level of its substrate 3'-phosphoadenosine-5'-phosphate (PAP); high levels of PAP were demonstrated to accumulate in sal1 mutants.…”

“…[2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] More recently, several plastid retrograde signaling pathways have been identified to regulate the expression of stress-related nuclear genes during several stresses such as high light, drought, wounding, heat, and excess ammonium. [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31] Based on the new stress-responsive plastid retrograde signaling pathways just reported in 2012 alone, this review will focus on properties of currently proposed molecular components in the plastid retrograde signaling network under stress. We also specifically discuss possible plastid retrograde signals involved in plant response to ammonium stress.…”

“…Several major signals, including singlet oxygen ( 1 O 2 ), 17-20 3'-phosphoadenosine 5'-phosphate (PAP), 26 hydrogen peroxide (H 2 O 2 ), 27 and methylerythritol cyclodiphosphate (MEcPP), 29 are known to be produced as metabolic intermediates in chloroplasts in response to a variety of stresses. However, the involvement of these signals remains to be established for heat and ammonium stress.…”