Faculty Opinions recommendation of Guard cell starch degradation yields glucose for rapid stomatal opening in arabidopsis.

Phytophthora infestans, the most damaging oomycete pathogen of potato, is specialized to grow sporangiophore through opened stomata for secondary inoculum production. However, it is still unclear which metabolic pathways in potato are manipulated by P. infestans in the guard cell–pathogen interactions to open the stomata. Here microscopic observations and cell biology were used to investigate antagonistic interactions between guard cells and the oomycete pathogen. We observed that the antagonistic interactions started at the very beginning of infection. Stomatal movement is an important part of the immune response of potato to P. infestans infection and this occurs through guard cell death and stomatal closure. We observed that P. infestans appeared to manipulate metabolic processes in guard cells, such as triacylglycerol (TAG) breakdown, starch degradation, H2O2 scavenging, and NO catabolism, which are involved in stomatal movement, to evade these stomatal defense responses. The signal transduction pathway of P. infestans-induced stomatal opening likely starts from H2O2 and NO scavenging, along with TAG breakdown while the subsequent starch degradation reinforces the opening process by strengthening guard cell turgor and opening the stomata to their maximum aperture. These results suggest that stomata are a barrier stopping P. infestans from completing its life cycle, but this host defense system can be bypassed through the manipulation of diverse metabolic pathways that may be induced by P. infestans effector proteins.

Download Full-text

GABA signalling modulates stomatal opening to enhance plant water use efficiency and drought resilience

Nature Communications ◽

10.1038/s41467-021-21694-3 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Bo Xu ◽

Yu Long ◽

Xueying Feng ◽

Xujun Zhu ◽

Na Sai ◽

...

Keyword(s):

Water Use Efficiency ◽

Water Use ◽

Guard Cell ◽

Plant Stress ◽

Stomatal Opening ◽

Fine Tuning ◽

Protein Amino Acid ◽

Gaba Production ◽

Anion Transporter ◽

Use Efficiency

AbstractThe non-protein amino acid γ-aminobutyric acid (GABA) has been proposed to be an ancient messenger for cellular communication conserved across biological kingdoms. GABA has well-defined signalling roles in animals; however, whilst GABA accumulates in plants under stress it has not been determined if, how, where and when GABA acts as an endogenous plant signalling molecule. Here, we establish endogenous GABA as a bona fide plant signal, acting via a mechanism not found in animals. Using Arabidopsis thaliana, we show guard cell GABA production is necessary and sufficient to reduce stomatal opening and transpirational water loss, which improves water use efficiency and drought tolerance, via negative regulation of a stomatal guard cell tonoplast-localised anion transporter. We find GABA modulation of stomata occurs in multiple plants, including dicot and monocot crops. This study highlights a role for GABA metabolism in fine tuning physiology and opens alternative avenues for improving plant stress resilience.

Download Full-text

Guard-Cell-Specific Expression of Phototropin2 C-Terminal Fragment Enhances Leaf Transpiration

Plants ◽

10.3390/plants11010065 ◽

2021 ◽

Vol 11 (1) ◽

pp. 65

Author(s):

Young-Sun Riu ◽

Hyun-Geun Song ◽

Hwi-Su Kim ◽

Sam-Geun Kong

Keyword(s):

Blue Light ◽

Guard Cell ◽

Ectopic Expression ◽

Stomatal Opening ◽

Chloroplast Movement ◽

35S Promoter ◽

Specific Expression ◽

Endogenous Expression ◽

Terminal Fragment ◽

Leaf Transpiration

Phototropins (phot1 and phot2) are plant-specific blue light receptors that mediate chloroplast movement, stomatal opening, and phototropism. Phototropin is composed of the N-terminus LOV1 and LOV2 domains and the C-terminus Ser/Thr kinase domain. In previous studies, 35-P2CG transgenic plants expressing the phot2 C-terminal fragment–GFP fusion protein (P2CG) under the control of 35S promoter showed constitutive phot2 responses, including chloroplast avoidance response, stomatal opening, and reduced hypocotyl phototropism regardless of blue light, and some detrimental growth phenotypes. In this study, to exclude the detrimental growth phenotypes caused by the ectopic expression of P2C and to improve leaf transpiration, we used the PHOT2 promoter for the endogenous expression of GFP-fused P2C (GP2C) (P2-GP2C) and the BLUS1 promoter for the guard-cell-specific expression of GP2C (B1-GP2C), respectively. In P2-GP2C plants, GP2C expression induced constitutive phototropin responses and a relatively dwarf phenotype as in 35-P2CG plants. In contrast, B1-GP2C plants showed the guard-cell-specific P2C expression that induced constitutive stomatal opening with normal phototropism, chloroplast movement, and growth phenotype. Interestingly, leaf transpiration was significantly improved in B1-GP2C plants compared to that in P2-GP2C plants and WT. Taken together, this transgenic approach could be applied to improve leaf transpiration in indoor plants.

Download Full-text

Action Spectra for Guard Cell Rb+ Uptake and Stomatal Opening in Vivia faba

PLANT PHYSIOLOGY ◽

10.1104/pp.51.1.82 ◽

1973 ◽

Vol 51 (1) ◽

pp. 82-88 ◽

Cited By ~ 76

Author(s):

Theodore C. Hsiao ◽

W. G. Allaway ◽

L. T. Evans

Keyword(s):

Guard Cell ◽

Stomatal Opening ◽

Action Spectra

Download Full-text

Ca2+ signalling in stomatal guard cells

Biochemical Society Transactions ◽

10.1042/bst0280476 ◽

2000 ◽

Vol 28 (4) ◽

pp. 476-481 ◽

Cited By ~ 23

Author(s):

M. R. McAinsh ◽

J. E. Gray ◽

A. M. Hetherington ◽

C. P. Leckie ◽

C. Ng

Keyword(s):

Signal Transduction ◽

Guard Cell ◽

Signal Transduction Pathway ◽

Guard Cells ◽

Stomatal Opening ◽

Cell Turgor ◽

Stomatal Guard Cells ◽

External Stimuli ◽

Spatial And Temporal Characteristics

Ca2+ is a ubiquitous second messenger in the signal transduction pathway(s) by which stomatal guard cells respond to external stimuli. Increases in guard-cell cytosolic free Ca2+ concentration ([Ca2+]cyt) have been observed in response to stimuli that cause both stomatal opening and closure. In addition, several important components of Ca2+-based signalling pathways have been identified in guard cells, including the cADP-ribose and phospholipase C/Ins(1,4,5)P3-mediated Ca2+-mobilizing pathways. The central role of stimulus-induced increases in [Ca2+]cyt in guard-cell signal transduction has been clearly demonstrated in experiments examining the effects of modulating increases in [Ca2+]cyt on alterations in guard-cell turgor or the activity of ion channels that act as effectors in the guard-cell turgor response. In addition, the paradox that Ca2+ is involved in the transduction of signals that result in opposite end responses (stomatal opening and closure) might be accounted for by the generation of stimulus-specific Ca2+ signatures, such that increases in [Ca2+]cyt exhibit unique spatial and temporal characteristics.

Download Full-text