As adjustable pores, each delimited by a pair of guard cells, stomata are central determinants of plant photosynthesis, transpirational cooling and ecological adaptability, which have huge impact on global water and carbon cycles, plant competitiveness and nutrients in foods. The specialised guard cell anatomy and membrane ion transport enable plants to adapt stomatal aperture rapidly to hormone and environment changes. In contrast to the highly conserved simple structure across land plants, the stomatal size, density and distribution patterns vary substantially among species or genotypes within a species providing ample genetic resources on which selection can operate. Study of the development and function of stomata is crucial to understand cell fate specification, signal transduction and plant–environment interactions and inform approaches to breed ‘climate change ready’ crop varieties with improved agricultural capacity and food nutrients.

Key Concepts

  • Stomata and active stomata control are a key evolutionary innovation vital for plants to survive and thrive on land.
  • Plants use stomata for gas exchange, water regulation, mineral transport, spore dispersal and pathogen defence.
  • Plants produce stomata in organised patterns and in environmentally optimised numbers.
  • Stomata vary widely in size and responsiveness among species or genotypes within a species.
  • The specialised guard cell morphology, anatomy and membrane ion transport enable plants to adapt stomatal aperture rapidly to hormone and environment changes.
  • Stomata have major influence on the growth and fitness of land plants and global environment as well as food security.
  • Revealing the molecular nature of stomatal regulators will inform us the approaches to breed climate resilient crops.

Keywords: climate change; crop production; food nutrients; guard cell; pathogen defence; plant adaptability; stomatal development; sustainable agriculture; water use efficiency

Figure 1. The phenotypes and distribution of stomata. (a,c) Dumbbell‐shaped stomata of Setaria viridis typical of the grasses. (b,d) The kidney‐shaped stomata typical of other species such as Commelina communis. (e) Stomata in grass are arranged strictly in cell files with the identical orientation. (f) Stomata distribute scattered and no‐isotropic orientation in C. communis.
Figure 2. The development of stomata. (a) Developmental framework of angiosperm stomata based on Arabidopsis. A subset of protodermal cells (white) acquires the MMC identity (dark blue) and divides asymmetrically to create a meristemoid (light blue). The meristemoid either differentiates directly into a GMC (guard mother cell) (red) or undergoes up to three rounds of amplifying divisions. The GMC divides symmetrically into paired young guard cells (purple), later forming the mature guard cell (dark green). (b) Developmental framework of monocot stomata based on rice. Protodermal cells gain the stomata precursor fate and divides asymmetrically to form GMCs (grass green). The GMC divides symmetrically to form immature GC (guard cell) pairs (light green) that differentiate into mature GCs (dark green).
Figure 3. Stomatal response to environmental signals and hormones. (a) In the short term, various factors control stomatal movements, such as blue light, low CO2, auxin as well as the high humidity that can induce stomatal opening, while darkness, high CO2, abscisic acid (ABA), salicylic acid (SA) and low humidity intend to induce stomatal closure. (b) In the long term, stomatal density is modified by time‐changing atmosphere carbon dioxide levels. When the atmosphere CO2 is rich, the stomatal density would be low. In contrast, when the atmosphere CO2 is low, the stomatal density would be high. (b) Reproduced by kind permission of Web Manager Trish Roque ( © The University of California Museum of Paleontology, Berkeley, and the Regents of the University of California.
Figure 4. Stomata evolution. Plants acquired the land around 480 million years ago (Mya), the acquisition of stomata approximately in 420 Mya. Mosses and hornworts of the bryophytes and all of vascular plants have stomata.


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Further Reading

Lau OS (2017) Stomata. In: eLS. Chichester: John Wiley & Sons, Ltd. DOI: 10.1002/9780470015902.a0002075.pub3.

Willmer C and Fricker M (1996) Stomata, 2nd edn. London: Chapman & Hall.

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He, Jingjing, and Liang, Yun‐Kuan(Feb 2018) Stomata. In: eLS. John Wiley & Sons Ltd, Chichester. [doi: 10.1002/9780470015902.a0026526]