From evolution to biotechnology: the impacts of genetically modifying
stomatal development

Robert Spencer Caine; C. Chater; X. Jin; C. Hepworth; E. Harrison; J. Sloan; J. Dunn; J. Hughes; Lee Hunt; W. Quick; A.Fleming; J. Gray

Abstract

From evolution to biotechnology: the impacts of genetically modifying stomatal development

Changes in climate, increasing human population and reducing
arable land area will lead to significant challenges in producing
enough food. Therefore, increasingly climate-resilient
crops will be required; which ideally will produce higher yields
in future climates. One way to improve crop resilience and
yield is via alterations to tiny pores on the epidermis called
stomata. These microscopic structures, which have been present
on land plants for over 400 million years, are fundamental
to both the success of land plants and the shaping of the terrestrial
biosphere. Stomata therefore are a key structures for
plant-environment interactions and are a key target for crop
improvement. Consisting of pairs of guard cells surrounding a
central pore, Stomata control gaseous diffusion into and out of
the plant. Open stomata allow CO2 uptake, regulate water loss
and permit a transpiration stream; enabling photosynthesis,
plant cooling and nutrient uptake. Conversely, closed stomata
restrict gaseous exchange (including water loss) and restrict
certain pathogens from entering into the leaf. Over the longer
term, plants can also alter stomatal development to more finely
tune gaseous exchanges with the environment, and if necessary,
tighten defenses against biotic attackers. Typically, plants
with fewer stomata have improved drought tolerance and resistance
to stomatal pathogens, but this may be accompanied by
reduced CO2 and nutrient uptake, and reduced capacity for
plant cooling. In recent times it has become possible to genetically
modify a large number of different land plant model
species. Here, I will outline the latest advances relating to how
stomatal development and plant performance can potentially
be altered via genetic alterations to stomata development across
multiple plant species. First considering Arabidopsis thaliana
and then onto the non-vascular land plant moss Physcomitrella
patens, I will discuss how reducing stomatal density affects
crop plant performance in a number of key species, including
barley, rice and wheat. I will predominantly focus on how this
has been achieved via the modulation of signaling peptides
called Epidermal Patterning Factors (EPFs). By assessing results
achieved thus far, I will identify both potential strengths and
weaknesses of adjusting EPF signaling in a number of different
species, and finishing by discussing future directions of this key
research area