14 February 2018 from 10:30 to 11:30

PhD Defence Chrysa Pantazopoulou

Mechanisms and consequences of neighbour detection in Arabidopsis thaliana

The global human population is rising rapidly every year, which in turn increases the demands for food production. For that reason crop production must be intensified which requires crop plants to grow in higher densities. This however leads to a very competitive environment, especially for light, that leads to a lower crop yield. Therefore Chrysa Pantazopoulou studied the basic principles needed to grow crop plants in high densities without this negative influence.

Also read the press release Eye-plant coordination determined by the eye about a research paper of Pantazopoulou and colleagues that was published in PNAS.

Weeds

In the presence of weeds, the competition for light becomes even more intense. Inside the dense canopy the light quality is changed due to the absorption of Red (R) and Blue (B) light for photosynthesis and the reflection of Far-red (FR) light from neighbour plants. A reduced R:FR ratio triggers the Shade Avoidance Syndrome (SAS) of the plant. This is a suite of responses that enhance individual plant fitness in dense stands by allocating carbon to petiole or stem elongation and upward movement of the leaf, thus ensuring light capture. These responses go at the expense of carbon allocation to leaf blades and to harvestable organs such as seeds or roots. In combination with a competition with weeds, this causes serious reductions of crop yield.

Two different scenarios

To combat these yield reductions, sustainable ways to suppress weeds and to minimize the allocation of resources towards SAS in the unwanted organs should be developed. Pantazopoulou studied the basic principles needed to achieve this by comparing two different scenarios. The first was changing the planting patterns in dense stands. The second was modifying the shade avoidance responses in dense stands from the very early stage, up to a fully shade avoiding developed canopy. Finally, she also investigated molecular mechanisms of shade avoidance regulation to generate knowledge for future modifications of SAS components.

Six conclusions 

  1. Canopy architecture can have a strong effect on plant growth and weed suppression

  2. Modification of shade avoidance responses may further optimize the canopy performance

  3. Upward leaf movement (hyponasty) is an important response for canopy performance and is triggered by early neighbor detection cues, such as touch FR-enrichment.

  4. Touch and local FR-induced hyponasty are regulated from tissue-dependent distinct pathways

  5. Supplemental FR-induced hyponasty and petiole elongation are local responses which are observed in the target leaf and not the systemic one

  6. Sensing the FR light in the lamina tip to control hyponasty is linked with optimal plant performance

Start date and time
14 February 2018 10:30
End date and time
14 February 2018 11:30
PhD candidate
C. (Chrysa) Pantazopoulou
Dissertation
Mechanisms and consequences of neighbour detection in Arabidopsis thaliana
PhD supervisor(s)
prof.dr. R. Pierikprof.dr. L.A.C.J. Voesenek