The effects of elevated carbon dioxide concentration on leaf growth and development in Populus

The composition of the Earth’s atmosphere is changing. Such changes can largely be<br/>attributed either directly or indirectly to anthropogenic activities. However, the effects<br/>that these changes will have on terrestrial vegetation in the future, represents an area<br/>of great uncertainty. The results that have been published in the literature have<br/>generally concluded that elevated atmospheric carbon dioxide concentration ([eCO2])<br/>causes increased above- and below-ground biomass compared to ambient conditions.<br/>Members of the Populus genus have risen to the forefront of plant research into the<br/>effects of [eCO2]. Members of the genus are extremely fast-growing, making them<br/>suitable candidates for use as biomass energy crops. The Populus trichocarpa<br/>sequence was released in 2006, hence unveiling a huge genetic resource to the plant<br/>science community.<br/>Although a large amount of studies to date have been dedicated to the effects of<br/>[eCO2] on plant growth, few have focussed on the underlying genetic basis of the<br/>changes. However, thanks to the genetic resources that are now freely available, this<br/>has now been addressed. In the series of experiments presented in this thesis a<br/>combination of morphological measurements, gene expression and protein studies<br/>were used to assess the effects of [eCO2] on Populus leaves.<br/>The results of the studies presented here have shown that there were some<br/>differences in various aspects of plant growth as a result of [eCO2], although the<br/>magnitude of the response was lower than has been reported previously in the<br/>literature. However, there were rather few changes in transcript expression (as<br/>assessed by microarrays) due to [eCO2]. This conclusion was reproducible across<br/>different microarray platforms. This result was further confirmed by a proteomics<br/>experiment, which showed that there were no proteins whose abundance differed<br/>significantly between ambient and elevated [CO2].<br/>It is possible that [eCO2] causes an additive effect on gene expression and hence the<br/>sensitivity of the techniques was such that these differences could not be identified.<br/>However, it may be possible that the plants demonstrate a plastic response to [eCO2]<br/>and that the techniques used to assess the response were inappropriate in this case. In<br/>such an instance, more targeted studies on particular biosynthetic pathways of interest<br/>(such as cell wall biosynthesis) may be more appropriate for any future trials.

Name dc:type.qualificationname

Ph.D.

Level dc:type.qualificationlevel

doctoral

Grantor dc:publisher.institution

University of Southampton

Year dc:date.issued

2008

Author dc:creator

• Graham, Laura Elizabeth

Advisor dc:contributor.advisor

• Taylor, Gail