Abstract
In natural and agricultural environments, one of the key stresses that plants face is competition from neighbours. Plant-plant interaction is a dynamic and multiple process that involves numerous changes in morphology, physiology andreproductive success (fitness). The mechanisms pertaining to competition and its interaction with other stresses are poorly understood yet could have important implications for breeding and crop management. Using a set of
Recombinant Inbred Lines derived from an Arabidopsis multiple advanced generation intercross (MAGIC), morphological and fitness traits were compared under competitive and non-competitive conditions, as well as under different
nutrient conditions. QTL mapping analysis was used to link phenotypic variation with different genomic regions. Competition and its combination with nitrogen availability decreased plant size and lateral branching, which is correlated with
reduced fruit number. QTL mapping found one potential QTL region related with fitness under competitive scenarios and one region associated with competitive ability. However, different QTL regions were found when competition was
combined with nitrogen availability. A strong QTL region was found for the ERECTA allele, which results in a semi-dwarf genotype. An independent test of the er mutation was associated with higher collective productivity under
competition and nutrient deficiency scenarios. The results of this study showed the complex and dynamic genetic response of competition. Increased density and nutrient availability clearly trigger different molecular mechanisms
associated with the phenotypic variation of several traits. Potential candidate genes identified in this study will help to decipher the molecular basis of plantplant interactions
| Date of Award | 2019 |
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| Original language | English |
| Awarding Institution |
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| Supervisor | John Doonan (Supervisor) |