Identification of a major QTL that alters flowering time at elevated [CO(2)] in Arabidopsis thaliana.

The transition from vegetative to reproductive stages marks a major milestone in plant development. It is clear that global change factors (e.g., increasing [CO(2)] and temperature) have already had and will continue to have a large impact on plant flowering times in the future. Increasing atmospheric [CO(2)] has recently been shown to affect flowering time, and may produce even greater responses than increasing temperature. Much is known about the genes influencing flowering time, although their relevance to changing [CO(2)] is not well understood. Thus, we present the first study to identify QTL (Quantitative Trait Loci) that affect flowering time at elevated [CO(2)] in Arabidopsis thaliana.We developed our mapping population by crossing a genotype previously selected for high fitness at elevated [CO(2)] (SG, Selection Genotype) to a Cape Verde genotype (Cvi-0). SG exhibits delayed flowering at elevated [CO(2)], whereas Cvi-0 is non-responsive to elevated [CO(2)] for flowering time. We mapped one major QTL to the upper portion of chromosome 1 that explains 1/3 of the difference in flowering time between current and elevated [CO(2)] between the SG and Cvi-0 parents. This QTL also alters the stage at which flowering occurs, as determined from higher rosette leaf number at flowering in RILs (Recombinant Inbred Lines) harboring the SG allele. A follow-up study using Arabidopsis mutants for flowering time genes within the significant QTL suggests MOTHER OF FT AND TFL1 (MFT) as a potential candidate gene for altered flowering time at elevated [CO(2)].This work sheds light on the underlying genetic architecture that controls flowering time at elevated [CO(2)]. Prior to this work, very little to nothing was known about these mechanisms at the genomic level. Such a broader understanding will be key for better predicting shifts in plant phenology and for developing successful crops for future environments

Frequency distribution of RIL responses for flowering time.

<p>The x-axis was calculated as days to flower at 700 ppm [CO₂] minus days to flower 380 ppm [CO₂]. Thus, positive values represent delays in flowering at elevated [CO₂] and negative values represent more rapid flowering (with 0 being no change in flowering time due to [CO₂]). Differences for parental Cvi-0 and SG are shown with arrows.</p

Response of the MFT knock-out mutant and wild-type (WT), which is Columbia (Col-0) to current (380 ppm) and elevated (700 ppm) CO₂.

<p>Symbols are means ± 1 standard error.</p

Linkage map showing the distribution of SNP markers across the five chromosomes used in our QTL study.

<p>The markers associated with particular flowering time genes are identified in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0049028#pone.0049028.s003" target="_blank">Table S1</a>.</p

The LOD score as a function of map location.

<p>The horizontal line at 2.5 is the significance threshold.</p