Plant eco‐devo: the potential of poplar as a model organism

Abstract

Summary Ecological developmental genetics is the study of how ecologically significant traits originate in the genome and how the allelic combinations responsible are maintained in populations and species. Plant development involves a continuous feedback between growth and environment and the success of individual genotype × environment interactions determines the passage of alleles to the next generation: the adaptive recursion. Outbreeding plants contain a large amount of genetic variation, mostly in the form of single nucleotide polymorphisms (SNPs). One of the challenges of eco‐devo is to distinguish neutral SNPs from those with ecological consequences. The complete genome sequence of Populus trichocarpa Torr. & A. Gray will be a significant aid in this endeavour. Occurring from California to Alaska, this is the first ecologically ‘keystone’ species to be sequenced. It has a rich natural history and is an obligate outbreeder. The individual sequenced, Nisqually‐1, appears to be heterozygous on average about every 100 bp over the c. 500 million bp of the genome. Overlaid on this within‐individual variation is some ecologically based between‐individual genotypic variation evident across the distribution of the species. The synthesis of information from genomics and ecology is now in prospect. This ‘ecomolecular synthesis’ is likely to provide a rich insight into the genomic basis of plant adaptation.

Admixture in European Populus hybrid zones makes feasible the mapping of loci that contribute to reproductive isolation and trait differences

“…An important aspect is that in evolutionary biology interest often will be directed toward identifying genomic segments subject to natural selection, rather than segments associated with a particular trait alone (Rieseberg et al, 1999;Wu, 2001). For simplicity, variation in such segments is referred to as 'adaptive or detrimental variation' from here onwards.Populus has been suggested as a 'model forest tree' for studying tree form, function, and evolution (Taylor, 2002), interactions between ecological carrier species and their communities (Whitham, 1989), and how ecology interacts with plant development (Cronk, 2005). The favorable genetic attributes of Populus such as small genome size (550 Mb; 2C ¼ 1.1 pg), diploidy throughout the genus (2n ¼ 38), porous species barriers (Rajora and Dancik, 1992;Martinsen et al, 2001;Floate, 2004), and a near-complete genome sequence with thousands of expressed sequence tags and markers (http://www.ornl.gov/sci/ipgc) make this genus an ideal candidate for evaluating the 'admixture mapping' approach in a 'non-human' organism.…”

Variability in Populus leaf anatomy and morphology in relation to canopy position, biomass production, and varietal taxon

“…The placement of species within a section has traditionally been based on morphological and reproductive characteristics, as well as on interspecific crossability [21,71]. However, classical taxonomic analysis, based on morphological characteristics, has proven to be very difficult because of wide intraspecific heteroblasty, high natural crossability among members of the genus, and the convergent morphology shown by hybrids and their parental species [16,63]. Relative indicators of parentage are still needed.…”

Nocturnal changes in leaf growth of Populus deltoides are controlled by cytoplasmic growth

“…Marsh, was used for the study as little is known about molecular mechanisms of leaf growth in trees compared with herbaceous plants. In addition, the genomic information that has become available for P. trichocarpa facilitates investigation of the regulatory mechanisms at the transcriptional level (Taylor 2002;Bhalerao et al 2003;Brunner et al 2004;Cronk 2005). Growth analysis was performed with an image sequence analysis technique developed for quantitative mapping of dicot leaf growth (Schmundt et al 1998) to characterise temporal as well as spatial growth patterns in leaves of P. deltoides at high resolution.…”