© 2002 Heron Publishing—Victoria, Canada
Leaf stomatal and epidermal cell development: identification of putative quantitative trait loci in relation to elevated carbon
dioxide concentration in poplar
Rachel Ferris (1, 2), L. Long (1), S. M. Bunn (1), K. M. Robinson (1), H. D. Bradshaw (3), A. M. Rae (1) and Gail Taylor (1, 2)
1. School of Biological Sciences, University of Southampton, Bassett Crescent East, Southampton S016 7PX, U.K. / 2. Authors to whom correspondence should be addressed (r.ferris@soton.ac.uk, g.taylor@soton.ac.uk) / 3. College of Forest Resources, University of Washington, Seattle, WA 98195, USA / Received February 26, 2001; accepted January 7, 2002; published online May 1, 2002
Summary
Genetic variation in stomatal initiation and density, and epidermal cell size and number were examined in a hybrid pedigree
of Populus trichocarpa T. & G. and P. deltoides Marsh in both ambient ([aCO2]) and elevated ([eCO2]) concentrations of CO2. We aimed to link anatomical traits with the underlying genetic map of F2 Family 331, composed of 350 markers across 19 linkage groups. Leaf stomatal and epidermal cell traits showed pronounced differences
between the original parents. We considered the following traits in the F2 population: stomatal density (SD), stomatal index (SI), epidermal cell area (ECA) and the number of epidermal cells per leaf
(ECN). In [eCO2], adaxial SD and SI were reduced in the F2 population, whereas ECA increased and ECN remained unchanged. In [aCO2], four putative quantitative trait loci (QTL) with logarithm of the odds ratio (LOD) scores greater than 2.9 were found for
stomatal traits on linkage group B: adaxial SI (LOD scores of 5.4 and 5.2); abaxial SI (LOD score of 3.3); and SD (LOD score
of 3.2). These results imply that QTL for SI and SD share linkage group B and are under genetic control. More moderate LOD
scores (LOD scores >/= 2.5) suggest QTL for SI on linkage groups A and B and for SD on linkage groups B, D and X with a probable
co-locating quantitative trait locus for SI and SD on linkage group D (position 46.3 cM). The QTL in both [aCO2] and [eCO2] for adaxial SD were co-located on linkage group X (LOD scores of 3.5 and 2.6, respectively) indicating a similar response
across both treatments. Putative QTL were located on linkage group A (position 89.2 cM) for both leaf size and ECN in [aCO2] and for ECA at almost the same position. The data provide preliminary evidence that leaf stomatal and cell traits are amenable
to QTL analysis.
Keywords:
cell number, cell size, CO2, leaf growth, Populus, stomatal development.
