Abstract
Background Correlated variation in shape and size (allometry) is a major component of natural diversity. Although ample research has been conducted on organ shape and size, little of it has considered the correlated variation of these two traits and quantitatively measured the variation in a common framework. The genetic basis of allometry variation in a single organ or among different organs is also relatively unknown. Results We examined the genetic basis for leaf and petal allometry within multiparent advanced generation intercross (MAGIC) populations of Arabidopsis thaliana. A principal component analysis of organ landmarks and outlines was conducted and used to quantitatively capture shape and size variation in leaves and petals. The genetic basis of leaf and petal allometry and the allometric covariation between leaves and petals was analyzed via QTL mapping. Five QTLs for the fourth leaf, 11 QTLs for the seventh leaf, and 12 QTLs for the petal size and shape were identified. Besides that, 12 QTLs were identified in association with the fourth leaf and petal allometry covariation, and eight QTLs were identified to associate with the seventh leaf and petal allometry covariation. In these confidence regions, many important candidate genes associated with cell proliferation, expansion, and differentiation contained alleles with maximum effects. Life-history traits, such as days to bolt, stem length, and rosette leaf number, were also measured and used to perform the QTL analysis within the MAGIC lines. The phenotype correlation and QTL overlap between leaf and petal allometry with life-history traits hinted at the genetic integration of organ allometry with the life-history traits and of the interaction of organ allometry with local adaptation. Conclusions Allometry describes the correlated variation in shape and size in one organ or related organs. Several QTLs were identified by using the MAGIC lines and the genes associated with cell proliferation and expansion may responsible for the leaf and petal allometry. Summarily, we explored the genetic basis of allometry variation of leaf and petal by using the MAGIC lines, and may provide important information for investigating the organ shape and size evolution in Arabidopsis.
THE GENETIC BASIS OF ALTITUDINAL VARIATION IN THE WOOD FROGRANA SYLVATICA. I. AN EXPERIMENTAL ANALYSIS OF LIFE HISTORY TRAITS
