The genetic control of leaf and petal allometric variations in Arabidopsis thaliana

Abstract

Background Organ shape and size co-variation (allometry) is an essential concept for the study of evolution and development. 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 A principal component analysis (PCA) of organ landmarks and outlines was conducted and used to quantitatively capture shape and size variation in leaves and petals of multiparent advanced generation intercross (MAGIC) populations of Arabidopsis thaliana . PCA indicated that size variation was a major component of allometry variation and revealed negatively correlated changes in leaf and petal size. After 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. These QTLs were not identical to those previously identified, with the exception of the ER locus. The allometry model was also used to measure the leaf and petal allometry covariation to investigate the evolution and genetic coordination between homologous organs. Totally, 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 QTL confidence regions, there were important genes associated with cell proliferation and expansion with alleles unique to the maximal effects accession. Besides that, the QTLs associated with life-history traits, such as days to bolting, stem length, and rosette leaf number, which was highly coordinated with climate change and local adaption, were QTL mapped and showed an overlap with leaf and petal allometry, which explained the genetic basis for their correlation. Conclusions This study explored the genetic basis for leaf and petal allometry and their interaction, which may provide important information for investigating the organ shape and size correlated variation and evolution in Arabidopsis .