Pleiotropy structures plant height and seeds weight scaling in barley
despite long history of domestication and breeding selection
Size scaling describes the relative growth rates of different body parts
of an organism following a positive correlation. The genetic mechanism
of the size scaling and how artificial selection influencing the pattern
of size scaling remain unexplored. Here we utilise diverse barley panel
with genome-wide single nucleotide polymorphisms (SNPs) and the
measurement of their plant height and seeds weight to explore the
genetic mechanisms that lead to a correlation of the two traits and the
influence of domestication and breeding selection on the size scaling.
Plant height and seeds weight are heritable and remain positively
correlated in domesticated barley regardless of growth type and habit.
Genome-wide association studies revealed eight SNPs to be associated
with both traits. Linkage decay analysis suggests that a considerable
proportion of genetic markers associated with either plant height or
seeds weight are closely linked in the chromosome. Common factor
analysis revealed twenty SNPs conferring pleiotropic effect on both
traits. Genes with multiple functions in plant growth and development
are involved in structuring plant height and seeds weight scaling.
Pleiotropy forms the genetic bases of plant height and seeds weight
scaling in barley. Our results suggest an alternative hypothesis for
seeds weight evolution in domestication that the selection in plant size
may have constrained variation in seeds weight. Our findings contribute
to the understanding of the genetic basis of size scaling and open a new
venue for seeking the underlying mechanism of a grand theory on
allometric scaling in plants.