Abstract
Artificial selection of high yield crops and better livestock is paramount importance in breeding programs. Selection of elite parents with preferred traits from a phalanx of inbred lines is extremely laborious, time-consuming and highly random. General combining ability (GCA) was proposed and has been widely used for the evaluation of parents in hybrid breeding for more than half a century. However, the genetic and molecular basis of GCA has been largely overlooked. Here, we present two pleotropic QTLs are accounting for GCA of days to heading (DTH), plant height (PH) and spikelet per panicle (SPP) using an F2-based NCII design, the BC3F2 population as well as a set of nearly isogenic lines (NILs) with five testers. Both GCA1 and GCA2 were loss-of-function gene in low-GCA parent and gain-of-function gene in high-GCA parent, encoding the putative Pseudo-Response Regulators, OsPRR37 and Ghd7, respectively. Overexpression of GCA1 in low-GCA parent significantly increases GCA effects in three traits. Our results demonstrate that two GCA loci associate with OsPRR37 and Ghd7 and reveal that the genes responsible for important agronomic traits could simultaneously account for GCA effects.