Genetic Dissection of Tiller Development in Barley

Crop yield in cereals is determined by different yield components such as seed weight, seed number per spike and tiller number. Negative correlations between these traits have hampered the genetic gain of total yield.  The trait-off between different yield components is often attributed to a limited amount of resources. However, recent evidence suggest that the same genes or regulatory modules may affect inflorescence branching (seed number) and shoot branching (tillering). We studied the pleiotropic effects of barley high and low tillering mutants on inflorescence branching. Based on this, two main mutant groups were characterized. The first group, which include the row type genes vrs1 and vrs4, exhibit an increased seed number and a reduced tiller number at maturity likely due to resource limitations at the end of their development. The second group, which includes the low tillering mutants als, lnt and int-b, are characterized by a reduction in seed and tiller number suggesting that in these loci are involved in the initiation and growth control of seeds and tillers. In addition, we used RNA-sequencing to gain insight into the genetic pathways affected by these genes. The transcriptional profiling, combined with genetic mapping to identify the causative gene(s), will provide insights into how genes affecting spike and inflorescence branching are regulated and control downstream targets.