Comparative Genomics of Shoot Branching

Shoot system architecture is of major agricultural significance. Many of the branching characteristics found in nature are selected to distribute resources between many small seed produced over an extended time period, and to allow flexibility in response to changing environmental conditions such as nutrient availability, or damage by herbivory. These features frequently work against agricultural priorities where, for example, the production of a smaller number of larger seed over a narrow window of time, with a greater uniformity in branching habit may be preferred. Thus breeding for improved yield stability is intimately associated with improvements in shoot system architectural characteristics. The groups collaborating in this project encompass world class expertise across the key gene systems that regulate branching. It is already clear that these systems operate throughout higher plants. However, it is equally clear that there are important differences in the way the systems operate in different species. We therefore propose a systematic comparative study of these gene systems, their actions, and their interactions in a range of species. This will form the basis for the development of a tool kit for marker assisted breeding for optimised branching habit, and for genetic modification of branching, when it becomes publicly acceptable.

Shoot system architecture is of major agricultural significance. Many of the branching characteristics found in nature are selected to distribute resources between many small seed produced over an extended time period, and to allow flexibility in response to changing environmental conditions such as nutrient availability, or damage by herbivory. These features frequently work against agricultural priorities where, for example, the production of a smaller number of larger seed over a narrow window of time, with a greater uniformity in branching habit may be preferred. Thus breeding for improved yield stability is intimately associated with improvements in shoot system architectural characteristics. The groups collaborating in this project encompass world class expertise across the key gene systems that regulate branching. It is already clear that these systems operate throughout higher plants. However, it is equally clear that there are important differences in the way the systems operate in different species. We therefore propose a systematic comparative study of these gene systems, their actions, and their interactions in a range of species. This will form the basis for the development of a tool kit for marker assisted breeding for optimised branching habit, and for genetic modification of branching, when it becomes publicly acceptable. We have chosen 5 gene systems for analysis, based on their known roles in the two key stages of axillary bud development- initiation and activation. This will support applications where branching must be completely eliminated, as well as those in which the levels of branching can be alterred whilst maintatining the possibility of some environmental plasticity. Furthermore, mutations in many of the selected genes have differential effects on axils at different positions along the primary shoot axis, offering the possibility of manipulation of specific branches.