Methods for Phenotyping Shoot Branching and Testing Strigolactone Bioactivity for Shoot Branching in Arabidopsis and Pea.

Shoot branching is a highly variable trait that evolves during plant development and is influenced by environmental and endogenous cues such as hormones. In particular, strigolactones (SLs) are hormones that play a key role in the control of shoot branching. Branch primordia, axillary buds formed in the leaf axils, display differential growth depending on their position in the plant and also respond to hormone signaling. In this chapter, we will describe how to quantify the degree of shoot branching in two plant model species, Arabidopsis and pea, commonly used to decipher the control of this complex trait. We will also propose several methods to perform treatments of SL or SL analogs, to investigate their bioactivity and effect on the shoot branching patterns of plants of different genotypes.