Characterizing Striga hermonthica Gibberellin Receptors and Investigating their Crosstalk with Strigolactone Receptors

Gibberellic acids (GAs) are a group of phytohormones known to stimulate germination of land plants. However, a root parasitic plant called Striga hermonthica (Striga) germinates poorly on GA, instead utilizes host root-exuded phytohormones strigolactones (SLs) to initiate germination. It remains unknown why GA signalling is not sufficient to germinate Striga. Here I report the identification and functional analysis of three Striga GA receptors, GA INSENSITIVE DWARF1-Like (GIL), and explored the crosstalk between GA and SL signalling pathways. ShGILs interacted with GA signalling targets, ShDELFAs, and overexpression of ShGIL complemented the germination defect of Atgid1ac loss-of-function mutant, indicating ShGILs may function as GA receptors. In addition, two ShGILs interacted with Striga SL receptors, ShHTLs, and overexpression of ShHTLs increased the GA requirement in GA auxotrophic Arabidopsis (ga1-10) suggesting GA-SL crosstalk and its role in regulating Striga germination. This study provides an insight in understanding GA signalling during Striga seed germination.M.Sc.2021-11-30 00:00:0