MSc Exit Seminar – Cynthia Wong (Lumba Lab)

In the sub-Saharan farmlands of Africa, a devastating parasite, Striga hermonthica affects approximately $300 million worth of crops every year. Striga seeds germinate in response to strigolactones (SLs) emitted by host roots but do not germinate in response to gibberellic acid (GA). To investigate this difference between parasitic and non-parasitic plants, we will determine the function of various GA signaling components from Striga by expressing them in Arabidopsis thaliana. At the molecular level, the presence of GA causes DELLA proteins to be degraded in order to elicit a GA response. Arabidopsis has five partially redundant DELLA genes, all of which are additively involved in regulating important biological processes such as germination, cell expansion, and floral development. Our bioinformatics analyses revealed multiple DELLA homologues in Striga (ShDELFAs). To characterize the functions of these homologues, we generated a series of Arabidopsis transgenics overexpressing each ShDELFA. We found that these homologues are functional in Arabidopsis. One behaves similarly to Arabidopsis DELLAs, such that it suppresses germination and vegetative growth, and degrades upon the presence of GA. In contrast, the others showed several unique characteristics, such as resistance in GA-induced degradation, and no visible suppression in vegetative development. Furthermore, I showed that Striga’s SL receptor circumvents the requirement of DELLA degradation to induce seed germination in Arabidopsis. Further study on how the role of GA impacts Striga germination may contribute to a solution in eradicating Striga infestations.

Thursday, December 17^th, 2020 at 1:00pm