Characterization of the kinesin KSE2 in stromule formation and function

Abstract

Chloroplasts play an important role during plant immunity and are the source for many cellular signals during the defense response. During the immune response chloroplasts send out stroma-filled tubular extensions called stromules. Stromules are induced during both PAMP-triggered immunity (PTI) and effector-triggered immunity (ETI). Stromules extend along microtubules, and since kinesins are the only microtubule motors in plants, we hypothesized that a kinesin provides the motive force for stromule extension and stromule-driven movement. Our lab overexpressed 8 different kinesins belonging to kinesin family 14. One of the candidates resulted in increased stromule length and faster chloroplast movement, which we named kinesin for stromule extension 2 (KSE2). My project is to characterize KSE2 to understand its role in stromule formation and function. To do this, I overexpressed 8 deletion constructs in N. benthamiana in which we deleted various domains of KSE2. These deletions include the calponin homology domain (ΔCH), the coiled-coiled 1 domain (ΔCC1), both the ΔCH and ΔCC1 (ΔCH+CC1), only the motor (Only Motor), no motor (ΔMotor), the coiled-coiled 2 domain (ΔCC2), the C-terminal tail (Δtail), both the CC2 and tail (ΔCC2-Tail). By examining and quantifying stromule and chloroplast dynamics of my constructs, I hope to discover the role of KSE2 in stromule formation and function. Additionally, I also look at how the overexpression of the deletion constructs effect cytoskeleton and stromule tip interactions. I also have started to examine the role KSE2 plays during PTI and ETI.