Overexpressing an Arabidopsis SEIPIN1 reduces rubber particle size in guayule

Authors: Chen, Grace; Ponciano, Grisel; Dong, Chen; Dong, Niu; Johnson, Kumiko; Bolton, Trinh; Williams, Tina; Wood, Delilah - De; Placido, Dante; McMahan, Colleen; Dyer, John

Submitted to: Industrial Crops and Products
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/6/2023
Publication Date: 2/15/2023
Citation: Chen, G.Q., Ponciano, G.P., Dong, C., Dong, N., Johnson, K., Bolton, T.T., Williams, T.G., Wood, D.F., Placido, D.F., McMahan, C.M., Dyer, J.M. 2023. Overexpressing an Arabidopsis SEIPIN1 reduces rubber particle size in guayule. Industrial Crops and Products. 195. Article 116410. https://doi.org/10.1016/j.indcrop.2023.116410.
DOI: https://doi.org/10.1016/j.indcrop.2023.116410

Interpretive Summary: Current commercial source of natural rubber NR is from Hevea (Hevea. brasiliensis). Hevea is cultivated only in Southeast Asian countries and is vulnerable to leaf blight diseases. To secure NR production, guayule (Parthenium argentatum Gray) has been developed as an alternative crop which can be grown in most agricultural regions. Various efforts have been made to increase guayule NR production, including germplasms selection, breeding, and genetic engineering. NR consists mainly of cis-1,4-polyisoprene synthesized in/on rubber particles (RPs). RPs are analogous to the lipid droplets (LDs) generated from the endoplasmic reticulum (ER), although the major components enclosed in the phospholipid monolayer structure of LDs are triacylglycerols, not polyisoprene. A prominent LD protein is SEIPIN conserved across eukaryotes and plays an important role in LD biogenesis. Arabidopsis contains three SEIPIN genes. Overexpression of AtSEIPIN1 in Arabidopsis results in increased numbers of large LDs in leaves, as well as in seeds, and increased seed oil content by up to 10% over wild-type seeds. This finding prompts us to investigate the effects of AtSEIPIN1 in guayule NR production. We discovered that AtSEIPIN1 reduced NR production in guayule. New mechanism of RP biogenesis are discussed.

Technical Abstract: A conventional source of natural rubber (NR) is from Hevea (Hevea. brasiliensis). NR production from Hevea is limited by its narrow growth region and susceptibility to leaf blight disease. To secure NR production, guayule (Parthenium argentatum Gray) has been developed as an alternative crop. NR consists mainly of cis-1,4-polyisoprene synthesized in/on rubber particles (RPs). RPs resemble lipid droplets (LDs) as both of them are generated from endoplasmic reticulum and consist of a hydrophobic core and a phospholipid monolayer. A prominent LD protein SEIPIN plays an essential role in controlling LD biogenesis. Overexpression of AtSEIPIN1 in Arabidopsis increases LD size and consequently increases its core constituent triacylglycerol content in seed. To investigate if AtSEIPIN1 can also increase the cis-1,4-polyisoprene in RP, we generated three independent transgenic guayule lines overexpressing AtSEIPIN1 (SEIoe). Compared with wild-type, SEIoe lines decreased NR quantity and quality. Besides, average RP sizes were reduced in SEIoe. Results of in vitro assay of rubber synthesis showed reduced rubber transferase activities in some SEIoe lines. The mechanisms of AtSEIPIN1 on influencing RP biogenesis and NR production in guayule are discussed.