The functionality of α-kafirin promoter and α-kafirin signal peptide

• Published in: Plant Cell, Tissue and Organ Culture
• Main Author: Liu G.; Lamont K.C.; Ahmad N.; Tomkins A.; Mudge S.R.; Gilding E.K.; Godwin I.D.
• Format: Article
• Language: English
• Published: Springer Netherlands 2017
• Online Access: https://www.scopus.com/inward/record.uri?eid=2-s2.0-84988359683&doi=10.1007%2fs11240-016-1093-3&partnerID=40&md5=d75ff127d5b98eb60e842012423127b8

Cereal grains offer great potential as a storage system for production of highly valuable proteins using biotechnological approaches, but such applications require tight temporal and spatial control of transgene expression. Towards this aim, we have undertaken a detailed analysis of α-kafirin (α-kaf) promoter and α-kaf signal peptide (sp) in transgenic sorghum plants, using green fluorescent protein gene (gfp) as a reporter. Constructs containing either the α-kaf promoter or the constitutive maize ubiquitin-1 (ubi) promoter driving either gfp or sp-gfp translational fusion were introduced into Sorghum bicolor inbred line Tx430 by particle bombardment. We show for the first time that the α-kaf promoter directs endosperm-specific transgene expression, with activity first detected at 10 days post-anthesis (dpa), peaking at 20 dpa, and remaining active through to physiological maturity. Furthermore, we demonstrate for the first time that the α-kafirin sp is sufficient to direct foreign protein to protein bodies in the endosperm. The evidence is also provided for possible mis-targeting by α-kaf sp in vegetative tissues of transgenic lines with ubi-sp-gfp, resulting in loss of reporter gene translational activity that no GFP signal was observed. These results demonstrate that α-kaf promoter and α-kaf sp are well suited for seed bioengineering to produce recombinant proteins in sorghum endosperm or deposit foreign proteins into sorghum protein bodies. © 2016, Springer Science+Business Media Dordrecht.