Abstract
Vicilins (7S globulins) are seed storage proteins and constitute the main protein family in legume seeds, particularly in narrow-leafed lupin (Lupinus angustifolius L.; NLL), where seven vicilin genes, called β1- to β7-conglutin have been identified. Vicilins are involved in germination processes supplying amino acids for seedling growth and plant development, as well as in some cases roles in plant defense and protection against pathogens. The roles of NLL β-conglutins in plant defense are unknown. Here the potential role of five NLL β-conglutin family members in protection against necrotrophic fungal pathogens was investigated and it was demonstrated that recombinant purified 6xHis-tagged β1- and β6-conglutin proteins exhibited the strongest in vitro growth inhibitory activity against a range of necrotrophic fungal pathogens compared to β2, β3, and β4 conglutins. To examine activity in vivo, two representative necrotrophic pathogens, the fungus Sclerotinia sclerotiorum and oomycete Phytophthora nicotianae were used. Transient expression of β1- and β6-conglutin proteins in Nicotiana benthamiana leaves demonstrated in vivo growth suppression of both of these pathogens, resulting in low percentages of hyphal growth and elongation in comparison to control treated leaves. Cellular studies using β1- and β6-GFP fusion proteins showed these conglutins localized to the cell surface including plasmodesmata. Analysis of cellular death following S. sclerotiorum or P. nicotianae revealed both β1- and β6-conglutins suppressed pathogen induced cell death in planta and prevented pathogen induced suppression of the plant oxidative burst as determined by protein oxidation in infected compared to mock-inoculated leaves.
Highlights
Plants are under constant exposure to potential microbial pathogens
Forty hours after Agrobacterium infiltration of β1- or β6conglutin protein constructs into N. benthamiana plants, agar plugs containing hyphae of S. sclerotiorum or P. nicotianae were placed on the infiltrated leaf areas and plants were incubated in a growth chamber at 18◦C for 3 days under a 16 h long-day light regime
The 6xHis-tag recombinant β-conglutin proteins were expressed in E. coli and purified using nickel affinity chromatography
Summary
Plants are under constant exposure to potential microbial pathogens. One of the mechanisms they employ to defend themselves is via the production of bioactive antimicrobial proteins (AMPs). Storage proteins perform essential roles in plant survival They provide a source of amino acids that can be mobilized and utilized for maintenance and growth during both seed embryonic developmental, and germination stages (Zienkiewicz et al, 2011; Tan-Wilson and Wilson, 2012; Jimenez-Lopez et al, 2016). Vicilins appear to play multifunctional roles, acting as an energy source and providing amino acids during the germination process, while in some cases, being involved in defense responses against fungi and insects (Yunes et al, 1998) This includes for example, vicilins from the legumes Vigna unguiculata (cowpea), V. radiata (mung bean), Phaseolus vulgaris (common bean) and Canavalia ensiformis (jack bean; Gomes et al, 1997, 1998; Oliveira et al, 1999; Coda et al, 2008). Insight into the potential inhibitory mechanisms by which these proteins act against pathogens was obtained through an assessment of their subcellular localization and impact on plant oxidative processes
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
