Quantitative comparison of the storage protein distribution in glandless and glanded cottonseeds

Authors: He, Zhongqi; Zhang, Dunhua; Mattison, Chris

Submitted to: Agricultural & Environmental Letters
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/19/2022
Publication Date: 5/11/2022
Citation: He, Z., Zhang, D., Mattison, C.P. 2022. Quantitative comparison of the storage protein distribution in glandless and glanded cottonseeds. Agricultural and Environmental Letters. 7(1). Article e20076. https://doi.org/10.1002/ael2.20076.
DOI: https://doi.org/10.1002/ael2.20076

Interpretive Summary: Common glanded (Gd) cottonseed contains scattered gland tissues filled with toxic gossypol in the kernels. Glandless (Gl) cottonseed is a new type of seed lacking these glands, thus containing only trace levels of gossypol. This work systematically evaluated the distribution pattern and the relative abundance of the major polypeptides observed in Gd and Gl cottonseed proteins. The observations presented here indicate that the genetic variation of gossypol synthesis/accumulation likely impacts the distribution and abundance of storage proteins in cottonseed. While the observed level of the 2S albumin storage proteins was basically same, Gl cottonseed showed a lower abundance of total vicilin isomers, but a higher abundance of legumins, compared to Gd cottonseed. Functional vicilin-like antimicrobial peptides 2-2 and oil-body structural oleosins were also found to be relatively higher in the Gl sample. The information presented here provides a description of the effects of gossypol gland depletion on major seed protein accumulation, quantity, and isoform diversity in cottonseed. Practical applications of these findings that incorporate the peptide profiling will aid the development of functional or bioactive cottonseed protein food products.

Technical Abstract: Common glanded (Gd) cottonseed contains scattered gland tissues filled with toxic gossypol in the kernels. Glandless (Gl) cottonseed is a new type of seed lacking these glands, thus containing only trace levels of gossypol. In this work, we quantitatively compared the content and migration pattern of proteins isolates of Gd and Gl cottonseed. The protein isolates of both cottonseeds were subjected to SDS-gel electrophoresis, and the protein gel bands were separated into seven partitions for peptide mass spectroscopic analysis. While multiple peptide fragments (isoformers) of vicilin and legumin proteins were present in both samples, the percentage of vicilins in total seed protein was higher in Gd (74.9%) than Gl (63.4%). In contrast, legumin proteins were more abundant in Gl (30.4%) than Gd (23.6%). Minor protein components such as lipid-related oleosins and vicilin-like antimicrobial peptides 2-2 were also observed at a relatively higher incidence in Gl compared to Gd, potentially reflecting a need for increased protein-related defense capability in the absence of gossypol against natural predators or adverse growth environment.