Glycine max Sec61 complex genes function in the soybean defense response to the parasitic nematode Heterodera glycines

Authors: TROELL, HALLIE - Mississippi State University; SHARMA, KESHAV - Mississippi State University; LAWRENCE, GARY - Mississippi State University; LAWRENCE, KATHY - Auburn University; ALKHAROUF, NADIM - Towson University; Klink, Vincent

Submitted to: Current Plant Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/18/2025
Publication Date: 3/24/2025
Citation: Troell, H.A., Sharma, K., Lawrence, G.W., Lawrence, K.S., Alkharouf, N.W., Klink, V.P. 2025. Glycine max Sec61 complex genes function in the soybean defense response to the parasitic nematode Heterodera glycines. Current Plant Biology. 42. Article e100474. https://doi.org/10.1016/j.cpb.2025.100474.
DOI: https://doi.org/10.1016/j.cpb.2025.100474

Interpretive Summary: Plants secrete proteins in order to accomplish a number of different functions, including resistance to devastating pathogens. However, a number of protein structures have never been studied to determine their potential role in basic biological processes or resistance. The plant secretion process has been examined in both sugar beet and soybean in order to better understand the role of a structure called the translocon, encoded by three genes called Sec61-alpha, Sec61-beta, and Sec61-gamma. Cell studies show all three are expressed in the root cell during a resistant reaction to a parasitic nematode. The transgenic expression of Sec61-alpha, Sec61-beta, and Sec61-gamma, each, significantly improves resistance while impairing their expression makes the plant more susceptible. Computational studies identify the proteins that are secreted during a resistant reaction in sugar beet during infection by a root pathogen. The results demonstrate a broad level of resistance can be obtained by the genetic engineering of Sec61 genes that have the potential to act in all frop plants, greatly benefitting stakeholders.

Technical Abstract: The Glycine max (soybean) secretory pathway performs important roles during the defense response to Heterodera glycines parasitism. However, the involvement of some aspects of the secretory machinery remains unexamined. The Sec61 complex of the eukaryote secretory pathway is composed of Sec61-a, Sec61-b, and Sec61-g which bind, forming a trimeric complex that imports proteins into the ER for their processing, transport, and secretion. Comparative analyses using Saccharomyces cerevisiae Sec61-a, Sec61-b, and Sec61-g protein sequences show G. max has homologs of each, 4 Sec61-a, 6 Sec61-b, and 4 Sec61-g paralogs. At least one paralog from each gene family is expressed in H. glycines-parasitized G. max root cells during its defense process. GmSec61-a, GmSec61-b, and GmSec61-g overexpression in the H. glycines-susceptible G. max[Williams 82/PI 518671] leads to an engineered defense response. In contrast, RNAi of GmSec61-a, GmSec61-b, and GmSec61-g in the H. glycines-resistant G. max[Peking/PI 548402] generates susceptibility. The combined opposite outcomes of GmSec61 overexpression and RNAi provide evidence that they function in the defense process, consistent with the hypothesis that the G. max secretion system plays a role in its defense to H. glycines parasitism. The identification of Sec61-a, Sec61-b, and Sec61-g homologs in 51 additional flowering plants spanning 20 Orders and 26 Families including the agriculturally-important Beta vulgaris ssp. vulgaris (sugar beet) demonstrates a potentially broad defense role not limited to these plant species. Computational studies identify genes encoding proteins having signal peptides in B. vulgaris parasitized by H. schachtii but undergoing a defense response further demonstrating the importance of Sec61 translocon in resistance.