GmHSP40.1, a nuclear-localized soybean J domain protein, participates in regulation of flowering time through interacting with EMF1 and JMJ14

Authors: ZHANG, CHI - Zhejiang Normal University; LAN, HU-JIAO - Zhejiang Normal University; LIAO, LI-NA - Zhejiang Normal University; HUANG, MIN-JUN - Zhejiang Normal University; XU, WEI - Zhejiang Normal University; ZHANG, HUI - Huazhong Agricultural University; MA, QIANQIAN - Zhejiang Normal University; LI, FENG - Huzhou University; CHENG, NINGHUI - Children'S Nutrition Research Center (CNRC); Nakata, Paul; WHITMAN, STEVEN - Iowa State University; LIU, JIAN-ZHONG - Zhejiang Normal University

Submitted to: Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/29/2024
Publication Date: 11/30/2024
Citation: Zhang, C., Lan, H., Liao, L., Huang, M., Xu, W., Zhang, H., Ma, Q., Li, F., Cheng, N., Nakata, P.A., Whitman, S.A., Liu, J. 2024. GmHSP40.1, a nuclear-localized soybean J domain protein, participates in regulation of flowering time through interacting with EMF1 and JMJ14. Plant Science. 352. Article 112342. https://doi.org/10.1016/j.plantsci.2024.112342.
DOI: https://doi.org/10.1016/j.plantsci.2024.112342

Interpretive Summary: Flowering is a prerequisite for plant food production. Thus, an understanding of the factors that regulate plant flowering is essential to our efforts to improve our ability to produce nutritious plant foods. In this study we investigate why the expression of a soybean heat shock protein in Arabidopsis results in a late flowering plant. Protein localization experiments revealed that the soybean heat shock protein resides within the nucleus of the cell. Protein-protein interaction studies showed that the soybean heat shock protein bound to two other proteins in the nucleus. These protein-protein complexes bound to and modified the DNA encoding two different genes that regulate flowering time. The DNA modifications affected the expression of these genes, and thus, altered the flowering time of the Arabidopsis plant, making it flower later than normal. It is our hope that by gaining a better understanding of the factors that regulate flowering time, we can, in the future, formulate new strategies to improve our ability to produce more nutritious plant foods.

Technical Abstract: Heat shock protein 40s (HSP40s) are a group of J domain proteins (JDPs), which serve as co-chaperones for heat shock protein 70s. We previously reported that over-expression of a soybean class C JDP, GmHSP40.1, in Arabidopsis activated defense responses. Surprisingly, a significantly delayed flowering phenotype was also observed for the GmHSP40.1-overexpressing (OE) lines. We provided evidence that the late-flowering phenotype observed in the GmHSP40.1-OE lines was not due to impaired pri-miRNA processing and pre-mRNA splicing. Instead, we found that GmHSP40.1 interacted and co-localized with both EMF1 and JMJ14, two major components in the EMF1 complex (EMF1c), which plays a key role in depositing and maintaining the H3K27me3 modification in the FT locus. Consistent with these interactions, the H3K27me3 modification at FT chromatin was significantly increased, whereas the H3K27me3 modification at FLC locus was significantly decreased in the GmHSP40.1-OE line compared with the wde-type Col-0. Interestingly, the H3K4me3 modification was just opposite to H3K27me3 modification at FT and FLC loci, suggesting an antagonistic relationship between these two modifications. Accordingly, the expression of FT and FLC was significantly reduced and increased, respectively, in the GmHSP40.1-OE line compared with that of Col-0. Lastly, we showed that both EMF1 and JMJ14 are genetically epistatic to GmHSP40.1-overexpression. Together, our results revealed that GmHSP40.1 negatively regulates flowering time through promoting the function of EMF1c via interacting with both EMF1 and JMJ14.