Genome-wide analysis of DWD proteins in soybean (Glycine max): Significance of Gm08DWD and GmMYB176 interaction in isoflavonoid biosynthesis


Bian, S., Li, X., Mainali, H., Chen, L. and Dhaubhadel, S. (2017) Genome-wide analysis of DWD proteins in soybean (Glycine max): Significance of Gm08DWD and GmMYB176 interaction in isoflavonoid biosynthesis. PLoS One, Jun 6; 12(6):e0178947. doi: 10.1371/journal.pone.0178947

Plain language summary

Isoflavonoids are a diverse group of legume-specific plant specialized metabolites that accumulate in soybean seeds during seed development. They play important roles in the interaction between plants and the environment as well as in human health and nutrition. Several clinical studies have identified the correlation between soy rich diet and reduction of chances of hormone dependent cancers, risk of cardiovascular diseases, reduction of menopause symptoms etc. The amount of isoflavonoids present in soybean seeds is influenced by both genetic and environmental factors that are not fully understood. Previously we identified a gene GmMYB176 in soybean whose protein product controls isoflavonoid biosynthesis. Here, we doscovered another protein Gm08DWD that can interact with GmMYB176 to regulate isoflavonoid synthesis. This finding is important to manipulate isoflavonoid level in soybean or introduction of this compound in other non-legume plants.


A subset of WD40 proteins with DWD motif has been proposed to serve as substrate receptor
of DDB-CUL4-ROC1 complex, thereby getting involved in protein degradation via
ubiquitination pathway. Here, we identified a total of 161 potential DWD proteins in soybean
(Glycine max) by searching DWD motif against the genome-wide WD40 repeats, and classified
them into 20 groups on the basis of their functional domains and annotations. These
putative DWD genes in soybean displayed tissue-specific expression patterns, and their
genome localization and analysis of evolutionary relationship identified 48 duplicated gene
pairs within 161 GmDWDs. Among the 161 soybean DWD proteins, Gm08DWD was previously
found to interact with an isoflavonoid regulator, GmMYB176. Therefore, Gm08DWD
and its homologue Gm05DWD were further investigated. Expression profile of both genes
in different soybean tissues revealed that Gm08DWD was expressed higher in embryo,
while Gm05DWD exhibited maximum transcript accumulation in leaf. Our protein-protein
interaction studies demonstrated that Gm08DWD interacts with GmMYB176. Although
Gm08DWD was localized both in nucleus and cytoplasm, the resulting complex of Gm08DWD
and GmMYB176 was mainly observed in the nucleus. This finding is consistent with the functional
localization of CUL4-E3 ligase complex. In conclusion, the survey on soybean potential
DWD protein is useful reference for the further functional investigation of their DDB1-binding
ability. Based on the functional investigation of Gm08DWD, we speculate that protein-protein
interaction between Gm08DWD and GmMYB176 may lead to the degradation of GmMYB176
through CUL4-DDB1complex.

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