|LIN, JINGYU - University Of Tennessee|
|MAZAREI, MITRA - University Of Tennessee|
|ZHAO, NAN - University Of Tennessee|
|HATCHER, CATHERINE - University Of Tennessee|
|WUDDINEH, WEGI - University Of Tennessee|
|RUDIS, MARY - University Of Tennessee|
|TSCHAPLINSKI, TIMOTHY - Department Of Energy|
|PANTALONE, VINCENT - University Of Tennessee|
|HEWEZI, TAREK - University Of Tennessee|
|CHEN, FENG - University Of Tennessee|
|STEWART, JR., CHARLES NEAL - University Of Tennessee|
Submitted to: Plant Biotechnology Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/7/2016
Publication Date: 5/23/2016
Citation: Lin, J., Mazarei, M., Zhao, N., Hatcher, C.N., Wuddineh, W.A., Rudis, M., Tschaplinski, T.J., Pantalone, V.R., Arelli, P.R., Hewezi, T., Chen, F., Stewart, Jr., C. 2016. Transgenic soybean overexpressing GmSamT1 exhibits resistance to multiple-HG types of soybean cyst nematode Heterodera glycines. Plant Biotechnology Journal. 14(11):2100-2109. doi:10.1111/pbi.12566.
Interpretive Summary: Soybean yields worldwide are limited by the soybean cyst nematode, a microscopic size roundworm attaching to the roots of the plant. Resistant cultivars have been the most effective means of controlling the nematodes, but it takes years to develop new cultivars using traditional plant breeding methods. Nematode populations are variable and have adapted to reproduce on resistant cultivars. Molecular methods may potentially allow faster development of soybean cultivars that are resistant to many different populations of soybean cyst nematode. Therefore, techniques to modify genes in the plant were used to produce soybean plants with nematode resistance. These genetically modified soybean plants reduced the development of nematodes using a chemical enzyme (GmSAMT1) that is produced in the plant roots. The more of the enzyme that was present, the more resistant the roots were to the nematode. In greenhouse evaluations the differences in appearance between normal and genetically modified plants are minimal. This research has broad application in controlling nematode populations.
Technical Abstract: Soybean (Glycine max (L.) Merr.) salicylic acid methyl transferase (GmSAMT1) catalyzes the conversion of salicylic acid to methyl salicylate. Prior results showed that when GmSAMT1 was overexpressed in transgenic soybean hairy roots, resistance is conferred against soybean cyst nematode (SCN), Heterodera glycines Ichinohe. In the current study, we produced transgenic soybean overexpressing GmSAMT1 and characterized their response to various SCN races. Transgenic plants conferred a significant reduction in the development of SCN HG type 220.127.116.11 (race 2), HG type 0 (race 3), and HG type 2.5.7 (race 5). Among transgenic lines, GmSAMT1 expression in roots was positively associated with SCN resistance. In some transgenic lines, there was a significant decrease in salicylic acid titer relative to control plants. No significant difference on the yield was observed between transgenics and control soybean plants grown in one greenhouse with 22°C day/night temperature, whereas the transgenic soybean plants had higher yield than control plants grown in another greenhouse with warmer (27°C day/ 23°C night) temperatures. In a one-year field experiment in Knoxville, Tenn., USA, there was no significant difference in seed yield between the transgenic and non-transgenic soybean under conditions with negligible SCN infection. We hypothesize that GmSAMT1 expression affects salicylic acid biosynthesis, which, in turn, attenuates SCN development, without negative consequences to soybean yield or other morphological traits. Thus, we conclude that GmSAMT1 overexpression confers broad resistance to multiple SCN races, which would be potentially applicable to commercial production.