Transgenic soybean overexpressing GmSAMT1 exhibits resistance to multiple‐HG types of soybean cyst nematode Heterodera glycines

Abstract

SummarySoybean (Glycine max (L.) Merr.) salicylic acid methyl transferase (GmSAMT1) catalyses 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 this 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 1.2.5.7 (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 seed yield differences were observed between transgenics and control soybean plants grown in one greenhouse with 22 °C day/night temperature, whereas transgenic soybean had higher yield than controls grown a warmer greenhouse (27 °C day/23 °C night) temperature. In a 1‐year field experiment in Knoxville, TN, there was no significant difference in seed yield between the transgenic and nontransgenic 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.

Overexpression of Salicylic Acid Carboxyl Methyltransferase (CsSAMT1) Enhances Tolerance to Huanglongbing Disease in Wanjincheng Orange (Citrus sinensis (L.) Osbeck)

“…Similarly, in tomatoes, SAMT overexpression elevates both SA and MeSA accumulation and promotes plant disease resistance [ 24 ]. However, in soybean and Arabidopsis , SAMT overexpression causes an increase in MeSA but a drop in SA levels that leads to a weakening of disease resistance in Arabidopsis but enhances resistance in soybean [ 22 , 23 , 26 ]. These results showed that SAMT1 has different roles in the regulation of MeSA and SA -mediated disease resistance in different species or varieties.…”

“…Also, silencing the NtSAMT1 gene has been shown to block the SAR [ 19 ]. Transgenic soybeans overexpressing GmSAMT1 exhibit resistance to soybean cyst nematode [ 22 , 23 ]. SAMT overexpression in transgenic tomato plants results in delayed disease symptoms following Xanthomonas campestris pv.…”

An (E,E)‐α‐farnesene synthase gene of soybean has a role in defence against nematodes and is involved in synthesizing insect‐induced volatiles

“…Active second-stage juvenile (J2) nematodes (1000 J2 SCN/plant) were used for inoculation. SCN inoculation and bioassay for transgenic hairy root overexpressing GmAFS were performed as previously described (Lin et al, 2016). The inoculation was carried out in a growth chamber for 2 days with 16-h day length and 25°C day/night temperature.…”

Overexpression of LcSABP, an Orthologous Gene for Salicylic Acid Binding Protein 2, Enhances Drought Stress Tolerance in Transgenic Tobacco

“…Salicylic acid is considered to be one of the key signals in plant defense mechanisms, and its relationship with plant stress resistance has been the focus of several studies. It is clear that SA can be used as a signaling molecule to induce plant disease resistance by activating the plant defense system (Lin et al, 2016; Klessig et al, 2018). It also plays important roles in tolerance to abiotic stresses, such as those induced by salt, heat, and heavy metals (Kang et al, 2014).…”