Bacillus simplex treatment promotes soybean defence against soybean cyst nematodes: A metabolomics study using GC-MS

Abstract

We aimed to profile the metabolism of soybean roots that were infected with soybean cyst nematodes and treated with Bacillus simplex to identify metabolic differences that may explain nematode resistance. Compared with control soybean roots, B. simplex-treated soybean roots contained lower levels of glucose, fructose, sucrose, and trehalose, which reduced the nematodes' food source. Furthermore, treatment with B. simplex led to higher levels of melibiose, gluconic acid, lactic acid, phytosphingosine, and noradrenaline in soybean roots, which promoted nematocidal activity. The levels of oxoproline, maltose, and galactose were lowered after B. simplex treatment, which improved disease resistance. Collectively, this study provides insight into the metabolic alterations induced by B. simplex treatment, which affects the interactions with soybean cyst nematodes.

Fig 1. The different stages of SCN in mock and Sneb545- treated soybeans roots at days 5 and 10.

5CI/10CI indicate mock-treated soybean roots and 5CI/10CI indicate Sneb545-treated soybean roots at days 5 and 10 after SCN inoculation respectively.

Fig 2. GC/MS TICs of soybean roots samples.

The y-axis indicates the relative mass abundance and the x-axis represents the retention time.

Fig 3. OPLS-DA model analysis performed on the most diverse sample at (A) day 5 and (B) day 10 post-inoculation.

CI indicates SCN-inoculated mock-treated soybean roots and TI indicates SCN-inoculated Sneb545-treated soybean roots.