Effects of H2S and rhizobia on AsA-GSH cycle in soybean plants under water deficiency
With the decrease of water content, the GSH content was no apparent increased by Q8 and Q8 + NaHS treatments under MW and SW conditions, and not obvious differences between the Q8 and Q8 +NaHS treatments (Fig. 7A). However, water deficiency caused an obvious change in GSSG content under four treatments. Compared with control, the GSSG content was substantially increased by Q8 and Q8+NaHS treatments under other three water conditions. Moreover, with the decrease of water content, the GSSG content had an obvious increase trend under Q8+NaHS treatment (Fig. 7B). Interestingly, Q8 and Q8+NaHS treatments increased the GSSG content under water deficiency in leaves, the ratio of GSH/GSSG was significantly reduced by two treatments (Fig. 7C).
In addition, the AsA content in control treatment was notably increased under SW condition compared with NW condition. With the decrease of water content, the AsA content by Q8 and Q8+NaHS treatments displayed a tendency to increase initially and then decrease. Under SW condition, the AsA content showed a significant decrease under Q8 and Q8+NaHS treatments compared with control (Fig. 7D). Compared with control, the DHA content was substantially reduced by Q8 and Q8+NaHS treatments under NW and MW conditions, but the change under SW condition was not obvious (Fig. 7E). With the decrease of water content, the DHA content was greatly increased by Q8 and Q8+NaHS treatments, while showed a downward trend under control treatment (Fig. 7E). As a result, we found that under NW and MW conditions, the AsA/DHA ratio of the four treatments had similar changing trends, and the AsA/DHA ratio of Q8 and Q8+NaHS treatments was much higher than that of control treatment. In addition, the AsA/DHA ratio of control treatment was significantly higher than other treatments under SW condition (Fig. 7F).
In addition, the MDHAR activity was affected by water deficiency under the four treatments, and Q8+NaHS treatment promoted MDHAR activity in the leaves under SW condition (Fig. 7G). Interestingly, the DHAR activity of Q8 and Q8+NaHS treatments was appreciably higher than that of control treatment under any water content. With the decrease of water content, the DHAR activity of leaves by the four treatments decreased to varying degrees. (Fig. 7H). The changes of GR activity among the four treatments of SW condition were similar to those of NW condition. The GR activity of Q8 and Q8 +NaHS treatments were much higher than that of control treatment (Fig. 7I).