The Physiological Responses of Maize Seedlings with Different Amylose Content to Drought Stress

In this study, we investigated the physiological responses of maize with different amylose content at seedlings to drought stress. For waxy maize (WMS) and normal maize (NMS), the decline of photosynthesis under drought stress (DS) was due to the stomatal limitation. DS increased the non-photochemical quenching coefficient (NPQ), whereas decreased the activities of peroxidase (POD) and the plant height (PH), compared with the plants under normal irrigation. The content of starch increased and decreased significantly upon moderate and severe drought stress, respectively. For high amylose maize (HAMSs), they showed stomatal limitation upon moderate stress, while non-stomatal limitation upon severe stress. The NPQ and POD showed contrary trend compared with WMS and NMS. DS significantly decreased the starch content and PH of them. The principal component analysis (PCA) showed HAMSs were more sensitive to drought than WMS and NMS. The GBSSIIa level of HAMSs was also lower than that of WMS and NMS. Therefore, we conclude that HAMSs respond to DS through redox regulation to avoid oxidative damage, whereas WMS and NMS by increasing starch biosynthesis, and the higher GBSSIIa level may produce more amylose, which could promote the growth of maize under drought effectively.