Changes in antioxidant system and sucrose metabolism in maize varieties exposed to Cd

Abstract

Different maize varieties respond differentially to cadmium (Cd) stress. However, the physiological mechanisms that determine the response are not well defined. Antioxidant systems and sucrose metabolism help plants to cope with abiotic stresses, including Cd stress. The relationship of these two systems in the response to Cd stress is unclear. Seed is sensitive to Cd stress during germination. In this study, we investigated changes in the antioxidant system, sucrose metabolism, and abscisic acid and gibberellin concentrations in two maize varieties with low (FY9) or high (SY33) sensitivities to Cd under exposure to CdCl2 (20 mg L−1) at different stages of germination (3, 6, and 9 days).The seed germination and seedling growth were inhibited under Cd stress. The superoxide, malondialdehyde, and proline concentrations, and the superoxide dismutase, peroxidase, catalase, and lipoxygenase activities increased compared with those of the control (CK; without Cd). The expression levels of three genes (ZmOPR2, ZmOPR5, and ZmPP2C6) responsive to oxidative stress increased differentially in the two varieties under Cd stress. The activity of the antioxidant system and the transcript levels of oxidative stress–responsive genes were higher in the Cd-tolerant variety, FY9, than in the sensitive variety, SY33. Sucrose metabolism was increased under Cd stress compared with that of the CK and was more active in the Cd-sensitive variety, SY33. These results suggest that the antioxidant system is the first response to Cd stress in maize, and that sucrose metabolism is cooperative and complementary under exposure to Cd.

Understanding the Active Mechanisms of Plant (Sesuvium portulacastrum L.) against Heavy Metal Toxicity

“…This eliminated the need for more hydrolyzing sucrose in the shoots, and then led to no increase in the glucose and fructose content in the shoots. Moreover, the observed increase in the accumulation of sucrose phosphate synthase in S. portulacastrum plants can be attributed to the activation of the pathway of converting glucose and fructose into sucrose, which is not broadly consistent with the earlier idea that the activities of the sucrose enzymes involved the biosynthesis direction were decreased under stress [ 28 ]. As a result, it is possible to speculate that the other active defense mechanisms described in this study played a larger role in protecting plant cells from ROS damage caused by heavy metal stress, and that carbohydrates metabolism passively preserved the fundamental conditions for physiological activities in heavy metals-resistant plants [ 28 ].…”

Cadmium-Induced Changes in the Accumulation of Sugars and the PsGolS Transcript in Pisum sativum L.

“…Moreover, similar to the presented results, the effect of Cd and the accumulation of sucrose or fructose changed during the Cd treatment [61]. Li et al [61] also suggested that changes in the sucrose metabolism were induced to maintain the osmotic balance in damaged cells and to protect the plant from Cd stress. The decrease in the water content is described as one of the effects of Cd stress on plants [60,62].…”

“…Analysis of the Cd effect on maize varieties suggests that sucrose metabolism may be a secondary Cd response, and that the Cd-sensitive variety used more carbohydrates to defend against Cd stress rather than to support the growth of the Cd-tolerant variety [59]. Moreover, similar to the presented results, the effect of Cd and the accumulation of sucrose or fructose changed during the Cd treatment [61]. Li et al [61] also suggested that changes in the sucrose metabolism were induced to maintain the osmotic balance in damaged cells and to protect the plant from Cd stress.…”

Screening for Low-Cadmium Accumulation in Maize Varieties Based on Species Sensitivity Distribution and Research on Soil Environmental Thresholds

“…Our study found significant differences in Cd absorption, transport, and accumulation among different maize varieties, likely due to genotypic differences. Previous research has shown that maize varieties differ in their response to Cd stress, with some varieties exhibiting higher antioxidant system activity and transcription levels of oxidative stress response genes [29]. Our study also found significant differences in Cd absorption among different maize organs, with the highest levels found in roots, followed by stems and leaves, ear axis, and kernels [30].…”