He Zhaoquan, Shang Xue, Jin Xiaoze, Wang Xiukang, Xing Yingying
School of Life Sciences, Yan'an University, Yan'an 716000, China.
Shaanxi Key Laboratory of Research and Utilization of Resource Plants on the Loess Plateau, College of Life Sciences, Yan'an University, Yan'an 716000, China.
Int J Mol Sci. 2024 Dec 29;26(1):200. doi: 10.3390/ijms26010200.
Ca and Mg are essential micronutrients for plant growth, and they play a crucial role in plant development and responses to adversity by influencing the activities of endogenous hormones and antioxidant enzymes. However, the specific mechanisms through which calcium (Ca) and magnesium (Mg) regulate the kernel sugar content through endogenous hormones and antioxidant enzymes remain unclear. In this study, we analyzed the impact of Ca and Mg on the physiology of maize leaves and kernel quality by determining the activities of antioxidant enzymes and endogenous hormones, and the kernel sugar content in maize leaves when supplemented with different levels of Ca and Mg. Our main findings were as follows: (1) Elevated Mg levels augmented superoxide dismutase (SOD) activity, bolstering antioxidant defenses, whereas low Ca and Mg levels diminished SOD activity. High Ca levels enhanced catalase (CAT) activity during kernel development. Low-Ca conditions stimulated gibberellin (GA) synthesis, while high-Ca and high-Mg conditions suppressed it. High Mg levels also elevated abscisic acid (ABA) levels, potentially improving stress tolerance. (2) High Ca levels increased the reducing sugar content in kernels, augmenting the energy supply, while both low and high Mg levels increased soluble sugars, with low Mg levels specifically enhancing the sucrose content, which is a critical energy reserve in plants. (3) CAT exerted a pivotal regulatory role in the sugar accumulation in maize kernels. GA, under the influence of Ca, modulated the sucrose and soluble sugar contents by inhibiting CAT, whereas ABA, under the influence of Mg, promoted CAT activity, thereby affecting the kernel sugar content. This study reveals a new mechanism through which the addition of Ca and Mg regulate the sugar content in maize kernels by affecting endogenous hormones and antioxidant enzyme activities. These findings not only enhance our understanding of the role of micronutrients in plant growth and development but also provide new strategies for improving crop yield and stress tolerance.
钙（Ca）和镁（Mg）是植物生长必需的微量营养元素，它们通过影响内源激素和抗氧化酶的活性，在植物发育和逆境响应中发挥关键作用。然而，钙（Ca）和镁（Mg）通过内源激素和抗氧化酶调节籽粒糖分含量的具体机制尚不清楚。在本研究中，我们通过测定抗氧化酶和内源激素的活性以及补充不同水平的Ca和Mg时玉米叶片中的籽粒糖分含量，分析了Ca和Mg对玉米叶片生理和籽粒品质的影响。我们的主要研究结果如下：（1）较高的Mg水平增强了超氧化物歧化酶（SOD）活性，增强了抗氧化防御能力，而低Ca和Mg水平则降低了SOD活性。高Ca水平在籽粒发育过程中增强了过氧化氢酶（CAT）活性。低钙条件刺激了赤霉素（GA）的合成，而高钙和高镁条件则抑制了它。高Mg水平还提高了脱落酸（ABA）水平，可能提高了胁迫耐受性。（2）高Ca水平增加了籽粒中的还原糖含量，增加了能量供应，而低Mg和高Mg水平均增加了可溶性糖，低Mg水平特别提高了蔗糖含量，蔗糖是植物中的关键能量储备。（3）CAT在玉米籽粒糖分积累中发挥了关键的调节作用。在Ca的影响下，GA通过抑制CAT来调节蔗糖和可溶性糖含量，而在Mg的影响下，ABA促进CAT活性，从而影响籽粒糖分含量。本研究揭示了添加Ca和Mg通过影响内源激素和抗氧化酶活性来调节玉米籽粒糖分含量的新机制。这些发现不仅加深了我们对微量营养元素在植物生长发育中作用的理解，也为提高作物产量和胁迫耐受性提供了新策略。
