Zhao Haiquan, Zhou Qiuping, Zhou Min, Li Chunxiao, Gong Xiaolan, Liu Chao, Qu Chunxiang, Si Wenhui, Hong Fashui
Medical College, Soochow University, Suzhou 215123, People’s Republic of China.
Biol Trace Elem Res. 2012 Jul;148(1):102-9. doi: 10.1007/s12011-012-9340-x.
Magnesium (Mg) deficiency has been reported to affect plant photosynthesis and growth, and cerium (Ce) was considered to be able to improve plant growth. However, the mechanisms of Mg deficiency and Ce on plant growth remain poorly understood. The main aim of this work is to identify whether or not Mg deprivation affects the interdependent nitrogen and carbon assimilations in the maize leaves and whether or not Ce modulates the assimilations in the maize leaves under Mg deficiency. Maize plants were cultivated in Hoagland’s solution. They were subjected to Mg deficiency and to cerium chloride administration in the Mg-present Hoagland’s media and Mg-deficient Hoagland’s media.After 2 weeks,we measured chlorophyll (Chl) a fluorescence and the activities of nitrate reductase (NR), sucrose-phosphate synthase(SPS), and phosphoenolpyruvate carboxylase (PEPCase)in metabolic checkpoints coordinating primary nitrogen and carbon assimilations in the maize leaves. The results showed that Mg deficiency significantly inhibited plant growth and decreased the activities of NR, SPS, and PEPCase and the synthesis of Chl and protein. Mg deprivation in maize also significantly decreased the oxygen evolution, electron transport,and efficiency of photochemical energy conversion by photosystem II (PSII). However, Ce addition may promote nitrogen and carbon assimilations, increase PSII activities,and improve maize growth under Mg deficiency. Moreover,our findings would help promote usage of Mg or Ce fertilizers in maize production.
据报道，镁（Mg）缺乏会影响植物的光合作用和生长，而铈（Ce）被认为能够促进植物生长。然而，镁缺乏和铈对植物生长的作用机制仍知之甚少。这项工作的主要目的是确定缺镁是否会影响玉米叶片中相互依存的氮和碳同化作用，以及铈是否会在缺镁条件下调节玉米叶片中的同化作用。玉米植株种植在霍格兰溶液中。在含有镁的霍格兰培养基和缺镁的霍格兰培养基中，对它们进行缺镁处理并施用氯化铈。两周后，我们在协调玉米叶片初级氮和碳同化作用的代谢检查点测量了叶绿素（Chl）a荧光以及硝酸还原酶（NR）、蔗糖磷酸合酶（SPS）和磷酸烯醇式丙酮酸羧化酶（PEPCase）的活性。结果表明，缺镁显著抑制了植物生长，降低了NR、SPS和PEPCase的活性以及叶绿素和蛋白质的合成。玉米缺镁还显著降低了光系统II（PSII）的放氧量、电子传递和光化学能量转换效率。然而，添加铈可能会促进氮和碳同化作用，增加PSII活性，并在缺镁条件下促进玉米生长。此外，我们的研究结果将有助于促进镁或铈肥料在玉米生产中的应用。
