title: Cerium relieves the inhibition of chlorophyll biosynthesis of maize caused by magnesium deficiency.
abstract: Lanthanoids (Ln) were demonstrated to improve chlorophyll formation and the growth of plants. But the mechanism of the fact that Ln promotes chlorophyll biosynthesis of plants is poorly understood. The main aim of the study was to determine Ln effects in chlorophyll formation of maize under magnesium (Mg) deficiency. Maize plants were cultivated in Hoagland's solution. They were subjected to Mg deficiency and to cerium administered in Mg-deficient Hoagland's media, and then the contents of various chlorophyll precursors and gen expressions of the key enzymes of chlorophyll biosynthesis were examined. The decrease of chlorophyll contents in maize leaves caused by Mg deficiency suggested an inhibition of chlorophyll synthesis that was inhibited by a reduction of the precursors as measured by analyzing the contents of δ-aminolevulinic acid, porphobilinogen, uroporphyrinogen III, Mg-protoporphyrin IX, and protochlorophyll, as well as the expression levels of magnesium chelatase, magnesium-protoporphyrin IX methyltransferase, and chlorophyll synthase; Mg deficiency significantly inhibited the transformation from coproporphyrinogen III or protoporphyrin IX to chlorophyll. However, cerium addition significantly relieved the inhibition of chlorophyll biosynthesis in maize caused by Mg deficiency and increased chlorophyll content and promoted a series of transformations from δ-aminolevulinic acid to chlorophyll and maize growth under Mg deficiency. It implied that cerium might partly substitute for the role of Mg.
authors.affiliation: Medical College of Soochow University, 215123 Suzhou, People's Republic of China.
authors.forename: Min
authors.initials: M
authors.lastname: Zhou
authors.forename: Xiaolan
authors.initials: X
authors.lastname: Gong
authors.forename: Wang
authors.initials: W
authors.lastname: Ying
authors.forename: Liu
authors.initials: L
authors.lastname: Chao
authors.forename: Mengmeng
authors.initials: M
authors.lastname: Hong
authors.forename: Ling
authors.initials: L
authors.lastname: Wang
authors.forename: Hong
authors.initials: H
authors.lastname: Fashui
mesh_terms: D000622:Aminolevulinic Acid / Q000378:metabolism; D002563:Cerium / Q000494:pharmacology*; D002734:Chlorophyll / Q000031:analogs & derivatives / Q000096:biosynthesis* / Q000378:metabolism; D003305:Coproporphyrinogens / Q000378:metabolism; D008190:Lyases / Q000378:metabolism; D008274:Magnesium / Q000378:metabolism*; D003313:Zea mays / Q000187:drug effects* / Q000378:metabolism*
chemical_list: D003305:Coproporphyrinogens; D002734:Chlorophyll; C016083:protochlorophyll; C028026:coproporphyrinogen III; D002563:Cerium; D000622:Aminolevulinic Acid; D008190:Lyases; C086788:magnesium chelatase; D008274:Magnesium