title: Virus-induced gene silencing of pea CHLI and CHLD affects tetrapyrrole biosynthesis, chloroplast development and the primary metabolic network.
abstract: The first committed and highly regulated step of chlorophyll biosynthesis is the insertion of Mg(2+) into protoporphyrin IX, which is catalyzed by Mg chelatase that consists of CHLH, CHLD and CHLI subunits. In this study, CHLI and CHLD genes were suppressed by virus-induced gene silencing (VIGS-CHLI and VIGS-CHLD) in pea (Pisum sativum), respectively. VIGS-CHLI and VIGS-CHLD plants both showed yellow leaf phenotypes with the reduced Mg chelatase activity and the inactivated synthesis of 5-aminolevulinic acid. The lower chlorophyll accumulation correlated with undeveloped thylakoid membranes, altered chloroplast nucleoid structure, malformed antenna complexes and compromised photosynthesis capacity in the yellow leaf tissues of the VIGS-CHLI and VIGS-CHLD plants. Non-enzymatic antioxidant contents and the activities of antioxidant enzymes were altered in response to enhanced accumulation of reactive oxygen species (ROS) in the chlorophyll deficient leaves of VIGS-CHLI and VIGS-CHLD plants. Furthermore, the results of metabolite profiling indicate a tight correlation between primary metabolic pathways and Mg chelatase activity. We also found that CHLD induces a feedback-regulated change of the transcription of photosynthesis-associated nuclear genes. CHLD and CHLI silencing resulted in a rapid reduction of photosynthetic proteins. Taken together, Mg chelatase is not only a key regulator of tetrapyrrole biosynthesis but its activity also correlates with ROS homeostasis, primary interorganellar metabolism and retrograde signaling in plant cells.
authors: National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, PR China.
authors: Tao
authors: T
authors: Luo
authors: Sha
authors: S
authors: Luo
authors: Wagner L
authors: WL
authors: Araújo
authors: Hagen
authors: H
authors: Schlicke
authors: Maxi
authors: M
authors: Rothbart
authors: Jing
authors: J
authors: Yu
authors: Tingting
authors: T
authors: Fan
authors: Alisdair R
authors: AR
authors: Fernie
authors: Bernhard
authors: B
authors: Grimm
authors: Meizhong
authors: M
authors: Luo
mesh_terms: D002736:Chloroplasts / Q000378:metabolism*; D020868:Gene Silencing / Q000502:physiology*; D018532:Pisum sativum / Q000235:genetics / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D045725:Tetrapyrroles / Q000096:biosynthesis*; D014780:Viruses / Q000235:genetics*
chemical_list: D010940:Plant Proteins; D045725:Tetrapyrroles