title: The stay-green phenotype of wheat mutant tasg1 is associated with altered cytokinin metabolism.
abstract: By measuring the cytokinin content directly and testing the sensitivity to the cytokinin inhibitor lovastatin, we demonstrated that tasg1 cytokinin metabolism is different from wild-type. Our previous studies have indicated that compared with wild-type (WT) plants, a wheat stay-green mutant tasg1 exhibited delayed senescence. In this study, we found that the root development of tasg1 occurred later than that of WT. The number of lateral roots was fewer, but the lateral root length was longer in tasg1 than in WT, which resulted in a lower root to shoot ratio in tasg1 than WT. The levels of cytokinin (CK), CK activity, and expression of CK metabolic genes were measured. We found that the total CK content in the root tips and leaf of tasg1 was greater than in WT. The accumulation of mRNA of the CK synthetic gene (TaIPT) in tasg1 was higher than in WT at 9 and 11 days during seedling growth, but the expression of CK oxidase gene (TaCKX) was significantly lower in tasg1. Furthermore, the CK inhibitor lovastatin was used to inhibit CK activity. When treated with lovastatin, both the chlorophyll content and thylakoid membrane protein stability were significantly lower in tasg1 than WT, consistent with the inhibited expression of senescence-associated genes (TaSAGs) in tasg1. Lovastatin treatment also inhibited the antioxidative capability of wheat seedlings, and tasg1 was more sensitive to lovastatin than WT, as indicated by the MDA content, protein carbonylation, and antioxidant enzyme activity. The decreased antioxidative capability after lovastatin treatment may be related to the down-regulation of some antioxidase genes. These results suggest that the CK metabolism was altered in tasg1, which may play an important role in its ability to delay senescence.
authors.affiliation: State Key Laboratory of Crop Biology, Shandong Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, 271018, Shandong, China.
authors.forename: Wenqiang
authors.initials: W
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Crop Biology, Shandong Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, 271018, Shandong, China.
authors.forename: Qunqun
authors.initials: Q
authors.lastname: Hao
authors.affiliation: State Key Laboratory of Crop Biology, Shandong Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, 271018, Shandong, China.|College of Life Science and Technology, Nanyang Normal University, Nanyang, 473061, Henan, China.
authors.forename: Fengxia
authors.initials: F
authors.lastname: Tian
authors.affiliation: State Key Laboratory of Crop Biology, Shandong Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, 271018, Shandong, China.
authors.forename: Qinxue
authors.initials: Q
authors.lastname: Li
authors.affiliation: State Key Laboratory of Crop Biology, Shandong Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, 271018, Shandong, China. wangw@sdau.edu.cn.
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
mesh_terms: D002734:Chlorophyll / Q000378:metabolism; D003583:Cytokinins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D015151:Immunoblotting; D008148:Lovastatin / Q000494:pharmacology; D008315:Malondialdehyde / Q000378:metabolism; D053858:Metabolic Networks and Pathways / Q000235:genetics; D009154:Mutation; D010641:Phenotype; D018515:Plant Leaves / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D018517:Plant Roots / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D050050:Protein Carbonylation / Q000187:drug effects; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors; D014908:Triticum / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism
chemical_list: D003583:Cytokinins; D010940:Plant Proteins; D002734:Chlorophyll; D008315:Malondialdehyde; D008148:Lovastatin
keywords: Antioxidative capability; Cytokinin metabolism; Stay-green; Thylakoid membrane proteins