Cotton cytosolic pyruvate kinase GhPK6 participates in fast fiber elongation regulation in a ROS-mediated manner
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Cotton cytosolic pyruvate kinase GhPK6 is preferentially expressed in the late stage of fiber elongation process, transgenic experiments indicated that its expression level was negatively correlated to cell expansion rate.
Pyruvate kinase (PK) plays vital regulatory roles in rapid cell growth in mammals. However, the function of PK in plant cell growth remains unclear. In allotetraploid upland cotton (Gossypium hirsutum L.), a total of 33 PK genes are encoded by the genome. Analysis of the transcriptome data indicated that only two cytosolic PK genes, GhPK6 and its duplicated gene GhPK26, are preferentially expressed in elongating cotton fiber cells. RT-qPCR and western blot analyses revealed that the expression of GhPK6 was negatively correlated with fiber elongation rate, which well explains the observed sharp increase of cytosolic PK activity at the end of fast fiber elongation process. Furthermore, virus-induced gene silencing of GhPK6 in cotton plants resulted in increased fiber cell elongation and reduced reactive oxygen species (ROS) accumulation. On the contrary, Arabidopsis plants ectopically expressing GhPK6 exhibited ROS-mediated growth inhibition, whereas the addition of ROS scavenging reagents could partly rescue this inhibition. These data collectively suggested that GhPK6 might play an important role in regulating cotton fiber elongation in a ROS-dependent inhibition manner.
KeywordsGossypium hirsutum Cytosolic pyruvate kinase H2O2 Virus-induced gene silencing Cell expansion
We are grateful to Professor Yule Liu for the gift of the VIGS vector pTRV1 and pTRV2. We thank members of our laboratory for their helpful discussions. This study was supported by the State Key Basic Research and Development Plan (2010CB126003), the National Natural Science Foundation of China (90608016), the National Transgenic Animals and Plants Research Project (2009ZX08005-026B) and the China Postdoctoral Science Foundation (2014M550074).
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