Phytocalpain controls the proliferation and differentiation fates of cells in plant organ development.
Calpain, a calcium-dependent cysteine protease, plays an essential role in basic cellular processes in animal cells, including cell proliferation, apoptosis, and differentiation. NbDEK encodes the calpain homolog of N. benthamiana. In this study, virus-induced gene silencing (VIGS) of NbDEK resulted in arrested organ development and hyperplasia in all the major plant organs examined. The epidermal layers of the leaves and stems were covered with hyperproliferating cell masses, and stomata and trichome development was severely inhibited. During flower development, a single dome-like structure was grown from the flower meristem to generate a large cylinder-shaped flower lacking any floral organs. At the cellular level, cell division was sustained in tissues that were otherwise already differentiated, and cell differentiation was severely hampered. NbDEK is ubiquitously expressed in all the plant tissues examined. In the abnormal organs of the NbDEK VIGS lines, protein levels of D-type cyclins (CycD)2, CycD3, and proliferating cell nuclear antigen (PCNA) were greatly elevated, and transcription of E2F (E2 promoter binding factor), E2F-regulated genes, retinoblastoma (Rb), and KNOTTED1 (KN1)-type homeobox genes was also stimulated. These results suggest that phytocalpain is a key regulator of cell proliferation and differentiation during plant organogenesis, and that it acts partly by controlling the CycD/Rb pathway.
Ahn
Joon-Woo
JW
Laboratory of Plant Genomics, Korea Research Institute of Bioscience and Biotechnology, Oun-dong 52, Yusong-gu, Taejon 305-333, Korea.
Kim
Moonil
M
Lim
Jeong Hwa
JH
Kim
Gyung-Tae
GT
Pai
Hyun-Sook
HS
D000595:Amino Acid Sequence; D002154:Calpain / Q000235:genetics / Q000502:physiology*; D002453:Cell Cycle / Q000235:genetics; D002454:Cell Differentiation / Q000502:physiology*; D002455:Cell Division / Q000502:physiology*; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000032:analysis; D015870:Gene Expression; D020868:Gene Silencing / Q000502:physiology; D018398:Homeodomain Proteins / Q000378:metabolism; D008969:Molecular Sequence Data; D018515:Plant Leaves / Q000254:growth & development; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D018547:Plant Stems / Q000254:growth & development; D017386:Sequence Homology, Amino Acid; D014026:Nicotiana / Q000235:genetics* / Q000821:virology
D018076:DNA, Complementary; D018398:Homeodomain Proteins; C405985:Knox1 protein, plant; D010940:Plant Proteins; D002154:Calpain