Mechanisms of Gene Regulation
Kang, Yongwon , Kim, Ryong Nam , Cho, Hye Sun , Choi, Doil , Pai, Hyun-sook .
Depletion of NbBPS1 causes uncontrolled cell proliferation in the vascular cambium and cell death in Nicotiana benthamiana.
The Arabidopsis bypass1 (bps1) mutant shows shoot and root defects with altered leaf vein patterns, likely caused by defective processing of a root-produced carotenoid-derived signal that controls shoot and root development (Curr. Biol. 14, 1739-1746). In this study, we analyzed further details of BPS deficiency by using virus-induced gene silencing (VIGS) in Nicotiana benthamiana. VIGS of NbBPS1, a homolog of Arabidopsis BPS1, caused the arrest in shoot and root growth, and subsequently plant death. At the cell level, NbBPS1 deficiency caused the abrogation of the root apical meristem, and intriguingly, hyperproliferation of the cambium and defective xylem differentiation in stems. In leaves, the cell size increased and the cell number decreased, accompanied by significantly elevated endoreduplication. Consistently, the leaf vascular system was also unusually amplified. Cell death caused by NbBPS1 deficiency involves the abolition of chloroplasts and mitochondria. VIGS of the transgenic N. benthamiana plants carrying the ARR5 promoter-GUS fusion gene indicates that loss of NbBPS1 function caused elevated cytokinin levels and/or cytokinin signaling in the vascular tissues of the stem. NbBPS1 has a transmembrane domain at the center, and NbBPS1-GFP fusion protein is associated with the ER. Consistent with the results in Arabidopsis, fluridone, an inhibitor of carotenoid biosynthesis, partially suppressed the leaf and root defects of the NbBPS1-depleted plants. Taken together, these results suggest that NbBPS1 plays a critical role in the control of cell proliferation/differentiation during plant organ development by regulating the root-derived signal, and the signal acts differentially in different meristems.
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1 - YONSEI UNIVERSITY, BIOLOGY, Yonsei Science Research Center S134, 134, Sinchon-dong, Seodaemun-gu,, Seoul, 120-749, South Korea
2 - Korea Research Institute of Bioscience & Biotechnology, #52 Eoeun-Dong, Yuseong-Gu, Daejeon, 305-333, South Korea
3 - Seoul National University, School of Biological Sciences, College Natural Sciences, Shinrim-Dong, Gwanak-Ku, Seoul, 151-742, Korea
Presentation Type: Plant Biology Abstract
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM