title: Assessment of penetrance and expressivity of RNAi-mediated silencing of the Arabidopsis phytoene desaturase gene.
abstract: RNA interference (RNAi) is of great value in plant functional genomics. However, the absence of RNAi phenotypes and the lack of uniform level of RNAi silencing has complicated gene identification. Here, the penetrance and expressivity of RNAi-mediated silencing of the phytoene desaturase (PDS) gene in Arabidopsis thaliana were examined quantitatively to provide a reference for the likely severity and distribution of silencing effects. Arabidopsis plants were transformed with an RNAi construct targeting PDS. Transgenic plants were examined for frequency of RNAi-mediated silencing and various silencing phenotypes. mRNA depletion level and RNAi expressivity were assayed by relative reverse transcription polymerase chain reaction (RT-PCR). High penetrance and variable expressivity of RNAi were demonstrated. An inverse correlation between PDS mRNA level and RNAi phenotype was seen. No direct relationship between copy number for the RNAi-generating transgene and phenotype was evident. Decreased RNAi penetrance in T2 plants was observed. It is suggested that variability in RNAi expressivity and postmeiotic decrease in RNAi penetrance constitute barriers for high throughput plant gene characterization.
authors.affiliation: Institute of Developmental and Molecular Biology and Department of Biology, Texas A and M University, College Station, TX 77843-3155, USA.
authors.forename: Tao
authors.initials: T
authors.lastname: Wang
authors.forename: Lakshminarayan M
authors.initials: LM
authors.lastname: Iyer
authors.forename: Rakesh
authors.initials: R
authors.lastname: Pancholy
authors.forename: Xiangyu
authors.initials: X
authors.lastname: Shi
authors.forename: Timothy C
authors.initials: TC
authors.lastname: Hall
mesh_terms: D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics; D002874:Chromosome Mapping; D032461:Chromosomes, Plant; D018506:Gene Expression Regulation, Plant; D010088:Oxidoreductases / Q000235:genetics / Q000378:metabolism*; D019683:Penetrance; D018515:Plant Leaves / Q000502:physiology; D030821:Plants, Genetically Modified; D034622:RNA Interference
chemical_list: D010088:Oxidoreductases; C022398:phytoene dehydrogenase