The Arabidopsis cytosolic Acyl-CoA-binding proteins play combinatory roles in pollen development.
In Arabidopsis, six acyl-CoA-binding proteins (ACBPs) have been identified and they have been demonstrated to function in plant stress responses and development. Three of these AtACBPs (AtACBP4-AtACBP6) are cytosolic proteins and all are expressed in floral organs as well as in other tissues. The roles of cytosolic AtACBPs in floral development were addressed in this study. To this end, a T-DNA insertional knockout mutant of acbp5 was characterized before use in crosses with the already available acbp4 and acbp6 T-DNA knockout mutants to examine their independent and combinatory functions in floral development. The single-gene knockout mutations did not cause any significant phenotypic changes, while phenotypic deficiencies affecting siliques and pollen were observed in the double mutants (acbp4acbp6 and acbp5acbp6) and the acbp4acbp5acbp6 triple mutant. Vacuole accumulation in the acbp4acbp6, acbp5acbp6 and acbp4acbp5acbp6 pollen was the most severe abnormality occurring in the double and triple mutants. Furthermore, scanning electron microscopy and transmission electron microscopy revealed exine and oil body defects in the acbp4acbp5acbp6 mutant, which also displayed reduced ability in in vitro pollen germination. Transgenic Arabidopsis expressing β-glucuronidase (GUS) driven from the various AtACBP promoters indicated that AtACBP6pro::GUS expression overlapped with AtACBP4pro::GUS expression in pollen grains and with AtACBP5pro::GUS expression in the microspores and tapetal cells. Taken together, these results suggest that the three cytosolic AtACBPs play combinatory roles in acyl-lipid metabolism during pollen development.
School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong, China.
An-Shan
AS
Hsiao
Department of Biological Sciences, University of Calgary, Calgary, Alberta, T2N1N4, Canada.
Edward C
EC
Yeung
School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong, China.
Zi-Wei
ZW
Ye
School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong, China mlchye@hkucc.hku.hk.
Mee-Len
ML
Chye
D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism*; D026261:Diazepam Binding Inhibitor / Q000235:genetics / Q000378:metabolism*; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D018525:Germination; D009154:Mutation / Q000235:genetics; D010641:Phenotype; D010938:Plant Oils / Q000378:metabolism; D011058:Pollen / Q000033:anatomy & histology / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D012098:Reproduction / Q000235:genetics
C495420:ACBP4 protein, Arabidopsis; C495421:ACBP5 protein, Arabidopsis; C532782:ACBP6 protein, Arabidopsis; D029681:Arabidopsis Proteins; D002352:Carrier Proteins; D026261:Diazepam Binding Inhibitor; D010938:Plant Oils
Acyl-CoA-binding protein; Exine; Lipid metabolism; Oil body; Reproduction