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Title: Differential expression of a novel gene EaF82a in green and yellow sectors of variegated Epipremnum aureum leaves is related to uneven distribution of auxin

Author
item HUNG, CHIU-YUEH - North Carolina State University
item UMSTEAD, MAKENDRA - North Carolina Central University
item CHEN, JIANJUN - University Of Florida
item HOLLIDAY, BRONWYN - North Carolina Central University
item KITTUR, FAROOQAHMED - North Carolina Central University
item HENNY, RICHARD - University Of Florida
item Burkey, Kent
item XIE, JIAHUA - North Carolina Central University

Submitted to: Physiologia Plantarum
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/24/2014
Publication Date: 12/1/2014
Citation: Hung, C., Umstead, M., Chen, J., Holliday, B.M., Kittur, F.S., Henny, R.J., Burkey, K.O., Xie, J. 2014. Differential expression of a novel gene EaF82a in green and yellow sectors of variegated Epipremnum aureum leaves is related to uneven distribution of auxin. Physiologia Plantarum. 152:749-762.

Interpretive Summary: Photosynthesis in higher plants occurs in special organelles called chloroplasts present in cells of leaves and other green tissues. Formation of chloroplasts requires the expression of genes from both the cell nucleus and the organelle itself. The complexity of this process is illustrated in naturally variegated plants that develop leaves containing both green tissue with normal chloroplasts and white or yellow tissue where chloroplast development is stopped at an early stage of organelle formation. In this study, a previously unknown gene named EaF82 was identified and shown to play a key role in the differential chloroplast development leading to leaf variegation in the house plant Epipremnum aureum ‘Golden Pothos’. These findings help lay the groundwork for future research on manipulating chloroplasts to facilitate the manufacture of biopharmaceuticals.

Technical Abstract: EaF82, a gene identified in previous studies of the variegated plant Epipremnum aureum, exhibited a unique expression pattern with greater transcript abundance in yellow sectors than green sectors of variegated leaves, but lower abundance in regenerated pale yellow plants than in green plants derived from tissue culture of leaf tissue. Studies of its full-length complementary DNA (cDNA) and promoter region revealed two family members with only the EaF82a gene expressed. Immunoblotting confirmed that EaF82a encodes a 12 kD protein, but no homolog was found in public available databases. EaF82a was predominantly present in the microsome-enriched fraction with accumulation consistent with its gene expression patterns in different color tissues. Confocal images of EaF82a-sGFP fusion proteins transiently expressed in protoplasts demonstrated its localization in the cytoplasm. Overexpressing EaF82a in tobacco and Arabidopsis did not cause leaf variegation. Transgenic Arabidopsis and tobacco plants carrying EaF82a promoter driving bacterial uidA (GUS) gene showed that GUS activities were exclusively in the close proximity of apical and lateral shoot meristems suggesting a potential role of EaF82 involving new leaf formation. In E. aureum, EaF82a is more abundant at the nodes where new lateral shoots just emerged and also at the lower side of node having more IAA compared to the upper side. EaF82a expression in etiolated transgenic Arabidopsis seedlings was found to be controlled by IAA under the influence of light. Current results point to a possible involvement of EaF82a in plastid development during the early stage of leaf formation.