Activation tagging of Arabidopsis POLYGALACTURONASE INVOLVED IN EXPANSION 2 promotes hypocotyl elongation, leaf expansion, stem lignification, mechanical stiffening, and lodging

Journal Article · Sat Feb 11 00:00:00 EST 2017 · The Plant Journal

DOI:https://doi.org/10.1111/tpj.13453· OSTI ID:1401261

Xiao, Chaowen ^[1]; Barnes, William J. ^[1]; Zamil, M. Shafayet ^[2]; Yi, Hojae ^[2]; Puri, Virendra M. ^[2]; Anderson, Charles T. ^[1]

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1. Department of Biology The Pennsylvania State University University Park PA 16802 USA, Center for Lignocellulose Structure and Formation The Pennsylvania State University University Park PA 16802 USA
2. Department of Agricultural and Biological Engineering The Pennsylvania State University University Park PA 16802 USA

Summary Pectin is the most abundant component of primary cell walls in eudicot plants. The modification and degradation of pectin affects multiple processes during plant development, including cell expansion, organ initiation, and cell separation. However, the extent to which pectin degradation by polygalacturonases affects stem development and secondary wall formation remains unclear. Using an activation tag screen, we identified a transgenic Arabidopsis thaliana line with longer etiolated hypocotyls, which overexpresses a gene encoding a polygalacturonase. We designated this gene as POLYGALACTURONASE INVOLVED IN EXPANSION 2 ( PGX 2 ), and the corresponding activation tagged line as PGX 2 ^AT . PGX 2 is widely expressed in young seedlings and in roots, stems, leaves, flowers, and siliques of adult plants. PGX 2‐ GFP localizes to the cell wall, and PGX 2 ^AT plants show higher total polygalacturonase activity and smaller pectin molecular masses than wild‐type controls, supporting a function for this protein in apoplastic pectin degradation. A heterologously expressed, truncated version of PGX 2 also displays polygalacturonase activity in vitro . Like previously identified PGX 1 ^AT plants, PGX 2 ^AT plants have longer hypocotyls and larger rosette leaves, but they also uniquely display early flowering, earlier stem lignification, and lodging stems with enhanced mechanical stiffness that is possibly due to decreased stem thickness. Together, these results indicate that PGX 2 both functions in cell expansion and influences secondary wall formation, providing a possible link between these two developmental processes.

• Sponsoring Organization: USDOE
• OSTI ID: 1401261
• Journal Information: The Plant Journal, Journal Name: The Plant Journal Vol. 89 Journal Issue: 6; ISSN 0960-7412
• Publisher: Wiley-Blackwell
• Country of Publication: United Kingdom
• Language: English