Expansins in deepwater rice internodes.

AUTOR(ES)

Cho, H T

RESUMO

Cell walls of deepwater rice (Oryza sativa L.) internodes undergo long-term extension (creep) when placed under tension in acidic buffers. This is indicative of the action of the cell wall-loosening protein expansin. Wall extension had a pH optimum of around 4.0 and was abolished by boiling. Acid-induced extension of boiled cell walls could be reconstituted by addition of salt-extracted rice or cucumber cell wall proteins. Cucumber expansin antibody recognized a single protein band of 24.5-kD apparent molecular mass on immunoblots of rice cell wall proteins. Expansins were partially purified by concanavalin A affinity chromatography and sulfopropyl (SP) cation-exchange chromatography. The latter yielded two peaks with extension activity (SP20 and SP29), and immunoblot analysis showed that both of these active fractions contained expansin of 24.5-kD molecular mass. The N-terminal amino acid sequence of SP20 expansin is identical to that deduced from the rice expansin cDNA Os-EXP1. The N-terminal amino acid sequence of SP29 expansin matches that deduced from the rice expansin cDNA Os-EXP2 in six of eight amino acids. Our results show that two expansins occur in the cell walls of rice internodes and that they may mediate acid-induced wall extension.

Documentos Relacionados

• Expansins and Internodal Growth of Deepwater Rice.
• Cuticle Biosynthesis in Rapidly Growing Internodes of Deepwater Rice.
• Expression of β-Expansins Is Correlated with Internodal Elongation in Deepwater Rice1
• The Biophysical Basis of Elongation Growth in Internodes of Deepwater Rice 1
• Xyloglucan endotransglycosylase activity in pea internodes. Effects of applied gibberellic acid.