Priming and Accelerated Aging Affect L-isoaspartyl Methyltransferase Activity in Tomato Seed
Year: 1996
Type: article
Abstract: Damage and degradation of cellular proteins is observed during seed deterioration due to aging. L-isoaspartyl methyltransferase (EC 2.1.1.77) is an enzyme hypothesized to play a role in limiting and repairing aging-induced damage of proteins. Tomato seeds ( Lycopersicon esculentum `New Yorker') were assayed for changes in L-isoaspartyl methyltransferase activity during accelerated aging and after osmotic priming. Accelerated aging of seeds for 1 to 4 days at 45°C and 100% humidity reduced germination from 94% to 71%, the mean time of germination (MTG) increased from 2.4 to 5.8 days and was accompanied by a correlative decrease in L-isoaspartyl methyltransferase activity R 2 = 0.90. Aged and untreated seeds were primed for 7 days at 20°C in darkness using aerated solutions of 3% KNO 3 or polyethylene glycol 8000 (PEG) with equivalent osmotic potential (–1.25 MPa). Priming with KNO 3 decreased the MTG but not germination percentage for untreated seeds. Priming did not affect L-isoaspartyl methyltransferase activity in untreated seeds but restored activity in aged seeds primed in KNO 3 to levels near that of untreated seeds. Priming with PEG did not effectively improve the MTG or increase L-isoaspartyl methyltransferase activity. During germination, enzyme activity remained constant for 48 hours post-imbibition and then declined suggesting the enzyme was developmentally regulated and inactivated or degraded as radicle emergence occurred.
Source: HortScience
Authors: S.T. Kester, R.L. Geneve, R.L. Houtz
Language: English
Subfield: Plant Science
Domain: Life Sciences
SDG: Zero hunger
Open Access status: bronze
OpenAlex ID: W2913447642