Protein Repairl-Isoaspartyl Methyltransferase1 Is Involved in Both Seed Longevity and Germination Vigor inArabidopsis

Abstract

The formation of abnormal amino acid residues is a major source of spontaneous age-related protein damage in cells. The protein L-isoaspartyl methyltransferase (PIMT) combats protein misfolding resulting from L-isoaspartyl formation by catalyzing the conversion of abnormal L-isoaspartyl residues to their normal L-aspartyl forms. In this way, the PIMT repair enzyme system contributes to longevity and survival in bacterial and animal kingdoms. Despite the discovery of PIMT activity in plants two decades ago, the role of this enzyme during plant stress adaptation and in seed longevity remains undefined. In this work, we have isolated Arabidopsis thaliana lines exhibiting altered expression of PIMT1, one of the two genes encoding the PIMT enzyme in Arabidopsis. PIMT1 overaccumulation reduced the accumulation of L-isoaspartyl residues in seed proteins and increased both seed longevity and germination vigor. Conversely, reduced PIMT1 accumulation was associated with an increase in the accumulation of L-isoaspartyl residues in the proteome of freshly harvested dry mature seeds, thus leading to heightened sensitivity to aging treatments and loss of seed vigor under stressful germination conditions. These data implicate PIMT1 as a major endogenous factor that limits abnormal L-isoaspartyl accumulation in seed proteins, thereby improving seed traits such as longevity and vigor. The PIMT repair pathway likely works in concert with other anti-aging pathways to actively eliminate deleterious protein products, thus enabling successful seedling establishment and strengthening plant proliferation in natural environments.

Overexpression of Nelumbo nucifera metallothioneins 2a and 3 enhances seed germination vigor in Arabidopsis

“…However, the molecular mechanism of seed vigor is unclear. During the past decades, considerable efforts 20 have been made to disclose the mechanisms of the underlying characteristics of seed storability and seed vigor (Debeaujon, Leon-Kloosterziel & Koornneef 2000;Clerkx 27 et al 2003;Rosnoblet et al 2007;Oge et al 2008;Shin, Kim & An 2009;Waterworth et al 2010). In this study, we show that the transcripts of MT2a, MT2b…”

Metabolic Processes During Seed Germination

“…In addition, drying and rapid seed dehydration processes influence DNA integrity [125]. Seeds have developed a number of repair mechanisms during seed germination, including the repair of membranes, as well as proteins and DNA [126].…”

Physiological and biochemical aspects of castor beans seeds deterioration stored in different packaging conditions and temperatures

“…Preservation of the seeds quality during storage, after their physiological maturity, depends on the species lifespan, its initial quality and storage conditions (Probert et al, 2007;Cardoso et al, 2012). Temperature and relative humidity are often cited as some of the key factors that affect adversely the seeds quality during storage, causing physical and chemical changes such as loss of the cell membrane integrity, decreased enzymatic activity, lipids peroxidation (Ellis and Hong, 2006;Oge et al, 2008) and, consequently, loss of vigor.…”

“…Temperature and relative humidity are often cited as some of the key factors that affect adversely the seeds quality during storage, causing physical and chemical changes such as loss of the cell membrane integrity, decreased enzymatic activity, lipids peroxidation (Ellis and Hong, 2006;Oge et al, 2008) and, consequently, loss of vigor.…”