Mitochondrial damage in the soybean seed axis during imbibition at chilling temperature

Mitochondrial damage in the soybean seed axis during imbibition at chilling temperature

2009

A:PS

The development ofm itochondria duri ngseed germination is essential for plant growth. However, the developmental process is still poorly understood. Temperature plays a key role in soybean germination, and in this study we characterized the mitochondrial ultrastructure and proteome after imbibition at 22, 10 and 4°C for 24 h. The mitochondria from the soybean seed axis can be divided into light and heavy mitochondria by Percoll density gradient centrifugation. The axes imbib d at 4°C mainly contained light mitochondria, which had lower levels of specific mitochondrial enzymes and oxidative phosphorylation activity. In contrast, the axes imbibed at 22°C mainly contained heavy mitochondria, which exhibited higher metabolism. Electron microscopy revealed that mitochondria in the axes imbibed at 4°C had a poorly developed internal membrane system with few cristae, while the mitochondria in the axes imbibed at 22°( developed more normally. Furthermore, we compared the axis mitochondrial proteomes during imbibition at different temperatures. The differentially expressed proteins were identified using ESI Q- TOF MSI MS (electrospray ionization quadrupole time of flight tandem mass spectrometry). Proteins involved in mitochondrial metabolites including malate dehydro genase (tricarboxylic acid cycle enzyme), putative A TP synthase subunit (oxidative phosphorylation complex subunits), mitochondrial chaperonin 60 (heat shock protein), arginase (urea cycle enzyme) and mitochondrial elongation factor Tu (mitochondrial genome transcript enzyme) were identified. The reduced expression of these proteins might not support normal mitochondrial metabolism. We conclude that chilling during imbibition causes mitochondrial damage at both ultrastructural and metabolic levels.

v.50(7):1305-1318, PLANT & CELL PHYSIOLOGY

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