Aluminum accumulation and its effects on acquired tolerance and proteome expression in tomato seeds during seed maturation
Aluminum (Al) is one of the most common elements in the earth crust (8%). The toxicity of Al is affected by the acidity of its environment. At pH levels lower than 5, the amount of aluminum in the Al3+ form dramatically reduces plant productivity. For this study, tomato (Solanum lycopersicum cv. Micro-Tom) fruits were used, because the interior of the fruit is naturally acidic (4.3-4.5), to investigate the effects of Al in maturing seeds in a hydroponic system. For the Al treatment, the hydroponic solution was supplemented with 50 µM Al (SO4)3. 18H 2O, and the controls were refreshed with only the Magnavaca's solution. After the treatment, Al accumulation in seeds and vascular tissues of tomato plants were detected in situ by means of morin (2’, 3, 4’, 5, 7-pentahydroxyflavone) staining. Seeds produced in tomato fruits that were harvested from treated plants were compared with the control. These seeds were germinated in a buffer (pH 4.0) solution supplemented with 50 µM AlK (SO4)2. 12H2O. A few seedlings from seeds that were produced by Al-treated tomato plants produced lateral roots, which were not found in seeds from non-treated plants. Differentially expressed proteins between the Al-enriched seeds and controls were identified using two-dimensional gel electrophoresis analysis. Identified proteins were those that are involved in gene expression and cell division (B2-type cyclin dependent kinase, protein suppressor of gene silencing, translationally-controlled tumor protein, gag-pol polyprotein-retrotransposon, and SANT/MYB protein); chaperones and protectants (Small heat shock protein, PI-phospholipase C PLC5, glutathione-S-transferase (GST), glutamate decarboxylase isoform, glutamine synthase, superoxide dismutase, and ASR4); phytohormone biosynthesis (IAA2, ABA aldehyde oxidase, jasmonate ZIM-domain protein 3, and brassinosteroid hydroxylase); and metabolic pathways (malic enzyme and alcohol dehydrogenase 2). Protein expression patterns suggests that tomato seeds may have expressed some tolerance mechanisms for dealing with the endogenous Al. The activities of five different antioxidant enzymes were also assessed. They include glutathione reductase, GST, peroxidase, catalase, and hydroxypyruvate reductase (HPR). Only HPR showed a significant difference between control and treated seed tissues. This study provided valuable new insights into molecular mechanisms associated with Al toxicity in tomato.
Plant biology|Plant sciences|Agricultural engineering
"Aluminum accumulation and its effects on acquired tolerance and proteome expression in tomato seeds during seed maturation"
ETD Collection for Tennessee State University.