Down-regulation of lipoxygenase gene reduces degradation of carotenoids of golden rice during storage

Planta. 2015 Jul;242(1):353-63. doi: 10.1007/s00425-015-2314-4. Epub 2015 May 12.

Abstract

Down-regulation of lipoxygenase enzyme activity reduces degradation of carotenoids of bio-fortified rice seeds which would be an effective tool to reduce huge post-harvest and economic losses of bio-fortified rice seeds during storage. Bio-fortified provitamin A-enriched rice line (golden rice) expressing higher amounts of β-carotene in the rice endosperm provides vitamin A for human health. However, it is already reported that degradation of carotenoids during storage is a major problem. The gene responsible for degradation of carotenoids during storage has remained largely unexplored till now. In our previous study, it has been shown that r9-LOX1 gene is responsible for rice seed quality deterioration. In the present study, we attempted to investigate if r9-LOX1 gene has any role in degradation of carotenoids in rice seeds during storage. To establish our hypothesis, the endogenous lipoxygenase (LOX) activity of high-carotenoid golden indica rice seed was silenced by RNAi technology using aleurone layer and embryo-specific Oleosin-18 promoter. To check the storage stability, LOX enzyme down-regulated high-carotenoid T3 transgenic rice seeds were subjected to artificial aging treatment. The results obtained from biochemical assays (MDA, ROS) also indicated that after artificial aging, the deterioration of LOX-RNAi lines was considerably lower compared to β-carotene-enriched transgenic rice which had higher LOX activity in comparison to LOX-RNAi lines. Furthermore, it was also observed by HPLC analysis that down-regulation of LOX gene activity decreases co-oxidation of β-carotene in LOX-RNAi golden rice seeds as compared to the β-carotene-enriched transgenic rice, after artificial aging treatment. Therefore, our study substantially establishes and verifies that LOX is a key enzyme for catalyzing co-oxidation of β-carotene and has a significant role in deterioration of β-carotene levels in the carotenoid-enriched golden rice.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Blotting, Southern
  • Carotenoids / metabolism*
  • Chromatography, High Pressure Liquid
  • Down-Regulation / genetics*
  • Gene Expression Regulation, Plant
  • Genes, Plant*
  • Genetic Vectors / metabolism
  • Lipoxygenase / genetics*
  • Lipoxygenase / metabolism
  • Oryza / enzymology*
  • Oryza / genetics*
  • Phenotype
  • Plants, Genetically Modified
  • Preservation, Biological*
  • RNA Interference
  • Seeds / genetics
  • Transformation, Genetic

Substances

  • Carotenoids
  • Lipoxygenase