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Engineering trienoic fatty acids into cottonseed oil improves low-temperature seed germination, plant photosynthesis and cotton fibre quality
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  • Lihong Gao,
  • Wei Chen,
  • Xiaoyu Xu,
  • Jing Zhang,
  • Tanoj Singh,
  • Shiming Liu,
  • Dongmei Zhang,
  • Lijun Tian,
  • Adam White,
  • Pushkar Shrestha,
  • Xue-Rong Zhou,
  • Danny Llewellyn,
  • Allan Green,
  • Surinder Singh,
  • Qing Liu
Lihong Gao
Changchun Normal University
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Wei Chen
Beihua University
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Xiaoyu Xu
CSIRO
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Jing Zhang
CSIRO
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Tanoj Singh
CSIRO
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Shiming Liu
CSIRO
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Dongmei Zhang
Shanghai Landscape Gardening Research Institute
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Lijun Tian
CSIRO
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Adam White
CSIRO
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Pushkar Shrestha
CSIRO
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Xue-Rong Zhou
CSIRO
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Danny Llewellyn
CSIRO
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Allan Green
CSIRO
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Surinder Singh
CSIRO
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Qing Liu
CSIRO
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Abstract

Alpha-linolenic acid (ALA, 18:3∆9,12,15) and γ-linolenic acid (GLA, 18:3∆6,9,12) are important trienoic fatty acids which are beneficial for human health in their own right, or as precursors for the biosynthesis of long chain polyunsaturated fatty acids. ALA and GLA in seed oil are synthesized from linoleic acid (LA, 18:2∆9,12) by the microsomal ω-3 fatty acid desaturase (FAD3) and ∆6 desaturase (D6D), respectively. Cotton (Gossypium hirsutum L.) seed oil composition was modified by transforming with a FAD3 gene from Brassica napus and a D6D gene from Echium plantagineum, resulting in approximately 30% ALA and 20% GLA, respectively. The total oil content in transgenic seeds remained unaltered relative to parental seeds. Despite the use of a seed-specific promoter for transgene expression, low levels of GLA and increased levels of ALA were found in non-seed cotton tissues. At low temperature the germinating cottonseeds containing the linolenic acid isomers elongated faster than the untransformed controls. ALA-producing lines also showed higher photosynthetic rates at cooler temperature and better fibre quality compared to both untransformed controls and GLA-producing lines. The oxidative stability of the novel cottonseed oils was assessed, providing guidance for potential food, pharmaceutical and industrial applications of these oils.