Long-chain polyunsaturated fatty acids in the green microalga Lobosphaera incisa contribute to tolerance to abiotic stresses

Amit Kugler, Boris Zorin, Shoshana Didi-Cohen, Maria Sibiryak, Olga Gorelova, Tatiana Ismagulova, Kamilya Kokabi, Puja Kumari, Alexander Lukyanov, Sammy Boussiba, Alexei Solovchenko, Inna Khozin-Goldberg

Research output: Contribution to journalArticlepeer-review

7 Scopus citations

Abstract

Lobosphaera incisa is a green microalga that accumulates high levels of the valuable omega-6 long-chain polyunsaturated fatty acids (LC-PUFA) arachidonic acid (ARA, 20:4n-6) in triacylglycerols (TAG) under nitrogen (N) starvation. LC-PUFA accumulation is a rare trait in photosynthetic microalgae with insufficiently understood physiological significance. In this study, RNAi was attempted, for the first time in L. incisa, to produce knockdown lines for the 5 desaturase gene. Two lines, termed modified lines, which were isolated during screening for transgenic events, demonstrated alterations in their LC-PUFA profile, ARA-biosynthesis gene expression and lipid class distribution. In line M5-78, which appeared to carry a mutation in the 6 elongase gene, LC-PUFA were substituted by 18:3n-6 in all glycerolipids. Line M2-35, for which the exact genetic background has not been established, displayed a dramatic reduction in 20:4n-6, concomitant with an augmented proportion of 18:1n-9, in particular in the extraplastidial membrane lipids and TAG. The physiological responses of the modified lines to stressful conditions were compared with the wild type and the 5 desaturase mutant. In the N-replete cells of modified lines, the frequency of lipid droplets was reduced, while a number of starch grains increased, suggesting altered partitioning of assimilated carbon into reserve products. Furthermore, both lines exhibited reduced ability to accumulate TAG under N deprivation and recover from N starvation. Both lines demonstrated lower photosynthetic pigment contents, impairments in photosynthesis under a range of stressful conditions, and less efficient functioning of photoprotection under optimal conditions. Possible implications of fatty acids modifications in the stress response of L. incisa are addressed.

Original languageEnglish
Pages (from-to)1205-1223
Number of pages19
JournalPlant and Cell Physiology
Volume60
Issue number6
DOIs
StatePublished - 1 Jun 2019

Keywords

  • Abiotic stress
  • Arachidonic acid
  • Desaturation
  • Photosynthetic performance
  • Triacylglycerol

ASJC Scopus subject areas

  • Physiology
  • Plant Science
  • Cell Biology

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