Elevating seed oil content in a polyploid crop by induced mutations in SEED FATTY ACID REDUCER genes.

Nirosha L Karunarathna,Lixi Jiang,Haoyi Wang,Hans-Joachim Harloff,Christian Jung

doi:10.1111/pbi.13381

Nirosha L Karunarathna, Lixi Jiang + Show 3 more

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https://doi.org/10.1111/pbi.13381

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Abstract

SummaryPlant‐based oils are valuable agricultural products, and seed oil content (SOC) is the major yield component in oil crops. Increasing SOC has been successfully targeted through the selection and genetic modification of oil biosynthesis. The SOC in rapeseed declined during the seed maturation and eventually caused the final accumulated seed oil quantity. However, genes involved in oil degradation during seed maturity are not deeply studied so far. We performed a candidate gene association study using a worldwide collection of rapeseed germplasm. We identified SEED FATTY ACID REDUCER (SFAR) genes, which had a significant effect on SOC and fatty acid (FA) composition. SFAR genes belong to the GDSL lipases, and GDSL lipases have a broad range of functions in plants. After quantification of gene expression using RNA‐seq and quantitative PCR, we used targeted (CRISPR‐Cas mediated) and random (chemical) mutagenesis to modify turnover rates of seed oil in winter rapeseed. For the first time, we demonstrate significant increase of SOC in a crop after knocking out members of the BnSFAR4 and BnSFAR5 gene families without pleiotropic effects on seed germination, vigour and oil mobilization. Our results offer new perspectives for improving oil yield by targeted mutagenesis.

Highlights

In the seeds of oil plants, triacylglycerols (TAGs) are the major energy resource required during germination
Previous studies reported that Seed oil content (SOC) peaks at seed maturation (Kelly et al, 2013, Wan et al, 2017) and degrades during seed desiccation indicating that the accumulation of lipids in seeds is not a unilateral synthesis process, but a dynamic balance between anabolism and catabolism, influenced by numerous external and internal factors (Kurat et al, 2006; Zhou et al, 2018)
With a candidate gene association study using a worldwide collection of rapeseed accessions, we identified SEED FATTY ACID REDUCER (SFAR) genes, which had a significant effect on SOC

Summary

Introduction

In the seeds of oil plants, triacylglycerols (TAGs) are the major energy resource required during germination. The free FAs are subjected to b-oxidation, a catabolic process by which FA molecules are broken down to produce acetyl-CoA, which is subsequently converted into 4carbon compounds via the glyoxylate cycle (Pracharoenwattana and Smith, 2008, Borek et al, 2015, Graham, 2008). Previous studies reported that SOC peaks at seed maturation (Kelly et al, 2013, Wan et al, 2017) and degrades during seed desiccation indicating that the accumulation of lipids in seeds is not a unilateral synthesis process, but a dynamic balance between anabolism and catabolism, influenced by numerous external and internal factors (Kurat et al, 2006; Zhou et al, 2018). Our knowledge about lipid decomposition during seed maturation is comparatively limited (Ding et al, 2019; Kanai et al, 2019; Kelly et al, 2013), and the biological implication of TAG degradation during seed development remains to be elucidated

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