Downregulation of key genes involved in carbon metabolism in Medicago truncatula results in increased lipid accumulation in vegetative tissue

• Author(s) / Creator(s)

  • Wijekoon, Champa
  • Singer, Stacy D.
  • Weselake, Randall J.
  • Petrie, James R.
  • Chen, Guanqun
  • Singh, Surinder
  • Eastmond, Peter J.
  • Acharya, Surya N.

• Alfalfa (Medicago sativa L.) is the most widely grown perennial forage crop and is a close relative of the model diploid legume Medicago truncatula Gaertn. However, use of alfalfa leads to substantial greenhouse gas emissions and economic losses related to inefficiencies in rumen fermentation. The provision of supplemental lipids has been used as a strategy to mitigate these issues, but it is a costly approach. The ability to enhance lipid content within the vegetative tissues of alfalfa would therefore be very advantageous. As such, our aim was to assess and select gene candidates to increase total shoot lipid content in M. truncatula using a virus‐induced gene silencing (VIGS) approach. We targeted gene homologs of the SUGAR‐DEPENDANT 1 (SDP1), ADP‐GLUCOSE‐PYROPHOSPHORYLASE SMALL SUBUNIT 1 (APS1), TRIGALACTOSYLDIACYLGLYCEROL 5 (TGD5), and PEROXISOMAL ABC TRANSPORTER 1 (PXA1) in M. truncatula for silencing. Reduced target transcript levels were confirmed and changes of shoot lipid content and fatty acid composition were measured. Silencing of SDP1, APS1, and PXA1 each resulted in significant increases in shoot total lipid content. Significantly increased proportions of α‐linolenic acid (18:3Δ9cis,12cis,15cis) were observed, and stearic acid (18:0) levels significantly decreased in the total acyl lipids extracted from vegetative tissues of each of the M. truncatula silenced plants. In contrast, palmitic acid (16:0) levels were significantly decreased in only SDP1‐ and PXA1‐silenced plants. Genes of PXA1 and SDP1 would be ideal targets for mutation as a means of improving the quality of alfalfa to increase feed efficiency and minimize greenhouse gas emissions from livestock production in the future.

• Date created

  2020-02-11

• Subjects / Keywords

  • forage legume
  • lipid metabolism
  • Virus-induced gene silencing
  • feed quality,
  • methane emissions

• Type of Item

  Article (Draft / Submitted)

• DOI

  https://doi.org/10.7939/r3-m64m-nz21

• License

  This is the peer reviewed version of the following article: Wijekoon, C., Singer, S. D., Weselake, R. J., Petrie, J. R., Chen, G., Singh, S., ... & Acharya, S. N. Down‐regulation of key genes involved in carbon metabolism in Medicago truncatula results in increased lipid accumulation in vegetative tissue. Crop Science., which has been published in final form at https://doi.org/10.1002/csc2.20124. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions. This article may not be enhanced, enriched or otherwise transformed into a derivative work, without express permission from Wiley or by statutory rights under applicable legislation. Copyright notices must not be removed, obscured or modified. The article must be linked to Wiley’s version of record on Wiley Online Library and any embedding, framing or otherwise making available the article or pages thereof by third parties from platforms, services and websites other than Wiley Online Library must be prohibited.