AUTHOR=Zhang Qing-Yu , Yu Rui , Xie Li-Hang , Rahman Md Mahbubur , Kilaru Aruna , Niu Li-Xin , Zhang Yan-Long 

TITLE=Fatty Acid and Associated Gene Expression Analyses of Three Tree Peony Species Reveal Key Genes for α-Linolenic Acid Synthesis in Seeds

JOURNAL=Frontiers in Plant Science

VOLUME=9

YEAR=2018

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2018.00106

DOI=10.3389/fpls.2018.00106

ISSN=1664-462X

ABSTRACT=<p>The increasing demand for healthy edible oil has generated the need to identify promising oil crops. Tree peony (<italic>Paeonia</italic> section <italic>Moutan</italic> DC.) is a woody oil crop with α-linolenic acid (ALA) contributing for 45% of the total fatty acid (FA) content in seeds. Molecular and genetic differences that contribute to varied FA content and composition among the wild peony species are, however, poorly understood. Analyses of FA content and composition during seed development in three tree peony species (<italic>Paeonia rockii</italic>, <italic>P. potaninii</italic>, and <italic>P. lutea</italic>) showed varied FA content among them with highest in <italic>P. rockii</italic>, followed by <italic>P. potaninii</italic>, and <italic>P. lutea</italic>. Total FA content among these species increased with seed development and reached its maximum in its final stage. Seed FA composition analysis of the three species also revealed that ALA (C18:3) was the most abundant, followed by oleic (C18:1) and linoleic (C18:2) acids. Additionally, quantitative real-time RT-PCR analyses of 10 key seed oil synthesis genes in the three tree peony species revealed that <italic>FAD3</italic>, <italic>FAD2</italic>, β<italic>-PDHC</italic>, <italic>LPAAT</italic>, and <italic>Oleosin</italic> gene expression levels positively correlate with total FA content and rate of accumulation. Specifically, the abundance of <italic>FAD3</italic> transcripts in <italic>P. rockii</italic> compared with <italic>P. potaninii</italic>, and <italic>P. lutea</italic> suggests that FAD3 might play an important role in synthesis of ALA via phosphatidylcholine-derived pathway. Overall, comparative analyses of FA content and composition in three different peony species revealed a correlation between efficient lipid accumulation and lipid gene expression during seed development. Further characterization and metabolic engineering of these key genes from peonies will allow for subsequent improvement of tree peony oil quality and production.</p>