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Enhancing micro RNA 167A expression in seed decreases the α‐linolenic acid content and increases seed size in Camelina sativa
Author(s) -
Na GunNam,
Mu Xiaopeng,
Grabowski Paul,
Schmutz Jeremy,
Lu Chaofu
Publication year - 2019
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/tpj.14223
Subject(s) - camelina , camelina sativa , biology , linolenic acid , biochemistry , transcription factor , fatty acid , arabidopsis , transcriptome , linoleic acid , gene expression , food science , microbiology and biotechnology , gene , ecology , mutant , crop
Summary Despite well established roles of micro RNA s in plant development, few aspects have been addressed to understand their effects in seeds especially on lipid metabolism. In this study, we showed that overexpressing micro RNA 167A (miR167 OE ) in camelina ( Camelina sativa ) under a seed‐specific promoter changed fatty acid composition and increased seed size. Specifically, the miR167 OE seeds had a lower α‐linolenic acid with a concomitantly higher linoleic acid content than the wild‐type. This decreased level of fatty acid desaturation corresponded to a decreased transcriptional expression of the camelina fatty acid desaturase3 ( Cs FAD 3 ) in developing seeds. MiR167 targeted the transcription factor auxin response factor (Cs ARF 8) in camelina, as had been reported previously in Arabidopsis. Chromatin immunoprecipitation experiments combined with transcriptome analysis indicated that Cs ARF 8 bound to promoters of camelina bZIP 67 and ABI 3 genes. These transcription factors directly or through the ABI 3‐ bZIP 12 pathway regulate Cs FAD 3 expression and affect α‐linolenic acid accumulation. In addition, to decipher the miR167A‐Cs ARF 8 mediated transcriptional cascade for Cs FAD 3 suppression, transcriptome analysis was conducted to implicate mechanisms that regulate seed size in camelina. Expression levels of many genes were altered in miR167 OE , including orthologs that have previously been identified to affect seed size in other plants. Most notably, genes for seed coat development such as suberin and lignin biosynthesis were down‐regulated. This study provides valuable insights into the regulatory mechanism of fatty acid metabolism and seed size determination, and suggests possible approaches to improve these important traits in camelina.