BackgroundBased on our previous studied on different provenances ofPistacia chinensis, some accessions with high quality and quantity of seed oils has emerged as novel source of biodiesel. To better developP. chinensisseed oils as woody biodiesel, a concurrent exploration of oil content, FA profile, biodiesel yield, and fuel properties was conducted on the seeds from 5 plus germplasms to determine superior genotype for ideal biodiesel production. Another vital challenge is to unravel mechanism that govern the differences in oil content and FA profile ofP. chinensisseeds across different accessions. FA biosynthesis and oil accumulation of oil plants are known to be highly controlled by the transcription factors. An integrated analysis of our recent transcriptome data, qRT-PCR detection and functional identification was performed as an attempt to highlight LEC1/WRI1-mediated transcription regulatory mechanism for high-quality oil accumulation inP. chinensisseeds.ResultsTo select ideal germplasm and unravel high oil accumulative mechanism for developingP. chinensisseed oils as biodiesel, five plus trees (accession PC-BJ/PC-AH/PC-SX/PC-HN/PC-HB) with high-yield seeds were selected to assess the variabilities in weight, oil content, FA profile, biodiesel yield and fuel property, revealing a variation in the levels of seed oil (50.76–60.88%), monounsaturated FA (42.80–70.72%) and polyunsaturated FA (18.78–43.35%), and biodiesel yield (84.98–98.15%) across different accessions. PC-HN had a maximum values of seed weight (26.23 mg), oil (60.88%) and biodiesel yield (98.15%), and ideal proportions of C18:1 (69.94%), C18:2 (17.65%) and C18:3 (1.13%), implying that seed oils of accession PC-HN was the most suitable for ideal biodiesel production. To highlight molecular mechanism that govern such differences in oil content and FA profile of different accessions, a combination of our recent transcriptome data, qRT-PCR detection and protein interaction analysis was performed to identify a pivotal role of LEC1/WRI1-mediated transcription regulatory network in high oil accumulation ofP. chinensisseeds from different accessions. Notably, overexpression ofPcWRI1orPcLEC1fromP. chinensisseeds in Arabidopsis could facilitate seed development and upregulate several genes relevant for carbon flux allocation (plastidic glycolysis and acetyl-CoA generation), FA synthesis, TAG assembly and oil storage, causing an increase in seed oil content and monounsaturated FA level, destined for biodiesel fuel property improvement. Our findings may present strategies for better developingP. chinensisseed oils as biodiesel feedstock and bioengineering its high oil accumulation.ConclusionsThis is the first report on the cross-accessions assessments ofP. chinensisseed oils to determine ideal accession for high-quality biodiesel production, and an effective combination ofPcWRI1orPcLEC1overexpression, morphological assay, oil accumulation and qRT-PCR detection was applied to unravel a role of LEC1/WRI1-mediated regulatory network for oil accumulation inP. chinensisseeds, and to highlight the potential application ofPcWRI1orPcLEC1for increasing oil production. Our finding may provide new strategies for developing biodiesel resource and molecular breeding.Supplementary InformationThe online version contains supplementary material available at 10.1186/s12870-023-04267-y.