Determination of superior Pistacia chinensis accession with high-quality seed oil and biodiesel production and revelation of LEC1/WRI1-mediated high oil accumulative mechanism for better developing woody biodiesel
Authors: Chen Feng , Lin Weijun , Li Wei , Hu Jinhe , Li Zhi , Shi Lingling , Zhang Zhixiang , Xiu Yu , Lin Shanzhi 
Published: January 2023

Abstract
Background: Based on our previous studied on different provenances of Pistacia chinensis, some accessions with high quality and quantity of seed oils has emerged as novel source of biodiesel. To better develop P. chinensis seed oils as woody biodiesel, a concurrent exploration of oil content, FA profile, biodiesel yield, fuel properties and 3D prediction model construction 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 of P. chinensis seeds across different accessions. FA synthesis 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 in P. chinensis seeds.
Results: To select ideal germplasm and unravel high oil accumulative mechanism for developing P. chinensis seed oils as biodiesel, five plus trees (accessionPC-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, and 3D model construction for fuel property prediction, 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 (60.95%) 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 assay was performed to identify a key role of LEC1/WRI1-mediated transcription regulatory network in high oil accumulation of P. chinensis seeds from different accessions. Notably, overexpression of PcWRI1 or PcLEC1 from P. chinensis seeds in Arabidopsis could facilitate seed development and upregulate several genes relevant for carbon allocation (plastidic glycolysis and acetyl-CoA generation), FA biosynthesis, TAG assembly and oil storage, leading to an increase in seed oil content and monounsaturated FA amount, destined for biodiesel property improvement. Our findings may present strategies for developing P. chinensis seed oils as biodiesel feedstock and bioengineering its high oil accumulation.
Conclusions: This is the first report on the cross-accessions assessments of P. chinensis seed oils and novel 3D modal construction of biodiesel property prediction to determine ideal accession for high-quality biodiesel production, and a combination of PcWRI1 and PcLEC1 overexpression, morphological assay, oil accumulation and qRT-PCR detection was conducted to unravel a role of LEC1/WRI1-mediated regulatory network for oil accumulation in P. chinensis seeds, and to highlight the potential application of PcWRI1 or PcLEC1 for increasing oil production. Our finding may provide new strategies for developing biodiesel resource and molecular breeding.