Heterologous Expression of Jatropha curcas Fatty Acyl-ACP Thioesterase A (JcFATA) and B (JcFATB) Affects Fatty Acid Accumulation and Promotes Plant Growth and Development in Arabidopsis

Transcription factor EgGRP2A regulates EgFATA expression and promotes oleic acid accumulation in oil palm (Elaeis guineensis)

The oil palm (Elaeis guineensis) is emerging as the world's most important and prolific oilseed crop, celebrated for its impressive oil yield. However, the molecular intricacies that govern lipid metabolism and fatty acid accumulation in oil palm fruits remain relatively underexplored. This study reveals a significant correlation between the expression of EgGRP2A, a transcription factor, and the expression of EgFATA in the oil palm. Yeast one-hybrid analysis and electrophoretic mobility shift assays (EMSA) reveal and confirm the binding interactions between EgGRP2A and the promoter region of EgFATA. Subsequent experiments in oil palm protoplasts show that transient overexpression of EgGRP2A leads to a marked upregulation of EgFATA expression. Conversely, downregulation of EgGRP2A in transgenic oil palm embryoids leads to a significant reduction in EgFATA expression. Metabolite profiling in the transgenic embryoids reveals a significant reduction in unsaturated fatty acids, particularly oleic acid. These findings promise profound insights into the regulatory orchestration of EgFATA and the synthesis of fatty acids, particularly oleic acid, in the oil palm. Furthermore, the results lay the foundation for future breeding and genetic improvement efforts aimed at increasing oleic acid content in oil palm varieties.

The identification and expression analysis of walnut Acyl-ACP thioesterases

Walnuts (Juglans regia L.), renowned for their nutritional potency, are a rich source of unsaturated fatty acids. Their regular intake plays a pivotal role in health maintenance and recuperation from a myriad of ailments. Fatty acyl-acyl carrier protein thioesterases, which orchestrate the hydrolysis of acyl-ACP thioester bonds, thereby yielding fatty acids of varying chain lengths, are instrumental in augmenting plant fatty acid content and modulating the balance between saturated and unsaturated fatty acids. Despite some investigative efforts into the synthesis and metabolic pathways of fatty acids in walnuts, our comprehension of Fat in walnuts remains rudimentary. This research undertook a comprehensive characterization of the JrFat family, predicated on the complete genome sequence of walnuts, leading to the identification of 8 JrFat genes and an exploration of their protein physicochemical properties. Utilizing Arabidopsis and soybean Fat genes as outgroups, JrFat genes can be categorized into 5 distinct subgroups, three of which encompass a pair of homologous gene pairs. These genes have demonstrated remarkable conservation throughout the evolutionary process, with highly analogous conserved base sequences. The promoter region of JrFats genes predominantly harbors light response and plant hormone response regulatory elements, with no discernible disparity in promoter elements among different JrFats. Predictive analyses indicate that JrFats proteins engage extensively with walnut fatty acid synthesis and metabolism-associated proteins. qRT-PCR analysis reveals an initial surge in the expression of JrFats during the development of walnut kernels, which either stabilizes or diminishes following the hard core period. Homologous gene pairs exhibit analogous expression patterns, and the expression trajectory of JrFats aligns with the dynamic accumulation of fatty acids in kernels. The expression of JrFatA2 exhibits a strong correlation with the content of Alpha-linolenic acid, while the expression of JrFatB2 is inversely correlated with the content of two saturated fatty acids. Collectively, these findings enrich our understanding of fatty acid synthesis and metabolism in walnuts and furnish gene resources for enhancing the content and ratio of fatty acids in walnuts.

Glycine max acyl-acyl carrier protein thioesterase B gene overexpression alters lipid content and fatty acid profile of Arabidopsis seeds

The fatty acyl-acyl carrier protein thioesterase B (FATB ) gene, involved in the synthesis of saturated fatty acids, plays an important role in the content of fatty acid and composition of seed storage lipids. However, the role of FATB in soybeans (Glycine max ) has been poorly characterised. This paper presents a preliminary bioinformatics and molecular biological investigation of 10 hypothetical FATB members. The results revealed that GmFATB1B , GmFATB2A and GmFATB2B contain many response elements involved in defense and stress responses and meristem tissue expression. Moreover, the coding sequences of GmFATB1A and GmFATB1B were significantly longer than those of the other genes. Their expression varied in different organs of soybean plants during growth, with GmFATB2A and GmFATB2B showing higher relative expression. In addition, subcellular localisation analysis revealed that they were mainly present in chloroplasts. Overexpression of GmFATB1A , GmFATB1B , GmFATB2A and GmFATB2B in transgenic Arabidopsis thaliana plants increased the seed oil content by 10.3%, 12.5%, 7.5% and 8.4%, respectively, compared to that in the wild-type and led to significant increases in palmitic and stearic acid content. Thus, this research has increased our understanding of the FATB family in soybeans and provides a theoretical basis for subsequent improvements in soybean quality.

Fatty Acid Biosynthesis Pathways Are Downregulated during Stigma Development and Are Critical during Self-Incompatible Responses in Ornamental Kale

In Brassicaceae, the papillary cells of the stigma are the primary site of the self-incompatibility (SI) responses. SI preserves the genetic diversity by selectively rejecting irrelevant or incompatible pollen, thus promoting cross fertilization and species fitness. Mechanisms that regulate SI responses in Brassica have been studied mainly on the mature stigma that often undermines how stigma papillary cells attain the state of SI during development. To understand this, we integrated PacBio SMRT-seq with Illumina RNA-seq to construct a de novo full-length transcriptomic database for different stages of stigma development in ornamental kale. A total of 48,800 non-redundant transcripts, 31,269 novel transcripts, 24,015 genes, 13,390 alternative splicing, 22,389 simple sequence repeats, 21,816 complete ORF sequences, and 4591 lncRNAs were identified and analyzed using PacBio SMRT-seq. The Illumina RNA-seq revealed 15,712 differentially expressed genes (DEGs) and 8619 transcription factors. The KEGG enrichment analysis of 4038 DEGs in the “incompatibility” group revealed that the flavonoid and fatty acid biosynthesis pathways were significantly enriched. The cluster and qRT-PCR analysis indicated that 11 and 14 candidate genes for the flavonoid and fatty acid biosynthesis pathways have the lowest expression levels at stigma maturation, respectively. To understand the physiological relevance of the downregulation of fatty acid biosynthesis pathways, we performed inhibitor feeding assays on the mature stigma. The compatible pollination response was drastically reduced when mature stigmas were pre-treated with a fatty acid synthase inhibitor. This finding suggested that fatty acid accumulation in the stigmas may be essential for compatible pollination and its downregulation during maturity must have evolved as a support module to discourage the mounting of self-incompatible pollen.