Functional and Predictive Structural Characterization of WRINKLED2, A Unique Oil Biosynthesis Regulator in Avocado

WRINKLED1 (WRI1), a member of the APETALA2 (AP2) class of transcription factors regulates fatty acid biosynthesis and triacylglycerol (TAG) accumulation in plants. Among the four known Arabidopsis WRI1 paralogs, only WRI2 was unable to complement and restore fatty acid content in wri1-1 mutant seeds. Avocado (Persea americana) mesocarp, which accumulates 60-70% dry weight oil content, showed high expression levels for orthologs of WRI2, along with WRI1 and WRI3, during fruit development. While the role of WRI1 as a master regulator of oil biosynthesis is well-established, the function of WRI1 paralogs is poorly understood. Comprehensive and comparative in silico analyses of WRI1 paralogs from avocado (a basal angiosperm) with higher angiosperms Arabidopsis (dicot), maize (monocot) revealed distinct features. Predictive structural analyses of the WRI orthologs from these three species revealed the presence of AP2 domains and other highly conserved features, such as intrinsically disordered regions associated with predicted PEST motifs and phosphorylation sites. Additionally, avocado WRI proteins also contained distinct features that were absent in the nonfunctional Arabidopsis ortholog AtWRI2. Through transient expression assays, we demonstrated that both avocado WRI1 and WRI2 are functional and drive TAG accumulation in Nicotiana benthamiana leaves. We predict that the unique features and activities of ancestral PaWRI2 were likely lost in orthologous genes such as AtWRI2 during evolution and speciation, leading to at least partial loss of function in some higher eudicots. This study provides us with new targets to enhance oil biosynthesis in plants

NOVEL STRUCTURAL CHARACTERISTICS OF OIL BIOSYNTHESIS REGULATOR PROTEIN IN AVOCADO

Plants synthesize and store oil, mostly triacylglycerol (TAG), in various storage tissues that serves as a source of carbon and energy. The process is transcriptionally controlled by WRINKLED1 (WRI1), a member of the APETALA2 (AP2) class of transcription factors, that regulates most of the fatty acid biosynthesis genes. Among the four Arabidopsis WRI1 paralogs, only WRI2 is nonfunctional and failed to complement wri1-1 mutant seeds. The oleaginous Avocado (Persea americana) fruit mesocarp (60-70% DW oil) showed high expression levels for orthologs of WRI2, along with WRI1 and WRI3. While the role of WRI1 as a master seed oil biosynthesis regulator is well-established, the function of WRI1 paralogs in non-seed tissues is poorly understood. We conducted structural analyses to elucidate distinct features of avocado WRI paralogs compared to their orthologs in seed tissues. Comprehensive comparative in silico analyses of WRI1 paralogs from Arabidopsis (dicot), maize (monocot), and avocado revealed distinct features associated with their function. Our analysis showed the presence of only one AP2 domain in all WRI2 orthologs, compared to two AP2 in others. The highly conserved N-terminal region and the less conserved C-terminal regions make up the primary structure of the proteins, with amino acid composition bias characteristic of intrinsically disordered proteins (IDPs). Additionally, the avocado WRI2 showed a high proportion of random coil secondary structure, although it lacks a C-terminal intrinsically disordered region (IDR). Also, both WRI1 and WRI2 have distinct predicted phosphorylation target sites compared to their orthologs, whereas WRI2 lacks a PEST motif. Finally, through transient expression assays, we demonstrated that both avocado WRI1 and WRI2 are functional and drive TAG accumulation in Nicotiana benthamiana leaves. Our study showed that avocado WRI2 is structurally different and is functional, unlike its ortholog in Arabidopsis. This study provides us with new targets to enhance oil biosynthesis in plants

In Silico Structural Studies and Molecular Docking Analysis of Delta6-desaturase in HUFA Biosynthetic Pathway

<p>Fish are an important source of highly unsaturated fatty acids (HUFA) such as eicosapentaenoic acid EPA (20:5 n-3) and docosahexaenoic acid DHA (22:6 n-3) and play a significant role in human nutrition. The fatty acyl delta6-desaturase (Δ6 desaturase) is a rate-limiting enzyme in the biosynthetic pathway of highly unsaturated fatty acids (HUFA) that converts polyunsaturated fatty acids (PUFA) such as linoleic (18:2n-6) and α-linolenic (18:3n-3) acids into HUFA. In this study, fatty acyl Δ6 desaturase was identified from pangasius (<i>Pangasianodon hypophthalmus</i>) and further analyzed for sequenced-based characterization and 3D structural conformation. Sequenced-based analysis revealed some important secondary information such as physicochemical property. e.g., isoelectric point, extinction coefficient, aliphatic index, and grand average hydropathy, among others, and also post-translational modification sites were identified. An evolutionary-conserved stretch of amino acid residue and a functionally significant conserved structural ancestor, N-terminal cytochrome b5 and membrane FADS-like superfamily, were identified. Protein association analysis showed a high confidence score with acyl-CoA synthetase, elovl5, elovl2, and phospholipase A2. Herein, we report, for the first time, a 3D native structure of Δ6 desaturase protein by homology modeling approach; molecular docking analysis was performed with linoleic (18:2n-6) and α-linolenic (18:3n-3) acids, which are the two key substrates in the HUFA biosynthetic pathway. This work provides insight into the structural and functional characterization of Δ6 desaturase, which is involved in HUFA biosynthesis as a rate-limiting enzyme.</p

Corrigendum: A Tree Peony Trihelix Transcription Factor PrASIL1 Represses Seed Oil Accumulation

[This corrects the article DOI: 10.3389/fpls.2021.796181.]

A Tree Peony Trihelix Transcription Factor PrASIL1 Represses Seed Oil Accumulation

In many higher plants, seed oil accumulation is governed by complex multilevel regulatory networks including transcriptional regulation, which primarily affects fatty acid biosynthesis. Tree peony (), a perennial deciduous shrub endemic to China is notable for its seed oil that is abundant in unsaturated fatty acids. We discovered that a tree peony trihelix transcription factor, PrASIL1, localized in the nucleus, is expressed predominantly in developing seeds during maturation. Ectopic overexpression of in leaf tissue and seeds significantly reduced total fatty acids and altered the fatty acid composition. These changes were in turn associated with the decreased expression of multitudinous genes involved in plastidial fatty acid synthesis and oil accumulation. Thus, we inferred that PrASIL1 is a critical transcription factor that represses oil accumulation by down-regulating numerous key genes during seed oil biosynthesis. In contrary, up-regulation of oil biosynthesis genes and a significant increase in total lipids and several major fatty acids were observed in silenced tree peony leaves. Together, these results provide insights into the role of trihelix transcription factor PrASIL1 in controlling seed oil accumulation. can be targeted potentially for oil enhancement in tree peony and other crops through gene manipulation

Occurrence, fate and removal of microplastics as heavy metal vector in natural wastewater treatment wetland system

Not AvailableMicroplastics pollution in aquatic ecosystems is of great concern; however, systemic investigations are still lacking in freshwater wetland systems used for wastewater treatment. The present study discusses such freshwater wetland system in Eastern India to understand its microplastics transport mechanism, heavy metals association and microplastics removal efficiency. Microplastics (63 ?m - 5 mm) were heavily found in surface water and sediments of treatment ponds (7.87 to 20.39 items/L and 2124.84 to 6886.76 items/kg) and associated wastewater canals (30.46 to 137.72 items/L and 1108.78 to 34612.87 items/kg). A high content of toxic metals (As, Cd, Cr, Cu, Ni, Pb and Zn) were found on the microplastics with polyethylene terephthalate and polyethylene as major plastics types which were also found in fishes and macroinvertebrates of treatment ponds. Machine learning algorithm revealed a close association between microplastics content in fishes and surface water, indicating risk associated with floating microplastics to the aquatic biota. The study also revealed that microplastics were acting as heavy metals vector and potentially causing fish contamination. Surface water microplastics removing efficiency of the treatment ponds was estimated to be 53%. The study bespeaks about transport of microplastics through wastew- ater canals and their retention in treatment ponds emphasizing sustainability maintenance of natural wastewater treatment systems especially considering microplastics contamination to the aquatic biota of freshwater wetland systems

National noncommunicable disease monitoring survey (NNMS) in India: Estimating risk factor prevalence in adult population.

BackgroundThe primary objective of National NCD monitoring survey (NNMS) was to generate national-level estimates of key NCD indicators identified in the national NCD monitoring framework. This paper describes survey study protocol and prevalence of risk factors among adults (18-69 years).Materials and methodsNNMS was a national level cross-sectional survey conducted during 2017-18. The estimated sample size was 12,000 households from 600 primary sampling units. One adult (18-69 years) per household was selected using the World Health Organization-KISH grid. The study tools were adapted from WHO-STEPwise approach to NCD risk factor surveillance, IDSP-NCD risk factor survey and WHO-Global adult tobacco survey. Total of 8/10 indicators of adult NCD risk factors according to national NCD disease monitoring framework was studied. This survey for the first time estimated dietary intake of salt intake of population at a national level from spot urine samples.ResultsTotal of 11139 households and 10659 adults completed the survey. Prevalence of tobacco and alcohol use was 32.8% (95% CI: 30.8-35.0) and 15.9% (95% CI: 14.2-17.7) respectively. More than one-third adults were physically inactive [41.3% (95% CI: 39.4-43.3)], majority [98.4% (95% CI: 97.8-98.8)] consumed less than 5 servings of fruits and / or vegetables per day and mean salt intake was 8 g/day (95% CI: 7.8-8.2). Proportion with raised blood pressure and raised blood glucose were 28.5% (95% CI: 27.0-30.1) and 9.3% (95% CI: 8.3-10.5) respectively. 12.8% (95% CI: 11.2-14.5) of adults (40-69 years) had ten-year CVD risk of ≥30% or with existing CVD.ConclusionNNMS was the first comprehensive national survey providing relevant data to assess India's progress towards targets in National NCD monitoring framework and NCD Action Plan. Established methodology and findings from survey would contribute to plan future state-based surveys and also frame policies for prevention and control of NCDs