Plants synthesize and store oil mostly as triacylglycerols (TAG) in seeds that is transcriptionally controlled by WRINKLED 1 (WRI1), an APETALA2 (AP2) transcription factor. In contrast, avocado (Persea americana) mesocarp, which accumulates ~70% lipids by dry weight showed high expression of WRI2, along with WRI1 and WRI3. Among the four Arabidopsis WRI paralogs, WRI2 is nonfunctional, while the others are expressed in a tissue-specific manner. Through in silico analysis, we identified that PaWRI2 has a single intact AP2 DNA-binding domain and lacks a C-terminal intrinsically disordered region (IDR3) and PEST motif, which likely results in a relatively stable protein, compared to its Arabidopsis ortholog. We further demonstrated that avocado WRI2 is functional, unlike Arabidopsis WRI2, and accumulates TAG when transiently expressed in Nicotiana benthamiana leaves. Additionally, co-infiltration of PaWRI2 with PaWRI1 and genes encoding for terminal step in TAG assembly, acyl-CoA:diacylglycerol acyltransferase 1 (DGAT1) and/or phospholipid:diacylglycerol acyltransferase 1 (PDAT1) also led to further increase in the lipid content and oleic acid levels in ‘benth’ leaves. Quantitative real-time PCR (qPCR) analyses of > 40 fatty acid biosynthetic pathway genes revealed that several were distinctly up or down regulated by the expression of PaWRI2 and PaWRI1. In conclusion, avocado WRI2 is capable of transactivation of fatty acid biosynthesis genes and TAG accumulation, synergistically with DGAT1 and PDAT1, in nonseed tissues. This study provides a functional role for WRI2 in a basal angiosperm species that is likely lost in modern angiosperms and thus provides basis for mechanistic differences in the transcriptional regulation of lipid biosynthesis among different plant species and between seed and nonseed tissues.
| Identifer | oai:union.ndltd.org:ETSU/oai:dc.etsu.edu:asrf-2017 |
| Date | 25 April 2023 |
| Creators | Behera, Jyoti Ranja, Kilaru, Aruna |
| Publisher | Digital Commons @ East Tennessee State University |
| Source Sets | East Tennessee State University |
| Detected Language | English |
| Type | text |
| Source | Appalachian Student Research Forum |
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