Title : Valuable resource for fructans genes in Agave angustifolia inferred through transcriptome analyses
Abstract:
The Agave genus covers about 200 species, of which 186 taxa are recognized in Mexico. Plants of A. angustifolia Haw. constitute the raw material for the elaboration of mezcal, and other distillates. Thus, over 750,000 L of mezcal beverage is exported annually to Asia, Europe, United States and Canada. Agave fructans, the main carbohydrate for mezcal production, can be used to prevent or treat several human diseases, and they are used as ingredients to improve color and flavor. Four fructosyltransferase enzymes are implicated in the fructan metabolism: Fructan:fructan 1-fructosyltransferase (1-FFT), Sucrose:sucrose 1-fructosyl transferase (1-SST), Fructan:fructan 6G-Fructosyltransferase (6G-FFT) and Sucrose:fructan 6-fructosyltransferase (6-SFT). The objective of this study was to compare the genetic profile of different plant tissues to elucidate the key genes for fructan synthesis of A. angustifolia, and the useful of transcriptomic data for phylogenetic analysis. Total RNA from young leaves, mature leaves, root and stem was purified. Twelve libraries were synthesized and sequenced on NovaSeq system. De novo transcriptome assembly was constructed using Trinity´s software. BLASTp, BLASTx and EggNOG-mapper were used to annotate the agave transcriptome. Differentially expressed transcripts (DETs) were determined using Limma tool. Gene involved for fructan metabolism was validated using RT-qPCR.
For phylogenetic analysis, orthologs among nine species of agave were identified and analyzed using the OrthoVenn3 Server. A total of 358,170 transcripts were assembled; from which, 174,414 had potential coding protein revealing the presence of at least 29,273 genes in A. angustifolia. Multidimensional plots showed that the first three dimensions accounted for 73% of the variability. The first dimension explained the most variation (43%) where a clear separation between root, stem and leaves was revealed. While the separations between the two leaf types were more apparent on the second and third dimensions. The pair wise comparisons between the plant tissues resulted in the estimation of 123,181 DETs (23,978 were up regulated and 79,203 were down regulated). As expected, transcriptome profiles differ between Agave tissues according to their respective physiological function. Moreover, seven fructosyltransferases and invertase´s genes were retrieved from our A. angustifolia assembly. Only 1-SST1 was found to be completely assembled (2896 bp). The remaining genes (1-SST2, 6G-FFT1, 6G-FFT2, 1-FFT, Vinv1 and Cwinv1) were found to be fragmented, composed of 2 to 4 transcripts. However, the expression behavior of the transcripts within the same gene was similar. Globally, the genes 1-SST1, 1-SST2 and 6G-FFT1 were up regulated in stem and roots. Moreover, 1-SST2 was also up regulated in youthful leaf and 1-FFT was only up regulated in stem. Likewise, 6G-FFT2 was up regulated in all tissues except in roots, and Vinv1 and Cwinv1 were up regulated in youthful leaf and roots. Also, the phylogenetic analysis revealed the closeness between A. angustifolia and A. tequilana, both species were classified in the Rigidae agave group. The data presented here provide a publicly available transcriptome resource for A. angustifolia. The results will promote advances in genetic and molecular studies and will facilitate the identification of candidate genes involved in the growth, development, and metabolism of this species.
Auidence Take Away Notes:
- The first assembly transcriptome resource of Mexican Agave angustifolia is presented.
- Biosynthesis and metabolism of carbohydrates, especially fructans, were discussed.
- Data obtained is publicly available, so audience can use these data for multiple genetic researches.
- The results obtained to broaden our knowledge about the genetics and biology of agave.
- The data could be used to evaluate and improve the harvesting and processing conditions of the agaves for more efficient production of Mezcal.
