Expression patterns of the genes encoding fructan active enzymes (FAZYs) alongside fructan constituent profiles in chicory (Cichorium intybus L.): effects of tissue and genotype variations

摘要

Dynamic transcriptional variations of genes encoding fructan active enzymes (FAZYs; 1-SST, 1-FFT, 1-FEHI, 1-FEHII) alongside their potential contributions regarding production/degradation of various carbohydrates (i.e., fructose, glucose, sucrose, 1-kestose, and inulin) were scrutinized in the two distinct genotypes of chicory (Cichorium intybus L.) namely "Germany variety" and "Iranian landrace", at flowering stage. Germany variety accumulated overall more amounts of fructose, sucrose, and inulin, while Iranian landrace contained the highest proportion of 1-kestose, and glucose. Furthermore, both 1-SST and 1-FFT genes were dramatically up-regulated in the root-harvested samples of both genotypes, though maximum transcripts of 1-SST and 1-FFT were respectively detected in landrace and Germany variety, suggesting a cultivar- and tissue-dependent phenomenon. Instead, in both genotypes, maximum transcript levels of 1-FEHI were detected in stem, while root, flower and leaf tissues possessed inferior magnitudes. Considering 1-FEHII, both genotypes exhibited a down-regulated behavior in four tissues (excluding landrace stem). Meanwhile, the chicory MYB transcription factor (CiMYB17) transcriptionally fluctuated among four tissues of both chicory genotypes, and exhibited significant correlation only with 1-FEHI in Germany, a moderate correlation with 1-FEHI in landrace, and lower associations with 1-SST, 1-FFT, and 1-FEHII, indicating its trivial regulatory roles in the complex regulation of FAZY gene expression, and subsequently biosynthesis/degradation of fructans under normal circumstances. Regarding landrace, both 1-SST and 1-FFT correlated only with glucose, while for Germany variety, 1-SST had a strong association with inulin, 1-ketose, alongside glucose, and 1-FFT had a strong correlation only with glucose. However, both 1-FEHI and 1-FEHII exhibited no considerable associations with all the carbohydrates studied. Notably, 1-FEHII negatively correlated with inulin content, indicating an "antagonistic" effect between inulin accumulation/production and 1-FEHII activity. The results, overall, demonstrated that variations in genotypes and/or tissues under study can synergistically/antagonistically influence expression patterns of FAZY genes alongside production/degradation of the corresponding fructans.