Overexpression of miR156 and Silencing SPL6RNAi and SPL13RNAi Genes in Medicago sativa on the Changes of Carbohydrate Physiochemical, Fermentation, and Nutritional Profiles

This study aimed to explore the comparative effects of overexpressing miR156 with individually silencing SPL6RNAi and SPL13RNAi genes on carbohydrate physiochemical, fermentation, and nutritional profiles of alfalfa (Medicago sativa). Three sub-genotypes of miR156 overexpressed (miR156 OE), SPL6RNAi, and SPL13RNAi grown with the wild type (WT) in a greenhouse were harvested 3 times at an early vegetative stage. Samples were freeze-dried, ground, and analyzed for carbohydrate nutritional profiles in terms of chemical composition, CNCPS fractions, energetic values, in vitro degradation, and fermentation characteristics. Results showed that miR156 OE had lower fiber and higher energy compared to all other genotypes. Moreover, miR156 OE had higher starch compared to SPL13RNAi and higher DM degradation compared to WT and SPL13RNAi. In conclusion, overexpression of miR156 decreased the fiber content of alfalfa but increased energy and DM degradation. SPL6RNAi was more similar to miR156 OE alfalfa in chemical composition and degradation, indicating that the SPL6RNAi gene plays an important role in the miR156 overexpression event.