Assessment of growth characteristics and forage quality of ZxNHX1-VP1-1 and ZxABCG11 transgenic alfalfa under field conditions

This study aimed to explore the effects of Zygophyllum xanthoxylum tonoplast Na⁺ compartmentalization gene ZxNHX1, H⁺-PPase (H⁺-pyrophosphatase) encoding gene ZxVP1-1, and cuticular wax transport gene ZxABCG11 on alfalfa “Xinjiang daye” growth, development and forage quality. We measured the indicators of growth, development and forage quality of wild type, ZxNHX1-VP1-1 transgenic, and ZxABCG11 transgenic alfalfa under field conditions. The results showed that: 1) Leaf area and hay yield of ZxNHX1-VP1-1 transgenic alfalfa were 56.4% and 74.5% higher than those of the wild type (WT), respectively; the net photosynthesis rate and water use efficiency were significantly higher than those of the WT (P < 0.05). The flowering period was 19 days longer than that of the WT. 2) The leaf area and stem diameter of ZxABCG11 transgenic alfalfa were significantly higher than those of the WT (P < 0.05). The net photosynthesis rate and water use efficiency were 81.7% and 80.5% higher than those of the WT (P < 0.05), respectively. The flowering period was 38 days longer than that of the WT. 3) Neutral detergent fiber (NDF), acid detergent fiber (ADF), and acid detergent lignin (ADL) of ZxNHX1-VP1-1 transgenic alfalfa were significantly lower than those of the WT (P < 0.05). The relative feed value of ZxNHX1-VP1-1 transgenic alfalfa was 35.4% higher than that of the WT. These results showed that overexpression of ZxNHX1 and ZxVP1-1 increased the biomass and nutritional quality of alfalfa and prolonged flowering time. Overexpression of ZxABCG11 affected the leaf area, stem diameter and photosynthetic capacity of alfalfa. Meanwhile, the flowering period of ZxABCG11 transgenic alfalfa was longer than that of the WT.