Fruit Characteristics of Transgenic pear (Pyrus communis L.) Trees During Long-Term Field Trials

The quality of transgenic fruits was studied only for apple, plum and citrus. We first evaluated the transgenic fruit characteristics of pear, which is one of the most consumed fruit crops. The size, shape and biochemical composition of fruits from field-grown pear trees with marker genes were analyzed for 5 years. Soluble solids, vitamin C, and phenolic compounds varied significantly between transgenic lines, but these deviations were inconsistent. Arbutin content and sugar:acidity ratio were the most stable parameters. One transgenic line showed a stable increase in fruit weight (by 12.2-21.2%). The extremely dry and hot season increased the total phenolics (2.6-3.6 times) and tannin (3.2-3.6 times) levels, but not flavonoids. The harvest year had a stronger effect on analyzed fruit parameters than the genotype. Our study found no unintended effects of genetic transformation on pear fruit quality and confirms the importance of long-term field tests for perennial transgenic plants.