Effect of Se application on selenium accumulation and fruit quality in pear (Pyrus ussuriensis)

Selenium (Se) is an essential trace element for both animals and plants. Se treatment can increase fruit Se concentration and shelf life. However, the mechanism underlying Se-delayed fruit ripening is still unclear. 'Nanhong' pear (Pyrus ussuriensis) is a typical climacteric fruit with high ethylene production and a rapid drop in firmness during the ripening process. In this research, two groups of Se (A and B treatments) were used to treat 'Nanhong' pear fruit. The results showed that these treatments could greatly increase the Se content but decreased the titratable acid content. Treatment A significantly decreased ethylene production, and the key genes controlling ethylene production, PuACSs and PuERF2, were inhibited by Se treatment. Our findings suggest that PuERF2 may play an important role in Se-mediated ethylene reduction. In addition, treatment A significantly decreased the stone cell content, and one lignin biosynthesis gene, PuC4H, was downregulated by treatment A, indicating that PuC4H may be the key gene responsible for stone cell reduction under Se treatment. Our findings provide a new medium to extend pear shelf life and improve fruit quality, which is beneficial to the development of the pear industry.