Differences in the Growth of Seedlings and the Selection of Fast-Growing Species in the Gleditsia Genus

Abstract

The Gleditsia genus has various uses, including those for medicinal, edible, chemical, timber, and ornamental purposes, and the genus is widely distributed in China. However, there is still a lack of understanding about the phenotypic and growth differences seen among species within the Gleditsia genus. In this study, we compared and analyzed the various species of Gleditsia seedlings in terms of their genotypes, chromosome numbers, physiological growth, photosynthesis, hormone content, and gene expression. The results showed that the genome size of the Gleditsia genus ranges from 686.08 M to 1034.24 M and that all Gleditsia species are diploid. Among the species studied, G. fera can be divided into fast-growing genotype, exhibited several advantages in terms of leaf type and photosynthetic capacity, high levels of GA3, and fast stem growth, making it a species with the potential for promotion and application. G. delavayi exhibited high levels of auxin and cytokinin and strong photosynthetic capacity, with rapid growth in terms of plant height. G. microphylla had the lowest levels of IAA, IBA, and NAA in the apical, and showed slow growth in terms of plant height. Weighted correlation network analysis (WGCNA) identified the hub genes associated with traits. This study lays a material and theoretical foundation for the development of new resources for Gleditsia breeding and rootstock selection and provides a basis for the mechanism of rootstock–scion interaction.