Higher-Quality Pumpkin Cultivars Need to Recruit More Abundant Soil Microbes in Rhizospheres

Two different qualities of pumpkin, cultivars G1519 and G1511, were grown in the same environment under identical management. However, their qualities, such as the contents of total soluble solids, starch, protein, and vitamin C, were significantly different. Do rhizospheric microbes contribute to pumpkin quality? To answer this question, this study investigated the soil microbial compositions in the rhizospheres of different quality pumpkin cultivars to determine the differences in these soil microbial compositions and thus determine how soil microbes may affect pumpkin quality. Firstly, a randomized complete block design with two pumpkin cultivars and three replications was performed in this study. The soil microbial compositions and structures in the rhizospheres of the two pumpkin cultivars were analyzed using a high-throughput sequencing technique. In comparison with the low-quality pumpkin cultivar (G1519), higher microbial diversity and richness could be found in the rhizospheres of the high-quality pumpkin cultivar (G1511). The results showed that there were significant differences in the soil bacterial and fungal community compositions in the rhizospheres of the high- and low-quality pumpkin cultivars. Although the compositions and proportions of microorganisms were similar in the rhizospheres of the two pumpkin cultivars, the proportions of Basidiomycota and Micropsalliota in the G1519 rhizosphere were much higher than those in the G1511 rhizosphere. Furthermore, the fungal phylum and genus Rozellomycota and Unclassified_p__Rozellomycota were unique in the rhizosphere of the high-quality pumpkin cultivar (G1511). All the above results indicate that soil microbes were enriched differentially in the rhizospheres of the low- and high-quality pumpkin cultivars. In other words, more abundant soil microbes were recruited in the rhizosphere of the high-quality pumpkin cultivar as compared to that of the low-quality cultivar. Rozellomycota and Unclassified_p__Rozellomycota may be functional microorganisms relating to pumpkin quality.