Abstract [Objective] This study aims to accelerate the innovation process of germplasm resources of the
seed-used pumpkin (Cucurbita pepo L.) by constructing a mutant library, which is critical for variety selection
and improvement of the genetic basis. [Methods] 1.8% ethyl methanesulfonate (EMS) was used to
treat ZHL4 seeds of the seed-used pumpkin for 15 h. Phenotypic variation was observed for M1 and M2
populations. Microstructural observation was performed for the mutant line ZHL4-33 of the M2 population.
[Results] (1) A total of 242 mutant plants with 45 phenotypic variations were screened in the M2
population, and the type of variations covered all growth periods and plant organs of the mutant plants,
with a total mutation frequency of 25.17%. (2) Leaf microstructure showed that the thickness of the fenestrated
tissue of the mutant was higher than the wild type, and the arrangement was compact and the
traces of the vascular layer were obvious. Stem microstructure showed that the vascular bundles of the
mutant were more and densely packed, and the conduit diameter was smaller than the wild type. The pith
was well developed, with a small cell gap and an increase in cell numbers. [Conclusion] A mutant library
of 425 M2 lines has been constructed, which lays a foundation for functional genomic analysis of the seedused
pumpkin as well as the selection and breeding of new varieties of seed-used pumpkin
