Genotype Screening of Recipient Resources with High Regeneration and Transformation Efficiency in Chrysanthemum

Abstract

Genetic transformation is one of the key steps in the molecular breeding of chrysanthemum, which relies on an optimal regeneration and transformation system. However, the regeneration system of different chrysanthemum cultivars varies, and the regeneration time of most cultivars is long. To screen cultivars with highly efficient regeneration, leaves and shoot tip thin cell layers (tTCL) from eight chrysanthemum cultivars with different flower colors and flower types were cultured on Murashige and Skoog media (MS) supplemented with 1.0–5.0 mg L−1 6-benzylaminopurine (6-BA) and 0.1–1.0 mg L−1 α-naphthaleneacetic (NAA). The results showed that the most efficient regeneration media were MS + 6-BA 1.0 mg L−1 + NAA 0.5 mg L−1 for leaf explants and MS + 6-BA 5.0 mg L−1 + NAA 0.1 mg L−1 for tTCL explants. Subsequently, another 13 chrysanthemum cultivars were screened by using the media, and finally, three cultivars with high regeneration efficiency were obtained from 21 cultivars. Among these, C1 had the highest regeneration efficiency: the regeneration rate of leaf explants reached 80.0% after 42 days of culture, and the regeneration rate of tTCL explants reached 100% after 31 days of culture. Furthermore, we also established the transformation system for C1 as follows: preculturing for one day, infecting with Agrobacterium suspension (OD600 = 0.6) for 10 min, and cultivating in the regeneration medium with 350 mg L−1 carbenicillin and 10 mg L−1 kanamycin, thus ultimately achieving a transformation rate of 4.0%. In this study, a new chrysanthemum cultivar with an efficient regeneration and transformation system was screened, which is beneficial to enrich the flower color of chrysanthemum transgenic plant recipients and to the functional research of flower color or type-related genes.