Abstract:

In order to improve the selection efficiency of melon materials with different pulp firmness types and accelerate developing varieties.The F₂ and BC₁F₁ populations were constructed with crisp melon materials 19A21,19A75 and soft melon materials N84,20S66 as parents.According to sensory testing statistics,the theoretical values of 3∶1 and 1∶1 for crispy and soft materials were consistent,indicating that the melon pulp firmness was controlled by a single gene,and crisp was dominant to soft.The changes of ACO activity and expression pattern of CmACO1 with different firmness types were analyzed with 4 materials.The results showed that the ACO activity of soft melon appeared at a peak during fruit development,but the crispy melon did not appear.The expression of CmACO1 in soft melon was significantly higher than that in crispy melon.This gene may be involved in regulating pulp firmness.According to the difference of insertion and deletion sites of CmACO1 in different materials,the InDel-Pf marker was developed.The InDel marker was used to detect the genotypes of 32 melon materials.Among them,crisp melon showed deletion band type,soft melon showed non-deletion band type,the marker polymorphism and pulp firmness were co-separated.Two F₂ populations were used to validate the InDel-Pf,the genotype and phenotype coincidence rates were 95.3% and 98.1%.The results showed that InDel-Pf marker had high accuracy in the actual identification of melon pulp firmness,which could effectively improve the efficiency of breeding selection and shorten the breeding cycle of improved varieties.

Key words: Melon, Pulp firmness, CmACO1, InDel marker, Assisted selection breeding