Tracing founder haplotypes of Japanese apple varieties: application in genomic prediction and genome-wide association study

Haplotypes provide useful information for genomics-based approaches,genomic prediction,and genome-wide association study.As a small number of superior founders have contributed largely to the breeding history of fruit trees,the information of founder haplotypes may be relevant for performing the genomics-based approaches in these plants.In this study,we proposed a method to estimate 14 haplotypes from 7 founders and automatically trace the haplotypes forward to apple parental(185 varieties)and breeding(659 F 1 individuals from 16 full-sib families)populations based on 11,786 single-nucleotide polymorphisms,by combining multiple algorithms.Overall,92%of the single-nucleotide polymorphisms information in the parental and breeding populations was characterized by the 14 founder haplotypes.The use of founder haplotype information improved the accuracy of genomic prediction in 7 traits and the resolution of genome-wide association study in 13 out of 27 fruit quality traits analyzed in this study.We also visualized the significant propagation of the founder haplotype with the largest genetic effect in genome-wide association study over the pedigree tree of the parental population.These results suggest that the information of founder haplotypes can be useful for not only genetic improvement of fruit quality traits in apples but also for understanding the selection history of founder haplotypes in the breeding program of Japanese apple varieties.

Current progress in application of 1-Methylcyclopropene to improve postharvest quality of cut flowers

Floral senescence or petal abscission that determine cut flower quality and longevity are primarily caused by the regulation of endogenous ethylene and perception of endogenous and exogenous ethylene in floral organs(such as the petals and gynoecium),in ethylene-sensitive species.Several attempts have been made to prolong flower quality and longevity using silver ions and other chemicals that inhibit ethylene production and perception in floral organs.Among the available compounds,1-methylcyclopropene(1-MCP)has been increasingly used as ethylene-action/perception inhibitor because of its ability to inhibit ethylene action/perception and it is environmentally safe.Although 1-MCP has been used in several cut flower crops for about 25 years,there has been no review yet that critically emphasizes the benefits or difficulties of using this compound for the prolongation of cut flower quality and longevity.Here,we outline the role of 1-MCP in inhibiting ethylene action/perception and petal senescence in cut flowers through the blocking of receptor binding sites,and we discuss how various factors affecting efficacy of 1-MCP(such as concentration,treatment time and temperature,genotype,and flower stage)are involved in the achievement of flower longevity.Moreover,we highlight the advantages of applying nonvolatile and liquid 1-MCP formulation types,as opposed to using the conventional 1-MCP treatment(powder formulation type).We expect that this review will provide useful information for the future utilization of 1-MCP for the maintenance of cut flower longevity.