Abstract
To understand the mode of flesh color inheritance in loquats (Eriobotrya japonica), segregation of flesh color (yellowish orange vs. whitish yellow) was investigated in 1,643 F1 progenies derived from 32 breeding populations. All F1 progenies obtained from the cross between whitish yellow cultivars had whitish yellow flesh. The segregation ratio between yellowish orange and whitish yellow indicated either 1 : 0 or 1 : 1 in F1 progenies between yellowish orange and whitish yellow cultivars. In F1 progenies among yellowish orange cultivars, the segregation ratio was either 1 : 0 or 3 : 1. These findings indicated that yellowish orange flesh was dominant to whitish yellow flesh. The gene corresponding to yellowish orange flesh is named the Ca gene. The genotype of yellowish orange cultivars is assigned as either Ca/Ca or Ca/ca and that of whitish yellow cultivars is ca/ca. Bulk screening was carried out to find a RAPD marker linked to the phenotype of yellowish orange fresh using 280 Operon primers. In total, 28 Operon primers provided 28 polymorphic fragments between the yellowish orange and whitish yellow bulk samples. They were subjected to linkage analysis using 37 F1 progenies between ‘Reigetsu’ and ‘Amakusagokuwase’. The 1,800 bps of RAPD fragment (OPH-01/1800) obtained from OPH-01 primer was linked to Ca gene at a recombination value of 0.081 with LOD value of 6.7. The validity of OPH-01/1800 to flesh color phenotype was evaluated among 41 loquat cultivars. The OPH-01/1800 marker was present among 78% of the yellowish orange flesh cultivars, in contrast, the OPH-01/1800 marker was absent from all whitish yellow flesh cultivars. These findings indicate that the OPH-01/1800 marker is useful to select yellowish orange flesh in a loquat breeding program.
