The genetic locus underlying red foliage and fruit skin traits is mapped to the same location in the two pear bud mutants 'Red Zaosu' and 'Max Red Bartlett'.

BACKGROUND

Red-skinned pears are attractive to consumers because of their aesthetic appeal and the antioxidant-associated health benefits provided by the anthocyanins in their red skin. In China, the 'Red Zaosu' (RZS) red bud mutation of the Zaosu (ZS) pear has been used as a parent in Asian pear breeding to generate new cultivars with crispy red fruit and red tender shoots resembling those of the 'Max Red Bartlett' (MRB) pears.

RESULTS

In this study, a segregation ratio of 1:1 was observed between plants with red or green shoots in four families with RZS as the only red shoot gene donor parent, suggesting that the red shoot trait of RZS is associated with a dominant gene. Three markers, In1400-1, In1579-1 and In1579-3, were chosen from 22 pairs of indel primers targeting regions in the vicinity of the previously identified red fruit skin locus of MRB and were able to effectively distinguish the eight red shoot plants from the eight green shoot plants. Linkage analysis indicated that the genetic distance between the two marker loci (In1579-1 and In1579-3) and the red shoot locus of RZS were both 1.4 cM, while the genetic distance between the In1400-1 marker and the red shoot locus was 2.1 cM. The physical position of the red locus in RZS should be in the 368.6 kb candidate interval at the bottom of LG4.

CONCLUSIONS

The genetic locus responsible for the red tender shoots of RZS was located in the same interval of the red fruit skin gene of MRB, meaning that the bud mutation loci of RZS and MRB may be the same or adjacent to each other, and the red shoot trait and the red fruit skin trait in RZS may be controlled by the same, or a closely linked locus. As a result, breeders could use red shoots as a morphological marker to select for the red-skinned hybrids from RZS families.