Triploid loquat (2n = 3x = 51) has stronger growth vigor and larger leaves, flowers, and fruit compared with its diploid parental plant (2n = 2x = 34), but the effects of triploidization on the contents of flavonoids and phenolics in leaves and flowers, which are the most important antioxidant compounds for pharmacological applications, have not been reported. In this report, 58 triploid loquat genotypes and seven corresponding diploid parental cultivars were used to evaluate the effects of triploidization on the contents of total flavonoids and phenolics and the antioxidant activities of leaves and flower buds. The results showed that the contents of total flavonoids and phenolics and their corresponding antioxidant activities were higher in most of the triploid loquat genotypes than their diploid parents. The antioxidant activities of leaves and flower buds were significantly correlated with the total flavonoids and phenolics contents in both diploid loquat and triploid loquat. It could be inferred that triploidization could increase the contents of flavonoids and phenolics in leaves and flower buds of loquat. Notably, the contents of total flavonoids and phenolics of leaves in triploid genotype ‘H3/24’ were the highest, reaching 212.00 mg rutin equivalent (RE)/g DW and 93.06 mg gallic acid equivalents (GAE)/g DW, respectively, which were significantly higher than those previously reported. Such a valuable trait may be stacked with other triploid traits that are already established, such as larger vegetative organs and better tolerance to various stresses, as a feasible strategy for breeding loquat cultivars with high pharmaceutical potency.
Mingxiu Liu, Peng Wang, Xu Wei, Qing Liu, Xiaolin Li, Guolu Liang and Qigao Guo
Jiangbo Dang, Tingrong Wu, Guolu Liang, Di Wu, Qiao He and Qigao Guo
A loquat (Eriobotrya japonica) seedling obtained from an open-pollinated triploid variety ‘Wuheguoyu’ (2n = 3x = 51) was verified as aneuploid and designated H39. It was shown to have five extra chromosome copies (2n = 39) compared with the diploid plant (2n = 2x = 34), one additional copy each for the 2nd, 4th, 7th, 9th, and 11th chromosomes. A number of novel features of leaf morphology was observed for H39 in comparison with ‘Ruantiaobaisha’ (2x, female progenitor) and ‘Wuheguoyu’ (3x, female parent), including increased leaf width, reduced leaf thickness, and narrowed palisade mesophyll and wax coat. Total chlorophyll content in unit area of H39 leaves was close to or slightly less than the diploid and triploid parent lines. Chlorophyll content in unit mass showed the opposite trend, with H39 having higher amount than the 2x and 3x. As we expected, H39 had the lowest net photosynthetic rates among the three lines. Furthermore, 8-month-old scions of H39 grew more slowly than those of the diploid and triploid lines, especially in plant height, which was much reduced (P < 0.01). These results indicated that the aneuploid H39 was a potential germplasm for breeding dwarfing loquat rootstock or interstock.