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Abstract：
Loquat is a widely grown subtropic fruit because of its unique ripening season, nutrient content, and smooth texture of its fruits. However, loquat is not well-received because the fruits contain many large seeds. Therefore, the development of seedless or few-seed loquat varieties is the main objective of loquat breeding. Polyploidization is an effective approach for few-seed loquat breeding, but the resource is rare. The few-seed loquat line H30-6 was derived from a seedy variety. Additionally, H30-6 was systematically studied for its fruit characteristics, gamete fertility, pollen mother cell (PMC) meiosis, stigma receptivity, in situ pollen germination, fruit set, and karyotype. The results were as follows. (1) H30-6 produced only 1.54 seeds per fruit and the fruit edible rate was 70.77%. The fruit setting rate was 14.44% under open pollination, and the other qualities were equivalent to those of two other seedy varieties. (2) The in vitro pollen germination rate was only 4.04 and 77.46% of the H30-6 embryo sacs were abnormal. Stigma receptivity and self-compatibility in H30-6 were verified by in situ pollen germination and artificial pollination. Furthermore, the seed numbers in the fruits of H30-6 did not significantly differ among any of the pollination treatments (from 1.59 ±0.14 to 2 ± 0.17). (3) The chromosome configuration at meiotic diakinesis of H30-6 was 6.87I + 9.99II + 1.07III +0.69IV +0.24V (H30-6), and a total of 89.55% of H30-6 PMCs presented univalent chromosomes. Furthermore, chromosome lagging was the main abnormal phenomenon. Karyotype analysis showed that chromosomes of H30-6 had no recognizable karyotype abnormalities leading to unusual synapsis on the large scale above. (4) The abnormal embryo sacs of H30-6 could be divided into three main types: those remaining in the tetrad stage (13.38%), those remaining in the binucleate embryo sac stage (1.41%), and those without embryo sacs (52.82%). Therefore, we conclude that the loquat line H30-6 is a potential few-seed loquat resource. The diploid loquat line H30-6 was with low gametophyte fertility, which may be driven by abnormal meiotic synapses. The low female gamete fertility was the main reason for the few seeds. This diploid loquat line provides a new possibility for breeding a few-seed loquat at the diploid level.
摘要：
枇杷是一种广泛种植的亚热带水果，因为它独特的成熟季节，营养成分，和水果的光滑质地。然而,枇杷不受欢迎，因为果实含有许多大种子。因此,发展无核或少籽枇杷品种是枇杷育种的主要目标。多倍体化是少粒枇杷育种的有效途径,但是资源很少。少粒枇杷系H30-6来自种子品种。此外,系统研究了H30-6的果实特性，配子生育能力,花粉母细胞减数分裂,柱头接受性，原位花粉萌发，水果套装，和核型。结果如下。（1）H30-6每果仅产生1.54粒种子，果实食用率为70.77％。开放式授粉下坐果率为14.44%,其他品质相当于另外两个种子品种的品质。(2)离体花粉萌发率仅为4.04,77.46%的H30-6胚囊异常。通过原位花粉萌发和人工授粉验证了H30-6的柱头接受性和自相容性。此外，H30-6果实中的种子数量在任何授粉处理中都没有显着差异（从1.59±0.14到2±0.17）。（3）H30-6减数分裂时的染色体构型为6.87I9.99II1.07III0.69IV0.24V（H30-6），共有89.55％的H30-6PMC呈现单价染色体。此外，染色体滞后是主要的异常现象。核型分析表明，H30-6的染色体没有可识别的核型异常，从而导致上述大规模的异常突触。（4）H30-6的异常胚囊可分为三种主要类型：保留在四分体阶段的胚囊（13.38％），保留在双核胚胎囊期（1.41％），和那些没有胚囊（52.82%）。因此,我们得出结论，枇杷系H30-6是一种潜在的少籽枇杷资源。二倍体枇杷系H30-6配子体育性低，这可能是由异常减数分裂突触驱动的。雌配子生育力低是种子少的主要原因。这种二倍体枇杷品系为在二倍体水平上育种少粒枇杷提供了新的可能性。
