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紫叶桦与裂叶桦杂交子代的种子活力及叶片性状分离

Segregation of Seed Vigor and Leaf Traits in Hybrid Progenies of Betula pendula 'Purple Rain' and Betula pendula 'Dplecprlicp'

  • 摘要:
    目的 为了研究紫叶桦和裂叶桦叶片目标性状的显隐性以及基因型,筛选优良杂交组合,为种子园营建奠定基础。
    方法 本试验以紫叶桦、裂叶桦以及白桦和欧洲白桦为杂交亲本,分别设计了不同杂交组合进行杂交制种。针对各杂交组合的种子千粒质量、种子活力以及杂种子代的生长量等进行差异显著性分析。研究各组合子代叶片目标性状的分离比例及规律,采用X2法对该分离比例进行可靠性检测,进而验证亲本基因型的推测。
    结果 分析表明,杂交组合间种子千粒质量、发芽率、发芽势、发芽指数及苗高、地径等性状的差异均达极显著(P < 0.01),紫叶桦的杂种种子千粒质量及活力性状的变异系数较高,达到66%~78%,其它性状及裂叶桦的杂种子代各性状变异系数为19%~47%,各性状的广义遗传力均在76%以上。综合种子千粒质量、种子活力、苗木生长以及叶片目标性状分离情况,选出LCK×Z1、Z4×1-28和LY×LCK 3个优良杂交亲本组合。根据紫叶桦的杂种子代全部呈现紫叶与绿叶2种类型,确定其为杂合基因型,紫叶为显性性状;又依据其子代紫叶与绿叶比例的9:7、1:1、1:3、3:5四种类型,确认紫叶由2对基因控制,属于互补作用,基因型为P_B_。根据裂叶桦的多个杂交组合中,仅与来自同一家系正常叶的半同胞个体(LCK)杂交才产生裂叶子代的现象,确定裂叶为隐性性状,该子代中裂叶与正常叶的分离比例为1:3,推断该性状也为2对基因控制,属于叠加效应,裂叶桦的基因型为ddbb。卡方检验结果支持上述基因型及表型的推测。
    结论 本研究确定紫叶性状为显性、裂叶性状为隐性,紫叶桦和裂叶桦的基因型分别为P_B_、ddbb,选出LCK×Z1、Z4×1-28和LY×LCK分别为紫叶桦和裂叶桦种子园营建时的优良杂交亲本组合。

     

    Abstract:
    Objective  To study the dormant and recessive leaf traits and genotypes of Betula pendula 'Purple Rain' and Betula pendula 'Dplecprlicp', to screen the elite hybrid combinations and lay a foundation for the establishment of seed orchard.
    Method  In this study, different mating designs were used among B. pendula 'Purple Rain', B. pendula 'Dplecprlicp', B. platyphylla Suk. and B. pendula. The seed weight, seed vigor, and growth were recorded from their progenies. Chi-square test was used to test the reliability of segregating ratio and the inference of parental genotype.
    Result  Significantly difference was found among the combinations of parental crosses (P < 0.01) in thousand-seed weight, germination rate, germination potential, germination index, height and diameter. Coefficient of variation (CV) of thousand-seed weight and seed vigor are 66% and 78% for B. pendula, whereas the other traits of CV for B. pendula 'Dplecprlicp' are between 19%~47%. The broad sense heritability for all traits is above 76%. Based on the weight of seed, grain vigor, seedling growth and leaf target traits, it was found that LCK×Z1, Z4×1-28 and LY×LCK are the elite hybrid combinations. Because the progeny of B. pendula 'Purple Rain' has two leaf types, purple and green, it is believed that B. pendula 'Purple Rain' is heterozygous and purple is a dominant trait. Based on the four segregation ratios of green and purple (9:7, 1:1, 1:3 and 3:5), the authors confirm that two pairs of gene P_B_are complementary. Only normal leaves of the same family of LCK half-sib produce lobed leaf progeny based on multiple cross combinations of birch. Therefore, lobed leaf is a recessive trait, and is controlled by two pairs of genes based on segregating ratio 1:3. They belong to a additive effect. The genotype of B. pendula 'Dplecprlicp' is ddbb. The result of Chi-square test confirms above inferences of genotypes and phenotypes.
    Conclusion  In this study, inheritance of recessive and dominant traits for leaf color and leaf shape was identified. The genotype of B. pendula 'Purple Rain' is P_B_, and B. pendula 'Dplecprlicp' is ddbb. LCK×Z1 and Z4×1-28 for the purple leaf and LY×LCK for the lobed leaf are chosen as the preferred combinations for each seed orchard establishment.

     

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