Spontaneous outcrossing in tomato depends on cultivar and environment and varies between individual flowers

Knowledge about the degree of spontaneous outcrossing of diverse genotypes is essential for breeding programmes, maintenance breeding, and seed production. For tomato (Lycopersicon esculentum Mill.), very limited scientific evidence for genotypic differences is available and evidence from Europe is scarce. To close this knowledge gap, six cultivars were investigated in three Central European locations as part of the Organic Outdoor Tomato Project. To determine outcrossing rates, the monogenetic “cut‐leaf” trait, which is dominant over the “potato‐leaf” trait, was used as morphological marker. The observed range of outcrossing was 0.0%–5.2%. Outcrossing was significantly influenced by cultivar and environment. The outcrossing rate of individual flowers varied within cultivars ranging from 0% to 37%. The potential of newly opened flowers to accept foreign pollen varied largely with the cultivar. Genotypic differences could partly be linked to flower morphology traits. The potential for recombination between tomato genotypes is generally very low but can be a source for new variation in on‐farm management.     

花楸树天然群体的异交率

采用水平淀粉凝胶电泳技术,对采自山东、山西、河北、辽宁4个省的6个花楸树天然群体的种子样本进行分析,所用同工酶多态位点分别为Pgm-1,Pgm-2,Pgm-3,Pgi-1,Pgi-2,Pgd-1,Pgd-2,Pgd-3,利用多位点异交率估算程序(MLT)估算6个群体的异交率.结果表明:花楸树各群体的花粉库与胚珠库中,各位点基因的配子比例差异不显著,基本处于平衡状态;各群体多位点异交率均在0.981以上,多位点异交率与单位点异交率平均值的差值(t_m-t_s)显示出花楸树各群体都存在轻度的自交或近交,说明花楸树属于混合交配类型,表现为高度异交.根据电泳数据计算的近交衰退δ=1,表明花楸树天然群体的近交衰退很大.