番茄耐裂果基因Cr3a的精细定位

以栽培番茄(Solanum lycopersicum)‘1052’为遗传背景的潘那利番茄(S.pennellii)‘LA0716’的渐渗系‘14h616’含有‘LA0716’第3染色体上长度为2.66Mb的片段,该片段含有番茄耐裂果基因Cr3a。以‘14h616’和‘1052’为亲本构建了番茄耐裂果基因Cr3a的亚渐渗系群体,以亚渐渗系群体F5代中易裂果和含有耐裂果基因Cr3a的耐裂果为材料制作石蜡切片,测量果实含水量。结果表明易裂果番茄与含Cr3a耐裂果番茄果皮角质层厚度和表皮细胞层数均无显著差异;但绿熟期易裂番茄果实含水量显著高于含Cr3a耐裂番茄。亚渐渗系群体遗传分析并结合表型鉴定结果表明,番茄耐裂性对易裂性为不完全显性关系,基因Cr3a的遗传贡献率是27.41%;将Cr3a定位于分子标记3-ZY75和3-ZY43约349kb范围内,在该区段内检测到47个候选基因。利用分子标记对以耐裂材料‘182h640’为母本、易裂材料‘182h680’为父本构建的F2群体及200份遗传背景不同的高代材料进行验证,符合性较好,选择准确度可达96%。本研究的结果为Cr3a的图位克隆和番茄耐裂果分子改良打下了坚实的基础。

Fine Mapping of Fruit Cracking-resistant Gene Cr3a in Tomato

The introgression line 14 h616 was derived from cultivated tomato inbred line 1052(Solanum lycopersicum 1052)and contained a 2.66 Mb fragment on chromosome 3 from S.pennellii LA0716,which contained a fruit cracking-resistance gene Cr3a.A sub-introgression population of tomato Cr3a resistance gene was constructed using 14 h616 and 1052 as parents.Making paraffin sections and measuring the water content of fruits from the crackable fruits and cracking-resistant fruits containing the Cr3a gene in introgression population F5 generation.Histological examination suggested that fruit cracking-resistant Cr3a did not significantly affect the thickness of the cuticle and the number of epidermal cells of fruits.Water content analysis showed that the fruits from the sub-introgression line embodying Cr3a contained less water than that from cultivated tomato inbred line 1052 in mature green stage.Genetic analysis and phenotypic identification of sub-introgression populations showed that tomato cracking-resistant gene Cr3a was incompletely dominant,and its genetic contribution rate is 27.41%.Cr3a was narrowed down to a 349 kb interval between molecular markers 3-ZY75 and 3-ZY43,which encoded 47 putative genes.Using molecular markers,the F2 population constructed with the cracking-resistant material 182 h640 as the maternal and the crackable material 182 h680 as the paternal,and 200 high-generation materials with different genetic backgrounds were analyzed.The conformity is good and the accuracy of assistant selection was 96%.The study results laid a solid foundation for the map-based cloning of Cr3a and the molecular improvement of tomato cultivars resistant to fruit cracking.