Breeding for thermotolerance in processes determining fruit set and pollen germination is increasingly needed as global warming progresses. We previously reported good yields at high temperatures from the F1 hybrid of the Capsicum chinense cultivars ‘Sy-2’ and ‘No. 3686’, both of which yield poorly at high temperatures. Moreover, the percentages of fruit set at high temperature in the F2 population segregated quantitively. In addition, percentages of fruit set in some F2 individuals exceeded those of the F1 hybrid. Analysis of the F2 population using double-digest restriction site-associated DNA sequencing (ddRAD-Seq) shows that the percentage of fruit set under high temperature is strongly associated to single nucleotide polymorphisms (SNPs) in a certain gene region of chromosome 6 and weakly associated to a gene region on the chromosome 3. Furthermore, the pollen germination rate is strongly associated to SNPs of the same regions on chromosomes 3 and 6. Analysis of the genotypes and traits in another F2 population shows that the genotype determined by the cleaved amplified polymorphic sequence marker designed on the candidate gene region is associated to the percentage of fruit set and the pollen germination rate at high temperatures, supporting the results of ddRAD-Seq. The presence of alleles from both the gene regions of chromosome 3 from ‘No. 3686’ and chromosome 6 from ‘Sy-2’ increased the percentage of fruit set additively. We suggest that genes controlling fruit set and pollen germination at high temperature are located in these two gene regions.

中文翻译：

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辣椒坐果耐热性和花粉萌发的海侵分离和基因区控制

随着全球变暖的进展，越来越需要在决定坐果和花粉萌发的过程中培养耐热性。我们之前报道了辣椒品种“Sy-2”和“No.”的 F1 杂种在高温下的良好产量。3686'，两者在高温下产量都很差。此外，F2种群中高温坐果的百分比定量分离。此外，一些 F2 个体的坐果率超过了 F1 杂种。使用双酶切酶切位点相关DNA测序（ddRAD-Seq）对F2群体进行分析表明，高温下坐果率与6号染色体某基因区域的单核苷酸多态性（SNPs）强相关，弱相关与染色体 3 上的基因区域相关联。此外，花粉萌发率与染色体 3 和 6 上相同区域的 SNP 密切相关。 对另一个 F2 种群的基因型和性状分析表明，由在候选基因区域设计的切割扩增多态序列标记确定的基因型为与坐果率和高温下的花粉发芽率有关，支持 ddRAD-Seq 的结果。来自 'No. 3 号染色体的两个基因区域的等位基因的存在。3686'和'Sy-2'的6号染色体增加了坐果率。我们认为控制高温下坐果和花粉萌发的基因位于这两个基因区域。对另一个F2群体的基因型和性状分析表明，在候选基因区域设计的切割扩增多态序列标记确定的基因型与坐果率和高温花粉萌发率相关，支持ddRAD的结果-Seq。来自 'No. 3 号染色体的两个基因区域的等位基因的存在。3686'和'Sy-2'的6号染色体增加了坐果率。我们认为控制高温下坐果和花粉萌发的基因位于这两个基因区域。对另一个F2群体的基因型和性状分析表明，在候选基因区域设计的切割扩增多态序列标记确定的基因型与坐果率和高温花粉萌发率相关，支持ddRAD的结果-Seq。来自 'No. 3 号染色体的两个基因区域的等位基因的存在。3686'和'Sy-2'的6号染色体增加了坐果率。我们认为控制高温下坐果和花粉萌发的基因位于这两个基因区域。