The present experiment was conducted to map resistance to Fusarium oxysporum f. sp. niveum (Fon) race 2 in a highly resistant Citrullus lanatus accession (EC794421). For this purpose, a F_2:3 population was developed by crossing a susceptible accession BIL-53 with EC794421. The F_2:3 progenies were screened in two bioassays employing artificial inoculation of conidial suspension (1 × 10⁶ conidia per ml; 5 ml per plant). Based on the F_2:3 progeny performance, the five most resistant and sensitive F₂ genotypes were identified and their corresponding genomic DNA was bulked to constitute the resistant and the susceptible bulks, respectively for performing QTL-seq analysis. Two statistically significant genomic regions were identified on chromosome 1 and chromosome 7; of which, the latter is novel and not reported earlier. Through target-locus refining employing QTL mapping, the QTLs on chromosomes 1 and 7 were narrowed down to two and a single microsatellite marker, respectively. These markers were also validated in two populations derived from different resistant accessions. The information generated in the current study will be of use of global breeders to incorporate the Fon race 2 resistance through marker-assisted introgression into elite commercial backgrounds of watermelon without incurring linkage drag.

进行本实验以绘制对Fusarium oxysporum f 的抗性。sp。高抗性Citrullus lanatus种质 (EC794421) 中的niveum ( Fon ) race 2 。为此，通过将易感种质 BIL-53 与 EC794421 杂交，开发了F _2:3种群。F _2:3后代在两个生物测定中筛选，采用人工接种分生孢子悬浮液（每毫升 1 × 10 ^{6 个}分生孢子；每株植物 5 毫升）。基于 F _2:3后代性能，五个最具抵抗力和敏感性的 F ₂鉴定了基因型，并将其相应的基因组 DNA 聚集成抗性和易感体，分别用于进行 QTL-seq 分析。在 1 号染色体和 7 号染色体上确定了两个具有统计学意义的基因组区域；其中，后者较新，此前未见报道。通过使用 QTL 作图的目标位点精炼，1 号和 7 号染色体上的 QTL 分别缩小到两个和一个微卫星标记。这些标记也在来自不同抗性种质的两个群体中得到验证。当前研究中产生的信息将被全球育种者用于整合Fon通过标记辅助渗入到西瓜的精英商业背景中而不会引起连锁阻力，从而抵抗第 2 种族。