Instituto de Biología Molecular y Celular de Plantas (IBMCP), Consejo Superior de Investigaciones Científicas (CSIC), Universitat Politècnica de València, Ingeniero Fausto Elio s/n, 46022, Valencia, Spain.
Universidad de Almería, Almería, Spain.
Theor Appl Genet. 2022 Mar;135(3):785-801. doi: 10.1007/s00122-021-03998-6. Epub 2021 Nov 25.
The gene underlying the melon fruit shape QTL fsqs8.1 is a member of the Ovate Family Proteins. Variation in fruit morphology is caused by changes in gene expression likely due to a cryptic structural variation in this locus. Melon cultivars have a wide range of fruit morphologies. Quantitative trait loci (QTL) have been identified underlying such diversity. This research focuses on the fruit shape QTL fsqs8.1, previously detected in a cross between the accession PI 124112 (CALC, producing elongated fruit) and the cultivar 'Piel de Sapo' (PS, producing oval fruit). The CALC fsqs8.1 allele induced round fruit shape, being responsible for the transgressive segregation for this trait observed in that population. In fact, the introgression line CALC8-1, carrying the fsqs8.1 locus from CALC into the PS genetic background, produced perfect round fruit. Following a map-based cloning approach, we found that the gene underlying fsqs8.1 is a member of the Ovate Family Proteins (OFP), CmOFP13, likely a homologue of AtOFP1 and SlOFP20 from Arabidopsis thaliana and tomato, respectively. The induction of the round shape was due to the higher expression of the CALC allele at the early ovary development stage. The fsqs8.1 locus showed an important structural variation, being CmOFP13 surrounded by two deletions in the CALC genome. The deletions are present at very low frequency in melon germplasm. Deletions and single nucleotide polymorphisms in the fsqs8.1 locus could not be not associated with variation in fruit shape among different melon accessions, what indicates that other genetic factors should be involved to induce the CALC fsqs8.1 allele effects. Therefore, fsqs8.1 is an example of a cryptic variation that alters gene expression, likely due to structural variation, resulting in phenotypic changes in melon fruit morphology.
该基因是位于果实形状 QTL fsqs8.1 下的一个基因，它是卵形家族蛋白的一个成员。果实形态的变化是由于基因表达的变化引起的，可能是由于该基因座的隐性结构变异。瓜类品种具有广泛的果实形态。已经确定了这种多样性的数量性状基因座 (QTL)。本研究集中在先前在 PI 124112 （CALC，产生细长果实）和 'Piel de Sapo' （PS，产生椭圆形果实）品种杂交中检测到的果实形状 QTL fsqs8.1。CALC fsqs8.1 等位基因诱导圆形果实形状，负责该群体中观察到的该性状的超亲分离。事实上，携带 fsqs8.1 基因座的 CALC8-1 导入系，将 fsqs8.1 基因从 CALC 导入 PS 遗传背景，产生了完美的圆形果实。通过基于图谱的克隆方法，我们发现 fsqs8.1 基因是卵形家族蛋白（OFP）的一个成员，CmOFP13，可能是拟南芥 AtOFP1 和番茄 SlOFP20 的同源物。圆形形状的诱导是由于 CALC 等位基因在早期卵巢发育阶段的高表达。fsqs8.1 基因座显示出重要的结构变异，CmOFP13 在 CALC 基因组中被两个缺失所包围。缺失在瓜类种质中存在的频率非常低。fsqs8.1 基因座中的缺失和单核苷酸多态性不能与不同瓜类品种果实形状的变异相关联，这表明应该涉及其他遗传因素来诱导 CALC fsqs8.1 等位基因的效应。因此，fsqs8.1 是一个改变基因表达的隐性变异的例子，可能是由于结构变异导致甜瓜果实形态的表型变化。
