Abstract

Most commercial peach [Prunus persica (L.) Batsch] cultivars have leaves with extrafloral nectaries (EFNs). Breeders have selected this character over time, as they observed that the eglandular phenotype resulted in high susceptibility to peach powdery mildew, a major disease of peach trees. EFNs are controlled by a Mendelian locus (E), mapped on chromosome 7. However, the genetic factor underlying E was unknown. In order to address this point, we developed a mapping population of 833 individuals derived from the selfing of “Malo Konare”, a Bulgarian peach cultivar, heterozygous for the trait. This progeny was used to investigate the E-locus region, along with additional resources including peach genomic resequencing data, and 271 individuals from various origins used for validation. High-resolution mapping delimited a 40.6 kbp interval including the E-locus and four genes. Moreover, three double-recombinants allowed identifying Prupe.7G121100, a LMI1-like homeodomain leucine zipper (HD-Zip) transcription factor, as a likely candidate for the trait. By comparing peach genomic resequencing data from individuals with contrasted phenotypes, a MITE-like transposable element of the hAT superfamily (mMoshan) was identified in the third exon of Prupe.7G121100. It was associated with the absence or globose phenotype of EFNs. The insertion of the transposon was positively correlated with enhanced expression of Prupe.7G121100. Furthermore, a PCR marker designed from the sequence-variants, allowed to properly assign the phenotypes of all the individuals studied. These findings provide valuable information on the genetic control of a trait poorly known so far although selected for a long time in peach.

中文翻译：

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在 PpLMI1 中插入 mMoshan 转座元件与桃 [Prunus persica (L.) Batsch] 花外蜜腺的缺失或球形表型相关

 抽象的

大多数商业桃 [ Prunus persica (L.) Batsch] 品种的叶子带有花外蜜腺 (EFN)。随着时间的推移，育种者选择了这个特征，因为他们观察到无腺表型导致对桃白粉病（桃树的一种主要疾病）的高度易感性。 EFN 由位于 7 号染色体上的孟德尔基因座 ( E ) 控制。然而， E背后的遗传因素尚不清楚。为了解决这个问题，我们开发了一个由 833 个个体组成的绘图群体，这些个体源自保加利亚桃品种“Malo Konare”的自交，该品种具有杂合性状。该后代用于研究E基因座区域，以及包括桃基因组重测序数据在内的其他资源，以及用于验证的来自不同来源的 271 名个体。高分辨率作图界定了 40.6 kbp 的间隔，包括E-位点和四个基因。此外，三个双重组体允许鉴定Prupe.7G121100 ，一种类似 LMI1 的同源域亮氨酸拉链 (HD-Zip) 转录因子，作为该性状的可能候选者。通过比较具有对比表型的个体的桃基因组重测序数据，在Prupe.7G121100的第三个外显子中鉴定出了 hAT 超家族 ( mMoshan ) 的 MITE 样转座元件。它与 EFN 的缺失或球形表型有关。转座子的插入与Prupe.7G121100的表达增强呈正相关。此外，根据序列变异设计的 PCR 标记可以正确分配所有研究个体的表型。 这些发现为桃子中长期以来被选择的性状的遗传控制提供了有价值的信息，但迄今为止人们对此知之甚少。