Boudehri Karima, Bendahmane Abdelhafid, Cardinet Gaëlle, Troadec Christelle, Moing Annick, Dirlewanger Elisabeth
Institut National de la Recherche Agronomique/UR0419, Unité de Recherches sur les Espèces Fruitières, Centre de Bordeaux, Villenave d'Ornon, France.
BMC Plant Biol. 2009 May 15;9:59. doi: 10.1186/1471-2229-9-59.
Acidity is an essential component of the organoleptic quality of fleshy fruits. However, in these fruits, the physiological and molecular mechanisms that control fruit acidity remain unclear. In peach the D locus controls fruit acidity; low-acidity is determined by the dominant allele. Using a peach progeny of 208 F2 trees, the D locus was mapped to the proximal end of linkage group 5 and co-localized with major QTLs involved in the control of fruit pH, titratable acidity and organic acid concentration and small QTLs for sugar concentration. To investigate the molecular basis of fruit acidity in peach we initiated the map-based cloning of the D locus.
In order to generate a high-resolution linkage map in the vicinity of the D locus, 1,024 AFLP primer combinations were screened using DNA of bulked acid and low-acid segregants. We also screened a segregating population of 1,718 individuals for chromosomal recombination events linked to the D locus and identified 308 individuals with recombination events close to D. Using these recombinant individuals we delimited the D locus to a genetic interval of 0.4 cM. We also constructed a peach BAC library of 52,000 clones with a mean insert size of 90 kb. The screening of the BAC library with markers tightly linked to D locus indicated that 1 cM corresponds to 250 kb at the vicinity of the D locus.
In the present work we presented the first high-resolution genetic map of D locus in peach. We also constructed a peach BAC library of approximately 15x genome equivalent. This fine genetic and physical characterization of the D locus is the first step towards the isolation of the gene(s) underlying fruit acidity in peach.
酸度是肉质果实感官品质的一个重要组成部分。然而，在这些果实中，控制果实酸度的生理和分子机制仍不清楚。在桃中，D位点控制果实酸度；低酸度由显性等位基因决定。利用一个由208棵F2桃树组成的桃后代群体，将D位点定位到连锁群5的近端，并与参与控制果实pH值、可滴定酸度和有机酸浓度的主要QTL以及糖浓度的小QTL共定位。为了研究桃果实酸度的分子基础，我们启动了基于图谱的D位点克隆。
为了在D位点附近生成高分辨率连锁图谱，使用酸含量高和低的混合分离群体的DNA筛选了1024对AFLP引物组合。我们还在一个由1718个个体组成的分离群体中筛选了与D位点相关的染色体重组事件，并鉴定出308个在D位点附近发生重组事件的个体。利用这些重组个体，我们将D位点限定在0.4 cM的遗传区间内。我们还构建了一个包含52000个克隆的桃BAC文库，平均插入片段大小为90 kb。用与D位点紧密连锁的标记筛选BAC文库表明，在D位点附近1 cM相当于250 kb。
在本研究中，我们展示了桃中D位点的首张高分辨率遗传图谱。我们还构建了一个约为15倍基因组当量的桃BAC文库。对D位点进行精细的遗传和物理特征分析是分离桃果实酸度相关基因的第一步。
