Dissecting the genetic pathway to extreme fruit size in tomato using a cross between the small-fruited wild species Lycopersicon pimpinellifolium and L. esculentum var. Giant Heirloom.
Dissecting the genetic pathway to extreme fruit size in tomato using a cross between the small-fruited wild species Lycopersicon pimpinellifolium and L. esculentum var. Giant Heirloom.
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作者：
Z. Lippman;S. Tanksley
为了确定特大番茄果实的遗传基础，对来自野生种Lycopersicon pimpinellifolium（平均果实重量，1g）和L.番茄巨大的传家宝，其果实超过1000克。QTL分析表明，大部分（67%）的果实大小的表型变异可以归因于6个主要的基因座定位在染色体1-3和11。没有一个QTL定位到基因组的新区域，所有这些都在以前的研究中报道过，涉及中等大小的番茄。这一结果表明，没有主要QTL以外的那些已经报道的参与进化的极大的果实。然而，这是第一次所有六个QTL都出现在一个群体中，这表明特别大的果实品种，如巨人传家宝，是预先存在的QTL等位基因的新组合的结果。其中一个QTL fw2.2已被克隆，并通过在心皮/果实发育早期全面控制细胞分裂来影响果实大小。然而，在本研究中检测到的最显着的QTL（fw11.3，lcn11.1）定位于第11染色体的底部，似乎发挥其对果实大小的控制心皮/室数。第二个主要基因座，也影响心皮数（因此果实大小），被定位到染色体2（fw2.1，lcn2.1）。我们认为这两个心皮数量QTL分别对应于早期经典遗传学家描述的基因座Fasciated（f）和子心皮室数量（lc）。
In an effort to determine the genetic basis of exceptionally large tomato fruits, QTL analysis was performed on a population derived from a cross between the wild species Lycopersicon pimpinellifolium (average fruit weight, 1 g) and the L. esculentum cultivar var. Giant Heirloom, which bears fruit in excess of 1000 g. QTL analysis revealed that the majority (67%) of phenotypic variation in fruit size could be attributed to six major loci localized on chromosomes 1-3 and 11. None of the QTL map to novel regions of the genome-all have been reported in previous studies involving moderately sized tomatoes. This result suggests that no major QTL beyond those already reported were involved in the evolution of extremely large fruit. However, this is the first time that all six QTL have emerged in a single population, suggesting that exceptionally large-fruited varieties, such as Giant Heirloom, are the result of a novel combination of preexisting QTL alleles. One of the detected QTL, fw2.2, has been cloned and exerts its effect on fruit size through global control of cell division early in carpel/fruit development. However, the most significant QTL detected in this study (fw11.3, lcn11.1) maps to the bottom of chromosome 11 and seems to exert its effect on fruit size through control of carpel/locule number. A second major locus, also affecting carpel number (and hence fruit size), was mapped to chromosome 2 (fw2.1, lcn2.1). We propose that these two carpel number QTL correspond to the loci described by early classical geneticists as fasciated (f) and locule number (lc), respectively.