The Cucurbitaceae family hosts many economically important fruit vegetables (cucurbits) such as cucumber, melon, watermelon, pumpkin/squash, and various gourds. The cucurbits are probably best known for the diverse fruit sizes and shapes, but little is known about their genetic basis and molecular regulation. Here, we reviewed the literature on fruit size (FS), shape (FSI), and fruit weight (FW) QTL identified in cucumber, melon, and watermelon, from which 150 consensus QTL for these traits were inferred. Genome-wide survey of the three cucurbit genomes identified 253 homologs of eight classes of fruit or grain size/weight-related genes cloned in Arabidopsis, tomato, and rice that encode proteins containing the characteristic CNR (cell number regulator), CSR (cell size regulator), CYP78A (cytochrome P450), SUN, OVATE, TRM (TONNEAU1 Recruiting Motif), YABBY, and WOX domains. Alignment of the consensus QTL with candidate gene homologs revealed widespread structure and function conservation of fruit size/shape gene homologs in cucurbits, which was exemplified with the fruit size/shape candidate genes CsSUN25-26-27a and CsTRM5 in cucumber, CmOFP1a in melon, and ClSUN25-26-27a in watermelon. In cucurbits, the andromonoecy (for 1-aminocyclopropane-1-carboxylate synthase) and the carpel number (for CLAVATA3) loci are known to have pleiotropic effects on fruit shape, which may complicate identification of fruit size/shape candidate genes in these regions. The present work illustrates the power of comparative analysis in understanding the genetic architecture of fruit size/shape variation, which may facilitate QTL mapping and cloning for fruit size-related traits in cucurbits. The limitations and perspectives of this approach are also discussed.

中文翻译：

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葫芦丝果实大小和形状变异的遗传结构：比较观点。

葫芦科家族有许多经济上重要的水果蔬菜（葫芦），例如黄瓜，甜瓜，西瓜，南瓜/南瓜和各种葫芦。葫芦可能以各种水果大小和形状而闻名，但对其遗传基础和分子调控知之甚少。在这里，我们回顾了有关在黄瓜，甜瓜和西瓜中鉴定的果实大小（FS），形状（FSI）和果实重量（FW）QTL的文献，从中推断出150个针对这些性状的共有QTL。对三个葫芦基因组的全基因组调查确定了在拟南芥属，番茄和水稻中克隆的八类水果或与谷物大小/体重相关的八类基因的253个同源物，这些基因编码的蛋白质含有特征CNR（细胞数调节剂），CSR（细胞大小）调节剂），CYP78A（细胞色素P450），SUN，卵酸盐，TRM（TONNEAU1招聘主题），YABBY和WOX域。共有QTL与候选基因同源物的比对揭示葫芦科中果实大小/形状基因同源物的广泛结构和功能保守性，例如黄瓜中的果实大小/形状候选基因CsSUN25-26-27a和CsTRM5，瓜中的CmOFP1a。和西瓜中的ClSUN25-26-27a。在葫芦科中，已知雄激素（1-氨基环丙烷-1-羧酸合酶）和心皮数（对于CLAVATA3）位点对果实形状具有多效性作用，这可能会使这些区域中果实大小/形状候选基因的鉴定复杂化。本工作说明了比较分析在理解果实大小/形状变异的遗传结构中的作用，这可能有助于QTL定位和克隆葫芦科中与果实大小相关的性状。还讨论了这种方法的局限性和前景。