The domestication of tomato (Solanum lycopersicum) has led to a massive increase in fruit size but at the cost of decreased sugar levels, a negative correlation that is probably the consequence of a loss of high-sugar alleles. In a study published in Nature, Zhang et al. engineer a sweet tomato that maintains its high yield and weight by mutating a gene that encodes a protein that regulates sugar accumulation.

Zhang et al. performed a genome-wide association study of both wild and cultivated tomato species to search for genomic regions that are associated with fruit sweetness. This analysis identified six genes, of which only one showed lower levels of expression in sweeter tomatoes. Functional characterization of this gene, known as SlCDPK27, as well as its paralogue SlCDPK26 showed that both of them encode kinases that are increasingly expressed during fruit ripening, at which stage they reduce sugar content by phosphorylating the sucrose synthase SlSUS3 (which promotes degradation of this enzyme). The authors showed that CRISPR–Cas9-mediated double knockout of SlCDPK27 and SlCDPK26 increases the sugar content of a commonly cultivated tomato variety by up to 30% without affecting fruit size.

番茄 （Solanum lycopersicum） 的驯化导致果实大小大幅增加，但以糖分水平降低为代价，这种负相关可能是高糖等位基因丢失的结果。在发表在《自然》杂志上的一项研究中，Zhang 等人通过突变编码调节糖积累蛋白质的基因，设计出一种甜番茄，使其保持高产量和重量。

Zhang 等人对野生和栽培番茄物种进行了全基因组关联研究，以寻找与水果甜味相关的基因组区域。该分析确定了 6 个基因，其中只有一个在较甜的西红柿中表现出较低的表达水平。该基因（称为 SlCDPK27）及其旁系同源物 SlCDPK26 的功能特征表明，它们都编码在果实成熟过程中越来越多地表达的激酶，在这个阶段，它们通过磷酸化蔗糖合酶 SlSUS3 （促进这种酶的降解）来降低糖含量。作者表明，CRISPR-Cas9 介导的 SlCDPK27 和 SlCDPK26 双敲除可将常用番茄品种的糖含量增加多达 30%，而不会影响果实大小。