All-flesh fruit in tomato is controlled by reduced expression dosage of<i>AFF</i>through a structural variant mutation in the promoter
Lei Liu, Kang Zhang, Jinrui Bai, Jinghua Lu, Xiaoxiao Lu, Junling Hu, Chun‐Yang Pan, Shumin He, Jiale Yuan, Yiyue Zhang, Min Zhang, Yanmei Guo, Xiaoxuan Wang, Zejun Huang, Yongchen Du, Feng Cheng, Junming Li
Abstract
The formation of locule gel is an important process in tomato and is a typical characteristic of berry fruit. In this study, we examined a natural tomato mutant that produces all-flesh fruit (AFF) in which the locule tissue remains in a solid state during fruit development. We constructed different genetic populations to fine-map the causal gene for this trait and identified SlMBP3 as the locus conferring the locule gel formation, which we rename as AFF. We determined the causal mutation as a 416-bp deletion in the promoter region of AFF, which reduces its expression dosage. Generally, this sequence is highly conserved among Solanaceae, as well as within the tomato germplasm. Using BC6 near-isogenic lines, we determined that the reduced expression dosage of AFF did not affect the normal development of seeds, whilst producing unique, non-liquefied locule tissue that was distinct from that of normal tomatoes in terms of metabolic components. Combined analysis using mRNA-seq and metabolomics indicated the importance of AFF in locule tissue liquefaction. Our findings provide insights into fruit-type differentiation in Solanaceae crops and also present the basis for future applications of AFF in tomato breeding programs.