Fruit firmness is crucial for storability, making cultivating varieties with higher firmness a key target in tomato breeding. In recent years, tomato varieties primarily rely on hybridizing ripening mutants to produce F₁ hybrids to enhance firmness. However, the undesirable traits introduced by these mutants often lead to a decline in the quality of the varieties. CRISPR/Cas9 has emerged as a crucial tool in accelerating plant breeding and improving specific target traits as technology iterates. In this study, we used a CRISPR/Cas9 system to simultaneously knock out two genes, FIS1 and PL, which negatively regulate firmness in tomato. We generated single and double gene knockout mutants utilizing the tomato genetic transformation system. The fruit firmness of all knockout mutants exhibited a significant enhancement, with the most pronounced improvement observed in the double mutant. Furthermore, we assessed other quality-related traits of the mutants; our results indicated that the fruit quality characteristics of the gene-edited lines remained statistically comparable to those of the wild type. This approach enabled us to create transgenic-free mutants with diverse genotypes across fewer generations, facilitating rapid improvements in tomato firmness. This study offers significant insights into molecular design breeding strategies for tomato.

The eggplant (Solanum melongena) is a popular vegetable around the world. However, the origin and evolution of eggplant has long been considered complex and unclear, which has become the barrier to improvements in eggplant breeding. Sequencing and comparative analyses of 13 complete chloroplast (cp) genomes of seven Solanum species were performed. Genome sizes were between 154,942 and 156,004 bp, the smallest genome was from S. torvum and the largest from S. macrocapon. Thirteen cp genomes showed highly conserved sequences and GC contents, particularly at the subgenus level. All genes in the 13 genomes were annotated. The cp genomes in this study comprised 130 genes (i.e., 80 protein-coding genes, 8 rRNA genes, and 42 tRNA genes), apart from S. sisymbriifolium, which had 129 (79 protein-coding genes, 8 rRNA genes, and 42 tRNA genes.). The rps16 was absent from the cp genome of S. sisymbriifolium, resulting in a nonsense mutation. Twelve hotspot regions of the cp genome were identified, which showed a series of sequence variations and differed significantly in the inverted repeat/single-copy boundary regions. Furthermore, phylogenetic analysis was conducted using 46 cp genomic sequences to determine interspecific genetic and phylogenetic relationships in Solanum species. All species formed two branches, one of which contained all cultivars of the subgenus Leptostemonum. The cp genome data and phylogenetic analysis provides molecular evidence revealing the origin and evolutionary relationships of S. melongena and its wild relatives. Our findings suggest precise intra- and interspecies relatedness within the subgenus Leptostemonum, which has positive implications for work on improvements in eggplant breeding, particularly in producing heterosis, expanding the source of species variation, and breeding new varieties.