## 3 Discussion  
Our earlier research revealed significant alterations in tomato fruit quality within the _I114_ disruption lines. These changes encompassed a slight decrease in the fruit's weight in line M7_5, as well as reduced titratable acidity, lowered moisture and protein contents, elevated fructose levels, modified organic acid composition, and an increased total phenol content coupled with enhanced antioxidant activity. These findings provided important insights into the role of L1L4 in regulating fruit quality and metabolic functions in tomatoes. The biochemical data, including shifts in organic acid profiles and sugar content, reinforce the idea that L1L4 acts as a key regulator of fruit metabolism. Fruit morphology is essential in determining both the crop yield and consumer preference. Initial genetic studies identified several critical genes that markedly influence the fruit shape, such as _SIN_, _OVATE_, and _FAS_[10]. Extensive research on these genes has laid the groundwork for understanding the molecular mechanisms guiding fruit development. These genes produce proteins that collectively govern cell proliferation, cell elongation, and ultimately, the final shape of the fruit. Tomato lines M7_5 and M29_2 displayed altered fruit morphology compared to the WT, characterized by a diminished distal end protrusion and a more ovoid form. These morphological differences suggest that mutations in the _I114_ lines affect the fruit shape. Supporting this conclusion, a disruption of the _NF-YA8_ gene near its DNA-binding domain (DNA BD) has been reported to reduce fruit ovoidity by 40% in about half of the tomato plants [5]. In the M7_5 mutant line, the increased distal angle may result from modified patterns of cell division and expansion at the fruit apex. Previous research has established that the distal end of the tomato fruit is formed by a cluster of cells that divide and expand to create the fruit tip [11]. The larger distal angle observed in mutant line M7_5 implies alterations in cell division and expansion in this area, leading to a broader fruit apex. The reduced distal end protrusion and ovoid shape in both mutant lines may be attributable to the changes in cell wall composition and characteristics. Prior studies have demonstrated that the cell wall's composition and properties influence the tomato fruit shape. In the present study, RNA-sequencing analysis played a pivotal role in identifying specific genes and pathways regulated by L1L4. Notably, line M7_5 contains a 2-base pair deletion near the DNA BD of the L1L4 transcription factor, causing a premature stop codon [9]. In contrast, line M29_2 possesses a 1-base pair insertion within the coding sequence that shifts the reading frame. By comparing the transcriptomes of these mutant lines to the WT, we sought to pinpoint the genes and pathways controlled by L1L4 that contribute to the observed changes in fruit morphology and quality. The hierarchical clustering analysis revealed a dramatic reversal of gene expression patterns in the M7_5 mutant compared to the WT. This finding strongly suggests that the disrupted _L1L4_ TF in M7_5 plays a crucial role in regulating gene expression, acting as a molecular switch. The observation that this TF acts as a molecular switch has broader implications for understanding gene regulatory networks. It suggests that TFs can act as crucial control points, and their disruption can have profound effects on the overall expression landscape. In the WT, the TF likely acts as either an activator or a repressor for specific sets of genes. In M7_5, the disruption of this TF gene leads to the derepression (activation) of genes it normally represses, while also causing the repression (decreased expression) of genes it normally activates. This reversal of gene expression patterns highlights the importance of disrupted TF in maintaining the proper balance of gene expression. Its disruption resulted in a global shift in the expression landscape, suggesting it acts upstream of numerous other regulatory factors.