## 4 Conclusions and Discussion  
In this study, ABA significantly promoted the accumulation of anthocyanin and soluble solid in strawberry fruit, but reduced fruit firmness and total titratable acid; thus, ABA regulated almost the entire fruit ripening process [46]. This significant acceleration of fruit ripening by ABA was accompanied by increased expression levels of series genes involved in anthocyanin biosynthesis (_PAL_, _CHS_, and _DFR_), softening (_PL_), and easier biosynthesis (_AAT_). PAL was discovered to trigger the production of anthocyanin [47]. CHS was indicated to increase the attractive red color of the strawberry fruit [48], and DFR was one of the key anthocyanin structural enzymes [49]. PL was responsible for the eliminative cleavage of spectate, and then oligosaccharides searches produced with 4-deoxy-\(\alpha\)-D-mann-4-enuronosyl groups at their non-reducing ends, resulting in fruit softening [50]. During ripening, strawberry fruit produced lots of secondary metabolites contributing to flavor and organoleptic peculiarities. [PERSON] and [PERSON] [51] discovered more than 350 compounds from strawberries, including alcohols, esters, aldehydes, furanone derivative ketones, sulfur compounds, and terpenes; however, there were only 20 compounds actually contributing to the aroma and flavor of strawberries [52]. Alcohol acyltransferase (AAT) was involved in the biosynthesis of short-chain esters, contributing to the blend of volatiles and defining the fruit aroma [53]. These results demonstrated that ABA regulated ripening by promoting softening metabolism and biosynthesis of anthocyanin and aroma in strawberries. Studies have suggested that some MADS members contributed to the fruit ripening of tomatoes [54], grape [55], strawberries [56; 57], and bananas [58]. The MADS-box gene _FaMADS1_ was suppressed with an accelerated ripening process following ABA treatment [28]. These results confirmed that _FaMADS1_ might play a negative role in fruit ripening via the downstream ABA signal transduction pathway connected to related metabolic processes. Previous studies have reported that tobacco rattle virus (TRV)-mediated VIGS was a rapid and feasible technique for analyzing fruit ripening of tomato [59] and strawberry [60; 61]. In the present study, the negative role of _FaMADS1_ in the ripening of strawberry fruit was verified through a gene silencing technique. Compared with the control (empty vector), _FaMADS1_-RNAi fruit exhibited accelerated ripening with high levels of anthocyanin and soluble pectin, low firmness, and protopectin content. In addition, an increase in the content levels of ester, ketone, acid, terpenes, and benzene was observed in the _FaMADS1_-RNAi fruit. The down-regulation of _FaMADS1_ resulted in increased expression levels of anthocyanin-related genes (_PAL6_, _C4H_, _4 CL_, _DFR_, and _UFGT_), softening-related genes (_PL_ and _XTH_), and aroma-related genes (_QR_ and _AAT_). In tomato, the silence experiment also caused changes in fruit ripening. [PERSON] et al. [62] found that postharvest ripening could be delayed by knocking down miR160a, and some related genes, such as _ARF10A_, _ARF10B_, and _ZRF17_, were up-regulated. Meanwhile, _FaMADS1_-RNAi significantly promoted the activities of PAL, 4 CL, C4H, DFR, PL, and AAT enzymes. These results collectively suggested that the _FaMADS1_ gene had a strong negative function in strawberry ripening. The gene _ABI_ encoded protein PP2C in the ABA signal pathway. _FaAB1_ and _FaAB12_ negatively regulated strawberry fruit ripening, whereas _FaAB14_ and _FaAB15_ positively regulated fruit ripening [5; 63]. Previous studies have confirmed that ABI and TRAB are the major transcription factors in the ABA signaling pathway [63; 18; 64; 65; 66]. In the present study, yeast one-hybrid analysis revealed that FaAB15-5, FaTRAB1, and FaABIS could interact with _FaMADS1_-pro1.