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Tomato is an economically crucial vegetable/fruit crop globally. Tomato is rich in nutrition and plays an essential role in a healthy human diet. Phenylpropanoid, a critical compound in tomatoes, reduces common degenerative and chronic diseases risk caused by oxidative stress. As an MYB transcription factor, ATMYB12 can increase phenylpropanoid content by activating phenylpropanoid synthesis related genes, such as PAL, C4H, 4CL, CHS. However, the heterologous expression of AtMYB12 in tomatoes can be altered through transgenic technologies, such as unstable expression vectors and promoters with different efficiency. In the current study, the efficiency of other fruit-specific promoters, namely E8S, 2A12, E4, and PG, were compared and screened, and we determined that the expression efficiency of AtMYB12 was driven by the E8S promoter was the highest. As a result, the expression of phenylpropanoid synthesis related genes was regulated by AtMYB12, and the phenylpropanoid accumulation in transgenic tomato fruits increased 16 times. Additionally, the total antioxidant capacity of fruits was measured through Trolox equivalent antioxidant capacity (TEAC) assay, which was increased by 2.4 times in E8S transgenic lines. TEAC was positively correlated with phenylpropanoid content. Since phenylpropanoid plays a crucial role in the human diet, expressing AtMYB12 with stable and effective fruit-specific promoter E8S could improve tomato’s phenylpropanoid and nutrition content and quality. Our results can provide genetic resources for the subsequent improvement of tomato varieties and quality, which is significant for human health.

BackgroundBanded leaf and sheath blight (BLSB) caused by the necrotrophic fungus Rhizoctonia solani is a devasting disease on maize worldwide, especially in China and Southeast Asia. It is important to understand the interaction mechanism between maize and R. solani for control of invasion and expansion.ResultsIn this study, the expression profile of maize infected by low virulence strain (LVS) and high virulence strain (HVS) of R. solani for 3 and 5 d was analyzed by RNA-sequencing. A total of 3015 and 1628 differentially expressed genes (DEGs) were identified under LVS and HVS infection, respectively. Meanwhile, these DEGs were classified by Gene Ontology (GO) for biological process analysis. Only defense-related GO terms were commonly enriched in LVS- and HVS-regulated genes. Furthermore, a core set of 388 up-regulated genes that are involved in maize response to R. solani infection were identified. Additionally, among the core genes, overexpressing ZmNAC41 and ZmBAK1 enhanced rice resistance to R. solani.ConclusionThe results in this study provide additional insight into maize defense mechanisms against R. solani, and the core genes identified in this study will be important resources for improving BLSB resistance in the future.

Fruit lycopene, shape, and resistance are essential traits in vegetables whose final product is fruit, and they are also closely related to and strictly regulated by multiple transcription factors. Lycopene, which can not be synthesized by human body only can ingested from the outside, was important in maintaining human health. During fruit ripening and post-harvest, tomato plants face a variety of biotic or abiotic stresses, which might inflict great damage to fruit quality due to its flat shape and pointed tip during storage and transportation. Therefore, there is an urgent need for key molecular switches to simultaneously improve fruit lycopene and resistance to biotic stress during ripening. Here, we identified the MYB transcription factor SlMYB1 in tomato plants which could bind to the promoters of lycopene synthesis-related genes, SlLCY1, SlPSY2, and the pathogen-related gene SlPR5 directly, to regulate the fruit lycopene and resistance to Botrytis cinerea in tomato. In addition to regulating lycopene synthesis, SlMYB1 also regulates the content of soluble sugar, soluble protein and flavonoid in tomato. What’s more, SlMYB1 could regulate the tomato fruit shape, making it smoother or flatter to prevent skin damage caused by vibration on fruits. RNA sequencing (RNA-seq) further showed that SlMYB1 fruit-specific expression lines had multiple differentially expressed genes compared with those from wild-type plants, suggesting that SlMYB1 might have multiple roles in fruit nutritional quality control and resistance to stresses, which is a rare occurrence in previous studies. In summary, our results revealed that SlMYB1 was an essential multi-functional transcription factor that could regulate the lycopene and resistance to Botrytis cinerea, and change the shape of fruit in tomato plants.

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