Yaojun Chang

Fruit shape is an important quality and yield trait of pear, and the fruit shape of ‘Laiyang Cili’ presents a spindle shape which seriously affects its commercial value. Calyx excision treatment could change the fruit shape, while the underlying genes and their regulatory mechanism remain poorly understood. In this study, we constructed RNA-seq libraries of pear treated with calyx excision to explore underlying regulatory mechanisms. At the early stage of the calyx excision treatment, the numbers of differentially expressed genes (DEGs) between each comparison group were relatively high and gradually decreased along with fruit development. The expression pattern of the DEGs ranked in the top 30 of the six groups had obvious divergence, and DEGs were mainly distributed in the “after calyx excision treatment (0 days)” (AC0d) and AC2d groups. The DEGs were mainly enriched in plant hormone signal transduction and plant defense response. We identified 17 candidate genes related to fruit shape and tested their expression patterns along with fruit development. Among them, nine candidate genes expression trends were consistent with fragments per kilobase of exon model per million mapped fragment (FPKM) values, including MYB62, outer envelope pore protein 62 (OEP62), auxin response factor 3 (ARF3), auxin-responsive protein 50 (SAUR50), protein phosphatase 2C 51 (PP2C 51), major allergen Pyr c 1 (PYRC1), aquaporin TIP1-3 (TIP1-3), transcription factor TGA4 (TGA4) and auxin-responsive protein 17 (IAA17). And then, weighted gene co-expression network analysis (WGCNA) analysis revealed that the OVATE family protein (OFP) and SUN domain-containing protein (SUN) were divided into the MEblue model, which had a positive correlation with calyx excision treatment, and the expression trend of LOC103960706 (OFP8) appeared cohesive with FPKM values. Pbr014104.1 and Pbr016952.1, which were the ortholog genes of LOC103960706, were further identified from the pear genome, and were found to be highly expressed in pear fruit through RT-PCR analysis. Taken together, the key stage determining the development of fruit shape was in the early stage after calyx excision treatment, and fruit shape regulation and development were co-regulated by multiple genes.

The reduction of chemical fertilizers is a management practice gradually being adopted in long-term fertilized soils. However, the effects of chemical fertilizer reduction on soil health have remained underexplored in orchard systems. Through a two-year field experiment, we investigated how the reduction of chemical fertilizers affects soil chemical properties, the soil quality index (SQI), and fruit yield and quality. The results indicated that chemical fertilizer reduction significantly increased soil pH and organic matter, while it decreased the available nitrogen and phosphorus contents in 2022 and 2023. The reduction of chemical P fertilizer enhanced the availability of Si, S, Mn, and Cu, while it had no impact on the availability of Mo, Fe, and B. Chemical fertilization reduction did not decrease fruit yield and quality, except for the 1/3N treatment. Moreover, the SQI for the N and 2/3N treatments was higher. The random forest model demonstrated that SQI and soil pH were the most important driving factors regulating fruit yield in response to chemical fertilizer reduction practices. Our study suggests that the appropriate reduction of chemical fertilizers can enhance SQI and the availability of micronutrients without decreasing fruit yield and quality, which may have direct implications for soil health.