**5. Organic Compounds in Vegetables and Its Interaction with Environment**

Flavonoids and volatile organic compounds act as important roles in the growth and developmental processes of vegetable crops, including the attraction of insect pollination, the inhibition of plants diseases and improvement in weed control.

In broccoli, anthocyanins contribute to the purple color and act as health-promoting antioxidants. Liu et al. identified major loci and candidate genes responsible for anthocyanin biosynthesis in broccoli [14]. Two QTLs on chromosomes 7 were identified to be tightly correlated with anthocyanin biosynthesis based on QTL-seq bulk segregant analysis. Further high-resolution mapping identified 14 candidate genes, providing a potential molecular marker into the breeding of novel varieties with abundant anthocyanins.

Volatile organic compounds released from plants are related to the allelopathy phenomenon, a chemical relationship of plant interaction. Xie et al. reviewed the recent advances in the allelopathy of volatile organic compounds (VOCs) of plants [15]. VOCs

had multiple allelopathic effects on plants, such as enzyme activity, dormancy, diseases resistance, ROS scavenging, plant-to-plant communication, and other aspects [15]. The research suggested that the allelopathy of VOCs can be utilized in the development of economical and effective measures for sustainable agriculture [15].

With germplasm evaluation, gene isolation, and marker development, both scientists and breeders are working closely to generate more efficient breeding technology, e.g., gene editing, and to produce more elite cultivars. With emerging substantial genomic data and tools, further collaboration is worthwhile for next-generation breeding technology, e.g., genome-based breeding by design, to generate green, environmentally adaptive vegetable cultivars with high yield and quality.

**Funding:** In doing this work, the authors were sponsored by grants from the the National Key Research and Development Plan (2021YFD1200201; 2018YFD1000800); National Natural Science Foundation of China (31972426; 31991182); the Wuhan Biological Breeding Major Project (2022021302024852); the International Cooperation Promotion Plan of Shihezi University (GJHZ202104); the Key Project of Hubei Hongshan Laboratory (2021hszd007); and the Fundamental Research Funds for the Central Universities (2662022YLPY001).

**Acknowledgments:** We gratefully acknowledge all the authors that participated in this Special Issue.

**Conflicts of Interest:** The authors declare no conflict of interest.

## **References**

