Bell Pepper Breeding for Phytophthora Resistance

Introduction

Disease resistance, enhanced fruit quality, and improved horticultural traits are traits that pepper growers look for. Pepper production is often limited by different diseases that reduce yield and fruit quality each year. Among these diseases, Phytophthora capsica (PCAP), known as crown and fruit rot, is a major threat to pepper production in Georgia.

Current pepper varieties possess PCAP resistance against some pathogen biotypes/races, but new races are evolving, and a lack of resistance seems to cause significant economic losses. Hence, having genetic resistance could increase profitability and sustainability.

A comprehensive research strategy was created in the University of Georgia vegetable breeding program to meet the needs of bell pepper growers. To achieve the breeding goals, we requested funding support for identifying potential resistant gene sources against PCAP and evaluating the pepper collection for horticultural traits so that identified resistant sources are utilized in the vegetable breeding program’s pre-breeding efforts.

Material and Methods

The pepper breeding research was conducted on the UGA Tifton campus field, greenhouse, and vegetable breeding laboratory.

Germplasm

To spearhead pepper breeding efforts, we utilized crop wild relatives (CWR), PI accessions, and breeding lines of peppers, and we acquired relevant germplasm from the public gene banks and other collaborators from Europe and Asia. Pepper breeding research was envisioned based on the disease screening evaluation to identify resistance sources to make specific breeding crosses to develop breeding material that likely possesses resistance against Phytophthora.

Acquired germplasm was grown in the UGA-Tifton Vegetable Park (TVP) field and was evaluated for horticultural traits while we increased the seeds of each cultivar. Evaluated horticultural traits were lodging, plant architecture, fruit shape, color, flowering, and maturity. During this field evaluation and increase in seeds, specific accessions (cultivars) were identified based on the preferences of our pepper growers.

Results

The vegetable breeding program progressed in facilitating the necessary steps to establish the new breeding program. Major steps of germplasm acquisition, seed increase, and preliminary data collection were achieved to pursue the envisioned pre-breeding and breeding research goals.

Trait Characterization

While increasing seeds in the greenhouse and field, we also utilized the opportunity to evaluate pepper germplasm and collect preliminary data on fruit set, flowering, lodging, plant architecture, and disease resistance (Figure 1).

Based on the 2024 evaluation and available information about the acquired breeding material, we selected 20 accessions that are likely useful in our breeding efforts to develop Phytophthora-resistant lines and cultivars (Table 1). These accessions have been included in subsequent disease screening to evaluate if they possess resistance against Phytophthora and other economically important diseases. These accessions have been included in our pre-breeding and breeding efforts to develop potential Phytophthora-resistant breeding cultivars.

Conclusion

Funding from the Georgia Agricultural Commodity Commission for Vegetables (GACCV) was very resourceful to support our proposed work to evaluate the pepper collection to identify potential resistance sources while we increase the seeds for downstream breeding research.

With this research, we were able to identify relevant pepper accessions that are likely suitable for our pepper growers’ preferences in terms of horticultural traits and potential PCAP resistance that we are including in our breeding efforts.