Research Project: Genetic Improvement of Lettuce, Spinach, Celery, Melon, and Related Species

Location: Crop Improvement and Protection Research

Publications (Clicking on the reprint icon will take you to the publication reprint.)

Unraveling the variation, phylogeny, and taxonomy of lactuca spp. for germplasm management and breeding - (Peer Reviewed Journal)
Lebeda, A., Majesky, L., Kristkova, E., Pink, D., Simko, I. 2025. Unraveling the variation, phylogeny, and taxonomy of lactuca spp. for germplasm management and breeding. Planta. 262. Article 148. https://doi.org/10.1007/s00425-025-04851-6.

A major and stable QTL confers impatiens necrotic spot virus resistance in lettuce cv. Eruption - (Peer Reviewed Journal)
Nayak, S., Richardson, K.L., Eriksen, R.L., Hasegawa, D.K., Wintermantel, W.M., Sapkota, M., Tang, X., Chen, S., Lin, M., Zhao, D., Beil, C.T., Sheehan, M.J., Simko, I. 2025. A major and stable QTL confers impatiens necrotic spot virus resistance in lettuce cv. Eruption. Theoretical and Applied Genetics. 138. Article 312. https://doi.org/10.1007/s00122-025-05058-9.

Agricultural irrigation using treated wastewater: Challenges and opportunities - (Peer Reviewed Journal)
Obijianya, C.C., Yakamercan, E., Karimi, M., Veluru, S., Simko, I., Eshkabilov, S., Simsek, H. 2025. Agricultural irrigation using treated wastewater: Challenges and opportunities. Water. 17(14). Article 2083. https://doi.org/10.3390/w17142083.

Breeding lettuce for biotic and physiological stress resilience and extended shelf-life - (Abstract Only)
Simko, I. 2025. Breeding lettuce for biotic and physiological stress resilience and extended shelf-life. Joint California Leafy Greens Research Board & Seed Central Event, June 26, 2025, Salinas, California.

Differential impact of SiO2 foliar application on lettuce response to temperature, salinity, and drought stress - (Peer Reviewed Journal)
Simko, I., Zhao, R.B., Peng, H. 2025. Differential impact of SiO2 foliar application on lettuce response to temperature, salinity, and drought stress. Plants. 14(12). Article 1845. https://doi.org/10.3390/plants14121845.

Genome-wide association study for drought tolerance in cowpea (Vigna unguiculata (L.) Walp.) at seedling stage using a whole genome resequencing approach - (Peer Reviewed Journal)
Ravelombola, W., Xiong, H., Bhattarai, G., Manley, A., Cason, J., Pham, H., Zia, B., Mou, B., Shi, A. 2025. Genome-wide association study for drought tolerance in cowpea (Vigna unguiculata (L.) Walp.) at seedling stage using a whole genome resequencing approach. International Journal of Molecular Sciences. 26(12). Article 5478. https://doi.org/10.3390/ijms26125478.

Integrative path modeling and QTL mapping identify maturity, stem strength, and cell wall composition driving lettuce resistance to Sclerotinia minor - (Peer Reviewed Journal)
Simko, I., Mamo, B., Cantu, S.L., Peng, H., Grube Sideman, R., Hayes, R.J., Subbarao, K.V. 2025. Integrative path modeling and QTL mapping identify maturity, stem strength, and cell wall composition driving lettuce resistance to Sclerotinia minor. Scientific Reports. 15. Article 19824. https://doi.org/10.1038/s41598-025-03775-1.

Enhancing nutrient content estimation in lettuces using hyperspectral image data and artificial neural networks with feature selection methods - (Proceedings)
Eshkabilov, S., Simko, I., Neha, F., Pranto, M.A., Simsek, H. 2025. Enhancing nutrient content estimation in lettuces using hyperspectral image data and artificial neural networks with feature selection methods. In: Kahraman, C., Cebi, S., Oztaysi, B., Onar, S.C., Tolga, C., Sari, I.U., Otay, I., editors. Artificial Intelligence in Human-Centric, Resilient and Sustainable Industries, Proceedings of the INFUS 2025 Conference, Volume 2. International Conference on Intelligent and Fuzzy Systems, July 29-31, 2025, Istanbul, Turkey. p. 234–242. https://doi.org/10.1007/978-3-031-97992-7_27.

Differential low oxygen response and transcriptomic shifts drive fresh-cut lettuce deterioration in modified atmosphere packaging - (Peer Reviewed Journal)
Peng, H., Lavelle, D.O., Truco, M., Michelmore, R.W., Simko, I. 2025. Differential low oxygen response and transcriptomic shifts drive fresh-cut lettuce deterioration in modified atmosphere packaging. Postharvest Biology and Technology. 227. Article 113571. https://doi.org/10.1016/j.postharvbio.2025.113571.

Effects of mesophyll conductance and nitrogen content on carbon assimilation during low-water stress in leaf lettuce cultivars - (Peer Reviewed Journal)
Eriksen, R.L., Kumar, P., Sandoya, G., Adhikari, N.D., Mou, B. 2025. Effects of mesophyll conductance and nitrogen content on carbon assimilation during low-water stress in leaf lettuce cultivars. Horticulturae. 11(4). Article 414. https://doi.org/10.3390/horticulturae11040414.

Insight into postharvest deterioration in fresh-cut lettuce through genetics and physiology - (Abstract Only)
Simko, I. 2025. Insight into postharvest deterioration in fresh-cut lettuce through genetics and physiology. Plant and Animal Genome Conference, January 14, 2025, San Diego, California.

Registration of six lettuce breeding lines with resistance to Fusarium wilt race 1 - (Germplasm Registration)
Richardson, K.L., McCreight, J.D., Nayak, S. 2025. Registration of six lettuce breeding lines with resistance to Fusarium wilt race 1. Journal of Plant Registrations. 19(1). Article e220423. https://doi.org/10.1002/plr2.20423.

Spatio-temporal dynamics of lettuce metabolome: A framework for targeted nutritional quality improvement - (Peer Reviewed Journal)
Simko, I. 2024. Spatio-temporal dynamics of lettuce metabolome: A framework for targeted nutritional quality improvement. Plants. 13(23). Article 3316. https://doi.org/10.3390/plants13233316.

Detection of novel pathogenic variants of Fusarium oxysporum f. sp. lactucae in California - (Peer Reviewed Journal)
Nayak, S., Richardson, K.L., Putman, A., LeBlanc, N.R., Martin, F.N., Li, N., McCreight, J.D. 2024. Detection of novel pathogenic variants of Fusarium oxysporum f. sp. lactucae in California. Plant Pathology. 74(2):295-307. https://doi.org/10.1111/ppa.14019.

Differential sources of resistance from Lactuca serriola against three races of Xanthomonas hortorum pv. vitians causing bacterial leaf spot of lettuce - (Peer Reviewed Journal)
Sandoya, G.V., Trent, M., Hayes, R.J., Lebeda, A., Rosenthal, E., Simko, I., Bull, C.T. 2025. Differential sources of resistance from Lactuca serriola against three races of Xanthomonas hortorum pv. vitians causing bacterial leaf spot of lettuce. Plant Disease. 109(3):615-622. https://doi.org/10.1094/PDIS-06-24-1239-RE.

Genome-wide association study of salt tolerance at the seed germination stage in lettuce - (Peer Reviewed Journal)
Das, M.K., Park, S., Adhikari, N.D., Mou, B. 2024. Genome-wide association study of salt tolerance at the seed germination stage in lettuce. PLoS ONE. 19(10). Article e0308818. https://doi.org/10.1371/journal.pone.0308818.

Host cell wall composition and localized microenvironment implicated in resistance to basal stem degradation by lettuce drop (Sclerotinia minor) - (Peer Reviewed Journal)
Simko, I., Mamo, B.E., Foster, C.E., Adhikari, N.D., Subbarao, K.V. 2024. Host cell wall composition and localized microenvironment implicated in resistance to basal stem degradation by lettuce drop (Sclerotinia minor). BMC Plant Biology. 24. Article 717. https://doi.org/10.1186/s12870-024-05399-5.

Assessing contents of sugars, vitamins, and nutrients in baby leaf lettuce from hyperspectral data with machine learning models - (Peer Reviewed Journal)
Eshkabilov, S., Simko, I. 2024. Assessing contents of sugars, vitamins, and nutrients in baby leaf lettuce from hyperspectral data with machine learning models. Agriculture. 14(6). Article 834. https://doi.org/10.3390/agriculture14060834.

Genetic dissection of diverse seed coat patterns in cowpea through a comprehensive GWAS approach - (Peer Reviewed Journal)
Xiong, H., Chen, Y., Ravelombola, W., Mou, B., Sun, X., Zhang, Q., Xiao, Y., Tian, Y., Luo, Q., Alatawi, I., Chiwina, K.E., Alkabkabi, H.M., Shi, A. 2024. Genetic dissection of diverse seed coat patterns in cowpea through a comprehensive GWAS approach. Plants. 13(9). Article 1275. https://doi.org/10.3390/plants13091275.

Status, gaps and perspectives of powdery mildew resistance research and breeding in cucurbits - (Peer Reviewed Journal)
Lebeda, A., Kristkova, E., Mieslerova, B., Dhillon, N.P.S., McCreight, J.D. 2024. Status, gaps and perspectives of powdery mildew resistance research and breeding in cucurbits. Critical Reviews in Plant Sciences. 43(4):211-290. https://doi.org/10.1080/07352689.2024.2315710.

Evaluation of lettuce germplasm for resistance to impatiens necrotic spot virus - (Peer Reviewed Journal)
Richardson, K.L., Nayak, S., Hasegawa, D.K., Eriksen, R.L. 2024. Evaluation of lettuce germplasm for resistance to impatiens necrotic spot virus. Euphytica. 220. Article 33. https://doi.org/10.1007/s10681-023-03285-z.

Proanthocyanidins: Key for resistance to Globisporangium (formerly Pythium) seed rot of pea - (Peer Reviewed Journal)
Ewing, E.E., Weeden, N.F., Simko, I. 2024. Proanthocyanidins: Key for resistance to Globisporangium (formerly Pythium) seed rot of pea. Journal of the American Society for Horticultural Science. 149(1):37-49. https://doi.org/10.21273/JASHS05340-23.

Phenotypic characterization, plant growth and development, genome methylation, and mineral elements composition of neotetraploid lettuce (Lactuca sativa L.) - (Peer Reviewed Journal)
Simko, I., Zhao, R.B. 2023. Phenotypic characterization, plant growth and development, genome methylation, and mineral elements composition of neotetraploid lettuce (Lactuca sativa L.). Frontiers in Plant Science. 14. Article 1296660. https://doi.org/10.3389/fpls.2023.1296660.

Development and validation of a mid-density DArTag-based genotyping platform for lettuce (Lactuca sativa) - (Abstract Only)
Ling, M., Sapkota, M., Tang, X., Eriksen, R.L., Mou, B., Richardson, K.L., Simko, I., Beil, C., Sheehan, M. 2024. Development and validation of a mid-density DArTag-based genotyping platform for lettuce (Lactuca sativa). Plant and Animal Genome Conference, January 16, 2024, San Diego, California.

Heat-tolerant lettuce germplasm (Lactuca sativa L.) identified in romaine and butterhead types for warmer plantings - (Peer Reviewed Journal)
Sandoya, G., Lafta, A., Mou, B. 2024. Heat-tolerant lettuce germplasm (Lactuca sativa L.) identified in romaine and butterhead types for warmer plantings. HortScience. 59(2):151-163. https://doi.org/10.21273/HORTSCI17368-23.

Phytochemical and agronomic characterization of high-flavonoid lettuce lines grown under field conditions - (Peer Reviewed Journal)
Cho, E., Gurdon, C., Zhao, R.B., Peng, H., Pouley, A., Raskin, I., Simko, I. 2023. Phytochemical and agronomic characterization of high-flavonoid lettuce lines grown under field conditions. Plants. 12(19). Article 3467. https://doi.org/10.3390/plants12193467.

Genetic architecture of salt tolerance in cowpea (Vigna unguiculata (L.) Walp.) at seedling stage using a whole genome resequencing approach - (Peer Reviewed Journal)
Ravelombola, W., Dong, L., Barickman, T.C., Xiong, H., Manley, A., Cason, J., Pham, H., Zia, B., Mou, B., Shi, A. 2023. Genetic architecture of salt tolerance in cowpea (Vigna unguiculata (L.) Walp.) at seedling stage using a whole genome resequencing approach. International Journal of Molecular Sciences. 24(20). Article 15281. https://doi.org/10.3390/ijms242015281.

Breeding lettuce for resistance against Sclerotinia minor - (Peer Reviewed Journal)
Simko, I., Subbarao, K.V., Hayes, R.J. 2023. Breeding lettuce for resistance against Sclerotinia minor. HortScience. 58(12):1526–1532. https://doi.org/10.21273/HORTSCI17399-23.

A genome-wide association study reveals region associated with seed protein content in cowpea - (Peer Reviewed Journal)
Chen, Y., Xiong, H., Ravelombola, W., Bhattarai, G., Barickman, C., Alatawi, I., Phiri, T.M., Chiwina, K., Mou, B., Tallury, S., Shi, A. 2023. A genome-wide association study reveals region associated with seed protein content in cowpea. Plants. 12(14). Article 2705. https://doi.org/10.3390/plants12142705.