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ARS Home » Pacific West Area » Salinas, California » Crop Improvement and Protection Research » Research » Publications at this Location » Publication #402819
Research Project: Genetics and Breeding of Lettuce, Spinach, Melon, and Related Species to Improve Production and Consumer-related Traits

Location: Crop Improvement and Protection Research

Title: QTL mapping and transcriptome analysis of seed germination under PEG-induced water stress in Lactuca spp.

Author
item Hwang, Sadal
item Simko, Ivan
item Mou, Beiquan

Submitted to: Scientific Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/28/2024
Publication Date: 11/7/2024
Citation: Hwang, S., Simko, I., Mou, B. 2024. QTL mapping and transcriptome analysis of seed germination under PEG-induced water stress in Lactuca spp. Scientific Reports. 14. Article 27157. https://doi.org/10.1038/s41598-024-77972-9.
DOI: https://doi.org/10.1038/s41598-024-77972-9

Interpretive Summary: Germination is a complex process requiring enough water in optimized environmental conditions. Even mild water stress considerably reduced the germination rate of lettuce varieties by 50%. A cultivar, Salinas, and a wild lettuce (prickly lettuce) were selected to make crosses and conduct genetic analyses in order to find genes controlling germination. The wild lettuce was more sensitive to drought than Salinas. Two genes for seed germination were detected on chromosomes 4 and 8 under mild drought conditions. The germination performance of two lettuce varieties were further evaluated in the soil. More research using controlled and field conditions will be necessary to determine which variety can germinate more effectively under drought conditions. Moreover, the RNA-sequencing analysis will provide profound information on how this type of wild lettuce is sensitive to water stress.

Technical Abstract: The significant effect of limited water availability on lettuce growth is well documented, but the mechanisms by which lettuce controls seed germination in response to water stress are currently unknown. To simulate water stress conditions, seed germination was evaluated at 10% polyethylene glycol (PEG) in two populations: cv. Salinas (L. sativa) × US96UC23 (L. serriola) recombinant inbred line (RIL) and USDA germplasm collection. More than half of both populations displayed less than 90% germination. The average broad-sense heritability (H2) for germination percentage was 0.81 across the populations. Two quantitative trait loci (QTL) on chromosomes 4 and 8 were identified in the RIL population. The wild lettuce, US96UC23, was used for RNA-Seq and network analyses comparing the control (distilled water, dH2O) and treatment (10% PEG) data. In total, 4,095 genes were differentially expressed. The top 20 gene ontology (GO) terms and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways were assessed by enrichment analysis. The consensus network analysis captured 44 modules. The top 20 gene networks in 10 significant modules were constructed to identify hub genes in each data. This study comprehensively explains QTL, GO terms, pathways, and gene networks associated with lettuce seed germination. The findings could be utilized for selection and genetics studies.