Identification of genetic loci in lettuce mediating quantitative resistance to fungal pathogens

Abstract

Key message We demonstrate genetic variation for quantitative resistance against important fungal pathogens in lettuce and its wild relatives, map loci conferring resistance and predict key molecular mechanisms using transcriptome profiling. Abstract Lactuca sativa L. (lettuce) is an important leafy vegetable crop grown and consumed globally. Chemicals are routinely used to control major pathogens, including the causal agents of grey mould (Botrytis cinerea) and lettuce drop (Sclerotinia sclerotiorum). With increasing prevalence of pathogen resistance to fungicides and environmental concerns, there is an urgent need to identify sources of genetic resistance to B. cinerea and S. sclerotiorum in lettuce. We demonstrated genetic variation for quantitative resistance to B. cinerea and S. sclerotiorum in a set of 97 diverse lettuce and wild relative accessions, and between the parents of lettuce mapping populations. Transcriptome profiling across multiple lettuce accessions enabled us to identify genes with expression correlated with resistance, predicting the importance of post-transcriptional gene regulation in the lettuce defence response. We identified five genetic loci influencing quantitative resistance in a F6 mapping population derived from a Lactuca serriola (wild relative) × lettuce cross, which each explained 5–10% of the variation. Differential gene expression analysis between the parent lines, and integration of data on correlation of gene expression and resistance in the diversity set, highlighted potential causal genes underlying the quantitative trait loci.

Leaf abaxial and adaxial surfaces differentially affect plant-fungal pathogen interactions

“…This generalist fungal pathogen is an endemic pathogen that infects more than a thousand plant species (Fillinger & Elad, 2016; Singh et al ., 2023). Potentiating Botrytis’ role as one of the top yield loss pathogens (Dean et al ., 2012), is the polygenic genetic architectures of both Botrytis’ virulence and the hosts’ resistance that influences a wide variety of specific mechanisms (Corwin & Kliebenstein, 2017; Pink et al ., 2022). Botrytis penetration of the host’s cells can be opportunistic through stomata and wounds or rely on turgor pressure and physical force via the infection cushion to rupture the cuticle and cell wall.…”

The complete genome of lettuce reveals centromere landscape and empowers breeding

“…Augustana ) (Shen et al, 2023). Although these assemblies have greatly facilitated lettuce research (Gao et al, 2022; Pink et al, 2022; Shen et al, 2023; Wei et al, 2021), they remain highly fragmented and incomplete, containing hundreds of gaps and omitting centromeres, rDNA and telomeres, and thus creating a bottleneck to genomic research, gene cloning and molecular breeding.…”

Polygenic pathogen networks control of host and pathogen transcriptional plasticity in the Arabidopsis-Botrytis pathosystem

“…In contrast to qualitative systems, most plant-pathogen interactions are not guided by large-effect loci. For example, plant interactions with generalist necrotrophic pathogens like Botrytis cinerea and Sclerotinia sclerotiorum are shaped by a myriad of moderate to small effect loci (Caseys et al 2021;Pink et al 2022;Derbyshire et al 2022). Thus, it remains unclear if the changes noted in large-effect co-transcriptome studies are transposable to a system in which numerous signals are varying in both the host and pathogen.…”

“…For example, plant interactions with generalist necrotrophic pathogens like Botrytis cinerea and Sclerotinia sclerotiorum are shaped by a myriad of moderate to small effect loci (Caseys et al . 2021; Pink et al . 2022; Derbyshire et al .…”