A single recessive gene conferring short leaves in romaine × Latin type lettuce (Lactuca sativa L.) crosses, and its effect on plant morphology and resistance to lettuce drop caused by Sclerotinia minor Jagger

Abstract

Understanding the relationship between plant morphology and disease resistance is crucial to successful lettuce breeding. Latin type cultivars are a potential useful source of resistance to Sclerotinia minor for breeding resistant romaine cultivars. However, resistance in Latin cultivars may be conditioned by their relatively short stature. The objective of this research was to determine the segregation for plant height and the relationship between plant height and S. minor resistance in romaine · Latin crosses. The frequency of short plants was conditioned by a single recessive gene in F 1 , F 2 and F 3 families from nine romaine · Latin crosses tested in 2007, 2008 and 2009 field experiments. The gene, named short leaf 1 (sl1), affects only leaf length in rosette plants and is morphologically distinct from other dwarfing genes. In two S. minor-infested field experiments with 75 F 3 romaine · ÔEruptionÕ families, no difference in disease incidence was detected between short (sl1sl1), tall (Sl1Sl1) or segregating families. Therefore, development of resistant romaine cultivars from crosses with ÔEruptionÕ is feasible.

Breeding Lettuce for Resistance against Sclerotinia minor

“…'Eruption' had a significantly lower DR than 'Hearts Delight' and 'Darkland' in all experiments, except in Summer 2012 and Fall 2010, when some comparisons were not significantly different. This further substantiates the high levels of resistance reported previously for 'Eruption' (Hayes et al 2010(Hayes et al , 2011Mamo et al 2019Mamo et al , 2021. Families from 'Darkland' × 'Eruption' and 'Hearts Delight' × 'Eruption' had DRs that were generally intermediate between 'Eruption' and their susceptible parent, which demonstrates that the use of 'Eruption' as a parent can result in germplasm with improved lettuce drop resistance.…”

“…Rapid bolting in particular is commonly cited as a plant trait that may condition lettuce drop resistance (Grube 2004;Hayes et al 2010;Mamo et al 2019Mamo et al , 2021Pink et al 2022). Among slow-bolting cultivars, the smallstature dark-red cultivar Eruption expressed a high level of partial resistance that did not appear to be associated with plant morphology or bolting (Hayes et al 2010(Hayes et al , 2011. Genetic analysis of a recombinant inbred line population derived from a cross between the susceptible cultivar Reine des Glaces and 'Eruption' detected four quantitative trait loci (QTLs) (Mamo et al 2019).…”

“…This is a result of the ability to select for desirable horticultural traits effectively, many of which are simply inherited, from early-generation material in field experiments. For example, the short stature of 'Eruption' was found to be conditioned by a single recessive locus (Hayes et al 2011). Selection through the F 2:3 generation in 'Eruption' × romaine crosses was sufficient to produce lines with a basic romaine architecture.…”

Baby Leaf Lettuce Germplasm Enhancement: Developing Diverse Populations with Resistance to Bacterial Leaf Spot Caused by Xanthomonas campestris pv. vitians

“…1600187>) is a dark red-colored cultivar developed by the seed company Enza Zaden B.V. for use in commercial baby leaf production. 'Eruption' carries the short leaf 1 (sl1) gene, which confers a diminutive stature to 'Eruption' that is architecturally similar to many Latin-type cultivars (Hayes et al, 2011a). Progeny from intertype crosses with 'Eruption' that do not inherit sl1 can have a romaine-type architecture.…”