Differential Sources of Resistance from Against Three Races of pathovar (Brown, 1918) Morinière et al. 2020 Causing Bacterial Leaf Spot of Lettuce.

Bacterial leaf spot (BLS) of lettuce ( L.) is caused by the bacterium pv. which is hypothesized to have at least three races of the pathogen present in North America as defined by their differential resistance phenotypes in lettuce cultivars/accessions.

Mapping and identification of genetic loci affecting earliness of bolting and flowering in lettuce.

Photoperiod and temperature conditions elicit different genetic regulation over lettuce bolting and flowering. This study identifies environment-specific QTLs and putative genes and provides information for genetic marker assay. Bolting, defined as stem elongation, marks the plant life cycle transition from vegetative to reproductive stage.

Genetics of Partial Resistance Against Race 2 in Wild and Cultivated Lettuce.

Lettuce () is one of the most economically important vegetables in the United States, with approximately 50% of the domestic production concentrated in the Salinas Valley of California. Verticillium wilt, caused by races 1 and 2 of the fungal pathogen , poses a major threat to lettuce production in this area. Although resistance governed by a single dominant gene against race 1 has previously been identified and is currently being incorporated into commercial cultivars, identification of resistance against race 2 has been challenging and no lines with complete resistance have been identified.

Genome-wide association mapping reveals loci for shelf life and developmental rate of lettuce.

Two major QTL, one for shelf life that corresponds to qSL4 and one, qDEV7, for developmental rate, were identified. Associated markers will be useful in breeding for improved fresh-cut lettuce. Fresh-cut lettuce in packaged salad can have short shelf life, and visible deterioration may start within a week after processing.

The genetics of resistance to lettuce drop (Sclerotinia spp.) in lettuce in a recombinant inbred line population from Reine des Glaces × Eruption.

Two QTLs for resistance to lettuce drop, qLDR1.1 and qLDR5.1, were identified.

Harvest of Lettuce from Verticillium-Infested Fields Has Little Impact on Postharvest Quality.

Verticillium wilt of lettuce, caused by the soilborne pathogen Verticillium dahliae, poses a serious threat to the California lettuce industry. Knowledge of disease development and its impact on postharvest marketability would facilitate better management of the affected fields. This study investigated postharvest marketability of 22 lettuce varieties harvested from two Verticillium-infested commercial lettuce fields in Salinas and Watsonville, CA, in 2005 using a randomized complete block design.

Accuracy, reliability, and timing of visual evaluations of decay in fresh-cut lettuce.

Visual assessments are used for evaluating the quality of food products, such as fresh-cut lettuce packaged in bags with modified atmosphere. We have compared the accuracy and the reliability of visual evaluations of decay on fresh-cut lettuce performed with experienced and inexperienced raters. In addition, we have analyzed decay data from over 4.

Molecular markers reliably predict post-harvest deterioration of fresh-cut lettuce in modified atmosphere packaging.

Fresh-cut lettuce is popular, but highly perishable product. Genetic studies of two bi-parental populations derived from crossing parents with rapid and slow rates of deterioration showed that the deterioration rate is a heritable trait (broad spectrum heritability, of 0.56-0.

Short-Term Host Selection Pressure Has Little Effect on the Evolution of a Monoclonal Population of Verticillium dahliae Race 1.

Understanding pathogen evolution over time is vital for plant breeding and deployment of host resistance. In the context of a soilborne pathogen, the potential of host-directed evolution of a Verticillium dahliae race 1 isolate and genotypic variation of V. dahliae associated with two major hosts (lettuce and tomato) were determined.

Non-destructive Phenotyping of Lettuce Plants in Early Stages of Development with Optical Sensors.

Rapid development of plants is important for the production of 'baby-leaf' lettuce that is harvested when plants reach the four- to eight-leaf stage of growth. However, environmental factors, such as high or low temperature, or elevated concentrations of salt, inhibit lettuce growth. Therefore, non-destructive evaluations of plants can provide valuable information to breeders and growers.

Comparing the Predictive Abilities of Phenotypic and Marker-Assisted Selection Methods in a Biparental Lettuce Population.

Breeding for traits with polygenic inheritance is a challenging task that can be done by phenotypic selection, marker-assisted selection (MAS) or genome-wide selection. We comparatively evaluated the predictive abilities of four selection models on a biparental lettuce ( L.) population genotyped with 95 single nucleotide polymorphisms and 205 amplified fragment length polymorphism markers.

Nondefoliating and Defoliating Strains from Cotton Correlate with Races 1 and 2 of Verticillium dahliae.

Verticillium wilt, caused by Verticillium dahliae, is an important disease of cotton worldwide. Isolates of V. dahliae can be characterized as race 1 or race 2 based on the responses of differential cultivars of tomato and lettuce, or as defoliating or nondefoliating based on symptom expression in cotton.

Screening of Wild and Cultivated Capsicum Germplasm Reveals New Sources of Verticillium Wilt Resistance.

Verticillium wilt caused by Verticillium dahliae is an important soilborne disease of pepper (Capsicum species) worldwide. Most commercial pepper cultivars lack resistance to this pathogen. Our objective was to identify resistance to two V.

Host Range of Verticillium isaacii and Verticillium klebahnii from Artichoke, Spinach, and Lettuce.

Verticillium is a genus that includes major vascular wilt pathogens. Recently, multilocus phylogenetic analyses of the genus identified five new species, including Verticillium isaacii and V. klebahnii, both of which occur in agricultural soils in coastal California and have been isolated from asymptomatic and diseased spinach and lettuce plants.

Resistance to Downy Mildew in Lettuce 'La Brillante' is Conferred by Dm50 Gene and Multiple QTL.

Many cultivars of lettuce (Lactuca sativa L.) are susceptible to downy mildew, a nearly globally ubiquitous disease caused by Bremia lactucae. We previously determined that Batavia type cultivar 'La Brillante' has a high level of field resistance to the disease in California.

Dynamics of verticillium species microsclerotia in field soils in response to fumigation, cropping patterns, and flooding.

Verticillium dahliae is a soilborne, economically significant fungal plant pathogen that persists in the soil for up to 14 years as melanized microsclerotia (ms). Similarly, V. longisporum is a very significant production constraint on members of the family Brassicaceae.

The Three Lineages of the Diploid Hybrid Verticillium longisporum Differ in Virulence and Pathogenicity.

Verticillium longisporum is an economically important vascular pathogen of Brassicaceae crops in different parts of the world. V. longisporum is a diploid hybrid that consists of three different lineages, each of which originated from a separate hybridization event between two different sets of parental species.

Host Genotype and Hypersensitive Reaction Influence Population Levels of Xanthomonas campestris pv. vitians in Lettuce.

Dynamics of population sizes of Xanthomonas campestris pv. vitians inoculated onto or into lettuce leaves were monitored on susceptible and resistant cultivars. In general, population growth was greater for susceptible (Clemente, Salinas 88, Vista Verde) than resistant (Batavia Reine des Glaces, Iceberg, Little Gem) cultivars.

The inheritance of resistance to bacterial leaf spot of lettuce caused by Xanthomonas campestris pv. vitians in three lettuce cultivars.

Lettuce yields can be reduced by the disease bacterial leaf spot (BLS) caused by the pathogen Xanthomonas campestris pv. vitians (Xcv) and host resistance is the most feasible method to reduce disease losses. The cultivars La Brillante, Pavane and Little Gem express an incompatible host-pathogen interaction as a hypersensitive response (HR) to California strains of Xcv resulting in resistance.

A real-time PCR assay for detection and quantification of Verticillium dahliae in spinach seed.

Verticillium dahliae is a soilborne fungus that causes Verticillium wilt on multiple crops in central coastal California. Although spinach crops grown in this region for fresh and processing commercial production do not display Verticillium wilt symptoms, spinach seeds produced in the United States or Europe are commonly infected with V. dahliae.

Comparative genomics yields insights into niche adaptation of plant vascular wilt pathogens.

The vascular wilt fungi Verticillium dahliae and V. albo-atrum infect over 200 plant species, causing billions of dollars in annual crop losses. The characteristic wilt symptoms are a result of colonization and proliferation of the pathogens in the xylem vessels, which undergo fluctuations in osmolarity.

The inheritance of resistance to Verticillium wilt caused by race 1 isolates of Verticillium dahliae in the lettuce cultivar La Brillante.

Verticillium wilt of lettuce caused by Verticillium dahliae can cause severe economic damage to lettuce producers. Complete resistance to race 1 isolates is available in Lactuca sativa cultivar (cv.) La Brillante and understanding the genetic basis of this resistance will aid development of new resistant cultivars.

Selenium accumulation in lettuce germplasm.

Selenium (Se) is an essential micronutrient for animals and humans. Increasing Se content in food crops offers an effective approach to reduce the widespread selenium deficiency problem in many parts of the world. In this study, we evaluated 30 diverse accessions of lettuce (Lactuca sativa L.

Population analyses of the vascular plant pathogen Verticillium dahliae detect recombination and transcontinental gene flow.

The fungal pathogen Verticillium dahliae has resulted in significant losses in numerous crops in coastal California, but lettuce remained unaffected until the mid-1990s. Since then outbreaks have decimated entire fields, but the causes of this sudden susceptibility of lettuce remain elusive. The population structure of V.