Leafy head is a unique type of plant architecture found in some vegetable crops, with leaves bending inward to form a compact head. The genetic and molecular mechanisms underlying leafy head in vegetables remain poorly understood. We genetically fine-mapped and cloned a major quantitative trait locus controlling heading in lettuce. The candidate gene (LsKN1) is a homolog of knotted 1 (KN1) from Zea mays. Complementation and CRISPR/Cas9 knockout experiments confirmed the role of LsKN1 in heading. In heading lettuce, there is a CACTA-like transposon inserted into the first exon of LsKN1 (LsKN1▽). The transposon sequences act as a promoter rather than an enhancer and drive high expression of LsKN1▽. The enhanced expression of LsKN1▽ is necessary but not sufficient for heading in lettuce. Data from ChIP-sequencing, electrophoretic mobility shift assays, and dual luciferase assays indicate that the LsKN1▽ protein binds the promoter of LsAS1 and down-regulates its expression to alter leaf dorsoventrality. This study provides insight into plant leaf development and will be useful for studies on heading in other vegetable crops.

Plants undergo profound physiological changes when transitioning from vegetative to reproductive growth. These changes affect crop production, as in the case of leafy vegetables. Lettuce is one of the most valuable leafy vegetable crops in the world. Past genetic studies have identified multiple quantitative trait loci (QTLs) that affect the timing of the floral transition in lettuce. Extensive functional molecular studies in the model organism Arabidopsis provide the opportunity to transfer knowledge to lettuce to explore the mechanisms through which genetic variations translate into changes in flowering time. In this review, we integrated results from past genetic and molecular studies for flowering time in lettuce with orthology and functional inference from Arabidopsis. This summarizes the basis for all known genetic variation underlying the phenotypic diversity of flowering time in lettuce and how the genetics of flowering time in lettuce projects onto the established pathways controlling flowering time in plants. This comprehensive overview reveals patterns across experiments as well as areas in need of further study. Our review also represents a resource for developing cultivars with delayed flowering time.

Flower opening and closure are traits of reproductive importance in all angiosperms because they determine the success of self- and cross-pollination. The temporal nature of this phenotype rendered it a difficult target for genetic studies. Cultivated and wild lettuce, Lactuca spp., have composite inflorescences comprised of multiple florets that open only once. Different accessions were observed to flower at different times of day. An F6 recombinant inbred line population (RIL) had been derived from accessions of L. serriola x L. sativa that originated from different environments and differed markedly for daily floral opening time. This population was used to map the genetic determinants of this trait; the floral opening time of 236 RILs was scored over a seven-hour period using time-course image series obtained by drone-based remote phenotyping on two occasions, one week apart. Floral pixels were identified from the images using a support vector machine (SVM) machine learning algorithm with an accuracy above 99%. A Bayesian inference method was developed to extract the peak floral opening time for individual genotypes from the time-stamped image data. Two independent QTLs, qDFO2.1 (Daily Floral Opening 2.1) and qDFO8.1, were discovered. Together, they explained more than 30% of the phenotypic variation in floral opening time. Candidate genes with non-synonymous polymorphisms in coding sequences were identified within the QTLs. This study demonstrates the power of combining remote imaging, machine learning, Bayesian statistics, and genome-wide marker data for studying the genetics of recalcitrant phenotypes such as floral opening time.One sentence summaryMachine learning and Bayesian analyses of drone-mediated remote phenotyping data revealed two genetic loci regulating differential daily flowering time in lettuce (Lactuca spp.).

The earliest account of Acinetobacter species dates back to 1911 when Beijerinck described an organism isolated from soil, originally named Micrococcus calcoaceticus [1]. The current genus designation was initially proposed by Brisou and Prévot in 1954, based on motility [2]. In 1968, a comprehensive survey completed by Baumann et al. provided sufficient data for a group species previously classified to at least 15 different genera and species and reclassified them to a single genus, for which the name Acinetobacter was proposed [2]. Currently, the genus Acinetobacter, which belongs to the class Gammaproteobacteria, is composed of 63 species with validly published names according to List of Prokaryotic names with Standing in Nomenclature, with Acinetobacter calcoaceticus as the type species (http://www.bacterio.net/acinetobacter.html; last accessed November 2019) and A. baumannii being the most clinically significant species, implicated in both nosocomial and community-derived infections [1]. This highly complex genus is widely distributed in soil, water, and animals, with members often associated with nosocomial infections-primarily aspiration pneumonia and catheter-associated bacteremia-as well as urinary tract infections [3]. The members are characteristically Gram-negative, oxidase-negative, strictly aerobic, and non-fermenting coccobacillus cells that occur in pairs under magnification [4] and exhibit twitching motility [5]. Typically, the DNA G+C content of Acinetobacter spp. is in the range of 34.9-47.0% [2, 6]. The major cellular fatty acids are typically C 18:1ω9c and C 16:0 [7], and the predominant polar lipid is phosphatidylethanolamine [8]. The major respiratory quinone is ubiquinone Q-9 [9]. In this study, we applied a polyphasic taxonomy approach to characterize and identify an isolate from raw chicken meat and proposed it as a novel species with the name Acinetobacter pullorum B301 T. Materials and Methods Bacterial Strains Strain B301 T was isolated from raw chicken meat obtained from a local market (Korea). Meat samples were homogenized in 225 ml of Dijkshoorn enrichment medium [10] in a stomacher for 2 min and incubated in a A bacterial strain, designated B301 T and isolated from raw chicken meat obtained from a local market in Korea, was characterized and identified using a polyphasic taxonomic approach. Cells were gram-negative, non-motile, obligate-aerobic coccobacilli that were catalase-positive and oxidase-negative. The optimum growth conditions were 30°C, pH 7.0, and 0% NaCl in tryptic soy broth. Colonies were round, convex, smooth, and cream-colored on tryptic soy agar. Strain B301 T has a genome size of 3,102,684 bp, with 2,840 protein-coding genes and 102 RNA genes. The 16S rRNA gene analysis revealed that strain B301 T belongs to the genus Acinetobacter and shares highest sequence similarity (97.12%) with A. celticus ANC 4603 T and A. sichuanensis WCHAc060041 T. The average nucleotide identity and digital DNA-DNA hybridization values for closely related species were below the cutoff va...

Cyclophilins (CYPs), a highly-conserved family of proteins, belong to a subgroup of immunophilins. Ubiquitous in eukaryotes and prokaryotes, CYPs have peptidyl-prolyl cis–trans isomerase (PPIase) activity and have been implicated as virulence factors in plant pathogenesis by oomycetes. We identified 16 CYP orthogroups from 21 diverse oomycetes. Each species was found to encode 15 to 35 CYP genes. Three of these orthogroups contained proteins with signal peptides at the N-terminal end, suggesting a role in secretion. Multidomain analysis revealed five conserved motifs of the CYP domain of oomycetes shared with other eukaryotic PPIases. Expression analysis of CYP proteins in different asexual life stages of the hemibiotrophic Phytophthora infestans and the biotrophic Plasmopara halstedii demonstrated distinct expression profiles between life stages. In addition to providing detailed comparative information on the CYPs in multiple oomycetes, this study identified candidate CYP effectors that could be the foundation for future studies of virulence.