Project description:Lettuce (Lactuca sativa L.) is one of the most important leafy vegetable that is consumed during its vegetative growth. The transition from vegetative to reproductive growth is induced by high temperature, which has significant economic effect on lettuce production. However, the progression of floral transition and the molecular regulation of bolting are largely unknown. Here we morphologically characterized the inflorescence development and functionally analyzed the FLOWERING LOCUS T (LsFT) gene during bolting regulation in lettuce. We described the 8 developmental stages during floral transition process. The expression of LsFT was negatively correlated with bolting in different lettuce varieties, and was promoted by heat treatment. Overexpression of LsFT could recover the late-flowering phenotype of ft-2 mutant. Knockdown of LsFT by RNA interference dramatically delayed bolting in lettuce, and failed to respond to high temperature. Therefore, this study dissects the process of inflorescence development and characterizes the role of LsFT in bolting regulation in lettuce.
Project description:The small RNAs and their targets were characterized in lettuce (Lactuca sativa) genome by deep sequencing the small RNA populations of leaf tissues (cv. Salinas, Cobham and Diana), inoculated with Bremia and mock. The small RNA targets were also validated using PARE/degradome data derived from the same tissues.
Project description:UV-B radiation is one of the major environmental stresses that triggers a variety of plant responses. However, limited information is available regarding plant biological reactions which help to circumvent the potentially harmful effects of UV-B radiation in lettuce (Lactuca sativa L.). In this study, RNA-seq was performed to identify differentially expressed genes in response to UV-B radiation.
Project description:The use of new natural eco-sustainable products is becoming an interesting option in order to reduce the use of chemical fertilizers and increase crop yields. Seaweed extracts are gained major attention as plant biostimulants due to their positive effect on plant-growth as well as on improving plants’ tolerance against abiotic stresses. Among the horticulture crops, lettuce (Lactuca sativa L.) is a major fresh vegetable crop in the Mediterranean area, which often requires the use of natural biostimulants to improve both the quantity and quality of production. The aim of this work was to assess the effect of either Chlorella vulgaris or Scenedesmus quadricauda extracts on lettuce seedlings (Lactuca sativa L.) by motoring the induced transcriptomic modifications using a RNASeq approach. The results showed that both C. vulgaris and S. quadricauda extracts positively influence the growth of lettuce seedlings. However, a higher reprogramming of the gene expression occurred in the case of C. vulgaris treatment than in S. quadricauda extract. Considering the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway functional enrichments, the main KEGG terms are in the “Biosynthesis of secondary metabolites”, “Metabolic pathways”, “Carbon metabolism” and “Biosynthesis of amino acids” categories. This study lays the basis for understanding the mechanisms and processes triggered by the use of microalgal extracts, which can represent an easier-to-handle and cheaper method for an eco-sustainable cultivation of lettuce plants than the application of chemicals.
Project description:Verotoxigenic Escherichia coli (VTEC) are a leading cause of food-borne illness. Fruit and vegetables are recognised as an important source of the pathogen and can account for ~ 25 % of food-borne VTEC outbreaks, globally. The ability of VTEC to colonise leaves and roots of leafy vegetables, spinach (Spinacia oleracea) and lettuce (Lactuca sativa), was compared. The highest levels of colonisation occurred in the roots and rhizosphere, whereas colonisation of the leaves was lower and significantly different between the species. Colonisation of the leaves of prickly lettuce (L. serriola), a wild relative of domesticated lettuce, was especially poor. Differential VTEC gene expression in spinach extracts was markedly different for three tissue types, with little overlap. Comparison of expression in the same tissue type, cell wall polysaccharides, for lettuce and spinach also showed substantial differences, again with virtually no overlap. The transcriptional response was largely dependent on temperatures that are relevant to plant growth, not warm-blooded animals. The data show that VTEC adaptation to plant hosts and subsequent colonisation potential is underpinned by wholescale changes in gene expression that are specific to both plant tissue type and to the species.
Project description:Verotoxigenic Escherichia coli (VTEC) are a leading cause of food-borne illness. Fruit and vegetables are recognised as an important source of the pathogen and can account for ~ 25 % of food-borne VTEC outbreaks, globally. The ability of VTEC to colonise leaves and roots of leafy vegetables, spinach (Spinacia oleracea) and lettuce (Lactuca sativa), was compared. The highest levels of colonisation occurred in the roots and rhizosphere, whereas colonisation of the leaves was lower and significantly different between the species. Colonisation of the leaves of prickly lettuce (L. serriola), a wild relative of domesticated lettuce, was especially poor. Differential VTEC gene expression in spinach extracts was markedly different for three tissue types, with little overlap. Comparison of expression in the same tissue type, cell wall polysaccharides, for lettuce and spinach also showed substantial differences, again with virtually no overlap. The transcriptional response was largely dependent on temperatures that are relevant to plant growth, not warm-blooded animals. The data show that VTEC adaptation to plant hosts and subsequent colonisation potential is underpinned by wholescale changes in gene expression that are specific to both plant tissue type and to the species.
Project description:Leaf size and flatness directly affect photosynthesis and are closely related to agricultural yield. The final leaf size and shape are coordinately determined by cell proliferation, differentiation, and expansion during leaf development. Lettuce (Lactuca sativa L.) is one of the most important leafy vegetables worldwide, and lettuce leaves vary in shape and size. However, the molecular mechanisms of leaf development in lettuce are largely unknown. In this study, we showed that the lettuce APETALA2 (LsAP2) gene regulates leaf morphology. LsAP2 encodes a transcriptional repressor that contains the conserved EAR motif, which mediates interactions with the TOPLESS/TOPLESS-RELATED (TPL/TPR) corepressors. Overexpression of LsAP2 led to small and crinkly leaves, and many bulges were seen on the surface of the leaf blade. LsAP2 physically interacted with the CINCINNATA (CIN)-like TEOSINTE BRANCHED1/CYCLOIDEA/PROLIFERATING CELL FACTOR (TCP) transcription factors and inhibited their transcriptional activation activity. RNA sequencing analysis showed that LsAP2 affected the expression of auxin- and polarity-related genes. In addition, LsAP2 directly repressed the abaxial identity gene KANADI2 (LsKAN2). Together, these results indicate that LsAP2 regulates leaf morphology by inhibiting CIN-like TCP transcription factors and repressing LsKAN2, and our work provides insights into the regulatory mechanisms of leaf development in lettuce.
Project description:Bolting is a key process in the growth and development of lettuce (Lactuca sativa L.). High temperature can induce earlier bolting which decreases in both quality and production of lettuce. However, knowledge underlying lettuce bolting is still lacking. To better understand the molecular basis of bolting, a comparative proteomics analysis was conducted on lettuce stems in the bolting period induced by high temperature (33 °C) compared with a control (20 °C) using iTRAQ-based proteomics, phenotypic measures, and biological verifications. High temperature induced lettuce bolting, while control temperature did not. Of the 6656 proteins identified, 758 proteins significantly altered their expression level induced by high-temperature relative to the control, of which 409 were up-regulated and 349 down-regulated. Proteins with abundance level change were mainly involved in photosynthesis, carbohydrate metabolism, stress response, hormone synthesis, and signal transduction. These differential proteins were mainly enriched in pathways associated with photosynthesis and tryptophan metabolism involving in auxin (IAA) biosynthesis. Among the differentially expressed proteins associated with photosynthesis and tryptophan metabolism were up-regulated. Moreover, in gibberellin (GA) biosynthesis pathway, 10 of main enzymes of P450 were up-regulated. Proteins related to SAUR and GRP, implicated in IAA and GA signal transduction were up-regulated, and the phosphorylation and ubiquitination related proteins regulating IAA and GA signal transduction were also induced. These findings indicate that a high temperature enhances the function of photosynthesis, IAA and GA synthesis and signal transduction to promote the process of bolting, which is in line with the physiology and transcription levels of IAA and GA metabolism. Our data provide a first comprehensive dataset for gaining novel understanding of the molecular basis underlying lettuce bolting induced by high temperature. It is potentially important for further functional analysis and genetic manipulation for molecular breeding to breed new cultivar of lettuce to restrain early bolting, which is vital for improving vegetable quality.
Project description:Calcium deficiency response in liverwort, Arabidopsis and lettuce: (1) Marchantia polymorpha: M. polymorpha wildtype and Gβ-null mutant plants (Tak-1, gpb1-2) were grown in control liquid Yamagami media (2 mM Ca) for 6 days. For RNA-seq experiments, 6 day old gemmalings were transferred to calcium deficiency (0 mM Ca) media. Samples were collected at 48 h after the transfer. The transcriptomic profiles were collected from two independent batches. In total four biological replicates were used for each condition and each genotype for a total of 16 samples. (2) Arabidopsis thaliana: For Arabidopsis RNA-seq experiment, 6-day old seedlings grown on ½ strength MS media with sucrose were transferred to Yamagami media with 2 mM or 0 mM CaCl2 and treated for 7 days. (3) Lactuca Sativa: For lettuce RNA-seq, 4-day old seedlings grown on water agar (1%) were transferred to Yamagami media with 2 mM or 0.15 mM CaCl2 and treated for 7 days. In total four and three biological replicates were used for each condition for a total of 8 and 6 samples respectively for Arabidopsis and lettuce.