Dataset Information

High resolution genetic dissection of the major QTL for tipburn resistance in lettuce, Lactuca sativa.

ABSTRACT: Tipburn is an important physiological disorder of lettuce, Lactuca sativa L., related to calcium deficiency that can result in leaf necrosis and unmarketable crops. The major quantitative trait locus, qTPB5.2, can account for up to 70% of the phenotypic variance for tipburn incidence in the field. This quantitative trait locus was genetically dissected to identify candidate genes for tipburn by creating lines with recombination events within the quantitative trait locus and assessing their resistance to tipburn. By comparing lines with contrasting haplotypes, the genetic region was narrowed down to ∼877 Kb that was associated with a reduction of tipburn by ∼60%. Analysis of the lettuce reference genome sequence revealed 12 genes in this region, one of which is a calcium transporter with a single nucleotide polymorphism in an exon between haplotypes with contrasting phenotypes. RNA-seq analysis of recombinants revealed two genes that were differentially expressed between contrasting haplotypes consistent with the tipburn phenotype. One encodes a Teosinte branched1/Cycloidea/Proliferating Cell factor transcription factor; however, differential expression of the calcium transporter was not detected. The phenotypic data indicated that there is a second region outside of the ∼877 Kb region but within the quantitative trait locus, at which a haplotype from the susceptible parent decreased tipburn by 10 to 20%. A recombinant line was identified with beneficial haplotypes in each region from both parents that showed greater tipburn resistance than the resistant parent; this line could be used as the foundation for breeding cultivars with more resistance than is currently available.

SUBMITTER: Macias-Gonzalez M

PROVIDER: S-EPMC8495944 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Similar Datasets

Project description:A diet rich in phytonutrients from fruit and vegetables has been acknowledged to afford protection against a range of human diseases, but many of the most popular vegetables are low in phytonutrients. Wild relatives of crops may contain allelic variation for genes determining the concentrations of these beneficial phytonutrients, and therefore understanding the genetic basis of this variation is important for breeding efforts to enhance nutritional quality. In this study, lettuce recombinant inbred lines, generated from a cross between wild and cultivated lettuce (Lactuca serriola and Lactuca sativa, respectively), were analysed for antioxidant (AO) potential and important phytonutrients including carotenoids, chlorophyll and phenolic compounds. When grown in two environments, 96 quantitative trait loci (QTL) were identified for these nutritional traits: 4 for AO potential, 2 for carotenoid content, 3 for total chlorophyll content and 87 for individual phenolic compounds (two per compound on average). Most often, the L. serriola alleles conferred an increase in total AOs and metabolites. Candidate genes underlying these QTL were identified by BLASTn searches; in several cases, these had functions suggesting involvement in phytonutrient biosynthetic pathways. Analysis of a QTL on linkage group 3, which accounted for >30% of the variation in AO potential, revealed several candidate genes encoding multiple MYB transcription factors which regulate flavonoid biosynthesis and flavanone 3-hydroxylase, an enzyme involved in the biosynthesis of the flavonoids quercetin and kaempferol, which are known to have powerful AO activity. Follow-up quantitative RT-PCR of these candidates revealed that 5 out of 10 genes investigated were significantly differentially expressed between the wild and cultivated parents, providing further evidence of their potential involvement in determining the contrasting phenotypes. These results offer exciting opportunities to improve the nutritional content and health benefits of lettuce through marker-assisted breeding.

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:Lettuce (Lactuca sativa L.) is a highly perishable horticultural crop with a relatively short shelf life due to leaf senescence that limits its commercial value and contributes to food waste. Postharvest senescence varies with influences of both environmental and genetic factors. Preharvest genetic factors can be indicative of postharvest quality. Discovery of additional preharvest markers to assess lettuce shelf life is an important step towards increasing the efficiency of lettuce breeding efforts for improved shelf life. We selected and evaluated three romaine lettuces with variable shelf lives with the aim of identifying preharvest markers of lettuce postharvest shelf life. We evaluated leaf morphological characteristics for each of the three cultivars. To assess molecular indicators of shelf life, we used an RNA sequencing approach to construct transcriptomic profiles of two of the cultivars, a short shelf life (SSL) breeding line 60184 and a long shelf life (LSL) cultivar ‘Okeechobee’ at maturity. We identified 552 upregulated and 315 downregulated differentially expressed (DE) genes between the genotypes. We found that 27 % of the DE lettuce genes had an Arabidopsis thaliana ortholog characterized as senescence-associated, indicating that variable expression of senescence-associated genes (SAGs) could serve as a tool for preharvest markers of postharvest shelf life. Notably, we identified several SAGs and functional groupings with highly differential expression between the cultivars. This includes several jasmonate ZIM-domain (JAZ), jasmonic acid (JA) signaling genes, chlorophyll a-b binding (CAB) chloroplast-associated genes, and cell wall modification genes including pectate lyases (PL) and expansins (EXP). This study presented an innovative approach for identifying molecular markers for preharvest factors linked to postharvest traits for prolonged shelf. These genes could potentially be developed further as preharvest predictors of shelf life for lettuce breeding

Dataset Information

High resolution genetic dissection of the major QTL for tipburn resistance in lettuce, Lactuca sativa.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets