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Exploring a defence-related gene in Tomato, Solanum lycopersicum

(a) Search for the tomato gene NCED2 and go to the gene tab.

  • What is the amino acid length of the only transcript of this gene?
  • Which chromosome and which strand of the genome is this gene located?

(b) Look at the gene Description field, what does this tell you about the cellular localisation of the protein product of this gene? Does this match the Gene Ontology (GO): Cellular component terms? Click on GO:Cellular component to check.

(c) Click on Gene expression. Which tissue has the highest expression of this gene according to the Tomato Genome Consortium?

(d) The summary at the top of the page (just above the Show transcript table button) shows us that there are nine paralogues of this gene. Click on the Gene gain/loss tree to look at the expansion of this gene family across all plants.

  • Which species has the largest number of members of this gene family?
  • Do any plants lack any genes in this family?

(e) Go to the transcript tab for this gene by clicking on the transcript ID Solyc08g016720.1.1 from the transcript table. Are there any Oligo probes that would be useful in targeting this gene experimentally?

(a) Go to plants.ensembl.org and type NCED2 into the search box, selecting Solanum locypersicum from the drop down menu. Click on the first result to go to the gene tab.

Click on the Show transcript table button if the transcript table is hidden. In the 4th column we see the protein length listed, 581 amino acids in length.

The location is listed at the top of the page, we can see that this is on Chromosome 8, between the base pairs 8,729,953 and 8,731,698, and on the forward strand.

(b) The gene description for this gene is ‘9-cis-epoxycarotenoid dioxygenase NCED2, chloroplastic’ which suggests the enzyme is localised to the chloroplast.

In the left-hand navigation panel, find the link to GO: Cellular location. We can see three results, chloroplast, plastid and chloroplast stroma, so this matches the gene description.

(c) Click on Gene expression in the left-hand navigation panel.

Darker shades of blue indicate higher expression. Hover your mouse over the heat-map to show a pop-up with the TPM (Transcripts Per Kilobase Million).

The 2cm fruit in the Tomato Genome Consortium has the highest expression at 103 TPM. You can also click on Filters at the top right and filter to high or medium expression.

(d) Click on the Gene gain/loss tree. You might find it easier to compare in the radial tree, click the two arrows icon at the top left of the image () to toggle to the radial view.

Look for the red lines, indicating the larger number of members and significant expansion. The number of members are listed just before the species name.

Brassica napus (oilseed rape) has the highest number of members in this gene family, nearly double compared to other species in the same genus.

Look for grey lines in the diagram. We can see that Triticum turgidum has no members of this gene family.

(e) Go to the transcript tab for this gene by clicking on the transcript ID Solyc08g016720.1.1 from the transcript table.

Find the Oligo probes link in the left-hand navigation panel. There is a single probe from Affymetrix, the AFFY TomGene, 20363698.