Courgette Jaune (Cucurbita pepo) — Plant Gene Profile | Zobium

Flavor & Sensory Profile

Dominant notes: mild vegetable, grassy green, faint floral, subtle squash.

Brix (typical): 2.8. Sweetness: low. Acidity: low.

Key Genes in Courgette Jaune

• Phytoene Synthase 1 (CsPSY1) — Encodes the first committed enzyme in the carotenoid biosynthesis pathway, converting geranylgeranyl diphosphate to phytoene; elevated activity in yellow-fruited zucchini cultivars is the primary driver of the golden-yellow skin colour characteristic of Courgette Jaune.: produces phytoene, lutein
• Carotenoid Cleavage Dioxygenase 1 (CsCCD1) — Encodes an enzyme that cleaves carotenoids into apocarotenoid volatiles including β-ionone and geranylacetone; activity links the yellow carotenoid pool to floral aroma notes, potentially giving Courgette Jaune a slightly more floral aroma than green-fruited courgettes.: produces β-ionone, geranylacetone
• Lipoxygenase 1 (CsLOX1) — Encodes a lipoxygenase enzyme that initiates oxidative cleavage of polyunsaturated fatty acids, producing the C6 volatile aldehydes (hexanal, (Z)-3-hexenal) responsible for the characteristic fresh-green, grassy aroma of raw courgette.: produces hexanal, (Z)-3-hexenal, (E)-2-hexenal
• Fruit Weight QTL 2.2 (CsFW2.2) — Encodes a negative regulator of cell division in developing fruit; allelic variation at this locus contributes to the range of fruit sizes observed across zucchini cultivars, influencing the moderate, elongated fruit dimensions typical of Courgette Jaune when harvested immature.: produces cell division regulator protein
• Fruit Shape SUN Locus (CsSUN) — Encodes a IQ67-domain protein that promotes elongated fruit shape by modulating cell elongation along the proximal–distal axis; high activity at this locus is a key genetic determinant of the cylindrical, elongated fruit shape defining the Zucchini Group.: produces IQ67-domain protein
• MYB Transcription Factor (Yellow Skin) (CsMYB) — Encodes an R2R3-MYB transcription factor that upregulates carotenoid biosynthesis genes in fruit exocarp; its elevated activity in Courgette Jaune relative to green-fruited zucchini cultivars is the regulatory switch responsible for golden-yellow pigmentation.: produces carotenoid pigments, lutein
• Polygalacturonase (CsPG) — Encodes a cell wall-degrading polygalacturonase enzyme; low activity in immature-harvested zucchini maintains firm, crisp fruit texture and extends post-harvest shelf life when fruit is picked young at 15–20 cm.: produces polygalacturonic acid fragments

Metabolic Pathways

• Carotenoid Biosynthesis — activity 70%: Drives golden-yellow skin and flesh pigmentation; carotenoid substrate pool also feeds CCD1-mediated volatile production (β-ionone, geranylacetone) contributing faint floral notes.
• Lipoxygenase Pathway — activity 60%: Primary source of fresh-green, grassy aroma volatiles (hexanal, (Z)-3-hexenal); dominant flavour impression of raw and lightly cooked courgette.
• Yellow Pigmentation — activity 72%: Confers the defining golden-yellow exocarp colour via elevated carotenoid accumulation; higher lutein content relative to green courgette may provide enhanced nutritional value.
• Fruit Shape & Size — activity 62%: Determines the elongated cylindrical fruit form and moderate fruit weight; polygenically inherited trait selected over centuries in Southern Europe for immature harvest at 15–20 cm.
• Cell Wall & Ripening — activity 35%: Low polygalacturonase activity in immature-harvested fruit maintains firm texture; fruit is typically consumed well before full physiological ripening and ethylene-driven softening.
• Phenolic / Flavonoid Pathway — activity 50%: Produces phenolic acids and flavonoids that contribute mildly bitter, astringent background notes; significantly upregulated under organic growing conditions (Kopczyńska et al. 2020, 2021).

Soil Microbiome Recommendations

• Rhizophagus irregularis — Improved phosphorus uptake supports deeper golden-yellow pigmentation and higher lutein content in the fruit skin.
• Bacillus velezensis — Elevated phenolic acids and flavonoids in the harvested fruit, consistent with the higher antioxidant levels observed in organically managed courgette (Kopczyńska et al. 2020).
• Trichoderma harzianum — Reduced incidence of Pythium and Fusarium root rots during the establishment phase, leading to more uniform plant stands and consistent fruit set.
• Bacillus subtilis — Potentially enhances characteristic fresh-green courgette aroma through jasmonate-mediated upregulation of LOX pathway enzymes.