The Identification of the Fruit Colour Gene of Oil Palm and Its Implications in Improving Palm Oil Yield

The fruit of the oil palm can vary considerably based on external appearance, most notably the colour of the fruit. The most common fruit is known as nigrescens which is deep violet to black at the apex and yellow at the base when unripe, and there is minimal colour change upon ripening.  The other major fruit type is virescens, which is green before ripening and exhibits a striking colour change to reddish-orange at maturity. Both the nigrescens and virescens fruits occur in nature. Surprisingly although the virescens trait is dominant, the number of virescens palms found in natural populations is small. However, virescens palms may be more desirable to planters as the marked difference in colour between ripe and unripe bunches makes it easier to identify ripe bunches, particularly in tall palms, where bunches can be obscured by fronds. The inheritance of exocarp colour of oil palm fruits was initially assessed in a population derived from the self-pollination of the tenera palm, T128, from the Malaysian Palm Oil Board’s (MPOB) Nigerian germplasm collection. The data, as expected, suggested that one Mendelian locus controlled the trait. Subsequently using the reference genome of Elaeis guineensis, we identified the R2R3 MYB transcription factor as the virescens (vir) gene that controls the exocarp colour of the fruit.  Five independent mutant alleles were identified in over 400 palms from MPOB’s E. guineensis germplasm collection from Africa. The identification of the gene has important implications in improving harvesting standards and hence oil yield.