Abscisic acid plays a key role in the regulation of date palm fruit ripening

Abstract

The date palm (Phoenix dactylifera L.) fruit is of major importance for the nutrition of broad populations in the world’s desert strip; yet it is sorely understudied. Understanding the mechanism regulating date fruit development and ripening is essential to customise date crop to the climatic change, which elaborates yield losses due to often too early occurring wet season. This study aimed to uncover the mechanism regulating date fruit ripening. To that end, we followed the natural process of date fruit development and the effects of exogenous hormone application on fruit ripening in the elite cultivar ‘Medjool’. The results of the current study indicate that the onset of fruit ripening occurre once the seed had reached maximum dry weight. From this point, fruit pericarp endogenous abscisic acid (ABA) levels consistently increased until fruit harvest. The final stage in fruit ripening, the yellow-to-brown transition, was preceded by an arrest of xylem-mediated water transport into the fruit. Exogenous ABA application enhanced fruit ripening when applied just before the green-to-yellow fruit color transition. Repeated ABA applications hastened various fruit ripening processes, resulting in earlier fruit harvest. The data presented supports a pivotal role for ABA in the regulation of date fruit ripening.

Genome‐wide association of dry (Tamar) date palm fruit color

“…Previous studies from Hazzouri et al (Hazzouri et al, 2015;Hazzouri et al, 2019) revealed that a retrotransposon insertion (named Ibn Majid) and a start codon mutation in an R2R3 MYB transcription factor encoded by the ortholog of the oil palm VIRESCENS gene (VIR gene) are likely the key genetic changes leading to the red and yellow color phenotype in dates at the Khalal stage (fresh fruit). Studies have shown that fruit pulp ripening (Khalalto-Rutab-to-Tamar), which also involves color transition from yellow to brown (Khalal-to-Rutab), showed an increase in endogenous abscisic acid (ABA) concentration (Awad, 2007;Shareef & Al-Khayri, 2020) and is preceded by an arrest of xylem-mediated water transport (Elbar et al, 2022).…”