Hatib, K. | Search bioRxiv

bioRxiv2026

Stem photosynthesis from wild Prunus arabica enhances growth, advances bloom and increases yield in cultivated almond

Rising winter temperatures threaten deciduous fruit tree productivity by depleting carbohydrate reserves during dormancy. This study investigated Stem Photosynthetic Capacity (SPC), a rare adaptive trait from wild Prunus arabica, as a mechanism to enhance almond carbon economy. Using extreme segregating groups from the F1 population (P. dulcis X P. arabica), we evaluated physiological performance through high-resolution lysimetric and multi-year orchard monitoring. High-SPC [SPC(+)] genotypes maintained significantly greater stem CO2 assimilation and transpiration during leafless periods compared to low-SPC [SPC(-)] progenies. Over five successive seasons, SPC(+) trees exhibited a 33.3% increase in trunk secondary growth and reached 10% bloom approximately 8 days earlier. Most importantly, the SPC(+) group achieved a 4.6-fold increase in mean kernel yield when compared to SPC(-) group. These findings demonstrate that SPC provides a flexible, supplementary winter carbon source that directly supports both vegetative and reproductive development. Integrating SPC into commercial almond breeding programs may offer a valuable strategy to improve climate resilience and help sustain yields under warming conditions. HighlightIntegrating stem photosynthesis into commercial almond hybrids provides a winter carbon source that advances blooming, expands trunk growth by [~]33%, and increases kernel yields by more than 4.5-fold.

Plant Biology↗

bioRxiv2023

Annual dynamics and distribution of Xylella fastidiosa in infected almond trees

This research focused on studying the dynamics of the bacterial pathogen Xylella fastidiosa in almond trees at different developmental stages and in various tree parts. The objective was to understand the annual distribution and concentration of X. fastidiosa within almond trees. Different tree parts, including leaf petioles, annual and perennial shoots, fruit parts, flowers, and roots, from ten X. fastidiosa-infected almond trees were sampled over two years. The distribution and concentration of X. fastidiosa were determined using qPCR and serial dilution plating. Throughout the study, X. fastidiosa was never found in the fruit, flowers, and roots of almond trees, but it was present in leaves and annual and perennial shoots. We show that the inability of X. fastidiosa to colonize roots is likely due to incompatibility with the GF677 rootstock. The presence of X. fastidiosa in shoots remained consistent throughout the year, while in leaf petioles it varied across developmental stages, with lower detection during early and late stages of the season. Similarly, viable X. fastidiosa cells could be isolated from shoots at all developmental stages, while in leaf petioles no successful isolations were achieved during the vegetative and nut growth stage. Examining the development of almond leaf scorch symptoms over time in trees with preliminary infections revealed that once symptoms have appeared on a single branch, other asymptomatic limbs were likely already colonized by the bacterium, hence, selective pruning of symptomatic branches is unlikely to cure the tree. Overall, this study enhances our understanding of X. fastidiosa dynamics in almonds and may have practical applications for its detection and control in almond orchards.

plant biology↗