Revealing the Genetic Components Responsible for the Unique Photosynthetic Stem Capability of the Wild Almond Prunus arabica (Olivier) Meikle

Almond [Prunus dulcis (Mill.) D. A. Webb] is a major deciduous fruit tree crop worldwide. During dormancy, under warmer temperatures and inadequate chilling hours, the plant metabolic activity increases and may lead to carbohydrate deficiency. Prunus arabica (Olivier) Meikle is a bushy wild almond species known for its green, unbarked stem, which stays green even during the dormancy period. Our study revealed that P. arabica green stems assimilate significantly high rates of CO2 during the winter as compared to P. dulcis cv. Um el Fahem (U.E.F.) and may improve carbohydrate status throughout dormancy. To uncover the genetic inheritance and mechanism behind the P. arabica stem photosynthetic capability (SPC), a segregated F1 population was generated by crossing P. arabica to U.E.F. Both parent’s whole genome was sequenced, and SNP calling identified 4,887 informative SNPs for genotyping. A robust genetic map for U.E.F. and P. arabica was constructed (971 and 571 markers, respectively). QTL mapping and association study for the SPC phenotype revealed major QTL [log of odd (LOD) = 20.8] on chromosome 7 and another minor but significant QTL on chromosome 1 (LOD = 3.9). As expected, the P. arabica allele in the current loci significantly increased the SPC phenotype. Finally, a list of 64 candidate genes was generated. This work sets the stage for future research to investigate the mechanism regulating the SPC trait, how it affects the tree’s physiology, and its importance for breeding new cultivars better adapted to high winter temperatures.

Revealing the genetic components responsible for the unique photosynthetic stem capability of the wild almond Prunus arabica (Olivier) Meikle

Almond (Prunus dulcis (Mill.) D. A. Webb) is a major deciduous fruit tree crop worldwide. During dormancy, under warmer temperatures and inadequate chilling hours, the plant metabolic activity increases and may lead to carbohydrate deficiency. Prunus arabica (Olivier) Meikle is a bushy wild almond species known for its green, un-barked stem, which stays green even during the dormancy period. Our study revealed that P. arabica green stems assimilate significantly high rates of CO2 during the winter as compared to P. dulcis cv. Um el Fahem (U.E.F), and may improve carbohydrate status throughout dormancy. To uncover the genetic inheritance and mechanism behind the P. arabicaStem Photosynthetic Capability (SPC), a segregated F1 population was generated by crossing P. arabica to U.E.F. Both parent’s whole genome was sequenced, and a single nucleotide polymorphism (SNP) calling identified 4,887 informative SNPs for genotyping. A robust genetic map for U.E.F and P. arabica was constructed (971 and 571 markers, respectively). QTL mapping and association study for the SPC phenotype revealed major QTL (log of odd (LOD)=20.8) on chromosome 7, and another minor but significant QTL on chromosome 1 (LOD=3.9). Finally, a list of 73 candidate genes was generated. This work sets the stage for future research to investigate the mechanism regulating the SPC trait, how it affects the tree’s physiology, and its importance for breeding new cultivars better adapted to high winter temperatures.

Radical Stories in the Kirstenbosch National Botanical Garden

When the Kirstenbosch National Botanical Garden was established in Cape Town, South Africa, in 1913, it was envisioned as a site that served white citizens. Kirstenbosch was presented as a landscape in which plants functioned as representatives of their wild habitats. The botanical garden’s curatorial practices silenced histories of colonial occupation, frontier violence, colonial agriculture, and slavery that had shaped the land on which it was built. Narratives that celebrated colonial histories were cultivated in monumental gardening. Throughout its existence, Kirstenbosch has centered Western epistemologies. Where Indigenous knowledge systems were featured, they were mediated through ethnobotany. While human stakeholders lacked commitment to transformation, emergent ecologies evolved that interrupted colonial narratives and Western epistemologies. Discussing histories of wild almond trees, hybrid plants, and cycads, the author suggests that the emergent ecologies around them introduced radical stories to Kirstenbosch. The emergent ecologies’ storytelling is radical because it works at the roots of plants and historical genealogies, and it roots different narratives—of ruination and new flourishing, diversity and local becomings, multispecies kinship and love—into Kirstenbosch. In doing so, the emergent ecologies introduce possibilities for reimagining the botanical garden as an institution of environmental governance from within its confines and its disciplines.

Current Situation, Global Potential Distribution and Evolution of Six Almond Species in China

Almond resources are widely distributed in Central Asia; its distribution has not been studied in detail. Based on the first-hand data of field investigation, climate variables and chloroplast genome data, climatic characteristics of six almond species in China were analyzed, and the global distribution and evolutionary relationship were predicted. The six almond species are concentrated between 27.99°N and 60.47°N. Different almond species have different climatic characteristics. The climate of the almond species distribution has its characteristics, and the distribution of almond species was consistent with the fatty acid cluster analysis. All the test AUC (area under curve) values of MaxEnt model were larger than 0.92. The seven continents except for Antarctica contain suitable areas for the six almond species, and such areas account for approximately 8.08% of the total area of these six continents. Based on the analysis of chloroplast DNA and the distribution characteristics, the evolutionary relationship of the six almond species was proposed, which indicated that China was not the origin of almond. In this study, the construction of a phylogenetic tree based on the chloroplast genome and the characteristics of geographical distribution were constructed. The six almond species in China may have evolved from “Unknown almond species” through two routes. The MaxEnt model for each almond species provided satisfactory results. The prediction results can provide the important reference for Prunus dulcis cultivation, wild almond species development and protection.

Micrografting Compatibility Between Two Almond Cultivars and Four Wild Species

Micropropagation and micrografting techniques are important methods used to obtain high quality plants. This research aimed to investigate the effect of wild almond species (Prunus communis, P. orientalis, P. korschinskii, and P. arabica) on the success of micrografting almond cultivars (Prunus dulcis cvs. Shami Furk and Dafadii)and determine which combination of growth regulators lead to the highest rate of multiplication in micrografted cultivars. The shoot tips were grafted onto the rooted rootstocks by inverted T-budding. The results indicated that Murashige and Skoog (MS) medium, supplemented with 1 mg/l benzyl adenine (BA), 0.1 mg/l indole-3-butyric acid (IBA) and 0.2mg/l gibberellic acid (GA3), achieved the highest shoot multiplication with an average of 5.31 and 3.67 shoots per explant and an average of 6.23cm and 4.98cm shoot length in cultivars Shami Furk and Dafadii, respectively. The highest grafting success rates were 80% and 74.26% obtained from Shami Furk/P. arabica and Dafadii/P. arabica combinations, respectively, while the lowest success rate was 50.63% with the Dafadii/P. orientalis combination. The liquid MS medium supplemented with 0.5 mg/l BA + 0.1 mg/l IBA achieved the highest micrografting success and scion shoot length. This research can be used to improve almond cultivation.