Characterization of Almond Scion/Rootstock Communication in Cultivar and Rootstock Tissues through an RNA-Seq Approach

Abstract

The rootstock genotype plays a crucial role in determining various aspects of scion development, including the scion three-dimensional structure, or tree architecture. Consequently, rootstock choice is a pivotal factor in the establishment of new almond (Prunus amygdalus (L.) Batsch, syn P. dulcis (Mill.)) intensive planting systems, demanding cultivars that can adapt to distinct requirements of vigor and shape. Nevertheless, considering the capacity of the rootstock genotype to influence scion development, it is likely that the scion genotype reciprocally affects rootstock performance. In the context of this study, we conducted a transcriptomic analysis of the scion/rootstock interaction in young almond trees, with a specific focus on elucidating the scion impact on the rootstock molecular response. Two commercial almond cultivars were grafted onto two hybrid rootstocks, thereby generating four distinct combinations. Through RNA-Seq analysis, we discerned that indeed, the scion genotype exerts an influence on the rootstock expression profile. This influence manifests through the modulation of genes associated with hormonal regulation, cell division, root development, and light signaling. This intricate interplay between scion and rootstock communication plays a pivotal role in the development of both scion and rootstock, underscoring the critical importance of a correct choice when establishing new almond orchards.

Keywords: Prunus dulcis; root development; scion/rootstock interaction; transcriptome; tree architecture.

Figure 1

The scion/rootstock combinations showed differences in vigor response. From left to right: ‘Isabelona’/‘GN-8’, ‘Isabelona’/Garnem^®, ‘Lauranne’/‘GN-8’ and ‘Lauranne’/Garnem^®.

Figure 2

Principal component analysis (PCA) of the global expression profile data from cultivar samples of the four scion/rootstock combinations. ISA/GN: ‘Isabelona’/Garnem^®; ISA/G8: ‘Isabelona’/‘GN-8’; LAU/GN: ‘Lauranne’/Garnem^®; LAU/G8: ‘Lauranne’/‘GN-8’.

Figure 3

Analysis of the cultivar effect on the rootstock transcriptome data. (A) Principal component analysis (PCA) of the global expression profile data from rootstock samples of the four scion/rootstock combinations. ISA/GN: ‘Isabelona’/Garnem^®; ISA/G8: ‘Isabelona’/‘GN-8’; LAU/GN: ‘Lauranne’/Garnem^®; LAU/G8: ‘Lauranne’/‘GN-8’. (B) Venn diagrams of differentially expressed genes (DEGs) for the four scion/roostock combinations.