Jean Yves Uwamungu

Apple represents one of the most economically significant fruit crops worldwide, and the performance of its scion is largely determined by the physiological and genetic characteristics of the rootstock. Despite their superior ecological adaptability and growth-controlling attributes, many dwarfing apple rootstocks exhibit inherently poor rooting competence, which poses a critical limitation to their large-scale clonal propagation and commercial utilization. Adventitious root (AR) formation is a pivotal yet highly intricate developmental process that governs the success of asexual propagation. It is orchestrated by a complex network of hormonal signaling, transcriptional regulation, metabolic reprogramming, and environmental cues. Over the past decade, remarkable advances have elucidated the physiological, biochemical, and molecular frameworks underpinning AR formation in apple rootstocks. This review provides an integrative synthesis of current progress in vegetative propagation techniques—including cutting, layering, and tissue culture—and systematically dissects the endogenous and exogenous factors influencing AR development. Particular emphasis is placed on the regulatory interplay among phytohormones, carbohydrate and nitrogen metabolism, phenolic compounds, transcription factors (such as WUSCHEL-RELATED HOMEOBOX (WOX), LATERAL ORGAN BOUNDARIES DOMAIN (LBD), and RESPONSE FACTOR (ARF families), and epigenetic modulators that collectively coordinate root induction and emergence. Furthermore, emerging insights into multi-omics integration and genotype-specific molecular regulation are discussed as strategic pathways toward enhancing propagation efficiency. Collectively, this review establishes a comprehensive theoretical framework for optimizing the asexual propagation of apple rootstocks and provides critical molecular guidance for breeding novel, easy-to-root genotypes that can drive the sustainable intensification of global apple production.

The WUSCHEL-related homeobox (WOX) gene family has a critical effect on plant development and abiotic stress. However, there have been no genome-wide studies on WOX genes within sweet cherry (Prunus avium L.). In the present work, eight PavWOX genes were discovered within sweet cherry at the genome-wide level, and they were mapped to six chromosomes. Based on phylogenetic relationships, these genes were classified into three groups, with genes in one group having similar gene structures and conserved motifs. Meanwhile, the PavWOX genes possessed cis-acting elements and functions associated with hormone responses, stress responses, and development. As revealed by expression patterns, certain PavWOX genes are specifically expressed within tissues, suggesting that they may have unique functions. Additionally, the gene family expression patterns under drought stress were analyzed. PavWOX4, PavWOX5, PavWOX13A, and PavWOX13B had increased expressions upon drought stress. In addition, the transcription factor of PavWOX4 and PavWOX13A was localized in the nucleus, confirming the estimated results. Our findings lay the foundation for determining the expression patterns and functions of the PavWOX gene family within sweet cherry and shed more light on the underlying regulatory mechanisms.

The induction of adventitious roots is a key factor restricting the vegetative propagation of apple dwarf rootstocks. PLETHORA (PLT) transcription factors are involved in the regulation of plant stem cell niche and adventitious root development. In this study, we identified the PLT1 gene in apples by bioinformatics and analyzed its evolutionary relationship. The MdPLT1 gene was cloned from M9-T337 to verify its subcellular localization and analyze its function in transgenic tobacco. The MdPLT1 protein contained two conserved AP2 domains which may be similar to those of poplar the PtrPLT2a and PtrPLT2b with 85% support. The CDS sequence of the MdPLT1 gene was 1638 bp, encoding 545 amino acids. The transcription factor MdPLT1 was localized in the nucleus. The number of adventitious roots of tobacco plants overexpressing MdPLT1 significantly increased. In the adventitious roots of MdPLT1-overexpressed plants, the expression levels of genes related to the NtPINs family and the NtYUCCAs family were significantly increased. The results showed that MdPLT1 positively regulated adventitious root formation. This study provided a theoretical basis for the establishment of the fast vegetative propagation of apple dwarf rootstocks.

The succession of arbuscular mycorrhizal fungi (AMF) communities during ecosystem development has received widespread attention, but the ecological mechanism that drives the succession of AMF communities during the restoration process in alpine meadow ecosystems remains unclear. Here, we treated ‘Black Beach’ (severely degraded alpine meadow) as the baseline for restoration (0 year), and selected the revegetated grassland ofElymus nutanswith different planting times (3, 7, 10, and 14 years) to analyze the species composition of the AMF community in mixed roots (at the whole‐plant‐community scale) and inE. nutansroots (at the single‐plant‐species scale). A total of 46 AMF phylotypes (mixed roots: 44;E. nutansroots: 46) were identified in both root systems, predominantly belonging to Glomeraceae. AMF species richness showed a single‐peak curve change across the restoration time and reached its peak at 3 years in both root systems. In mixed roots, the soil available nitrogen not only directly changed the AMF species composition but also indirectly changed the AMF species composition through plant richness. In theE. nutansroots, only the soil available nitrogen drove changes in AMF species composition through changes in plant richness. Our results indicate thatE. nutans, a key species in the restoration process of revegetated grassland, can enhance its regulation to assemble the AMF community through soil available nitrogen at the two research scales, suggesting that the scientific management of soil nitrogen availability during restoration succession could strengthen the mutual symbiosis of ‘plant‐AMF,’ thereby retarding the occurrence of secondary degradation of revegetated grassland.