Most tree fruits are commercially grown on different root systems, hence called composite plants. The section provides the root system as the rootstock, and the atop ground portion is called the scion. The combination is selected based on different traits of scion varieties, rootstock, and prevailing edaphic situations. The dated back plant propagation technique of joining two plants (grafting/budding) that directly communicates new physiological traits to the desirable scion variety from the rootstock remains unclear. In spite of this, this propagation technique continues widely applied in the multiplication of several fruit plant species. In a grafted plant, rootstocks impacted the scion variety’s growth, yield and quality attributes, physiology, nutrient accumulation as well as biotic and abiotic stress tolerance in many ways. Modern research in plant science for next-generation sequencing providing new vital information about the molecular interactions in composite plants multiplied using grafting. Now it was confirmed that genetic exchange is occurring between rootstock and scion variety through grafting joints. In this aspect, we discuss the process and the molecular mechanism of rootstock scion interactions. This review finally explains the dynamics of rootstock–scion interactions as well as their effect on physiology in terms of production, environmental stresses, and fruit quality. The morphological, physiochemical, and molecular mechanisms have been reviewed to develop an integrated understanding of this unknowable process that questions existing genetic paradigms. The present review summarizes the reported molecular mechanism between scion and rootstock and the impact of rootstocks on the production biology of scion varieties of economically important fruit crops and identifies numerous key points to consider when conducting rootstock scion interaction experiments. Rootstocks may offer a non-transgenic approach to rapidly respond to the changing environment and expand agricultural production of perennial fruit crops where grafting is possible in order to meet the global demand for fruit, food, and demands of the future.

An investigation was undertaken to adjudge the in vitro salt tolerance and biochemical changes due to NaCl on four grape rootstocks (Dogridge, SO4, H-144 and 3309C). The in vitro two-node micro-cuttings from the established cultures were sub-cultured on rooting medium comprising Murashige and Skoog (MS) basal medium supplemented with 0.5 μM indolebutyric acid (IBA), 200 mg dm⁻³ activated charcoal and different NaCl concentrations ranging from 0 to 125 mM. The surviving and proliferated cultures were further sub-cultured four times on respective media. Dogridge and H-144 tolerated 125 and 100 mM NaCl, respectively, while SO4 and 3309C survived only up to 75 mM NaCl. Contents of proteins, proline, K⁺ and Na⁺ in tissue increased in all genotypes due to NaCl supplementation, while contents of chlorophyll and total soluble sugars declined. Higher K⁺/Na⁺ ratio was registered in Dogridge and H-144 than in SO4 and 3309C. The relative NaCl tolerance for different grape rootstocks under study could be ranked as Dogridge > H-144 > SO4 and 3309C.

To explore the quality rootstocks which impart better quality fruits in mango varieties, we studied the interactive effect of the scion and rootstock using five mango varieties (Mallika, Amrapali, Dashehari, Pusa Arunima, and Pusa Surya) grafted on three rootstocks (Olour, Kurukkan, and K-5). A total of 25 physico-chemical parameters were studied in the five grafted varieties viz., fruit weight, yield efficiency, fruit per plant, pulp percent, total soluble solids (TSS), acidity, physiological loss in weight (PLW), peel thickness, respiration rate, etc., and were found to be altered through scion–rootstock interaction. Among the five mango varieties, Olour rootstock proved best to improve the fruit quality and shelf life using the grafting approach. Physico-chemical-traits-based clustering was unable to precisely group scion varieties according to their grafting rootstock. A total of 35 shelf-life specific markers were designed from ripening genes, such as expansin, polygalactouranase, ethylene insensitive, ethylene sensitive, etc. Of these specific primers, 24 showed polymorphism among the studied genotypes. The gene diversity (GD), allele per locus (An), polymorphism information content (PIC), and major allele frequency (MAF) observed were 0.43, 2.00, 0.34, and 0.63, respectively. Cluster analysis clearly showed that scion grafted on Kurukkan and Olour rootstock, and scion varieties grafted on K-5 rootstock grouped together have more similarity. A total of eight simple sequence repeats loci (SSRs) markers were associated with eight physiological traits. Strong association of SSR loci NMSLC-12 and NMSLC-14 with yield efficiency and fruit weight were observed with a phenotypic variance of 85% and 70%, respectively.

Our aim was to screen new hyper-variable mango SSRs (MSSRs) designed from Amrapali genome sequences to find polymorphic ones between Amrapali and Sensation parental genotypes. Out of 253 MSSRs screened against Amrapali and Sensation genotypes, 212 were polymorphic, of which 8 MSSRs showed aa, bb or bb, aa allelic patterns. MSSRs showing polymorphism in terms of homozygous for ‘a’ allele in Amrapali and homozygous ‘b’ allele for Sensation and vice versa were selected for assignment of parentage of hand-pollinated (Amrapali x Sensation) hybrids and open-pollinated Amrapali. MSSR markers were mapped back to the Amrapali genome version 3.0 NCBI GenBank database. MSSRs (M109, P125, M15, and M73) assigned parentage to more than 88.0% of hand-pollinated hybrids. P125 confirmed parentage of 93.61% progenies followed by M109 (90.43%), M15 (89.36%), and M73 (88.29%). Randomly three MSSRs, viz. M109, P125, and M73, were used for assignment of parentage of OP seedlings of Amrapali. Out of 22 OP seedlings, only 2 seedlings showed the identical heterozygous allelic pattern and their hybrid origin was confirmed. It is concluded that MSSRs (P125, M109, M15, and M73) from the Amrapali genome have immense value in MAS in mango and can be utilised for early stage selection of true hybrids.