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.

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.

Research background. There is considerable diversity in newly developed pummelo × sweet orange citrus hybrids. Most hybrids showed lower peel thickness and high juice yield but there is a lack of information on fruit quality parameters and molecular characterization. Therefore, the aim of the current study is to determine the content of antioxidants and properties of the fresh juice of 24 new pummelo × sweet orange citrus hybrids (Citrus maxima [Burm. f.] Osbeck × Citrus sinensis [L.] Osbeck) and the parental genotypes along with molecular characteristics determined using acidity specific markers. Experimental approach. The correlation and estimate of inheritance of the fruit juice properties: ascorbic acid, total phenol, total flavonoid, total antioxidant, total soluble solid and sugar contents, pH, titratable acidity, along with sensory evaluation was performed. Molecular characterization of these hybrids was carried out using de novo generated acidity specific simple sequence repeat (SSR) markers. Results and conclusions. The main constituents of the fruit juice of pummelo × sweet orange hybrids were observed in the range of w(ascorbic acid)=40.00–58.13 mg/100 g, total phenols expressed as gallic acid equivalents w(GAE)=40.67–107.33 mg/100 g, total antioxidants expressed as Trolox equivalents b(Trolox)=2.03–5.49 μmol/g, total flavonoids expressed as quercetin equivalents w(QE)=23.67–59.33 mg/100 g, along with other properties: total soluble solids=7.33–11.33 %, w(total sugar)=2.10–5.76 %, w (reducing sugar)=1.69–2.78 %, w(non-reducing sugar)=0.39–3.17 % and titratable acidity 1.00–2.11 %. The above parameters differed significantly in the fruit juice of the evaluated pummelo × sweet orange hybrids. Considering these parameters, the hybrids SCSH 17-9, SCSH 13-13, SCSH 11-15 and SCSH 3-15 had superior antioxidant properties in terms of these parameters. A higher heritability (≥80 %) was also observed for all juice properties. Molecular characterization of pummelo × sweet orange hybrids showed that >50 % of the hybrids were grouped with medium acidity parents. Both molecular and biochemical parameter-based clustering showed that interspecific hybrids exhibit transgressive segregation with increased antioxidants that help alleviate the health problems. Novelty and scientific contribution. These newly developed pummelo × sweet orange citrus hybrids are a valuable source of high-quality antioxidants for a healthy diet. The identification of trait markers that enable selection at the seedling stage is of great benefit to citrus breeders, as the characteristic features of a mature tree are not yet visible at the juvenile stage.

In the present study, variation in phytochemical properties was estimated in 16 newly developed interspecific citrus hybrids (Citrus maxima [Burm. f.] Osbeck × C. sinensis [L.] Osbeck) and parental genotypes. Results showed that the interspecific hybridization of pummelo with sweet orange significantly improved the fruit quality traits. Ascorbic acid, total phenol, total flavonoids, total carotenoid, and lycopene content in the fruit juice of studied genotypes varied from 37.8 to 72.02 mg/100 mL, 19.63–112.59 GAE mg/100 mL, 1.09–2.39 QE mg/100 mL, 34.6–519.81 μg/100 mL, and 17.59–395.71 μg/100 mL, respectively. Among the new hybrids, the highest antioxidant value (DPPH assay) was recorded as 2.53 TE μmol/mL as against the 2.22 TE μmol/mL in sweet orange cv. Mosambi. The citrus hybrid genotypes SCSH-9-2/12, SCSH-9-10/12, SCSH-11-9/13, SCSH-11-15/12, and SCSH-17-19/13 proved superior for studied phytochemicals. Pearson’s correlation and principal component analyses revealed the association among the traits and key components underlying the genetic variations. The bitterness properties were studied by quantifying naringin and limonin content in the fresh and stored juice (24 h storage at 4 °C) in addition to the sensory evaluation. The new hybrid SCSH-9-2/12, SCSH-9-10/12, and SCSH-11-9/13 have very low limonin content (<1.0 mg/L) with the least delayed bitterness properties, thus proving their potential for juice processing and storage.

The influence of rootstocks on mineral nutrient composition in the edible tissue of citrus fruits has not been explored so far. This study assessed leaf and juice mineral nutrients of sweet orange (Citrus sinensis (L.) Osbeck) cultivars (‘Pusa Sharad’ and ‘Pusa Round’) grafted onto different rootstocks (‘RLC-6’, ‘C-35’, ‘X-639’, ‘Yamma Mikan’, ‘Soh Sarkar’, ‘RLC-7’, and ‘Jatti Khatti’). Deviation from optimum percentage (DOP) index was employed as an integrative measure to assess leaf mineral nutrient balance for specific scion–rootstock combinations. The relative abundance of leaf mineral nutrients was ranked as follows: Ca > K > P > S > Mg > Na > Fe > Mn > Zn > Cu. Overall, rootstock ‘X-639’ demonstrated superior mineral nutrient uptake efficiency across grafted plants of both scion cultivars, as indicated by higher leaf mineral nutrient concentrations. Juice mineral nutrient concentrations followed the order K (930.87–1362.17 mg L⁻¹), Ca (346.40–651.33 mg L⁻¹), P (116.23–236.97 mg L⁻¹), Mg (64.60–102.50 mg L⁻¹), S (49.35–74.34 mg L⁻¹), Na (25.61–47.88 mg L⁻¹), Fe (4.76–7.92 mg L⁻¹), Zn (1.79–4.34 mg L⁻¹), Mn (0.73–1.62 mg L⁻¹), and Cu (0.41–0.71 mg L⁻¹), indicating distinct differences in the accumulation pattern of macro- and micro-mineral nutrients in the edible tissues across the studied scion–rootstock combinations. Multivariate analysis revealed that the rootstocks significantly influenced juice mineral nutrient levels, indicating rootstock-mediated agronomic biofortification. Rootstock ‘RLC-6’ enhanced juice K levels, and ‘Soh Sarkar’ improved juice Mg contents, while ‘X-639’ improved juice micronutrient (Zn, Mn, Cu) accumulation in both cultivars. This study constitutes the first comprehensive investigation that explicitly evaluates the influence of rootstocks on the enhancement of mineral nutrient content in the edible tissues of citrus fruits. It further elucidates how rootstock selection can indirectly affect dietary mineral intake, thereby highlighting its potential role for improved nutrition.