Rootstock-mediated carbohydrate metabolism, nutrient contents, and physiological modifications in regular and alternate mango (Mangifera indica L.) scion varieties.

Abstract

Most of the popular scion varieties of mango possess alternate/irregular bearing. There are many external and internal factors assigned, among them carbohydrate reserves, and nutrient content plays important roles in the floral induction process in many crop species. In addition to that rootstock can alter the carbohydrate reserve and nutrient acquisition of scion varieties in fruit crops. The present investigation was carried out to understand the effect of rootstocks on the physiochemical traits of leaf, and bud and nutrient content in regular and alternate bearing varieties of mango. The rootstock "Kurukkan" promoted starch content in leaves of both alternate bearing varieties 'Dashehari' (5.62 mg/g) and regular 'Amrapali' (5.49 mg/g) and encouraged higher protein content (6.71 mg/g) and C/N ratio (37.94) in buds of alternate bearing 'Dashehari'. While Olour rootstock upregulated the reducing sugar in leaves of 'Amrapali' (43.56 mg/g) and promoted K (1.34%) and B (78.58 ppm) content in reproductive buds of 'Dashehari'. Stomatal density in 'Dashehari' scion variety was found higher on Olour rootstock (700.40/mm 2), while the rootstock fails to modify stomatal density in the scion variety regular bearer 'Amrapali'. Further, a total of 30 carbohydrate metabolism-specific primers were designed and validated in 15 scion/rootstock combinations. A total of 33 alleles were amplified among carbohydrate metabolism-specific markers, which varied from 2 to 3 alleles with a mean of 2.53 per locus. Maximum and minimum PIC value was found for NMSPS10, and NMTPS9 primers (0.58). Cluster analysis revealed that scion grafted on Kurukkan rootstock clustered together except 'Pusa Arunima' on Olour rootstock. Our analysis revealed that Fe is the key component that is commonly expressed in both leaf and bud. Although Stomatal density (SD) and Intercellular CO2 Concentration (Ci) are more specific to leaf and Fe, B, and total sugar (TS) are abundant in buds. Based on the results it can be inferred that the physiochemical and nutrient responses of mango scion varieties are manipulated by the rootstock, hence, the scion-rootstock combination can be an important consideration in mango for selecting suitable rootstock for alternate/irregular bearer varieties.