Differential Expression Of miRNA Across The Grafted Tissues Collected From Heterografts Involving Different Genera Of Cucurbitaceae Family

Grafting is a commonly used horticultural technique which involves insertion of a shoot (scion) of one plant into the shoot of the other plant (i.e. a rootstock) so that the two tissues merge, and establish together to survive rest of the life cycle. The current research is to compare regulation changes of microRNAs across the reciprocal grafts in contrast to their non-grafted counterparts involving various species. miR156, miR164, miR166, cuc_nov_7, cuc_sr_1, cuc_sr_4 cuc_sr_5 and cuc_sr_6 were selected. The scion leaf tissues of the grafted WM (watermelon)-JOL (Jack O’ Lantern cultivar of pumpkin) showed significant up regulation with respect to miR164, cuc_sr_6, and cuc-sr-1. Significant down regulation was noted in the case of cuc-nov-7.  The reciprocal graft, JOL-WM scion tissue showed significant upregulation in miR164 and down regulation in cuc_sr_6 when compared to the non-grafted WM. Scion tissue of LAG (Maces variety of Lagenaria-MEL (Melon) exhibited significant up regulation with miR156, miR164, miR166, cuc_sr_6, cuc_nov-7, cuc-sr-4 and cuc-sr-5 when compared to non-grafted MEL. Between the WM and LAG, all the microRNAs had higher abundance of expression in the matured tissues of LAG than in the WM. A consistent trend of decreased expression for all the eight microRNAs was noted for the mature WM leaf when compared to the seedling stage of WM.  Upon grafting, LAG as scion did not show any significant change for any of the microRNA, whereas WM leaf and stem had shown several folds up regulation for all the microRNAs except in cuc-sr-4 and cuc-sr-5. Another important observation is in WM scion, all the microRNAs in fruit tissues down regulated consistently. Our study clearly showed that miR156, miR164, miR166, cuc-nov-7, cuc-sr-1, cuc-sr-6 differentially regulated in heterografts.