Suberin Biopolymer in Rice Root Exodermis Reinforces Preformed Barrier Against Meloidogyne graminicola Infection

Exploration of novel genetic resources against root-knot nematode (RKN) is necessary to strengthen the resistance breeding program in cultivated rice, and investigations on the role of genotype-specific root anatomy in conferring a structural barrier against nematode invasion are largely underexplored. Here, we reported a highly-resistant rice germplasm Phule Radha that conferred remarkably lower RKN parasitic fitness in terms of reduced penetration and delayed development and reproduction when compared with susceptible cultivar PB1121. Using histological and biochemical analyses, we demonstrated that an enhanced suberin deposition in the exodermal root tip tissue of Phule Radha compared to PB1121 can effectively form a penetrative barrier against RKN infection, and this preformed barrier in the control tissue did not necessarily alter to a greater extent when challenged with RKN stress. Using qRT-PCR analysis, we showed that a number of suberin biosynthesis genes were greatly expressed in the exodermis of Phule Radha compared to PB1121. In sum, the present study established the role of rice exodermal barrier system in defense against an important soil-borne pathogen.