Cell Wall Dynamics in the Parasitic Plant (Striga)and Rice Pathosystem

Abstract

Intheplant-plantpathosystemofrice(Oryzasativa)andthepar asitic plant Striga hermonthica, cell walls from either plant are important defensive and offensive structures. Here, we reveal the cell wall dynamics in both Striga and rice using simulta neous RNA sequencing. We used weighted gene co-expression network analysis to home in on cell wall modification processes occurring in interactions with a resistant rice cultivar (Nippon bare) compared with a susceptible one (IAC 165). Likewise, we comparedthecellwalldynamicsinStrigainfectingresistantand susceptible rice. Ourstudyrevealedanintensebattlementatthe Striga-rice cell walls involving both parasite (offense) and host (defense) factors, the outcome of which makes the difference between successful or failed parasitism. Striga activates genes encoding cell wall-degrading enzymes to gain access to the host, expansinstoallowforcellelongation,andpectinmethylesterase inhibitors for rigidity during infection. In the susceptible host, immuneresponseprocesses are not induced, and Striga-derived cell wall-degrading enzymes easily breach the host cell wall, re sulting in successful parasitism. In contrast, the resistant host invokes immuneresponsesmodulatedbyphytohormonestofor tify the cell wall through polysaccharides and lignin deposition. Through these processes, the cell wall of the resistant host suc cessfully obstructs parasite entry. We discuss the implications of these findings in the context of practical agriculture in which cell wall modification can be used to manage parasitic plants. †Corresponding authors: E. S. Bellis; ebellis@astate.edu,