Lignin and cellulose content differences in roots of different cotton cultivars associated with different levels of Fusarium wilt race 4 (FOV4) resistance-response

Abstract

Fusarium wilt disease is caused by fungal pathogen Fusarium oxysporum f. sp. vasinfectum (FOV) race 4 (FOV4), which enters the plant through the root system for its successful colonization of xylem. Plant cell wall forms the primary barrier against pathogen infection in addition to providing the mechanical support. However, the role of cell walls for developing FOV4 resistance has not been explored. The present study focused on examining the variation in lignin and cellulose contents in root tissue of Pima (Gossypium barbadense L.) and Upland (G. hirsutum L.) cotton with different levels of FOV4 wilt resistance-response. Traditional cultivar-checks susceptible Pima S-7, resistant Pima S-6, susceptible Upland Stoneville 474, and resistant Upland PSSJ-FRU14 (U77B) were used in the present study. Biochemical differences in root cell walls were investigated first by a rapid visual staining method for both lignin (phloroglucinol-HCL) and cellulose (Congo red) contents of root cross sections at three stages of cotton plant development followed by biochemical estimation of root lignin and cellulose contents. These studies revealed differences between susceptible and resistant cultivars at specific stages visually by rapid staining as well as biochemically in their cellulose and lignin contents within Pima and Upland cultivars. This is the first report in lignin and cellulose content estimation of Pima and Upland resistant and susceptible FOV4 cotton cultivars and paves the way for developing cell wall mediated FOV resistance.