Cell Wall Biomolecular Composition Plays a Potential Role in the Host Type II Resistance to Fusarium Head Blight in Wheat

Abstract

Fusarium head blight (FHB) is a serious disease of wheat worldwide. Cultivar resistance to FHB depends on biochemical factors that confine the pathogen spread in spikes. Breeding for cultivar resistance is considered the most practical way to manage this disease. In this study, different spectroscopy and microscopy techniques were applied to discriminate resistance in wheat genotypes against FHB. Synchrotron-based spectroscopy and imaging techniques, including focal plane array infrared and X-ray fluorescence (XRF) spectroscopy were used to understand changes in biochemical and nutrients in rachis following FHB infection. Sumai3 and Muchmore were used to represent resistant and susceptible cultivars to FHB, respectively, in this study. The histological comparison of rachis showed substantial differences in the cell wall thickness between the cultivars after infection. Synchrotron-based infrared imaging emphasized substantial difference in biochemical composition of rachis samples between the two cultivars prior to visible symptoms; in the resistant Sumai3, infrared bands representing lignin and hemicellulose were stronger and more persistent compared to the susceptible cultivar. These bands may be the candidates of biochemical markers for FHB resistance. Focal plane array infrared imaging (FPA) spectra from the rachis epidermis and vascular bundles revealed a new band (1710 cm−1) related to the oxidative stress on the susceptible cultivar only. XRF spectroscopy data revealed differences in nutrients composition between cultivars, and between controls and inoculated samples, with substantial increases observed for Ca, K, Mn, Fe, Zn, and Si in the resistant cultivar. These nutrients are related to cell wall stability, metabolic process, and plant defense mechanisms such as lignification pathway and callose deposition. The combination of cell wall composition and lignification plays a role in the mechanism of type II host resistance to FHB. Biochemical profiling using the synchrotron-based spectroscopy holds potential for screening wheat genotypes for FHB resistance.

Wheat flag leaf epicuticular wax morphology and composition in response to moderate drought stress are revealed by SEM, FTIR‐ATR and synchrotron X‐ray spectroscopy

“…Fourier transform infrared (FTIR) spectroscopy has become an established method for phenotyping traits associated with stress response, such as identifying cell wall biochemical markers associated with frost damage in spring wheat seeds (Xin et al ), resistance to Fusarium head blight in spring wheat (Lahlali et al , ), selection of superior barley ( Hordeum vulgare L.) cultivars by endosperm protein quality (Liu and Yu ) or differences in grain feed quality for livestock (Walker et al ). On a tissue‐specific level, FTIR spectroscopy can be used to localize total lignin, protein, cellulose, carbohydrates and lipid distributions at spatial resolutions of 1–20 μm (Vijayan et al ).…”

The Brachypodium distachyon UGT Bradi5gUGT03300 confers type II fusarium head blight resistance in wheat

“…This could also result from variations in cell wall composition, before or after infection, in these species. Indeed, variations in cell wall composition during F. graminearum infection have been already described between susceptible and resistant wheat cultivars (Lahlali et al ., ). A final explanation could be the pattern of anther extrusion of the wheat variety used in this study, Apogee.…”

Showcasing the application of synchrotron‐based X‐ray computed tomography in host–pathogen interactions: The role of wheat rachilla and rachis nodes in Type‐II resistance to Fusarium graminearum

“…Some studies suggest cell‐wall lignification to be an important component of FHB resistance in moderately resistant wheat genotypes and have concluded that FTIR‐based markers can be used to differentiate genotypes (Atanasova‐Penichon et al, ; Gunnaiah & Kushalappa, ; Lahlali et al, ; Lahlali et al, ). In contrast, our study did not find any consistent results for some important bipolymeric compounds such as cellulose, pectin, and xylan.…”

“…To determine the small spectral changes in the fingerprint region (1,800–600/cm), a second derivative spectroscopy technique was employed using the Savitzky–Golay algorithm (nine smoothing points). The FTIR peaks for the various bipolymeric compounds (Table ) were assigned using the Quick Peaks routine in OriginPro software version 9.1 (OriginLab Coorporation, MA, USA) using the settings described in Lahlali et al (). Quantitative data were measured for important biopolymers such as lignin, pectin, cellulose, and xylan by integrating the area under the specific bands using OriginPro software (Table ).…”

“…So far, only two studies (from coauthor Dr. Karunakaran's group) used synchrotron‐based techniques to study the Fg –wheat interaction. These studies used Fourier‐transform midinfrared (FTIR) spectroscopy to focus mainly on the biochemical changes occurring in the cultivars with differential resistance responses (Lahlali et al, ; Lahlali et al, ). Our study utilized synchrotron X‐ray imaging to elucidate structural changes resulting from Fg infection in near‐isogenic lines (NILs) segregating for Sumai 3‐derived resistance genes ( Fhb1 , Fhb2 , and Fhb5 ) that carried less than 4% donor alleles.…”