Mucilage Polysaccharide Composition and Exudation in Maize From Contrasting Climatic Regions

Abstract

Mucilage, a gelatinous substance comprising mostly polysaccharides, is exuded by maize nodal and underground root tips. Although mucilage provides several benefits for rhizosphere functions, studies on the variation in mucilage amounts and its polysaccharide composition between genotypes are still lacking. In this study, eight maize (Zea mays L.) genotypes from different globally distributed agroecological zones were grown under identical abiotic conditions in a randomized field experiment. Mucilage exudation amount, neutral sugars and uronic acids were quantified. Galactose (∼39–42%), fucose (∼22–30%), mannose (∼11–14%), and arabinose (∼8–11%) were the major neutral sugars in nodal root mucilage. Xylose (∼1–4%), and glucose (∼1–4%) occurred only in minor proportions. Glucuronic acid (∼3–5%) was the only uronic acid detected. The polysaccharide composition differed significantly between maize genotypes. Mucilage exudation was 135 and 125% higher in the Indian (900 M Gold) and Kenyan (DH 02) genotypes than in the central European genotypes, respectively. Mucilage exudation was positively associated with the vapor pressure deficit of the genotypes’ agroecological zone. The results indicate that selection for environments with high vapor pressure deficit may favor higher mucilage exudation, possibly because mucilage can delay the onset of hydraulic failure during periods of high vapor pressure deficit. Genotypes from semi-arid climates might offer sources of genetic material for beneficial mucilage traits.

The Renaissance of Plant Mucilage in Health Promotion and Industrial Applications: A Review

“…The properties of plant-derived mucilages depend on their chemical structures and compositions. In recent years, extensive efforts have been made to link the quality (nutritional value, functional and technological features) of plant mucilages to their chemical compositions [2,[53][54][55]. The important attributes of mucilages and factors impacting their quality are summarized in Figure 3.…”

“…"Green" techniques used for the extraction of plant biological compounds have recently received more attention, improving extraction yield, reducing process time and the need for chemicals, and lowing costs. Further research in needed on optimizing the parameters of mucilage extraction from plants [2,[53][54][55].…”

Transcriptomic Responses of Rhizobium phaseoli to Root Exudates Reflect Its Capacity to Colonize Maize and Common Bean in an Intercropping System

“…A reporter-gene approach confirmed that polygalacturonase is highly expressed in maize exudates from monoculture or in association with bean (Figure 7A). Sugars such as galactose, fucose, mannose, arabinose, xylose, and glucose together with uronic acids like galacturonic acid and glucuronic acid are the main components of mucilage (Nazari et al, 2020). Genes for transporters and enzymes for metabolism of these sugars were expressed in maize exudates, so Ch24-10 perhaps consumes them as carbon sources once they are released from plant polymers or directly from the exudates.…”

Biogels in Soils: Plant Mucilage as a Biofilm Matrix That Shapes the Rhizosphere Microbial Habitat

“…Mucilage increases the water content of the rhizosphere, connects soil particles, increases the soil liquidphase connectivity, and facilitates root water uptake under drought, due to its high viscosity and low surface tension (Young, 1995;Carminati et al, 2010;Ahmed et al, 2015;Benard et al, 2019;Zarebanadkouki et al, 2019). Mucilage absorbs 27-589 times more water than its dry weight (McCully and Boyer, 1997;Huang and Gutterman, 1999;Capitani et al, 2013;Nazari et al, 2020), which is considerably higher than the amount of water absorbed by a similar quantity of EPS. The binding of negatively charged uronic acids to Ca 2+ governs hydrationdehydration dynamics in biogels (Dean et al, 2007;North et al, 2014;Brax et al, 2019).…”