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The Chinese University of Hong Kong (2018)

Rhizosheath formation and its role in root development under drought stress

LIU,Tieyuan

Titre : Rhizosheath formation and its role in root development under drought stress

Auteur : LIU,Tieyuan

Université de soutenance : The Chinese University of Hong Kong

Grade : Doctor of Philosophy (PhD) in Biology 2018

Résumé partiel
The rhizosheath,a layer of soil particles that adheres firmly to the root surface by a combination of root hairs and mucilage, may improve tolerance to drought stress. Setaria italica(foxtail millet), a member of the Poaceae family, is an important food and fodder crop in arid regionsand forms a larger rhizosheath under drought conditions. Rhizosheath formation under drought conditions has been studied, but the regulation of root hair growth and rhizosheath size in response to soil moisture remains unclear. To address this question, in this study we monitored root hair growth and rhizosheath development in response to a gradual decline in soil moisture. Here, we determined that soil moisture of 10–14% (w/w) stimulated greater rhizosheath production compared to other soil moisture levels. Root hair density and length also increased at this soil moisture level, which was validated by measurement of the expressionof root hair-related genes. These findings contribute to our understanding of rhizosheath formation in response to soil water stress.Panicum virgatumL.(switchgrass), a member of the Poaceae family, is an important biofuel and fodder crop in arid regions. The five ecotype varieties of switchgrasshavea broadrange of rhizosheathsizesunder drought conditions. While rhizosheath formation under drought conditionshas been studied, no studies have focusedonmetabolic aspectsof rhizosheath formation. To further understand rhizosheath formation,two varietiesof switchgrass(cv. Alamo and cv. Kanlow) with differentrhizosheath sizesafter drought stress were selected to analyzethe metabolic differences in water deficit conditions. The primary metabolites related to rhizosheath size in switchgrass shoots and roots underdrought stress were determined by gas chromatography mass spectrophotometry (GC-MS). In this study, the levels of several amino acids (arginine, isoleucine, cysteine and methionine) and sugars(kestose, raffinose, fructose, fucose, sorbose and xylose) in the soil-sheathed roots of Alamo and Kanlow were significantly changed in response to drought stress and rhizosheath weight. Our results highlight the importance of utilizing metaboliteprofilingin plant physiology studyand provide abetter understanding of rhizosheath formation at the cellular level

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Page publiée le 20 décembre 2022