Molecular and structural characterization of expansins modulated by fungal endophytes in the Antarctic Colobanthus quitensis (Kunth) Bartl. Exposed to drought stress

Characterization of the Cell Wall Component through Thermogravimetric Analysis and Its Relationship with an Expansin-like Protein in Deschampsia antarctica

“…The resulting structural model showed a similar folding that is characteristic of the other expansins, displaying two domains each with a small cavity, named open groove, that crosses both domains ( Figure 5 A). This corresponds to the typical characteristic of expansins previously described in the literature [ 17 , 43 , 44 , 45 , 46 , 47 , 48 ]. The open groove located in the central part of the DaEXLA2 structural model is the region through which the protein interacts with ligands [ 17 , 43 , 44 , 45 , 46 , 47 , 48 ].…”

“…This corresponds to the typical characteristic of expansins previously described in the literature [ 17 , 43 , 44 , 45 , 46 , 47 , 48 ]. The open groove located in the central part of the DaEXLA2 structural model is the region through which the protein interacts with ligands [ 17 , 43 , 44 , 45 , 46 , 47 , 48 ]. In other proteins of the alpha-expansin family, it has been described as the area where the HFD motif is oriented, syndicated as the catalytic motif [ 18 , 19 , 20 , 21 , 22 , 23 ].…”

“…Although the effect of expansin proteins on cell walls is known, different authors have related these proteins with the response of the plant to stress [ 17 , 30 , 42 , 43 ]. For example, Jones and McQueen-Mason (2004) report a high expression of the gene EXPA1 during drought stress compared to EXPA2 and EXPA3 in Craterostigma plantagineum Hochst [ 42 ].…”

“…An innovative method is the thermogravimetric analysis (TGA) that has been widely used in different investigations, and recently, we performed different studies on the changes in the physiological properties in the cell wall of the strawberry fruit [ 12 , 13 , 14 ]. Complementary, the expansins are proteins acting during the extensibility of the cell wall, and it has been described that the levels of transcripts coding for these proteins increase under stress conditions, suggesting an important role in the adaptability of plants to various adverse conditions [ 15 , 16 , 17 ]. The expansin proteins comprise non-enzymatic cell wall proteins that belong to a superfamily with four clades: the α-expansin and β-expansin family that are present in all land plants [ 18 , 19 , 20 , 21 , 22 , 23 ], and two other families named “like α-expansin” and “like β-expansin” proteins that have been found in plants [ 18 , 21 , 22 , 24 ], fungi [ 20 ], and bacteria [ 23 ].…”

“…A second study showed that expansin-like B1 overexpression (BrEXLB1) increases the drought tolerance and induces a higher rate of photosynthesis and root growth in the plants of Brassica rapa L. [ 31 ]. Recently, we showed that five expansin genes modulated by fungal endophytes in the Antarctic C. quitensis plants exposed to drought, increase their relative expression in response to hydric stress [ 17 ]. Despite this evidence showing the influence of expansin protein in the plant performance under drought stress, it is unknown if the expansins proteins can play a role in the cell wall remodeling in the D. antarctica plants.…”