Identification and characterization of the EXPA7, EXPA18 and EXT10 genes in Turbinicarpus lophophoroides (Werderm.) Buxb. & Backeb; and their expression analysis in the root under abiotic stress.

Expansin and extensin are proteins involved in resistance to various abiotic stresses by processes of cell wall modification and in the formation and elongation of the hairy root. They are located in several organs of the plant included root epidermis. Turbinicarpus lophophoroides is a cactus model to studies these genes in adventitious and transformed roots. In this study, we identified and characterized the expansin7, expansin18 and extensin10 genes in T. lophophoroides. Bioinformatic analysis indicated that the expansin sequences contained the motifs: HTFYG, HFD, YRR, VPC and YW; and certain conserved cysteine (C) residues. Regarding extensin10, the sequence contains the conserved SPPPP (SP4), YYS and YV motifs. The expression analysis in adventitious and transformed roots under osmotic stress (300 mM mannitol), heat (37 °C) and cold (4 °C); shows a higher expression of TlExpA18 in both roots, a decrease in TlExpA7 in transformed roots and a null expression in TlExt10 in both roots. In addition, a morphological comparison of the maturation/differentiation zone, meristem and cap between adventitious and transformed roots by SEM was performed, finding differences in the quantity and length of the hairy roots and the shape of the root cap. Overall, the study concluded that TlExpA18 and TlExpA7 belong to expansin family and TlExt10 belong to extensin family. The expression characteristics of TlExpA18, TlExpA7 and TlExt10 will facilitate the investigation of its function in stress response and other physiological processes in T. lophophoroides.