*3.1. Phylogeny Analysis and Protein Sequence Analysis*

Genome surveys of LEA subfamily proteins (e.g., LEA\_1 to LEA\_6, SMP and DEHYDRIN) were done for *A. thaliana* [28], rice [36] and maize [37]. *C. songorica* is a perennial monocotyledonous desert plant with a high tolerance for drought stress. Investigation of stress responsive proteins encoded by *LEA* family genes in a desert plant should benefit crop improvement for drought and other abiotic stresses. Phylogenetic analysis grouped the CsLEA proteins into eight different subfamilies. Several *C. songorica* and Arabidopsis Dehydrin subfamily proteins were clustered together with high bootstrap values, which implied potential significant functional similarities between *C. songorica* and Arabidopsis DEHYDRIN proteins. Many of the Arabidopsis Dehydrin proteins are known as stress regulatory proteins such as RAB18 (*AtLea51*) and COR47 (*AtLea4*), two ABA and cold inducible proteins [38,39], ERD14 (*AtLea4*) and ERD10 (*AtLea5*), two disordered chaperon proteins [40] and Dehydrin Xero2 (*AtLea33*), a disordered cold responsive protein with membrane binding activity [41].

Sequence alignment using CsDehydrin proteins and their Arabidopsis counterparts revealed that all *C. songorica* Dehydrin proteins contained YKS segments but lacked the lysine rich segment. The K segment is critical for the formation of structural disordered alpha-helical compounds that can enhance bindings between proteins and their targeted molecules [10,42]. The presence of the K segment in *C.songorica* DEHYDRIN proteins emphasizes their role in limiting aggregation of molecules and thence promoting proper cellular homeostasis during dehydration stresses [11]. Additionally, the detection of the S segment in the *C. songorica* DEHYDRIN protein also suggests their implication in enhancing plant tolerance against abiotic stresses through protein phosphorylation, as previous studies indicated that the S segment participates in calcium binding through protein phosphorylation [43]. The findings above support the fact that disordered LEA proteins are flexible

proteins, capable of adjusting their conformation to maintain proper cellular homeostasis during detrimental stress conditions [43,44].
