Legume Genomics and Genetics 2025, Vol.16, No.5, 204-214 http://cropscipublisher.com/index.php/lgg 211 not only promotes root growth but also enhances root tolerance under salt stress (Figure 3). The effect of GmEXPB2 is more comprehensive. It not only promotes root elongation but also improves root nodule formation and phosphorus absorption capacity (Zhou et al., 2014; Kong et al., 2019). In other words, these genes are not merely "auxiliary tools", but a core link in root development and stress response. Figure 3 Overexpression of GsEXPB1 significantly promoted cultivated soybean hairy roots growth and salt stress tolerance. (A) Construction of expression vector, P35S indicates CaMV35S promoter, HA indicates HA protein tag, NOS indicates terminator. (B) Detection results of gene transcription and protein expression in transgenic hairy roots. (C) Phenotypic observation of hairy roots overexpressing GsEXPB1 under normal growth conditions and salt stress, bar = 2 cm (Adopted from Feng et al., 2022) 8 Concluding Remarks The expansin gene in leguminous plants is complex, but there are indeed patterns to follow. They are not a type of "uniform specification" genes, but a large family with diverse structures and functions, classified into four subgroups: EXPA, EXPB, EXLA and EXLB. Many members have similar conservative domains and repetitive motifs, which look like traces left by their "ancestors". The reason why they are increasing in number is mainly driven by fragment replication and serial replication, while the subsequent functional differentiation is gradually shaped by various selective pressures.
RkJQdWJsaXNoZXIy MjQ4ODYzNA==