Cloning and expression analysis of SgSTOP1 and SgSTOP2 in Stylosanthes guianensis

Aluminium (Al) toxicity is one of the major factors limiting crop growth and production in acid soils. Transcription factor STOP is an important Al tolerance candidate gene in plants, as it can regulate the expression of Al-tolerant genes in response to Al toxicity. In this study, SgSTOP1 and SgSTOP2, which encode the zinc finger protein, were cloned from Al-tolerant stylo (Stylosanthes guianensis) genotype ‘TPRC2001-1’ using RT-PCR. The full lengths of SgSTOP1 and SgSTOP2 were 1 515 and 1 077 bp, which encoded 504 and 358 amino acid residues, respectively. The protein molecular weights of SgSTOP1 and SgSTOP2 were 56.2 and 39.7 kDa, respectively. Subcellular localization prediction showed that both SgSTOP1 and SgSTOP2 were located in the nucleus. Furthermore, SgSTOP1 and SgSTOP2 belonged to the ZF-C₂H₂ family, and both contained four conserved zinc finger domains. The expression of SgSTOP1 was significantly enhanced in leaves and roots of stylo subjected to Al treatment (P < 0.05), whereas the transcript of SgSTOP1 was not regulated by Al toxicity (P > 0.05), suggesting that SgSTOP1 may be involved in stylo adaptation to Al toxicity. Taken together, this study provided candidate genes for further analysis of the molecular mechanisms underlying stylo adaptation to Al toxicity.