Abstract
Proton (H+) and aluminum (Al) rhizotoxicity are two major factors limiting crop production in acid soils. Orthologs of the zinc-finger transcription factor, Sensitive To Proton Rhizotoxicity1 (STOP1), have been found to play an essential role in the tolerance to both stresses by regulating the transcription of multiple H+ and Al tolerant genes. In the present study, color three GmSTOP1 homologs were identified in the soybean genome. All three GmSTOP1 exhibited similar properties as reflected by the harboring of four potential zinc finger domains, localizing in the nucleus, and having transactivation activity. Expression profiling showed that H+ stress slightly modulated transcription of all three GmSTOP1s, while Al significantly up-regulated GmSTOP1-1 and GmSTOP1-3 in root apexes and GmSTOP1-3 in basal root regions. Furthermore, complementation assays in an Arabidopsis Atstop1 mutant line overexpressing these GmSTOP1s demonstrated that all three GmSTOP1s largely reverse the H+ sensitivity of the Atstop1 mutant and restore the expression of genes involved in H+ tolerance. In contrast, only GmSTOP1-1 and GmSTOP1-3 could partially recover Al tolerance in the Atstop1 mutant. These results suggest that the function of three GmSTOP1s is evolutionarily conserved in H+ tolerance, but not in Al tolerance.
Highlights
Agricultural production is limited on acid soils, which comprise approximately 50% of the world’s potentially arable lands (von Uexküll and Mutert, 1995)
The results demonstrate that all three GmSTOP1s play important roles in H+ tolerance, while only GmSTOP1-1 and GmSTOP1-3 could partially recover Al tolerance in Arabidopsis Atstop1 mutant
A homolog search resulted in retrieval of three Sensitive To Proton Rhizotoxicity1 (STOP1) homologs in the soybean genome, which were named GmSTOP11 (Glyma.10G215200), GmSTOP1-2 (Glyma.16G156400) and GmSTOP1-3 (Glyma.20G176500) based on genome localization
Summary
Agricultural production is limited on acid soils, which comprise approximately 50% of the world’s potentially arable lands (von Uexküll and Mutert, 1995). There are several constraints limiting plant growth on acid soils, including deficiency of mineral nutrients, such as phosphorus (P), calcium (Ca), and magnesium (Mg), as well as, toxicity of excessive ions, including aluminum (Al3+), hydrogen (H+), and manganese (Mn2+) (Ishitani et al, 2004). Among these stresses, Al toxicity has been widely acknowledged as a major constraint on crop production (Kochian et al, 2004; Ma, 2007; Bojórquez-Quintal et al, 2017). Al and H+ toxicities are physiologically linked to one another
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