GhSTOP1, a C2H2 type zinc finger transcription factor is essential for Aluminum and proton stress tolerance and lateral root initiation in cotton.

The Aluminum (Al) and proton (H+ ) ions are major acid soil stress factors deleteriously affecting plant root growth and crop yield. In our preliminary studies, cotton seedlings (Gossypium hirsutum L.) displayed very sensitive phenotypes to Al and H+ rhizotoxicities. Based on previous Arabidopsis results, we aimed to characterize the Al stress responsive Sensitive to Proton rhizotoxicity 1 (GhSTOP1) transcription system in cotton by RNAi mediated down-regulation. With the help of seed embryo apex explants, we developed transgenic cotton plants overexpressing a GhSTOP1-RNAi cassette with NPTII selection. Kanamycin tolerant T1 seedlings were further considered for Al and H+ stress tolerance studies. Down-regulation of the GhSTOP1 displayed increased sensitivity to Al and proton rhizotoxicities and the root growth was significantly reduced in RNAi-lines. The expression profile of GhALMT1 (Aluminum-activated Malate Transporter 1), GhMATE (Multidrug and Toxic Compound Extrusion), GhALS3 (Aluminum Sensitive 3) and the key genes involved in the GABA shunt were downregulated in the transgenic RNAi lines. Additionally, the lateral root initiation process was delayed and the expression of GhNAC1 which is involved in lateral root initiation was also suppressed in transgenic lines. Besides, overexpression of GhSTOP1 in Arabidopsis accelerated root growth and AtMATE and AtALMT1 expression under Al stress conditions. These analyses indicate that the GhSTOP1 is necessary for the expression of several genes which are necessary for acid soil tolerance mechanisms and lateral root initiation. This article is protected by copyright. All rights reserved.