Analysis On Gene Expression Correlation Between Vacuolar H～+-pyrophosphatase And TRANSPORT INHIBITOR RESPONSE1 (TIR1) In Arabidopsis Thaliana And Halophyte Chenopodium Glaucum

Vacuolar H+-pyrophosphatase is a kind of proton pump existing in most land plant. It regulates auxin-mediated organ development by constructing proton gradient. However, whether there is a correlation between V-H+-PPase expression and auxin signal transduction genes expression is still suspensive.The present study mainly focuses on relevant gene expression correlation between V-H+-PPase (AVP1 & CgVP1) and auxin signal transduction gene TIR1(AtTIR1 & CgTIR1) in Arabidopsis and halophytes Chenopodium glaucum in gene transcription level.The research comprises: detection of expression of AVP1, AtTIR1 and AtNAC2 in Arabidopsis and CgVP1 and CgTIR1 in Chenopodium glaucum; measurement of Na~+, K~+ content and ratio and their relationship with V-H+-PPase and TIR1 expression in Arabidopsis and Chenopodium glaucum after NaCl and IAA treatment after NaCl treatment, respectively; effects of NaCl and IAA treatment on content and distribution of auxin in Arabidopsis.First, Arabidopsis and Chenopodium glaucum were treated with NaCl stress and NaCl shock. Then expression of related genes was tested by using RT-PCR. The results showed that both NaCl stress and NaCl shock regulated expression of V-H+-PPase and TIR1 in Arabidopsis and Chenopodium glaucum. However, for Arabidopsis and Chenopodium glaucum seedling, just after NaCl shock, V-H+-PPase and TIR1 expressed in similar pattern; for the mature Arabidopsis and Chenopodium glaucum, V-H+-PPase and TIR1 expressed in similar pattern after NaCl stress.Secondly, Arabidopsis and Chenopodium glaucum seedlings were treated with IAA, and expression of the two genes were tested by using RT-PCR. The results showed that the expression of V-H+-PPase and TIR1 were induced by IAA; in Arabidopsis root and Chenopodium glaucum cotyledon, 5μM IAA treatment promoted the expression of V-H+-PPase and TIR1.Meanwhile, Na~+, K~+ content and their ratio of Arabidopsis and Chenopodium glaucum treated with NaCl stress and (or) NaCl shock was determined. The results showed that in Arabidopsis and Chenopodium glaucum seedlings, Na~+ content after NaCl stress increased much more than that after NaCl shock, but K~+ content keeped similar after NaCl stress and shock treatment, therefore Na~+/K~+ also increased after the two treatments. It suggested that the two treatments had different effects on cell membrane permeability and membrane potential, so the intracellular signal transduction was impacted, and the expression of V-H+-PPase and TIR1 were very different in the two treatments.Finally, GUS activity of Arabidopsis DR5::GUS mutant was measured after NaCl shock and IAA treatment. The results showed that the expression of AVP1 and AtTIR1 was induced by NaCl shock, but NaCl shock did not affect auxin synthesis and polar transport. The distribution of auxin showed organ specificity after IAA treatment.In addition, the expression of AtNAC2, acting downstream of AtTIR1, was tested after NaCl and IAA treatment, respectively. The findings indicated that its expression had little relevance with AtTIR1, suggesting intracellular signal transduction pathway was a complex process, auxin signal transduction from upstream to downstream be regulated by salt stress and other factors.These results suggested that in Arabidopsis and halophytes Chenopodium glaucum, V-H+-PPase and TIR1 gene expression was regulated both by salt stress signal and auxin signal, salt stress and auxin signal transduction interact with each other.