Heme Oxygenase1 And Nitric Oxide Involved In Methane-Induced Cucumber Adventitious Root Formation

Aerobic methane (CH4) releasing from plants has led to an intense scientific and public controversy in the recent years. Although this phenomenon has been repeated and confirmed by different scales of measurement, the potential function of CH4 for plant itself is still largely unknown. Recent studies showed that a series of gaseous signal molecules were involved in adventitious root formation. So that whether CH4 is a new gaseous signal molecule and effect on cucumber adventitious root formation is worth to study. Nitric oxide (NO) and heme oxygenase 1 (HOI) were active signal molecules, they effected on many physiological processes in plants. This paper studied the effects of CH4 on cucumber adventitious root formation. And we researched the effect of NO and HO 1 in this process further more.All of our results showed that:(1) MRW could induce cucumber adventitious root formation and regulate CsHO1 transcripts and protein levels as time ging on. HO1 inhibitor ZnPP inhibited MRW-induced adventitious root formation, and further inhibited MRW up-regulated of HO1 transcripts and protein levels, but CO could reverse the above process. Then we investigated the effect of HO1/CO signal system on target gene of adventitious root formation. The results showed that MRW up-regulated CsCDPK1/5, CsDNAJ-1, CsAUX22B/D-like and CsCDC6 transcripts in different degree, then HO1 inhibitor ZnPP inhibited MRW’s up-regulation of above target genes, but the process can be reversed by CO. Inhibitor experiments showed that this process might be related to calcium signal(2) MRW was similar with auxin that increased the content of endogenous CH4. The NO scavenger PTIO could inhibit MRW-induced adventitious root formation, suggesting that NO was involved in MRW induced cucumber adventitious root formation. We made further efforts on confirming NO sources, found that NO may come from the pathway relied on the L-arginine and the pathway of DAO/PAO depredating polyamine. Then we tested the broad-spectrum impact of MRW on plants, found that MRW also could promote the soybean and mungbean adventitious root formation.In short, we used pharmacology and molecular biology approaches, showing that CH4 induced cucumber adventitious root formation as a new gaseous signal molecule, and NO and HO1 might be involved in this process.