Carbon monoxide-induced adventitious rooting of hypocotyl cuttings from mung bean seedling

Abstract

In this paper, the regulatory role of exogenous carbon monoxide (CO) during the generation and development of adventitious roots in mung bean (Phaseolus radiatus L. cv. Mingguang) hypocotyl cuttings was surveyed. The results indicated that, like nitric oxide (NO), CO donor Hematin induced adventitious rooting in dose-and time-dependent manners. These responses were also proven by the addition of gaseous CO aqueous solution with different concentrations. Additionally, the above CO-mediated effect was differently reversed when CO scavenger hemoglobin (Hb), CO specific synthetic inhibitor ZnPPIX, the auxin transport inhibitor NPA and nitric oxide synthase (NOS) inhibitor L-NAME were added with Hematin, respectively. Furthermore, after being treated with CO for 36 h, NO fluorescence was significantly enhanced and mainly distributed in the zone of vascular bundles whereas the specific NO scavenger cPTIO significantly inhibited NO fluorescence induced by CO, indicating that CO induces adventitious rooting of hypocotyl cuttings from mung bean seedling probably mediated by NO/NOS pathway.Carbon monoxide (CO) and nitric oxide (NO), two diatomic gaseous molecules, belong to mid-valent oxide of carbon and nitrogen element, respectively. In fact, CO shares many physical and chemical properties with NO. Recent studies showed that formation of CO in animal tissues is mainly catalyzed by heme oxygenase (HO, EC 1.14.99.3) from heme. Also, the regulation of respiration, cardiovascular, nerve and immune systems by CO was mainly mediated by NO signal, and cyclic GMP (cGMP) was by far the commonest second messenger [1][2][3][4] .While in plants, although several laboratories have reported the direct emission of CO by living green plants when exposed to sunlight or during seedling growth since 1959 [5,6] , little was known about the exact mechanism of biosynthesis and even biological roles of CO in plants, and HO was also thought of as potential sources of CO in plant cells [7] . Meanwhile, endogenous NO in plants is produced mainly by nitric oxide synthase (NOS) or nitrate reductase (NR), and was further proven to participate in many physiological processes in plants, such as plant defense responses, seed germination, root organogensis and stress tolerance [8][9][10][11] . In 2002, Pagnussat et al. [12] first discovered that NO donor sodium nitroprusside (SNP) promoted the adventitious root formation in cucumber seedlings, a similar response to that obtained with IAA. More recently, She and Huang [13,14] also found that SNP induced the generation and development of adventitious roots in mung bean hypocotyl cuttings. It was well known that the formation of adventitious roots is an important issue in the research of developmental biology. Given the similar properties of both NO and CO, does CO exhibit the same regulatory role in the process of adventitious rooting? In this work, we discovered that CO induced the adventitious root generation in mung bean hypocotyl cuttings. Furthermore, through pharmacological and surgical approaches c...

The Heme Oxygenase/Carbon Monoxide System Is Involved in the Auxin-Induced Cucumber Adventitious Rooting Process

“…Figure 1 shows two parameters of root growth, adventitious root number and length, in cucumber explants. As expected (Xu et al, 2006), in comparison with water treatment, concentrations between 0.1 and 100 mM hematin and hemin significantly induced adventitious root numbers and root length in a dose-dependent manner (P , 0.05 or P , 0.01), with a maximal response at 10 mM hematin and hemin. We further applied an inhibitor of basipetal auxin efflux, naphthylphthalamic acid (NPA; 10 mM, auxin depleted), to determine if inhibiting auxin transport would influence the adventitious rooting process, HO activity, and CO content.…”

“…On the other hand, Zimmerman et al (1933) found that exogenous CO induced the initiation and stimulation of adventitious roots in plants, but little was known about the underlying mechanism of the above role of endogenous CO or even its signal transduction pathway. Recently, our results proved that exogenous CO induces adventitious rooting of hypocotyl cuttings (primary roots removed) from mung bean (Vigna radiata) seedlings (Xu et al, 2006). More recently, we also found that CO produced by HO might mediate the induction of growth elongation of wheat (Triticum aestivum) root segments by IAA, which might be related to NO/cGMP-dependent pathways .…”

“…Our previous report found that exogenous CO aqueous solution or its artificial donor hematin was able to induce adventitious rooting of hypocotyl cuttings (primary root removed) from mung bean seedlings (Xu et al, 2006); a similar phenomenon was first discovered using CO gas (Zimmerman et al, 1933). In this report, we further show that hematin and hemin, or CO aqueous solution, applied to auxin-nondepleted or auxin-depleted cucumber explants was able to dose-dependently induce adventitious root formation (Figs.…”

Involvement of carbon monoxide produced by heme oxygenase in ABA-induced stomatal closure in Vicia faba and its proposed signal transduction pathway

“…Furthermore, involvement of CO gas in different biological processes was also found. For instance, it acts as a compound with hormonal effects, affecting seed dormancy and germination [14] , and even inducing the adventitious rooting [15] .…”

Adventitious root formation in Arabidopsis : underlying mechanisms and applications

“…In addition to above mentioned phytohormones, other endogenous factors have also been identified to play a role in AR formation, such as calcium (Ca 2+ ) (Bellamine et al, 1998), sugar (Li andJia, 2013), phenolics (Rout, 2006), polyamines (Nag et al, 2001), nitric oxide (NO) (Pagnussat et al, 2002(Pagnussat et al, , 2003(Pagnussat et al, , 2004, carbon monoxide (Xu et al, 2006), cyclic guanosine monophosphate (cGMP), mitogen-activated protein kinase (MAPKs) (Pagnussat et al, 2003(Pagnussat et al, , 2004, wounding related compounds (Van der Krieken et al, 1997), and peroxidase (Syros et al, 2004). Some of these molecules may function in signaling and mediate auxin-induced adventitious rooting and auxinresponse gene expression.…”