Involvement of nitric oxide in ABA-induced stimulation of adventitious root formation in derooted mung bean ,Vigna radiata L. wilczek seedlings
2010
Tartoura, K.A.H.
The present study aimed to investigate whether nitric oxide (NO) is involved in the ABA-induced adventitious root formation (ARF) in derooted Vigna radiata seedlings due to Its nature as a second messenger in stress responses. 7-day-old derooted mung bean seedlings were treated with the plant growth regulator ABA, NO donor sodium nitroprusside (SNP), and ABA in combination with the specific NO scavenger 2-(4-carboxyphenyl)4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (carboxy-PTIO) or the nitric oxide synthase (NOS) inhibitor N. .nitro-l-arginine (L-NNA). Results showed that application of ABA and SNP significantly stimulated ARF in a concentration dependent manner. However, the NO specific scavenger carboxy-PTIO and the NOS-inhibitor L-NNA suppressed the stimulatory effect of ABA on ARF in derooted V. radiata seedlings, indicating that endogenous NO plays a vital role in the ABA induced ARF; and it can be implied that the generation of NO catalyzed by NOS-like enzyme. In addition, data showed that ABA-treated cuttings had higher levels of NO, hydrogen peroxide (H. O. ), and lower levels of superoxide anion (02. ) than those of untreated ones. Further, ABA-treated cutting also contained higher activities of the antioxidant enzymes, i.e. [superoxide dismutase (SOD), catalase(CAT), guaiacol peroxidase (GPX), and ascorbate peroxidase (APX)), than those of the control treatment; however, carboxy-PTIO + ABA-treated cuttings had lower activities of such enzymatic activities at 120 h of ABA treatment. These results suggest that NO is involved in the ABA-induced stimulation of mung bean ARF most probably mediated via creating optimal levels of O. and H202 and enhancement of antioxidant enzymatic activities. It may be concluded that endogenous NO 'plays a vital role in ABA-induced de novo root formation in derooted V. radiata seedlings.
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