Effects of exogenous nitric oxide on glycinebetaine metabolism in maize (Zea mays L.) seedlings under drought stress
Zhang, L. (Chinese Academy of Sciences and Northwest A&F Univ., Shaanxi (China). Inst. of Soil and Water Conservation) | Zhao, Y. (Northwest A&F Univ., Shaanxi (China). Coll. of Life Sciences) | Zhai, Y. (Northwest A&F Univ., Shaanxi (China). Coll. of Life Sciences) | Gao, M. | Zhang, X. | Wang, K. | Nan, W. | Liu, J.
In this study, we investigated the effects of exogenously applied nitric acid (NO) source i.e., sodium nitroprusside (SNP), NO scavenger i.e., 2-(4-carboxypheny-4,4,5,5-tetramethylimidazoline-1-1oxyl-3-oxide, potassium salt (cPTIO), NO inhibitor i.e., NaN3, and NOS inhibitor i.e., N Omega-nitro-larginine methyl ester hydrochloride (L-NAME) on eglycinbetaine (GB) metabolism in root tips and leaves of maize seedlings under drought stress (DS). The accumulation of NO peaked earlier than that of GB in shoot tips and leaves. The maximum NO content in root tips was attained earlier than that in leaves, while the reverse was observed with respect to GB content. The concentrations of NO, GB and choline in root tips and leaves of maize seedlings under DS were greater in the plants which received exogenous SNP application as compared to those in plants without SNP application. Exogenous SNP application also increased betaine aldehyde dehydrogenase (BADH) activity in leaves. The GB metabolism was negatively influenced by exogenous applications of either PTIO, NaN3 or L-NAME. The combined application of NaN3 and L-NAME had the most serious negative effects. These results demonstrate that GB metabolism in drought stressed maize plants was significantly enhanced by exogenous NO application. The accumulation of greater level of NO in maize seedlings contributed to increase GB accumulation by regulating BADH activity and choline content. This study provides a direct evidence of regulation of GB metabolism in maize plants under drought stress by exogenous application of NO.
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