Effects Of Narciclasine On Auxin Transport And Cytoskeleton In Arabidopsis Thaliana Roots

Phytohormones and some secondary metabolites play a central role in plant growth and development. Narciclasine (NCS), a kind of alkaloid which is isolated from bulbs of Narcissus tazetta L, could markedly inhibit many physiological functions in plants and animals, for example, the postembryonic development of Arabidopsis, rice and wheat. In the study, we investigated the mechanism of NCS-induced inhibition in Arabidopsis root development.The main results are shown as follows:1. We studied the effects of NCS on cytoskeleton in the Arabidopsis marker line of microfilament protein (GFP-FABD2) with the method of Laser Scanning Confocal Microscopy (LSCM). The results showed that NCS changed the contents and distribution of microfilament protein, which changed into parallel to twist at the mature zone of main roots and increased at the area of plasma membrane. Meanwhile, the root hair also shows the twist of microfilament protein. NCS induced the more microfilament protein in the main root tip.2. The NCS treatment significantly decreased auxin contents at the root tip when the auxin report gene DR5-GFP was used. The expression of DR5 was markedly inhibited with the increasing time and concentration of NCS, which could be partially rescued through the exogenous application of auxin.3. NCS significantly decreased the contents of PIN protein and effected the polar contribution of PIN1 and PIN 2 in the Arabidopsis GFP and GUS marker line of PIN protein (PIN1,3,4,7). The further study showed that NCS increased the gene expression ofPIN2, but inhibited the gene expressions of PIN1, PIN3, PIN7 and PGP19.4. The high-concentration NCS resulted in the loss of gravitropism in Arabidopsis roots, which couldn’t be abolished through the exogenous application of auxin, The further study showed that NCS reduced the contents of starch in 7-days-old Arabidopsis.Taken together, NCS affected the contents, distribution and gene expressions of PIN proteins as well as the structure of microfilament protein, which might finally resulted in the inhibition of the development of Arabidopsis roots.