Dear Editor, Flavonols are synthesized by flavonol synthase （FLS） enzymes （Martens et al., 2010）. These compounds absorb UV-B light in the 280-320-nm region and their concentration increases in plants exposed to ...Dear Editor, Flavonols are synthesized by flavonol synthase （FLS） enzymes （Martens et al., 2010）. These compounds absorb UV-B light in the 280-320-nm region and their concentration increases in plants exposed to environmental abiotic and biotic stresses, including UV-B; consequently, flavonols are thought to act as UV-B filters （Agati et al., 2011）. It has been also suggested that these metabolites function as reactive oxygen species （ROS） scavengers, as they contain an OH- group in the 3-position of the flavonoid skeleton, which allows them to chelate metals, inhibiting the formation of free radicals and ROS accumula- tion, once formed （Agati et al., 2009）. For these reasons, it has been suggested that flavonols play uncharacterized roles in UV responses （Verdan et al., 2011）. Nevertheless, despite the fact that the role of flavonols in UV-B protection has been inferred, the protection conferred by flavonols on the target sites of UV-B-damage has not been directly proven in planta.展开更多
Dear Editor, The maize Mutator （MuDRIMu） transposon family is the most active DNA transposon in plants （Lisch, 2002）. The Mu family contains diverse elements, all sharing similar -215-bp terminal inverted repeats...Dear Editor, The maize Mutator （MuDRIMu） transposon family is the most active DNA transposon in plants （Lisch, 2002）. The Mu family contains diverse elements, all sharing similar -215-bp terminal inverted repeats （TIRs）. MuDR is the autonomous element, and a transcriptionally active MuDR is required for transposition of the non-autonomous Mu elements （Chomet et al., 1991）. MuDR contains two genes, mudrA and mudrB （Figure 1A）; mudrA encodes the MURA transposase, and mudrB encodes a protein with unknown function. To avoid the deleterious effects of transposons, plants have acquired mechanisms to epigenetically silence them. Silenced Mu ele- ments become heavily methylated, and their reactivation is very rare. To date, only UV-B radiation treatments have reac- tivated silenced Mu （Walbot, 1999）.展开更多
文摘Dear Editor, Flavonols are synthesized by flavonol synthase （FLS） enzymes （Martens et al., 2010）. These compounds absorb UV-B light in the 280-320-nm region and their concentration increases in plants exposed to environmental abiotic and biotic stresses, including UV-B; consequently, flavonols are thought to act as UV-B filters （Agati et al., 2011）. It has been also suggested that these metabolites function as reactive oxygen species （ROS） scavengers, as they contain an OH- group in the 3-position of the flavonoid skeleton, which allows them to chelate metals, inhibiting the formation of free radicals and ROS accumula- tion, once formed （Agati et al., 2009）. For these reasons, it has been suggested that flavonols play uncharacterized roles in UV responses （Verdan et al., 2011）. Nevertheless, despite the fact that the role of flavonols in UV-B protection has been inferred, the protection conferred by flavonols on the target sites of UV-B-damage has not been directly proven in planta.
文摘Dear Editor, The maize Mutator （MuDRIMu） transposon family is the most active DNA transposon in plants （Lisch, 2002）. The Mu family contains diverse elements, all sharing similar -215-bp terminal inverted repeats （TIRs）. MuDR is the autonomous element, and a transcriptionally active MuDR is required for transposition of the non-autonomous Mu elements （Chomet et al., 1991）. MuDR contains two genes, mudrA and mudrB （Figure 1A）; mudrA encodes the MURA transposase, and mudrB encodes a protein with unknown function. To avoid the deleterious effects of transposons, plants have acquired mechanisms to epigenetically silence them. Silenced Mu ele- ments become heavily methylated, and their reactivation is very rare. To date, only UV-B radiation treatments have reac- tivated silenced Mu （Walbot, 1999）.
