title: Nitric oxide is involved in integration of UV-B absorbing compounds among parts of clonal plants under a heterogeneous UV-B environment.
abstract: In nature, ultraviolet-B (UV-B) radiation is highly heterogeneous, both spatially and temporally. Plants exposed to UV-B radiation produce UV-B absorbing compounds that function as a protective filter. For clonal plants under heterogeneous UV-B radiation conditions, integration among ramets can allow irradiated ramets to benefit un-irradiated ramets by causing them to increase their UV-B absorbing compounds content. In this study, we evaluated integration between pairs of clonal ramets of Glechoma longituba under heterogeneous or homogeneous UV-B conditions. We determined the levels of UV-B absorbing compounds, nitric oxide (NO) and hydrogen peroxide (H2O2) and measured the activity of phenylalanine ammonia-lyase (PAL) in connected ramet pairs under homogeneous or heterogeneous UV-B conditions. Under heterogeneous UV-B conditions, the UV-B absorbing compounds content increased in leaves of irradiated and un-irradiated ramets, but not in the connecting stolons. The NO content increased in irradiated and un-irradiated leaves and stolons, but the H2O2content did not. Application of NO synthesis inhibitors and an NO blocker to irradiated ramets blocked the increase in UV-B absorbing compounds and PAL activity in un-irradiated ramets. These results suggested that NO is involved in the integration process for UV-B absorbing compounds among ramets. Our findings suggested that a UV-B-induced increase in NO transmits a signal to un-irradiated ramets via the stolon, leading to an increase in PAL activity and UV-B absorbing compounds content. The internal translocation of signal enables members of clonal networks to function as a whole unit and to mount an efficient defensive response to localized UV-B radiation.
authors.affiliation: Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education, Northwest University, Xi'an, 710069, China.
authors.forename: Xiao
authors.initials: X
authors.lastname: Liu
authors.affiliation: Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education, Northwest University, Xi'an, 710069, China.|Xi'an Botanical Garden of Shaanxi Province, Institute of Botany of Shaanxi Province, Xi'an, 710061, China.
authors.forename: Qian
authors.initials: Q
authors.lastname: Li
authors.affiliation: Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education, Northwest University, Xi'an, 710069, China.
authors.forename: Ming
authors.initials: M
authors.lastname: Yue
authors.affiliation: Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education, Northwest University, Xi'an, 710069, China.|Environmental Protection Research Institute, Xi'an Research Institute of China Coal Technology & Engineering Group Corp, Xi'an, 710054, China.
authors.forename: Xiaofei
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education, Northwest University, Xi'an, 710069, China.
authors.forename: Ruichang
authors.initials: R
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education, Northwest University, Xi'an, 710069, China.
authors.forename: Bing
authors.initials: B
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education, Northwest University, Xi'an, 710069, China.
authors.forename: Ming
authors.initials: M
authors.lastname: Wang