UV-B Inhibits Leaf Growth through Changes in Growth Regulating Factors and Gibberellin Levels

FINA, JULIETA;; CASADEVALL, ROMINA;; ABD ELGAWAD, HAMADA;; ELS PRINSEN; MARIOS N. MARKAKIS; BEEMSTER, GERRIT;; CASATI PAULA

PLANT PHYSIOLOGY.

AMER SOC PLANT BIOLOGISTS

Lugar: Rockville; Año: 2017 vol. 174 p. 1110 - 1126

0032-0889

Ultraviolet-B (UV-B) radiation affects leaf growth in a wide range of species. In this work, we demonstrate that UV-B levelspresent in solar radiation inhibit maize (Zea mays) leaf growth without causing any other visible stress symptoms, including theaccumulation of DNA damage. We conducted kinematic analyses of cell division and expansion to understand the impact ofUV-B radiation on these cellular processes. Our results demonstrate that the decrease in leaf growth in UV-B-irradiated leaves isa consequence of a reduction in cell production and a shortened growth zone (GZ). To determine the molecular pathwaysinvolved in UV-B inhibition of leaf growth, we performed RNA sequencing on isolated GZ tissues of control and UV-B-exposedplants. Our results show a link between the observed leaf growth inhibition and the expression of specific cell cycle anddevelopmental genes, including growth-regulating factors (GRFs) and transcripts for proteins participating in differenthormone pathways. Interestingly, the decrease in the GZ size correlates with a decrease in the concentration of GA19, theimmediate precursor of the active gibberellin, GA1, by UV-B in this zone, which is regulated, at least in part, by the expression ofGRF1 and possibly other transcription factors of the GRF family.