Actin filaments altered distribution in wheat (Triticum aestivum) “Bending Root” to respond to enhanced Ultraviolet-B radiation

Distribuição alterada dos filamentos de actina no trigo (Triticum aestivum) “Raiz dobrada” para responder à radiação ultravioleta B aprimorada

Abstract

Plants adjust their shoot growth to acclimate to changing environmental factors, such as to enhanced Ultraviolet-B (UV-B) radiation. However, people have ignored that plant roots can also respond to UV-B light. Here, we find the morphology curled wheat roots under UV-B radiation, that we call, “bending roots.” The curly region is the transition zone of the root after observed at the cellular level. After exposed to enhanced UV-B radiation for 2 d (10.08 KJ/m²/d), cell size decreased and actin filaments gathered in wheat roots. We also find that H₂O₂ production increased and that content of the indole-3-acetic acid (IAA) increased remarkably. The pharmacological experiment revealed that actin filaments gathered and polymerized into bundles in the wheat root cells after irrigated H₂O₂ and IAA. These results indicated that actin filaments changed their distribution and formed the “bending root,” which was related to H₂O₂ production and increase in IAA. Overall, actin filaments in wheat root cells could be a subcellular target of UV-B radiation, and its disruption determines root morphology.

Keywords:
UV-B radiation; actin dynamics; wheat; root morphogenesis