Is Ca2+ involved in the signal transduction pathway of boron deficiency? New hypotheses for sensing boron deprivation.
Plants sense and transmit nutrient-deprivation signals to the nucleus. This increasingly interesting research field advances knowledge of signal transduction pathways for mineral deficiencies. The understanding of this topic for most micronutrients, especially boron (B), is more limited. Several hypotheses have been proposed to explain how a B deprivation signal would be conveyed to the nucleus, which are briefly summarized in this review. These hypotheses do not explain how so many metabolic and physiological processes quickly respond to B deficiency. Short-term B deficiency affects the cytosolic Ca(2+) levels as well as root expression of genes involved in Ca(2+) signaling. We propose and discuss that Ca(2+) and Ca(2+)-related proteins - channels/transporters, sensor relays, and sensor responders - might have major roles as intermediates in a transduction pathway triggered by B deprivation. This hypothesis may explain how plants sense and convey the B-deprivation signal to the nucleus and modulate physiological responses. The possible role of arabinogalactan-proteins in the B deficiency signaling pathway is also taken into account.
Departamento de Fisiología, Anatomía y Biología Celular, Universidad Pablo de Olavide, E-41013 Sevilla, Spain. Electronic address: agonfon@upo.es.
Agustín
A
González-Fontes
Departamento de Fisiología, Anatomía y Biología Celular, Universidad Pablo de Olavide, E-41013 Sevilla, Spain.
M Teresa
MT
Navarro-Gochicoa
Departamento de Fisiología, Anatomía y Biología Celular, Universidad Pablo de Olavide, E-41013 Sevilla, Spain.
Juan J
JJ
Camacho-Cristóbal
Departamento de Fisiología, Anatomía y Biología Celular, Universidad Pablo de Olavide, E-41013 Sevilla, Spain.
M Begoña
MB
Herrera-Rodríguez
Departamento de Fisiología, Anatomía y Biología Celular, Universidad Pablo de Olavide, E-41013 Sevilla, Spain.
Carlos
C
Quiles-Pando
Departamento de Fisiología, Anatomía y Biología Celular, Universidad Pablo de Olavide, E-41013 Sevilla, Spain.
Jesús
J
Rexach
D001895:Boron / Q000172:deficiency / Q000378:metabolism*; D015220:Calcium Channels / Q000378:metabolism; D020013:Calcium Signaling / Q000502:physiology*; D006706:Homeostasis / Q000502:physiology; D009088:Mucoproteins / Q000378:metabolism; D010940:Plant Proteins / Q000378:metabolism; D010944:Plants / Q000378:metabolism*; D044169:Receptors, Calcium-Sensing / Q000378:metabolism
D015220:Calcium Channels; D009088:Mucoproteins; D010940:Plant Proteins; D044169:Receptors, Calcium-Sensing; C006619:arabinogalactan proteins; D001895:Boron
ACA; Arabinogalactan-proteins; Boron deficiency; CAX; CML; CNGC; CaM; Calcium signaling; Calcium transporters; Transcription factors; autoinhibited Ca(2+)-ATPase; calmodulin; calmodulin-like protein; cation/H(+) exchanger; cyclic nucleotide-gated ion channel