On a quest for stress tolerance genes: membrane transporters in sensing and adapting to hostile soils.
Abiotic stresses such as salinity, drought, and flooding severely limit food and fibre production and result in penalties of in excess of US$100 billion per annum to the agricultural sector. Improved abiotic stress tolerance to these environmental constraints via traditional or molecular breeding practices requires a good understanding of the physiological and molecular mechanisms behind roots sensing of hostile soils, as well as downstream signalling cascades to effectors mediating plant adaptive responses to the environment. In this review, we discuss some common mechanisms conferring plant tolerance to these three major abiotic stresses. Central to our discussion are: (i) the essentiality of membrane potential maintenance and ATP production/availability and its use for metabolic versus adaptive responses; (ii) reactive oxygen species and Ca(2+) 'signatures' mediating stress signalling; and (iii) cytosolic K(+) as the common denominator of plant adaptive responses. We discuss in detail how key plasma membrane and tonoplast transporters are regulated by various signalling molecules and processes observed in plants under stress conditions (e.g. changes in membrane potential; cytosolic pH and Ca(2+); reactive oxygen species; polyamines; abscisic acid) and how these stress-induced changes are related to expression and activity of specific ion transporters. The reported results are then discussed in the context of strategies for breeding crops with improved abiotic stress tolerance. We also discuss a classical trade-off between tolerance and yield, and possible avenues for resolving this dilemma.
School of Land and Food, University of Tasmania, Private Bag 54, Hobart, Tas 7001, Australia Sergey.Shabala@utas.edu.au.
Sergey
S
Shabala
School of Land and Food, University of Tasmania, Private Bag 54, Hobart, Tas 7001, Australia ARC Centre of Excellence in Plant Energy Biology, School of Agriculture, Food and Wine, University of Adelaide, PMB 1, Glen Osmond, SA 5064, Australia.
Jayakumar
J
Bose
Department of Plant and Environmental Science, University of Copenhagen, DK-1871 Frederiksberg, Denmark.
Anja Thoe
AT
Fuglsang
School of Land and Food, University of Tasmania, Private Bag 54, Hobart, Tas 7001, Australia Centro Universitario de Investigaciones Biomédicas, Universidad de Colima, 28045 Colima, México.
Igor
I
Pottosin
D000222:Adaptation, Physiological; D055864:Droughts; D055868:Floods; D026901:Membrane Transport Proteins / Q000235:genetics* / Q000378:metabolism; D018521:Plant Physiological Phenomena; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D054712:Salinity
D026901:Membrane Transport Proteins; D010940:Plant Proteins
Breeding; H+-ATPase; NAPHX oxidase; drought; exchangers; flooding; ion channels; membrane potential; potassium homeostasis; pumps; pyrophosphatase; reactive oxygen species; salinity; voltage gating.