Abstract
Cold stress is a significant environmental factor that negatively affects plant growth and development in particular when it occurs during the growth phase. Plants have evolved means to protect themselves from damage caused by chilling or freezing temperatures and some plant species, in particular those from temperate geographical zones, can increase their basal level of freezing tolerance in a process termed cold acclimation. Cold acclimation improves plant survival, but also represses growth, since it inhibits activity of the growth-promoting hormones gibberellins (GAs). In addition to GAs, the steroid hormones brassinosteroids (BRs) also take part in growth promotion and cold stress signaling; however, in contrast to Gas, BRs can improve cold stress tolerance with fewer trade-offs in terms of growth and yields. Here we summarize our current understanding of the roles of BRs in cold stress responses with a focus on freezing tolerance and cold acclimation pathways.
Highlights
Cold stress represents a substantial risk for plant growth and development and impacts on plant distribution and crop production
Plants are most susceptible to frost during periods of active vegetative and reproductive growth, since growing, hydrated tissues are especially vulnerable to injury caused by freezing of cellular fluids (Nishiyama, 1995)
It can be assumed that the activation of cold responsive (COR) genes enables chilling stress protection and cold acclimation for increased freezing tolerance in capable plant species, many of the described physiological events that take place when cold stress occurs have not been linked to up-stream signaling cascades as yet, and the sequence of events following cold stress exposure is often unclear
Summary
Cold stress represents a substantial risk for plant growth and development and impacts on plant distribution and crop production. A reduction of GA levels and signaling activity contributes to restraint growth and enhances plant tolerance to several abiotic stress types including cold, drought, and osmotic stress (Achard et al, 2006, 2008; Magome et al, 2008).
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