Sensitivity of flowering plant gametophytes to temperature fluctuations

Research on plant responses to temperature stress is receiving increased interest due to the growing awareness about global warming. High and low temperature stresses help establish the narrow geographic distribution of some cultivated plants, the limited geographic extension of some other economically nutritionally important species, and also induce irregular bearing for some species. However, the understanding of plant responses to temperature stress lags behind other biotic and abiotic stresses probably due to the complex response at the molecular, cellular, and organismal level. Temperature stress affects, indeed, many developmental processes during the plant's life cycle. However, the reproductive stage, the outcome of which represents the economic value for many cultivated plants, is especially vulnerable. Here the effect of low and high temperature stresses during the flowering phase is reviewed in flowering plants in an attempt to unravel sensitive stages that are behind irregular cropping. The review presents detailed findings from 33 previously published reports spanning 19 different flowering plant species. Both the male and female organs of the flower are especially sensitive to temperature fluctuations both during their development before pollination and during the post-pollination stage. The effect of temperature stress is, however, obscured by the complex male female interaction superimposed on the individual behavior of each organ. Interestingly, a review of the literature on this topic shows that genetic variation does exist in reproductive behavior under temperature fluctuations. This genetic diversity must be preserved and characterized in further detail to understand how plants naturally cope with changing environmental conditions, which will, undoubtedly, help us to design better strategies to face current and future challenging temperature fluctuations. (C) 2011 Elsevier B.V. All rights reserved.