Carboxylates, such as malate and citrate, are widely acknowledged to have a central role in plant metabolism. They are involved in the production of energy and its storage as well as contributing to the cellular osmolyte pool and participating in the regulation of cellular pH. As we discuss here, recent research has demonstrated the functional importance of carboxylate excretion into the soil, ...

Stomata are adjustable pores in the plant epidermis that regulate gas exchange between the plant and atmosphere; they are present on the aerial portions of most higher plants. Genetic pathways controlling stomatal development and distribution have been described in some detail for one dicot species, Arabidopsis, in which three paralogous bHLH transcription factors, FAMA, MUTE and SPCH, control ...

The hypothesis of optimal stomatal conductance predicts conductance should vary with changes of the vapor pressure difference between leaf and air (VPD) to keep the partial derivative of transpiration rate (E) with respect to assimilation rate (A) constant ( partial differentialE/ partial differentialA = lambda). Stomatal conductance of Amaranthus powellii Wats. decreased strongly with increasi...

Evidence suggests that heavy-metal tolerance can be induced in plants following pre-treatment with non-toxic metal concentrations, but the results are still controversial. In the present study, tobacco plants were exposed to increasing Zn2+ concentrations (up to 250 and/or 500 μM ZnSO4) with or without a 1-week acclimation period with 30 μM ZnSO4. Elevated Zn2+ was highly toxic for plants, and ...

A number of studies show that environmental stress conditions such as drought, high salt, and air pollutants increase polyamine levels in plant cells. However, little is understood about the physiological function of elevated polyamine levels. We report here that polyamines regulate the voltage-dependent inward K(+) channel in the plasma membrane of guard cells and modulate stomatal aperture, a...

Microbes trigger stomatal closure through microbe-associated molecular patterns (MAMPs). The bacterial pathogen Pseudomonas syringae pv. tomato (Pst) synthesizes the polyketide toxin coronatine, which inhibits stomatal closure by MAMPs and by the hormone abscisic acid (ABA). The mechanism by which coronatine, a jasmonic acid-isoleucine analog, achieves this effect is not completely clear. React...

End-of-season drought or "terminal drought," which occurs after flowering, is considered the most significant abiotic stress affecting crop yields. Wheat crop production in Mediterranean-type environments is often exposed to terminal drought due to decreasing rainfall and rapid increases in temperature and evapotranspiration during spring when wheat crops enter the reproductive stage. Under suc...

Rising atmospheric [CO2] is associated with increased air temperature, and this warming may drive many rare plant species to extinction. However, to date, studies on the interactive effects of rising [CO2] andwarming have focussed on just a few widely distributed plant species. Wollemi pine (Wollemia nobilisW.G.Jones, K.D.Hill, & J.M.Allen), formerly widespread in Australia, was reduced to a re...

There is a long-standing controversy as to whether drought limits photosynthetic CO2 assimilation through stomatal closure or by metabolic impairment in C3 plants. Comparing results from different studies is difficult due to interspecific differences in the response of photosynthesis to leaf water potential and/or relative water content (RWC), the most commonly used parameters to assess the sev...