A strong association is implicit between mitochondrial function and the energy demands of cells responding to stress. Yet, the dynamics of this organelle-cellular dependency have been difficult to resolve. This study examines a new diagnostic parameter namely, mitochondrial maintenance and self-restoration as exhibited by the course of respiratory functions (states 3 and 4 respiratory rates, respiratory control) of mitochoudria extracted during and after exposure of intact `Hass' avocado (Persea americana) fruit to different stress atmospheres: anoxia (100% N2) or high (25% and 75%) CO2 for varying durations. Comparisons are made with direct exposure of the mitochondria themselves to similar atmospheres. In general, exposure of the fruit to CO2 rich atmospheres enhanced the capacity of their mitochondria to restore energy-linked functions whereas anoxia caused irreparable damage. The physiological (climacteric) state of the fruit also affected the stress capacity of the mitochondria contained therein, anaerobiosis being more harmful to mitochondria in riper fruit. In contrast to their effects in vivo, in vitro anoxia appeared to sustain mitochondrial energy-linked functions, whereas high CO2 was clearly harmful. These and other observations are discussed in the context of mitochondrial self-restoration or homeostasis and its relevance to postharvest stress-atmosphere storage for purposes such as pathogen suppression or insect control.
My aim in this brief presentation is to illustrate how the interplay of senescence and homoeostasis can offer a context within which to question and, in part, explain various postharvest phenomena. I should like to begin by briefly noting the status of principal phenomena and related paradigms that have influenced postharvest research, namely the respiratory climacteric, ethylene, and molecular (genetic) determinants.
potassium homeostasis in the cytoplasm is vital to avoid sodium toxicity and maintain cells with normal metabolism and functioning ( Shabala and Pottosin, 2014 ). In this study, the higher K + content in leaves compared with roots could be due to a
In an attempt to analyze genetically the interaction of endogenous auxin concentration and adventitious root formation, an EMS mutagenized M2 population of Arabidopsis thaliana was screened for mutants with altered abilities to form adventitious roots. A selected recessive nuclear mutant, rooty (rty), is characterized by extreme proliferation of roots, inhibition of shoot development and other morphological alterations suggestive of auxin or ethylene effects. The rty phenotype occurs in wild type seedlings grown on auxin containing medium and relatively normal growth is stimulated in rty seedlings growing on cytokinin containing medium. Analysis by GC-MS found that endogenous IAA concentrations in rty are 2 to 17 times higher than in wild type depending on tissue type and IAA form. Dose response experiments with IAA and NAA indicated that rty does not express increased sensitivity to auxin. These data suggest that the rty phenotype is due to elevated endogenous auxin. A genetic map location for rty and possible roles for the wild type RTY gene product in regulating auxin concentration will be presented.
micronutrient homeostasis (i.e., processes ensuring that the various endogenous environments of cells is such that these metals are maintained within a non-toxic physiological range) during the post-budbreak canopy expansion growth phase of pecan. Either
, enzyme activities, and AsA-GSH-controlled redox homeostasis In B. semperflorens , the activities of antioxidant enzymes, including SOD, CAT, APX, MDHAR, DHAR, and GR, were unaffected by DMTU treatment, while they were increased under LT conditions ( Fig
a new redox homeostasis under the stress condition ( Foyer and Noctor, 2005 ). Proteomic studies have identified several proteins associated with plant tissue responses at low temperature; they are involved in several processes, including signal
of plant salt tolerance through its role in ion homeostasis and Na + /K + discrimination under salinity conditions ( Hamdia and Shaddad, 2010 ). It has been shown that a low concentration of exogenous GB is very efficient in reducing the K + loss in
-Cortines, M. 2010 Validation of reference genes for quantitative real-time PCR during leaf and flower development in Petunia hybrida BMC Plant Biol. 10 1 11 Miller, G. Suzuki, N. Ciftci-Yilmaz, S. Mittler, R. 2010 Reactive oxygen species homeostasis and
stress. Overall, NO has the positive effect of maintaining ion homeostasis in bermudagrass subjected to high salinity. However, why K and Ca content showed same changing trends when treated with SNP or PTIO plus L-NAME under normal situation remains