Limitation of Nocturnal ATP Import into Chloroplasts Seems to Affect Hormonal Crosstalk, Prime Defense, and Enhance Disease Resistance in Arabidopsis thaliana

Abstract

When grown under short-day conditions at low light, leaves of an Arabidopsis thaliana (accession Col-0) mutant with defects in the two genes encoding plastid ATP/ADP antiporters (so-called ntt1-2 null mutants) display a variety of physiological changes. These include the formation of necrotic lesions and the accumulation of hydrogen peroxide in the leaves. Here, we show that, under short-day conditions, leaves of the ntt1-2 mutant display enhanced resistance to Hyaloperonospora arabidopsidis, Botrytis cinerea, and Pseudomonas syringae pv. tomato DC3000. Resistance to these pathogens was associated with constitutively elevated levels of the plant hormone salicylic acid and, eventually, jasmonic acid, and constitutive or primed activation after pathogen attack of various defense genes that are dependent on these hormones. In addition, the antagonistic crosstalk between the salicylic acid and jasmonic acid signaling pathways seems to be affected in ntt1-2. Because the enhanced resistance of ntt1-2 to H. arabidopsidis was not seen when the mutant was grown under long-day conditions, our findings argue that nocturnal ATP import into chloroplasts is crucial to keep A. thaliana from runaway activation of pathogen resistance.

Potato Annexin STANN1 Promotes Drought Tolerance and Mitigates Light Stress in Transgenic Solanum tuberosum L. Plants

“…In summary, we assume that annexin-mediated protection of chloroplasts from ROS-induced damage is of utmost importance for plant stress resistance and recovery. Chloroplasts host crucial biosynthesis pathways (e.g., of hormones, Car, amino acids, and lipids) and are the site of cross-talk between basic metabolic pathways and stress responses, which places them in a key position with respect to coordination of defense responses [ 93 , 94 ].…”

Salicylic acid and its location in response to biotic and abiotic stress

“…It implies therefore a well-defined communication between the site of perception of such stimuli and the chloroplasts. In particular, the chloroplasts appear to be closely involved in the coordination of defence responses [32]. Research in this field awaits now further attention.…”

Protein Degradation Rate in Arabidopsis thaliana Leaf Growth and Development

“…This leaves chloroplasts dependent on import of respiration-derived ATP for most biosynthetic processes including protein synthesis. The importance of ATP import for chloroplast maintenance is also evident by reports that restriction of ATP import through NTT translocators can lead to dwarf and necrotic leaf phenotypes (Reinhold et al, 2007) and can disrupt hormonal signaling (Schmitz et al, 2010). Our calculations are based on the caveat that respiration is the only net source of ATP available for protein synthesis in plants.…”