Antisense-mediated S-adenosyl-L-methionine decarboxylase silencing affects heat stress responses of tobacco plants.

Understanding the molecular mode(s) of plant tolerance to heat stress (HS) is crucial since HS is a potential threat to sustainable agriculture and global crop production. Polyamines (PAs) seem to exert multifaceted effects in plant growth and development and responses to abiotic and biotic stresses, presumably via their homeostasis, chemical interactions and contribution to hydrogen peroxide (H2O2) cellular 'signatures'. Downregulation of the apoplastic POLYAMINE OXIDASE (PAO) gene improved thermotolerance in tobacco (Nicotiana tabacum L.

Underexpression of apoplastic polyamine oxidase improves thermotolerance in Nicotiana tabacum.

Polyamines (PAs) and hydrogen peroxide (HO), the product of PA oxidation by polyamine oxidase (PAO), are potential players affecting plant growth, development and responses to abiotic/biotic stresses. Genetically modified Nicotiana tabacum plants with altered PA/HO homeostasis due to over/underexpression of the ZmPAO gene (S-ZmPAO/AS-ZmPAO, respectively) were assessed under heat stress (HS). Underexpression of ZmPAO correlates with increased thermotolerance of the photosynthetic machinery and improved biomass accumulation, accompanied by enhanced levels of the enzymatic and non-enzymatic antioxidants, whereas ZmPAO overexpressors exhibit significant impairment of thermotolerance.

Deregulation of apoplastic polyamine oxidase affects development and salt response of tobacco plants.

Polyamine (PA) homeostasis is associated with plant development, growth and responses to biotic/abiotic stresses. Apoplastic PA oxidase (PAO) catalyzes the oxidation of PAs contributing to cellular homeostasis of reactive oxygen species (ROS) and PAs. In tobacco, PAs decrease with plant age, while apoplastic PAO activity increases.

Silencing S-Adenosyl-L-Methionine Decarboxylase (SAMDC) in Nicotiana tabacum Points at a Polyamine-Dependent Trade-Off between Growth and Tolerance Responses.

Polyamines (PAs) are nitrogenous molecules that are indispensable for cell viability and with an agreed-on role in the modulation of stress responses. Tobacco plants with downregulated SAMDC (AS-SAMDC) exhibit reduced PAs synthesis but normal levels of PA catabolism. We used AS-SAMDC to increase our understanding on the role of PAs in stress responses.

Exploring biodiversity in the bacterial community of the Mediterranean phyllosphere and its relationship with airborne bacteria.

We studied the structure and diversity of the phyllosphere bacterial community of a Mediterranean ecosystem, in summer, the most stressful season in this environment. To this aim, we selected nine dominant perennial species, namely Arbutus unedo, Cistus incanus, Lavandula stoechas, Myrtus communis, Phillyrea latifolia, Pistacia lentiscus, Quercus coccifera (woody), Calamintha nepeta, and Melissa officinalis (herbaceous). We also examined the extent to which airborne bacteria resemble the epiphytic ones.