Physiological and Genetic Modifications Induced by Plant-Growth-Promoting Rhizobacteria (PGPR) in Tomato Plants under Moderate Water Stress.

Physiological, metabolic, and genetic changes produced by two plant growth promoting rhizobacteria (PGPR) Pseudomonas sp. (internal code of the laboratory: N 5.12 and N 21.24) inoculated in tomato plants subjected to moderate water stress (10% polyethylene glycol-6000; PEG) were studied. Photosynthesis efficiency, photosynthetic pigments, compatible osmolytes, reactive oxygen species (ROS) scavenging enzymes activities, oxidative stress level and expression of genes related to abscisic acid synthesis (ABA; 9-cis-epoxycarotenoid dioxygenase NCDE1 gene), proline synthesis (Pyrroline-5-carboxylate synthase P5CS gene), and plasma membrane ATPase (PM ATPase gene) were measured. Photosynthetic efficiency was compromised by PEG, but bacterial-inoculated plants reversed the effects: while N5.12 increased carbon fixation (37.5%) maintaining transpiration, N21.24 increased both (14.2% and 31%), negatively affecting stomatal closure, despite the enhanced expression of NCDE1 and plasma membrane ATPase genes, evidencing the activation of different adaptive mechanisms. Among all parameters evaluated, photosynthetic pigments and antioxidant enzymes guaiacol peroxidase (GPX) and ascorbate peroxidase (APX) responded differently to both strains. N 5.12 increased photosynthetic pigments (70% chlorophyll a, 69% chlorophyll b, and 65% carotenoids), proline (33%), glycine betaine (4.3%), and phenolic compounds (21.5%) to a greater extent, thereby decreasing oxidative stress (12.5% in Malondialdehyde, MDA). Both bacteria have highly beneficial effects on tomato plants subjected to moderate water stress, improving their physiological state. The use of these bacteria in agricultural production systems could reduce the amount of water for agricultural irrigation without having a negative impact on food production.

Cultivar and Metal-Specific Effects of Endophytic Bacteria in Helianthus tuberosus Exposed to Cd and Zn.

Plant growth promoting endophytic bacteria (PGPB) isolated from Brassica napus were inoculated in two cultivars of Helianthus tuberosus (VR and D19) growing on sand supplemented with 0.1 mM Cd or 1 mM Zn. Plant growth, concentrations of metals and thiobarbituric acid (TBA) reactive compounds were determined. Colonization of roots of H. tuberosus D19 by Pseudomonas sp. 262 was evaluated using confocal laser scanning microscopy. Pseudomonas sp. 228, Serratia sp. 246 and Pseudomonas sp. 262 significantly enhanced growth of H. tuberosus D19 exposed to Cd or Zn. Pseudomonas sp. 228 significantly increased Cd concentrations in roots. Serratia sp. 246, and Pseudomonas sp. 256 and 228 resulted in significantly decreased contents of TBA reactive compounds in roots of Zn exposed D19 plants. Growth improvement and decrease of metal-induced stress were more pronounced in D19 than in VR. Pseudomonas sp. 262-green fluorescent protein (GFP) colonized the root epidermis/exodermis and also inside root hairs, indicating that an endophytic interaction was established. H. tuberosus D19 inoculated with Pseudomonas sp. 228, Serratia sp. 246 and Pseudomonas sp. 262 holds promise for sustainable biomass production in combination with phytoremediation on Cd and Zn contaminated soils.

Characterization of bacterial communities associated with Brassica napus L. growing on a Zn-contaminated soil and their effects on root growth.

The interaction between plant growth-promoting bacteria (PGPB) and plants can enhance biomass production and metal tolerance of the host plants. This work aimed at isolating and characterizing the cultivable bacterial community associated with Brassica napus growing on a Zn-contaminated site, for selecting cultivable PGPB that might enhance biomass production and metal tolerance of energy crops. The effects of some of these bacterial strains on root growth of B. napus exposed to increasing Zn and Cd concentrations were assessed. A total of 426 morphologically different bacterial strains were isolated from the soil, the rhizosphere, and the roots and stems of B. napus. The diversity of the isolated bacterial populations was similar in rhizosphere and roots, but lower in soil and stem compartments. Burkoholderia, Alcaligenes, Agrococcus, Polaromonas, Stenotrophomonas, Serratia, Microbacterium, and Caulobacter were found as root endophytes exclusively. The inoculation of seeds with Pseudomonas sp. strains 228 and 256, and Serratia sp. strain 246 facilitated the root development of B. napus at 1,000 µM Zn. Arthrobacter sp. strain 222, Serratia sp. strain 246, and Pseudomonas sp. 228 and 262 increased the root length at 300 µM Cd.

Is the butterfly Tomares ballus (Lepidoptera: Lycaenidae) a potential pest of Lens culinaris (Leguminosae)?

The lentil (Lens culinaris) is identified as a new host plant of the lepidopteran Tomares ballus. Five larvae of T. ballus were found on 19 May, 2007 in a crop of "castellana" lentils in Toledo Province, Spain and reared in the laboratory. The larval brown spiracles are slightly darker than the rest of the pupa. Traditional cultural practices reduce the insect's probability of completing its life-cycle. We present flight phenology data for T. ballus from the unedited Atlamar database (1,073 records from 1887 to 2003), based on the 438 records for which the year, month and day are known. This period coincides with the flowering and formation of the legumes of various species of leguminosae, such as lentils. The peak activity of the imagos occurs in the second half of March and the first half of April, and the last larvae must be present in the field until the beginning of June.

Is the butterfly Tomares ballus (Lepidoptera: Lycaenidae) a potential pest of Lens culinaris (Leguminosae)?

The lentil (Lens culinaris) is identified as a new host plant of the lepidopteran Tomares ballus. Five larvae of T. ballus were found on 19 May, 2007 in a crop of "castellana" lentils in Toledo Province, Spain and reared in the laboratory. The larval brown spiracles are slightly darker than the rest of the pupa. Traditional cultural practices reduce the insect’s probability of completing its life-cycle. We present flight phenology data for T. ballus from the unedited Atlamar database (1 073 records from 1887 to 2003), based on the 438 records for which the year, month and day are known. This period coincides with the flowering and formation of the legumes of various species of leguminosae, such as lentils. The peak activity of the imagos occurs in the second half of March and the first half of April, and the last larvae must be present in the field until the beginning of June. Rev. Biol. Trop. 57 (3): 623-634. Epub 2009 September 30.

La lenteja (Lens culinaris) es una nueva planta hospedera de la mariposa Tomares ballus. Hallamos cinco larvas el 19 de mayo de 2007 en un cultivo de lentejas de la variedad "castellana" en la provincia de Toledo, España y las criamos en el laboratorio. Los espiráculos, de color marrón, son ligeramente más oscuros que el resto de la pupa. Las prácticas culturales tradicionales reducen al insecto la probabilidad de completar su ciclo de vida. Se presenta la fenología de datos de vuelo para T. ballus a partir de la base de datos Atlamar (1 073 registros de 1887 a 2003), sobre la base de los 438 registros en que se conocen año, mes y día. Este período coincide con la floración de diversas especies de leguminosas, incluyendo las lentejas. El pico de actividad de los imagos se produce en la segunda quincena de marzo y la primera quincena de abril, y las últimas larvas deben estar presentes en el campo hasta principios de junio.