Detection and Frequency of Lily Viruses in Argentina.

In a survey of lily growing fields in various regions of Argentina, three viruses, Lily symptomless virus (LSV), Lily mottle virus (LMoV), and Cucumber mosaic virus (CMV), were found in Longiflorum, Asiatic, Oriental, Longiflorum × Asiatic (LA), and Oriental × Trumpet (OT) hybrids. The areas surveyed were between latitude 26° 56' S and 43° 03' S, and longitude 65° 21' W and 71° 29' W. Virus detection was performed by double-antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) using polyclonal antiserum. In infected samples, viruses detected in decreasing order were LSV (60.5%), LMoV (51.0%), and CMV (28.7%) present in single or mixed infections. Virus infection varied among tested hybrids from 36.0% (Oriental Montecristo) to 94.7% (Lilium longiflorum Avita) in 2006 and from 38.9% (OT Yelloween) to 82.1% (LO Triumphator) in 2007, with an overall incidence of 64.1 and 70.7% in 2006 and 2007, respectively. A variation in virus incidence among localities was also observed. The highest virus incidence (89.6 and 87.6% in 2006 and 2007, respectively) was observed in Bahía Blanca (38° 44' S, 62° 16' W). The lowest virus incidences, detected in Trevellin (43° 03' S, 71° 29' W) and in Malargüe (35° 28' S, 69° 35' W), were 47.4 and 48.6% in 2006 and 2007, respectively. Moreover, a different distribution of each virus was observed between localities. The high occurrence of viruses infecting lily crops in Argentina could be due to both the use of infected bulbs for propagation and the lack of preventive virus vector control measures.

Agrobacterium rhizogenes vs auxinic induction for in vitro rhizogenesis of Prosopis chilensis and Nothofagus alpina

The induction and improvement of in vitro rhizogenesis of microshoots of Prosopis chilensis (Mol.) Stuntz and Nothofagus alpina (Poep. et Endl. Oerst.) were compared using Agrobacterium rhizogenes (Ar) versus indole-3-butyric acid (IBA) in the culture media. Microshoots of P. chilensis (1-2 cm length), coming from in vitro grown seedlings, were cultivated in a modified Broadleaved Tree Medium (BTMm) containing half salt concentration of macronutrients and 0.05 mg x L(-1) benzilaminopurine (BAP). After 30 days, microshoots with 2-4 leaves were selected and cultured in BTMm-agar in presence or abscense of Ar and in combination with IBA. For N. alpina, the apical shoots with the first 2 true leaves, from 5 weeks old seedlings, were cultured in the abovementioned medium, but with 0.15 mg x L(-1) of BAP. After 2 months, microshoots with 2-3 leaves were selected and cultured in BTMm-agar, supplemented with 5 mg x L(-1) IBA or in liquid BTMm on perlite and, in the presence or absence of A. rhizogenes (Ar) and in combination with 3 mg x L(-1) IBA. Rooting in P. chilensis reached 100.0% when Ar infection was produced in the presence of IBA, increasing both, the number and dry weight of roots. In N. alpina, 90.0% of rooting efficiency was obtained when Ar infection was produced in liquid culture and in the absence of auxin. (AU)

Agrobacterium rhizogenes vs auxinic induction for in vitro rhizogenesis of Prosopis chilensis and Nothofagus alpina

The induction and improvement of in vitro rhizogenesis of microshoots of Prosopis chilensis (Mol.) Stuntz and Nothofagus alpina (Poep. et Endl. Oerst.) were compared using Agrobacterium rhizogenes (Ar) versus indole-3-butyric acid (IBA) in the culture media. Microshoots of P. chilensis (1-2 cm length), coming from in vitro grown seedlings, were cultivated in a modified Broadleaved Tree Medium (BTMm) containing half salt concentration of macronutrients and 0.05 mg x L(-1) benzilaminopurine (BAP). After 30 days, microshoots with 2-4 leaves were selected and cultured in BTMm-agar in presence or abscense of Ar and in combination with IBA. For N. alpina, the apical shoots with the first 2 true leaves, from 5 weeks old seedlings, were cultured in the abovementioned medium, but with 0.15 mg x L(-1) of BAP. After 2 months, microshoots with 2-3 leaves were selected and cultured in BTMm-agar, supplemented with 5 mg x L(-1) IBA or in liquid BTMm on perlite and, in the presence or absence of A. rhizogenes (Ar) and in combination with 3 mg x L(-1) IBA. Rooting in P. chilensis reached 100.0% when Ar infection was produced in the presence of IBA, increasing both, the number and dry weight of roots. In N. alpina, 90.0% of rooting efficiency was obtained when Ar infection was produced in liquid culture and in the absence of auxin.

Growth and productivity of different Pleurotus ostreatus strains on sunflower seed hulls supplemented with N-NH4+ and/or Mn(II).

The mycelial growth rates in lineal growth assay, yield, and production rate of five Pleurotus ostreatus strains were evaluated in response to different levels of Mn(II) and/or NH4+ in a substrate containing sunflower seed hulls as a main energy and nutritional component. Each strain showed different basal values for mycelial growth rate and biological efficiency on sunflower seed-hull substrate. Adding growth limiting mineral nutrients increased the mycelial growth rate by 13-25%. Primordia initiation for the first flush appeared between day 24 and 28 and days to the second crop ranged from 39 to 51. Biological efficiency increased over control values and reached 60-112%, depending on the strain and the concentration of Mn(II) and NH4+. This study demonstrated the advantage of selecting the most productive P. ostreatus strains in a substrate formulated with sunflower seed hulls to provide the main energy and nutritional ingredients and supplemented with Mn(II) and/or NH4+.

Changes in peroxidases associated with radiation-induced sprout inhibition in garlic (Allium satiyum L.).

The effects of an acute dose of gamma-rays (10 Gy) to post-dormant garlic cloves on inner sprout growth and changes in peroxidases and soluble proteins were evaluated up to 100 days of storage in darkness at 19 +/- 1 degree C and 42 +/- 2% relative humidity. Radiation-induced inhibition of sprout growth became evident after 25 days of treatment and was synchronous with a marked increase in peroxidase activity. Thin-layer isoelectric focusing revealed that radiation induced an increase in the number of anodic peroxidase isoenzymes at 100 days, suggesting modifications in the vascularization process. Neither the soluble protein content nor the protein pattern were affected by irradiation. These results are discussed in terms of a possible mediating effect of peroxidase on radiation-induced sprout inhibition in garlic.

Epicuticular wax and water stress in Eragrostis curvala cultivars: I. Morphology and distribution

Se estudió la ultraestructura de la superficie foliar en seis cultivares de pasto llorón, Eragrostis curvula (Schrader) Nees, de diferente grado de tolerancia a la sequía. Mediante microscopía eletrónica de barrido se observó que los cultivares más tolerantes a dicho factor ambiental poseen una capa cerosa apicuticular abaxial más gruesa y compleja que los susceptibles. Por gravimetría se determinó también que en estos cultivares más tolerantes la cantidad total de cera es mayor. Se discute la relación entre la cantidad y distribución de la cera epicuticular y la resistencia a la sequía en esta especie

Epicuticular wax and water stress in Eragrostis curvula cultivars: II. Effect of water stress on the quantity and morphology of epicuticular wax

Se estudió el efecto del déficit hídrico sobre la cantidad, morfología y distribución de la cera epicuticular en dos cultivares de pasto llorón de diferente grado de tolerancia a la sequía. Mediante gravimetría y microscopía electrónica de barrido se encontró que la cantidad de cera epicuticular foliar aumentó luego que las plantas fueron sometidas a un régimen de sequía. Sin embargo, el contenido de cera epicuticular en plantas normalmente regadas de este cultivar es menor que en aquellas pertenecientes al cv. Don Eduardo, más resistentes al estrés hídrico. También se observó un cambio en la morfología de los cristales de cera en tal situación

Ultrastructural evidence of abscisic acid binding sites in guard cells of Vicia faba

Se presenta el uso de una técnica citoquímica que utiliza anticuerpo contra ácido abscísico (ABA) unido al complejo peroxidasa-antiperoxidasa (PAP) por globulina de oveja anti-conejo, para localizar sitios de unión de ABA a nivel de la membrana plasmática, mediante microscopía electrónica. La identificación de las características moléculas cíclicas de PAP confirma, en alta resolución, la tinción específica en secciones ultrafinas, a lo largo de la membrana plasmática de protoplastos de células estomáticas de Vicia faba. La intensidad de la tinción inmunocitoquímica sobre la membrana plasmática que enfrenta al apoplasto fue mayor en especímenes incubados con ABA 10**4 M, así como en aquellos sometidos a estrés hídrico, en comparación con los controles. Mediante el uso de este método sensible, se presenta evidencia ultraestructural del hipotético sitio de acción del ABA en las células estomáticas

Epicuticular wax and water stress in Eragrostis curvala cultivars: I. Morphology and distribution

Se estudió la ultraestructura de la superficie foliar en seis cultivares de pasto llorón, Eragrostis curvula (Schrader) Nees, de diferente grado de tolerancia a la sequía. Mediante microscopía eletrónica de barrido se observó que los cultivares más tolerantes a dicho factor ambiental poseen una capa cerosa apicuticular abaxial más gruesa y compleja que los susceptibles. Por gravimetría se determinó también que en estos cultivares más tolerantes la cantidad total de cera es mayor. Se discute la relación entre la cantidad y distribución de la cera epicuticular y la resistencia a la sequía en esta especie (AU)

Epicuticular wax and water stress in Eragrostis curvula cultivars: II. Effect of water stress on the quantity and morphology of epicuticular wax

Se estudió el efecto del déficit hídrico sobre la cantidad, morfología y distribución de la cera epicuticular en dos cultivares de pasto llorón de diferente grado de tolerancia a la sequía. Mediante gravimetría y microscopía electrónica de barrido se encontró que la cantidad de cera epicuticular foliar aumentó luego que las plantas fueron sometidas a un régimen de sequía. Sin embargo, el contenido de cera epicuticular en plantas normalmente regadas de este cultivar es menor que en aquellas pertenecientes al cv. Don Eduardo, más resistentes al estrés hídrico. También se observó un cambio en la morfología de los cristales de cera en tal situación (AU)

Ultrastructural evidence of abscisic acid binding sites in guard cells of Vicia faba

Se presenta el uso de una técnica citoquímica que utiliza anticuerpo contra ácido abscísico (ABA) unido al complejo peroxidasa-antiperoxidasa (PAP) por globulina de oveja anti-conejo, para localizar sitios de unión de ABA a nivel de la membrana plasmática, mediante microscopía electrónica. La identificación de las características moléculas cíclicas de PAP confirma, en alta resolución, la tinción específica en secciones ultrafinas, a lo largo de la membrana plasmática de protoplastos de células estomáticas de Vicia faba. La intensidad de la tinción inmunocitoquímica sobre la membrana plasmática que enfrenta al apoplasto fue mayor en especímenes incubados con ABA 10**4 M, así como en aquellos sometidos a estrés hídrico, en comparación con los controles. Mediante el uso de este método sensible, se presenta evidencia ultraestructural del hipotético sitio de acción del ABA en las células estomáticas (AU)