RESUMO
False shamrock (Oxalis triangularis), native to South America, is an ornamental and popular plant bulb, commercialized for their attractive shape and color (purple triangular leaves) (Taha et al., 2013). In Chile, a rust was detected in O. triangularis plants growing from April to June in several gardens (n=10) in the city of Valdivia, estimating a disease incidence between 80 and 100%. The symptoms appeared as diffuse chlorotic spots from the upperside of leaves, where infected tissues eventually become completely necrotic, and yellow rust pustules were observed on the underside of leaves. Severe symptoms on infected leaves were consistently observed, showing necrosis on entire leaves. Symptomatic plants (n=50) were collected, and three representative isolates from different localities (OX1, OX2, and OX3) were used for morphological and genetic identification. Uredinia (n=20) were hypophyllous, erumpent, yellow, and irregularly distributed, with sizes from 340 to 850 µm in diameter. Urediniospores (n=150) were yellow, subglobose to globose, equinulate, with measures of 14.2 - 17.7 x 14.7 - 17.2 µm. Teliospores were absent. Based on morphological characters, this rust was identified as a Puccinia sp. These morphological characteristics coincided with those indicated by Safránková (2014), Abbasi et al. (2018), and Khouader et al. (2018). To classify this rust genetically, sequences analyses were performed using the ITS region of the rDNA (ITS4/ITS5) (White et al., 1990). The DNA was extracted using a commercial kit. The results indicated 99% similarity with two reference sequences of P. oxalidis (MH325473 and MH325474) available at GenBank (NCBI http://www.ncbi.nlm.nih.gov/BLAST/). The sequences obtained were deposited in GenBank (ON259085 to ON259087). Based on the maximum parsimony phylogenetic tree, the sequences of Chilean isolates were clustered with those of P. oxalidis references. Pathogenicity tests were conducted using three isolates (OX1 to OX3). Surface disinfection of leaves of O. triangularis (n=36 plants), were performed by spraying 1% NaOCl solution for 1 min. Subsequently, 2 mL of urediniospores suspensions of each isolate (OX1 to OX3) at a concentration of 106 urediniospores/mL, were sprayed with an atomizer on the underside of the leaves of all plants. Urediniospores were obtained following the methodology proposed by Ferrada et al. (2020). Control leaves were disinfested and inoculated with sterile distilled water. Plants of O. triangularis of 90-day-old were incubated in a humid chamber (24°C, 80% HR), with a photoperiod of 12 light /12 dark. At 11 days post-inoculation, all leaves inoculated developed chlorosis spots and pulverulent pustules (averaged 10.9 to 25.4 pustules per leaf), and then at 26 days post-inoculation, affected leaves showed necrotic tissues. The identity of these isolates was confirmed morphologically. The symptoms in the control leaves were negative. To our knowledge, this is the first report of multiple occurrences of the leaf rust disease on gardens of false shamrock caused by P. oxalidis in Valdivia, south of Chile. Previously, P. oxalidis has been reported to cause leaf rust disease in O. triangularis in the Czech Republic (Safránková, 2014) and O. debilis in Korea (Lee et al., 2018). The leaf rust disease could represent a threat to the ornamental gardens of O. triangularis in Valdivia. Currently, epidemiological studies of leaf rust disease are necessary to develop management strategies in gardens of O. triangularis.
RESUMO
Common bean (Phaseolus vulgaris L.) is an important grain legume cultivated worldwide as food for humans and livestock (Schwartz et al., 2005). Common beans in central Chile reach up to 3,893 ha from which 1,069 ha are located in the Maule region. Common bean is produced by small farmers who have limited access to fertilization, technical irrigation, and crop protection. In spring 2018, bean plants initially showed a slight yellowing and premature senescence 50 days after sowing (das) until showing wilting symptoms (70 -100 das) in Curepto fields (35 05'S; 72 01'W), Maule region. The basal part of affected plants displayed internal reddish-brown discoloration of the vascular tissues. Based on the plant external symptoms, we estimated an incidence between 15% and 45% in bean fields. Nine symptomatic plants were collected, and surface washed with sterile water and disinfested with 75% ethanol (v/v). Then small fragments (5-mm) from damage vascular tissue from each plant were cut and placed on Petri dishes containing PDA acidified with 0.5 ml/l of 92% lactic acid (APDA, 2%). The isolations were incubated for seven days at 25°C. Nine Fusarium-like isolates from single-spore on APDA (2%) became pale vinaceous, floccose with abundant aerial mycelium and dark vinaceous reverse colony, with a growing rate of 10.8 to 11.6 mm/d at 25°C (Lombard et al., 2019). Phialides were short, singular growing laterally on the mycelium. Macroconidia were hyaline, fusiform with basal foot cells shaped to pointed and apical cells tapered, 2-5 septate, and 28.6 to 47.6 (av. 38.1) µm long x 2.2 to 3.6 (av. 3.1) µm wide. Microconidia were hyaline, oval to ellipsoid, one-celled, and 4.5 to 10.9 (av. 6.1) µm long and 2.2 to 3.3 (av. 2.7) µm wide (n=50 spore). For molecular identification, three isolates (Curi-3.1, Be-8.1, and Be-11.3) were sequenced using PCR amplification of the partial sequences of beta-tubulin (BT) and translation elongation factor 1-α gene (TEF) (Lombard et al., 2019). NCBI BLAST analysis showed 99 to 100% similarity with sequences (TEF; BT) of strain CPC 25822 of Fusarium oxysporum. The maximum-likelihood phylogenetic analysis placed the Chilean isolates in the F. oxysporum complex clade. Chilean sequences were deposited into GenBank under accession numbers MW419125, MW419126, MW419127 (TEF) and MW419128, MW419129, MW419130 (BT). Pathogenicity tests (isolates Curi-3.1, Be-8.1, and Be-11.3) were conducted under greenhouse (15-28°C, 85%RH) on healthy bean plants (n=30) cv. Blanco Español INIA cultivated in pots (sand/peat moss/soil) at the University of Talca. Plants that are 30 days-old were inoculated using 200 µl of conidial suspension (106 conidia/ml) on wounded roots (crown). Control plants (n=10) were similarly inoculated with sterile distilled water. After 45 days, all inoculated plants with F. oxysporum isolates developed necrotic lesions on vascular tissue, and chlorosis, and wilting while control plants remained healthy. This experiment was conducted twice. The pathogen was reisolated (100%) from diseased plants and molecularly identified as F. oxysporum. To our knowledge, this is the report of a severe outbreak of F. oxysporum causing Fusarium yellows in P. vulgaris in the Maule region, Chile. Previously, F. oxysporum has been reported affecting tomato (Sepúlveda-Chavera et al., 2014) and blueberry in Chile (Moya-Elizondo et al., 2019).
RESUMO
The aim of this study is to evaluate the survival rate and effective antagonistic activity against Botrytis cinerea, responsible for grey mould on harvested fruits and vegetables, of yeast Rhodotorula mucilaginosa, isolated and identified from the natural microbiota of murta (Chilean guava) berries, after spray drying at different inlet air temperatures, mass per volume ratio of encapsulating agent (maltodextrin) and feed flow rates. The 100% survival of the yeast was obtained after spray drying with 18% maltodextrin at 130 °C inlet temperature and a feed flow rate of 9.25 mL/min. The dried yeast obtained under such conditions had the highest antagonistic activity in vitro and in vivo on apples, which showed that spray drying is a valid method to produce active dried cells of R. mucilaginosa that can be used for biocontrol of grey mould spoilage. It was also found that the encapsulating agent maltodextrin improved the in vitro antagonistic activity of R. mucilaginosa.
RESUMO
RESUMEN Fundamento: El cronotipo es un atributo de los seres humanos, que refleja su fase circadiana individual, y repercute en las funciones biológicas y psicológicas, tanto en la salud como en la enfermedad. Su estudio es particularmente valioso en escenarios educacionales. Objetivo: caracterizar el cronotipo de estudiantes universitarios en relación con el tipo de carrera que estudian. Métodos: e realizó un estudio analítico trasversal, en una serie de 273 estudiantes universitarios, seleccionados por muestreo aleatorio simple, estructurados en tres grupos bajo criterio de procedencia: 88 de Ciencias Técnicas, 88 de Ciencias Sociales y Humanísticas y 97 de Ciencias Médicas. Se exploró el cronotipo de cada sujeto por medio del Cuestionario de Matutinidad- Vespertinidad. Para cada grupo fueron calculadas las puntuaciones medias resultantes del cuestionario y las proporciones de individuos matutinos, intermedios y vespertinos. Resultados: las puntuaciones medias de los tres grupos estuvieron enmarcadas en el rango de cronotipo intermedio, y no se constaron diferencias estadísticamente significativas. El 67 % de los sujetos fueron clasificados como intermedios, el 23,8 % como matutinos y el 9,2 % como vespertinos; las proporciones de los cronotipos por grupos tampoco mostraron diferencias significativas. Conclusión: existió un claro predominio del cronotipo intermedio, seguido en frecuencia por el matutino y el vespertino. No se demostró que el tipo de carrera influyera en las puntuaciones, ni en las proporciones de las tipologías circadianas por grupos.
ABSTRACT Foundation: Chronotype is an attribute of human beings, which reflects its individual circadian phase, and affects biological and psychological functions, both in health and disease. Its study is particularly valuable in educational settings. Objective: to characterize the chronotype of university students in relation to the type of career they study. Methods: a cross-sectional analytical study was conducted in a series of 273 university students, selected by simple random sampling, structured in three groups based on provenance criteria: 88 from Technical Sciences, 88 from Social and Humanistic Sciences and 97 from Medical Sciences. The chronotype of each subject was explored through the Morningness and Eveningness Questionnaire. For each group the mean scores of the questionnaire and the proportions of morning, intermediate and evening individuals were calculated. Results: the mean scores of the three groups were framed in the intermediate chronotype range, and there were no statistically significant differences. Subjects were classified as 67% of as intermediate, 23.8% as morning and 9.2 % as evening; chronotype proportions by groups also showed no significant differences. Conclusion: there was a clear predominance of intermediate chronotype, followed in frequency by morning and evening. It was not demonstrated that the type of career influenced scores, nor in proportions of the circadian typologies by groups.
