Phenotyping of barley (Hordeum vulgare) responses to spot blotch caused by different isolates of the fungus Cochliobolus sativus

Barley is one of the major crops in the world, and spot blotch, caused by the fungus Cochliobolus sativus, is an important disease that affects it. Spot blotch can cause major yield losses and reduce the quality of the seeds, especially in wet, warm climates. The pathogen can also infect the roots of barley plants, causing common root rot. Due to climate change and the spread of the pathogen through modern transportation, the risk of yield losses due to spot blotch has been increasing. Cochliobolus sativus is a hemibiotrophic fungus that is usually found in nature in its asexual form (Bipolaris sorokiniana). I used the tape method, a so far little used technique for testing resistance, to try to find good sources of resistance to C. sativus in barley. The tested lines were provided by Nordic breeders, who previously tested them under standard field and greenhouse conditions. Different fungal isolates that had been isolated from different locations in Sweden were used in this experiment. The lesions were later scored with a 1-9 scale, and the plants were classified as resistant, moderately resistant, moderately susceptible, or susceptible to a certain fungal isolate. It was found that there is a significant barley genotype-fungal isolate interaction, which means that barley lines may respond differently to each fungal isolate. The barley lines suggested as resistance sources were resistant or moderately resistant to all three fungal isolates. The barley lines coded as PPP112, PPP201, PPP206, PPP207, PPP250, PPP252, PPP260, PPP265, PPP269, PPP272 and PPP274 are the genotypes thus identified as potential resistance sources for breeding. I found that there is a positive correlation between lesions in the leaves with diffuse necrotic reactions and gray spots and fungal aggressiveness, suggesting possible mechanisms of infection that could be studied further. In the end, I could not compare the results from the tape method with the results provided by breeders, since the fungal isolates used in these experiments were too different. SLU, Swedis

Fenotipado radicular para la resistencia a la sequía en Solanum spp

[ES] La sequía es un gran problema para la agricultura, ya que destruye o merma considerablemente las cosechas. Por eso la mejora genética de las plantas para la tolerancia a sequía es una necesidad acuciante. Para mejorar las plantas genéticamente, es necesario tener herramientas de fenotipado adecuadas para poder identificar las plantas con las características deseadas. La berenjena cultivada es una planta que es bastante tolerante a la sequía, y posee una gran variedad de especies relacionadas que podrían ser interesantes para introgresar más genes de tolerancia al estrés hídrico. Desarrollar un buen protocolo para el fenotipado de las raíces podría ayudar a seleccionar plantas resistentes a sequía. A la hora de fenotipar ha sido un problema el que tanto la berenjena como las especies silvestres relacionadas presentan problemas de germinación o de latencia. Por este motivo los objetivos de este trabajo fueron: a) desarrollar un protocolo de germinación rápida para la berenjena y sus especies relacionadas y b) desarrollar un protocolo de evaluación de los sistemas radiculares en planta joven in vitro en condiciones de estrés y c) estudiar los sistemas radiculares de la berenjena y otras especies relacionadas en condicionesde estrés. Para obtener un protocolo optimizado de germinación se planteó un diseño ortogonal donde se probaron combinaciones de diferentes tratamientos (sumergir las semillas en agua, luz, calor, oscuridad, aplicación de GA3 o KNO3) que en la literatura se describen como positivos para la germinación. Se utilizaron tanto semillas jóvenes con latencia (menos de un año tras la recolección del fruto) y viejas (sin latencia). Los resultados mostraron los valores positivos para la germinación de semillas jóvenes de sumergir las semillas en agua, aplicar KNO3 y dejarlas a la luz. Se observó también que la lejía a la concentración utilizada (al 30%) es muy dañina para las semillas. Por otro lado se observó que las semillas viejas y jóvenes respondieron de forma diferente a los tratamientos, probablemente debido a la presencia de factores de latencia en las últimas. La técnica empleada para el fenotipado de las raíces fue crecer las plantas en placas mediante cultivo in vitro. Esta técnica permite estudiar la arquitectura de las raíces en la planta joven y aplicar distintos tratamientos. En nuestro caso utilizamos dos tratamientos: uno control y otro con polietilienglicol que simulaba el estrés hídrico. Aunque por problemas en la germinación no pudimos evaluar todos los genotipos planteados en el experimento, los resultados mostraron que existen diferencias en la arquitectura radicular de la berenjena y sus especies relacionadas, dando lugar a respuestas adaptativas de la raíz al estrés hídrico.[EN] Drought is a very important problem for modern crops, because it destroys or significantly reduces them, even when modern irrigation technology is used. That's why genetic breeding of plants for tolerance to drought is vital. But in order to do the breeding, it is crucial to have the right phenotyping tools that would help to identify the plants with the desired characteristic. The cultivated eggplant is quite tolerant to drought, and has a great variety of related species that could be used to introgress genes for water stress tolerance. Developing a good protocol for the phenotyping of the roots could help in the backcrossing program. While phenotuping the roots, the problem of the poor germination of the seeds of wild species and the eggplant hybrids was encountered. That is why the objectives of this wor include a) developing a protocol for the rapid germination of the eggplant and its related specied; b) developing a protocol to evaluate the root I architecture of the young plant in vitro in stress conditions; and c) studying the root system of the eggplant and related species in stress conditions. To develop a protocol for seed germination, an orthogonal array design was done, and it included eight combinations of the treatments (imbibition with water, light, heat, applying GA3 and KNO3). Young, dormant seeds (less than a year old) and old, non dormant seeds were used. The treatments that were proved to have a positive effect on the germination of young seeds were submerging them with water and applying KNO3, as well as leaving them under the light. Bleach, which is used for the disinfection of the seeds for in vitro, was found to be very harmful for the seeds at the concentration that was used (30%). Young and old seeds responded differently to the treatment, because of the dormancy of the young seeds. The technique used to phenotype the roots was growing them on plates in in vitro culture. This technique lets us study the architecture of the roots of young plants, applying different treatments. Two treatments were used: a control one and a water stress one, simulated by polyethylene glycol. And, although due to problems in germination not all the genotypes could not be evaluated, results showed the differences in the root architecture of the eggplants and the related species, proving the existence of adaptation to water stress.Atucha Zamkova, A. (2015). Fenotipado radicular para la resistencia a la sequía en Solanum spp. http://hdl.handle.net/10251/54301

Methods for Measuring Frost Tolerance of Conifers: A Systematic Map

Frost tolerance is the ability of plants to withstand freezing temperatures without unrecoverable damage. Measuring frost tolerance involves various steps, each of which will vary depending on the objectives of the study. This systematic map takes an overall view of the literature that uses frost tolerance measuring techniques in gymnosperms, focusing mainly on conifers. Many different techniques have been used for testing, and there has been little change in methodology since 2000. The gold standard remains the field observation study, which, due to its cost, is frequently substituted by other techniques. Closed enclosure freezing tests (all non-field freezing tests) are done using various types of equipment for inducing artificial freezing. An examination of the literature indicates that several factors have to be controlled in order to measure frost tolerance in a manner similar to observation in a field study. Equipment that allows controlling the freezing rate, frost exposure time and thawing rate would obtain results closer to field studies. Other important factors in study design are the number of test temperatures used, the range of temperatures selected and the decrements between the temperatures, which should be selected based on expected frost tolerance of the tissue and species