Abstract Garberoglio, M. J.; G. E. González, M. A. Kryvenki & A. M. Gottlieb. 2023. Genome size variation of southern South American species of Ilex (Aquifoliaceae). Darwiniana, nueva serie 11(1): 167-179. The genus Ilex (Aquifoliaceae) has several species appreciated by their ornamental value and nutraceutical and medicinal properties. Southern South America is a major center of biodiversity, with ca. 13-15 species. However, they have been scarcely studied, particularly regarding cytogenetics. For instance, chromosome numbers have been solely documented in eight species, while the DNA content (genome size or 2C-value) has been recorded just for three species. To contribute to the characterization of Ilex species from southern South America, here we established the genome size of I. brasiliensis, I. brevicuspis, I. integerrima, I. microdonta, I. pseudobuxus, I. taubertiana and I. theezans as novel data, and verified the DNA content for I. argentina, I. dumosa and I. paraguariensis. Our results indicate that the mean DNA content at the interspecific level ranges between 1.691 pg, as in I. pseudobuxus and 3.600 pg as in I. theezans. Yet, an individual of I. theezans from Paraguay showed about half the genome size. These unexpected outcomes for I. theezans lead us to propose the coexistence of diploid and polyploid cytotypes for this species. I. brasiliensis was determined to have 2n=40 chromosomes and regular meiosis, for the first time. In sum, this work is a contribution to the knowledge of an understudied plant family. Gaining insight on genetic biodiversity is relevant for the potential use of non-industrialized species for the improvement of economically significant ones.

Resumen Garberoglio, M. J.; G. E. González, M. A. Kryvenki & A. M. Gottlieb. 2023. Variación en el tamaño del genoma de especies de Ilex (Aquifoliaceae) del sur de Sudamérica. Darwiniana, nueva serie 11(1): 167-179. El género Ilex (Aquifoliaceae) posee especies muy apreciadas por su valor ornamental y sus propiedades nutracéuticas y medicinales. El sur de Sudamérica es un importante centro de diversificación, con ca. 13-15 especies registradas. Sin embargo, estas han sido escasamente estudiadas, particularmente en lo que respecta a la citogenética. Por ejemplo, el número de cromosomas se ha documentado únicamente en ocho especies, mientras que el contenido de ADN (tamaño del genoma o valor 2C) se ha reportado solo en tres especies. Para contribuir a la caracterización de las especies de Ilex del sur de Sudamérica, en el presente estudio se determinó el tamaño del genoma de I. brasiliensis, I. brevicuspis, I. integerrima, I. microdonta, I. pseudobuxus, I. taubertiana e I. theezans, siendo estos datos novedosos, y se verificó el valor 2C para I. argentina, I. dumosa e I. paraguariensis. Nuestros resultados indican que el contenido promedio de ADN a nivel interespecífico oscila entre 1,691 pg, como en I. pseudobuxus, y 3,600 pg como en I. theezans. Sin embargo, para un individuo de I. theezans de Paraguay se obtuvo un valor 2C de aproximadamente la mitad. Estos resultados inesperados para I. theezans nos llevan a proponer la coexistencia de citotipos diploides y poliploides en esta especie. Además, se determinó por primera vez el número cromosómico de I. brasiliensis (2n=40) y se observó que la meiosis es regular. En suma, este trabajo contribuye al conocimiento de una familia de plantas poco estudiada. Conocer la biodiversidad genética en Ilex es básico para el potencial uso de las especies no industrializadas en el mejoramiento de las de importancia económica.

Abstract: Cyclodextrin glycosyltransferases (CGTases) are important enzymes in the biotechnology field because they catalyze starch conversion into cyclodextrins and linear oligosaccharides, which are used in food, pharmaceutical and cosmetic industries. The CGTases are classified according to their product specificity in α-, β-, α/β- and γ-CGTases. As molecular markers are the preferred tool for bacterial identification, we employed six molecular markers (16S rRNA, dnaK, gyrB, recA, rpoB and tufA) to test the identification of a CGTase-producing bacterial strain (DF 9R) in a phylogenetic context. In addition, we assessed the phylogenetic relationship of CGTases along bacterial evolution. The results obtained here allowed us to identify the strain DF 9R as Paenibacillus barengoltzii, and to unveil a complex origin for CGTase types during archaeal and bacterial evolution. We postulate that the α-CGTase activity represents the ancestral type, and that the γ-activity may have derived from β-CGTases.

Pathogens within the Diaporthe complex cause seed decay, stem blight and stem canker on soybean, representing a serious threat for this crop species. We herein utilize worldwide sequence data retrieved from Genbank in order to assess the species boundaries between the soybean stem canker causal agents, and define whether or not they should be regarded as members of the same biological species. These studies were complemented with compatibility tests, in order to validate our findings from a biological standpoint. Species delimitation assays supported the occurrence of a speciation event between D. caulivora and D. phaseolourm var. meridionalis. A speciation hypothesis between D. aspalathi and D. phaseolourm var. meridionalis was also supported, based on three reciprocally monophyletic substitutions at locus EF1-α. Compatibility tests further validated species delimitation assays indicating that D. caulivora has developed barriers to gene exchange with D. phaseolorum var. meridionalis. Clarification of the specific boundaries of the SSC pathogens and related entities will be an important asset to future research in soybean pathology, epidemiology and breeding.