The Toluca valley, located in central Mexico, is thought to be the center of origin of the potato late blight pathogen Phytophthora infestans. We characterized over 500 individuals of P. infestans sampled from populations with a geographical distance of more than 400 km in six regions adjacent to the Toluca valley in three states including Michoacán, Mexico, and Tlaxcala. Our sampling occurred on a predominant east to west gradient and showed significant genetic differentiation. The most western sampling location found in Michoacán was most differentiated from the other populations. Populations from San Gerónimo, Juchitepec, and Tlaxcala clustered together and appeared to be in linkage equilibrium. This work provides a finer understanding of gradients of genetic diversity in populations of P. infestans at the center of origin.

This study evaluates the impact of biotic elicitors and hormone regimes on the in vitro establishment, shoot multiplication, and organogenesis of Solanum tuberosum L. cv. Fianna under controlled laboratory conditions. Explants derived from pre-treated tubers were cultured on Murashige and Skoog (MS) medium supplemented with vitamins and varying concentrations of growth regulators or elicitors. Aseptic establishment achieved a high success rate (~95%) using a 6% sodium hypochlorite disinfection protocol. Multiplication was significantly enhanced with a combination of 0.2 mg L⁻¹ naphthaleneacetic acid (NAA) and 0.5–1.0 mg L⁻¹ benzylaminopurine (BAP), producing the greatest number and length of shoots and roots. Direct organogenesis was stimulated by bio-elicitors Activane^®, Micobiol^®, and Stemicol^® in (MS) basal medium at mid-level concentrations (0.5 g or mL L⁻¹), improving shoot number, elongation, and root development. Activane^®, Micobiol^®, and Stemicol^® are commercial elicitors that stimulate plant defense pathways and morphogenesis through salicylic acid, microbial, and jasmonic acid signaling mechanisms, respectively. Indirect organogenesis showed significantly higher callus proliferation in Stemicol^® and Micobiol^® treatments compared to the control medium, resulting in the highest fresh weight, diameter, and friability of callus. The results demonstrate the potential of biotic elicitors as alternatives or enhancers to traditional plant growth regulators in potato tissue culture, supporting more efficient and cost-effective micropropagation strategies.

To catalog and promote the conservation and use of crop wild relatives, comprehensive phenotypic and genotypic information must be available. Plant genotyping has the power to resolve the phylogenetic relationships between crop wild relatives, quantify genetic diversity, and identify marker-trait associations for expedited molecular breeding. However, access to cost-effective genotyping strategies is often limited in underutilized crops and crop wild relatives. Potato landraces and wild species, distributed throughout Central and South America, exhibit remarkable phenotypic diversity and are an invaluable source of resistance to pests and pathogens. Unfortunately, very limited information is available for these germplasm resources, particularly regarding phenotypic diversity and potential use as trait donors. In this work, more than 150 accessions corresponding to 12 species of wild and cultivated potatoes, collected from different sites across the American continent, were analyzed using computer vision and morphometric methods to evaluate leaf size and shape. In total, more than 1100 leaves and leaflets were processed and analyzed for nine traits related to size, shape, and color. The results produced in this study provided a visual depiction of the extensive variability among potato wild species and enabled a precise quantification of leaf phenotypic differences, including shape, color, area, perimeter, length, width, aspect ratio, convexity, and circularity. We also discussed the application and utility of inexpensive but comprehensive morphometric approaches to catalog and study the diversity of crop wild relatives. Finally, this study provided insights for further experimental research looking into the potential role of leaf size and shape variation in plant–insect interactions, agronomic productivity, and adaptation.

Potato is an essential crop worldwide, and optimizing micropropagation techniques is important for enhancing germplasm conservation and large-scale production. This study focuses on the in vitro propagation of two potato varieties, Agata and Fianna, emphasizing optimizing sterilization protocols, shoot induction, rooting, and microtuber production. Apical buds from healthy, disease-free plants were selected as explants. These buds were surface-sterilized using 70% ethanol and sodium hypochlorite (NaOCl) with Tween-20. The explants were excised from tuber sprouts and cultured on Murashige and Skoog (MS) medium supplemented with various concentrations of plant growth regulators, including benzylaminopurine (BAP) at 0.10–0.40 mg/L, gibberellic acid (GA3) at 0.20–1.00 mg/L, and naphthalene acetic acid (NAA) at 0.01 and 0.04 mg/L to promote root development. The study also explored the effects of these hormonal treatments on shoot induction, proliferation, and rooting. Significant differences were observed between the two varieties regarding oxidation, contamination, and aseptic conditions, with Fianna demonstrating better resistance to oxidation and contamination than Agata. Shoot multiplication was most efficient with BAP concentrations of 0.40 mg/L for Fianna and 0.30 mg/L for Agata. Root induction was maximized with higher sucrose concentrations (110 g/L) and GA3 (1.00 mg/L) for Agata, while moderate concentrations of these compounds produced optimal results for Fianna. Microtuber formation was most successful with moderate sucrose (80–100 g/L) and GA3 (0.25–0.75 mg/L) concentrations. This study provides valuable insights into optimizing tissue culture practices for potato propagation, enhancing both microtuber production and the overall efficiency of potato production systems.

Con el objetivo de estudiar la relación cuantitativa entre el rendimiento de papa (Solanum tuberosum L.) de dos cultivares (‘Alpha’, susceptible, y ‘Zafiro’, moderadamente resistente al tizón tardío), y la severidad del patógeno en Toluca, México, que se manejó mediante aplicaciones semanales de 0.575 kg i.a ha^-1, 1.15 kg i.a ha^-1 y sin aplicación, del fungicida Clorothalonil. Hubo diferencias estadísticas entre cultivares y entre dosis del fungicida en un mismo cultivar (P < 0.05). La relación entre el rendimiento y la severidad de la enfermedad se describe por modelos de regresión lineal. El rendimiento por categorías comerciales (“primera”, “segunda” y “tercera”) estuvo en función de la severidad acumulada a los 80 d después de la siembra en el cultivar ‘Zafiro’, y a los 58 d en ‘Alpha’ para “primeras”; y para el total, a los 65 d para “segundas” y a los 94 d para “terceras”. El coeficiente de determinación varió entre 54 y 78 % en los modelos de ‘Alpha’, mientras que en ‘Zafiro’ fue de 54 a 75 %. La pérdida en rendimiento fue menor en ‘Zafiro’, pues sus epifitias fueron menos intensas hasta al inicio de la tuberización. Se concluye que es necesario considerar al inicio de tuberización como punto crítico. El periodo previo es el más importante para reducir pérdidas, por lo que el manejo deberá encaminarse a retrasar el inicio de las epifitias en esa etapa y de su intensidad.