Horizontal gene transfer contributes to plant evolution : the case of Agrobacterium T-DNAs

Horizontal gene transfer (HGT) can be defined as the acquisition of genetic material from another organism without being its offspring. HGT is common in the microbial world including archaea and bacteria, where HGT mechanisms are widely understood and recognized as an important force in evolution. In eukaryotes, HGT now appears to occur more frequently than originally thought. Many studies are currently detecting novel HGT events among distinct lineages using next-generation sequencing. Most examples to date include gene transfers from bacterial donors to recipient organisms including fungi, plants, and animals. In plants, one well-studied example of HGT is the transfer of the tumor-inducing genes (T-DNAs) from some Agrobacterium species into their host plant genomes. Evidence of T-DNAs from Agrobacterium spp. into plant genomes, and their subsequent maintenance in the germline, has been reported in Nicotiana, Linaria and, more recently, in Ipomoea species. The transferred genes do not produce the usual disease phenotype, and appear to have a role in evolution of these plants. In this paper, we review previous reported cases of HGT from Agrobacterium, including the transfer of T-DNA regions from Agrobacterium spp. to the sweetpotato [ Ipomoea batatas (L.) Lam.] genome which is, to date, the sole documented example of a naturally-occurring incidence of HGT from Agrobacterium to a domesticated crop plant. We also discuss the possible evolutionary impact of T-DNA acquisition on plants

Utilization of engineered resistance to viruses in crops of the developing world, with emphasis on sub-Saharan Africa

Engineering for viral resistance • Viruses and CancerViral diseases in crop plants constitute a major obstacle to food security in the developing world. Subsistence crops, including cassava, sweetpotato, potato, banana, papaya, common bean, rice and maize are often infected with RNA and/or DNA viruses that cannot be controlled with pesticides. Hence, healthy planting materials and virus-resistant cultivars are essential for high yields of good quality. However, resistance genes are not available for all viral diseases of crop plants. Therefore, virus resistance engineered in plants using modern biotechnology methods is an important addition to the crop production toolbox.Peer reviewe

The horizontal gene transfer of Agrobacterium T-DNAs into the series Batatas (genus Ipomoea) genome is not confined to hexaploid sweetpotato

The discovery of the insertion of IbT-DNA1 and IbT-DNA2 into the cultivated (hexaploid) sweetpotato [Ipomoea batatas (L.) Lam.] genome constitutes a clear example of an ancient event of Horizontal Gene Transfer (HGT). However, it remains unknown whether the acquisition of both IbT-DNAs by the cultivated sweetpotato occurred before or after its speciation. Therefore, this study aims to evaluate the presence of IbT-DNAs in the genomes of sweetpotato's wild relatives belonging to the taxonomic group series Batatas. Both IbT-DNA1 and IbT-DNA2 were found in tetraploid I. batatas (L.) Lam. and had highly similar sequences and at the same locus to those found in the cultivated sweetpotato. Moreover, IbT-DNA1 was also found in I. cordatotriloba and I. tenuissima while IbT-DNA2 was detected in I. trifida. This demonstrates that genome integrated IbT-DNAs are not restricted to the cultivated sweetpotato but are also present in tetraploid I. batatas and other related species

Determinación de haplotipos de Bactericera cockerelli en la provincia de Huancabamba - Piura, Peru

Bactericera cockerelli es un insecto polífago que afecta solanáceas de importancia económica como papa (Solanum tuberosum), tomate (Solanum lycopersicum), berenjena (Solanum melongena), tabaco (Nicotiana tabacum) y otras solanáceas silvestres (CABI, 2022). El daño causado puede ser de dos formas, la directa la producen principalmente las ninfas. Al succionar la savia para alimentarse segregan toxinas a la planta además de las excretas que dejan en las hojas pueden dar origen a la formación de hongos saprófitos. El daño indirecto es aún más alarmante pues B. cockerelli es el vector de la bacteria Candidatus Liberibacter solanacearum (CaLso) (sinónimo Ca. Liberibacter psyllaurous). Esta bacteria ocasiona la devastadora enfermedad llamada zebra chip o papa manchada (Pérez et al., 2021). Con el objetivo de entender la dinámica poblacional temporal y espacial de B. cockerelli se está empleando un nivel de clasificación más específico mediante los haplotipos. Definiendo un haplotipo como la forma genética que difiere de cualquier otra forma por variaciones en su secuencia de ADN en al menos un nucleótido (Cerna et al., 2021). Estudios han identificado cuatro tipos de haplotipos mitocondriales dentro de Estados Unidos que están asociados a cuatro regiones geográficas: Oeste. Central, Noroeste, Suroeste (Swisher et al., 2014). En Sudamérica, específicamente en Ecuador se dio el primer reporte de B. cockerelli afectando plantaciones de papa, y mediante el análisis de la secuencia COI se determinó que los especímenes correspondían al haplotipo central. El psílido de la papa está ampliamente distribuido en América del Norte (México, Estados Unidos y Canadá) y también en países de Centroamérica como Guatemala, Honduras y Nicaragua (Castillo et al., 2019)

A Temperature-Dependent Phenology Model for the Sweetpotato Whitefly Bemisia tabaci MEAM1 (Hemiptera: Aleyrodidae)

The sweetpotato whitefly Bemisia tabaci (Gennadius) MEAM1 (Hemiptera: Aleyrodidae) is widely distributed in tropical and subtropical regions affecting more than 600 different species of cultivated and wild plants. Due to the large number of viruses it can transmit, the species is one of the most important economic insect pests in the world. Determination of the pest’s temperature-dependent population growth potential is crucial knowledge for understanding the population dynamics and spread potential of the species and the diseases it can transmit, as well as for designing effective pest management strategies. B. tabaci MEAM1 development, mortality and reproduction were studied at seven constant temperatures in the range from 12° to 35°C. The Insect Life Cycle Modeling (ILCYM) software was used to fit nonlinear equations to the data and establish an overall phenology model to simulate life-table parameters based on temperature. Life tables of B. tabaci MEAM1 established at naturally fluctuating temperature in La Molina, Lima, during different seasons, covering the entire temperature range of the species' predicted performance curve, were used to validate the model. The overall model predicted population development within the temperature range of 13.9° to 33.4°C with a maximum finite rate of population increase (=1.138) at 26.4°C. The model gave good predictions when compared with observed life tables and published data. The established process-based physiological model presented here for B. tabaci MEAM1 can be used predicting the species distribution potential based on temperature worldwide and should prove helpful in adjusting pest management measures

Reporte sobre colecta de Bactericera cockerelli en Huancabamba-Piura, Perú

Bactericera cockerelli es un insecto polífago que afecta solanáceas de importancia económica como papa (Solanum tuberosum), tomate (Solanum lycopersicum), berenjena (Solanum melongena), tabaco (Nicotiana tabacum) y otras solanáceas silvestres (CABI, 2022) El daño causado puede ser de dos formas, la directa la producen principalmente las ninfas. Al succionar la savia para alimentarse segregan toxinas a la planta además de las excretas que dejan en las hojas pueden dar origen a la formación de hongos saprófitos. El daño indirecto es aún más alarmante pues B. cockerelli es el vector de la bacteria Candidatus Liberibacter solanacearum (CaLso) (sinónimo Ca. Liberibacter psyllaurous). Esta bacteria ocasiona la devastadora enfermedad llamada zebra chip o papa manchada (Pérez et al., 2021) “El psílido de la papa y CaLso se han convertido en el problema fitosanitario de mayor importancia económica de la papa y otras solanáceas cultivadas en los países donde han sido reportados y son considerados plagas cuarentenarias” (Castillo & Llumiquinga, 2021). La papa es uno de los cultivos alimenticios más importantes a nivel mundial, ocupa el tercer lugar en términos de consumo después del arroz y el trigo (CIP, 2016). En el Perú, la papa se cultiva en 19 de los 24 departamentos del Perú y constituye la base de la alimentación del poblador especialmente de la sierra, debido a su alto contenido de carbohidratos, vitaminas y minerales (MINAGRI, 2013). La presencia de B. cockerelli en el Perú fue confirmada por Servicio Nacional de Sanidad Agraria (SENASA) en diciembre del 2021 reportando los primeros hallazgos en la provincia de Huancabamba, departamento de Piura. Hasta la fecha y pese al constante monitoreo de los especialistas en la zona aún no se ha confirmado la detección de la bacteria Candidatus Liberibacter solanacearum. El presente tiene como finalidad describir la metodología empleada para colectar individuos de B. cockerelli en 31 puntos de la provincia de Huancabamba