Juan Carlos Noa-Carrazana

A Single Banana Streak Virus Integration Event in the Banana Genome as the Origin of Infectious Endogenous Pararetrovirus

ABSTRACT Sequencing of plant nuclear genomes reveals the widespread presence of integrated viral sequences known as endogenous pararetroviruses (EPRVs). Banana is one of the three plant species known to harbor infectious EPRVs. Musa balbisiana carries integrated copies of Banana streak virus (BSV), which are infectious by releasing virions in interspecific hybrids. Here, we analyze the organization of the EPRV of BSV Goldfinger (BSGfV) present in the wild diploid M. balbisiana cv. Pisang Klutuk Wulung (PKW) revealed by the study of Musa bacterial artificial chromosome resources and interspecific genetic cross. cv. PKW contains two similar EPRVs of BSGfV. Genotyping of these integrants and studies of their segregation pattern show an allelic insertion. Despite the fact that integrated BSGfV has undergone extensive rearrangement, both EPRVs contain the full-length viral genome. The high degree of sequence conservation between the integrated and episomal form of the virus indicates a recent integration event; however, only one allele is infectious. Analysis of BSGfV EPRV segregation among an F1 population from an interspecific genetic cross revealed that these EPRV sequences correspond to two alleles originating from a single integration event. We describe here for the first time the full genomic and genetic organization of the two EPRVs of BSGfV present in cv. PKW in response to the challenge facing both scientists and breeders to identify and generate genetic resources free from BSV. We discuss the consequences of this unique host-pathogen interaction in terms of genetic and genomic plant defenses versus strategies of infectious BSGfV EPRVs.

Coat protein sequence comparisons of three Mexican isolates of papaya ringspot virus with other geographical isolates reveal a close relationship to American and Australian isolates

Summary. The coat protein gene of the papaya ringspot virus was cloned and sequenced in three Mexican isolates (two from Veracruz, and one from Chiapas). The sequences of these viral isolates were compared to those of eleven isolates from other parts of the world. They had higher similarity to isolates from Australia and the United States than to Asian isolates. A region of about one hundred nucleotides neighboring the putative aphid transmission triplet of the coat protein, contained repeats of an EK (glutamic acid-lysine) motif in all the sequences. The bearing of this region on the genetic relationships and geographical distribution of the isolates is analyzed and discussed.

Distribution of Papaya ringspot virus and Papaya mosaic virus in papaya plants (Carica papaya) in Mexico.

We report the results of a survey for the presence of Papaya ringspot virus (PRSV) along the coasts of the Gulf of Mexico and the Pacific Ocean, in 15 federal states of Mexico that account for over 98% of the national papaya production. More than 80 locations were visited in 58 counties. Out of a total of 267 papaya leaf samples, 157 tested positive for PRSV. We tested for the presence of three other viruses because of the occurrence of severe, atypical symptoms in plantations. Only Papaya mosaic virus (PapMV) was detected. PRSV was present in every county. PapMV was less frequent, but its overall distribution was almost identical. PRSV and PapMV occurred in single or mixed infections of papaya and other host species that could function as virus reservoirs. We investigated the diversity of the coat protein (CP) sequences of 36 PRSV isolates. The amino acid sequence divergence among all isolates ranged from 0.4 to 9.9%, and was comparable to that found in other regions of the world. In contrast to most of these world regions, there is a clear correlation between CP sequence variation and the geographical origins of the virus isolates.

Coat protein gene sequence of a Mexican isolate of Sugarcane mosaic virus and its infectivity in maize and sugarcane plants

(SrMV) [2, 3]. Initially, viral isolates foundin sugarcane were designated as strains of SCMV and those found in maize asstrainsofMDMV,butbasedonreclassification,isolatesofSCMVandMDMVcanbe found in maize. Both SCMV and MDMV cause systemic mosaic symptomsand occasional stunting, and are not visually distinguishable in maize plants.The isolates can only be differentiated through nucleotide sequence comparison,specific serological reactions, or inoculation in differentials plants.

Antagonism or synergism between papaya ringspot virus and papaya mosaic virus in Carica papaya is determined by their order of infection.

Antagonism between unrelated plant viruses has not been thoroughly described. Our studies show that two unrelated viruses, papaya ringspot virus (PRSV) and papaya mosaic virus (PapMV) produce different symptomatic outcomes during mixed infection depending on the inoculation order. Synergism occurs in plants infected first with PRSV or in plants infected simultaneously with PRSV and PapMV, and antagonism occurs in plants infected first with PapMV and later inoculated with PRSV. During antagonism, elevated pathogenesis-related (PR-1) gene expression and increased reactive oxygen species production indicated the establishment of a host defense resulting in the reduction in PRSV titers. Polyribosomal fractioning showed that PRSV affects translation of cellular eEF1α, PR-1, β-tubulin, and PapMV RNAs in planta, suggesting that its infection could be related to an imbalance in the translation machinery. Our data suggest that primary PapMV infection activates a defense response against PRSV and establishes a protective relationship with the papaya host.

Diversity and colonization of arbuscular mycorrhizal fungi in the tree fern Alsophila firma in rainy and dry season

Alsophila firma is a deciduous tree fern considered as an emblematic species of Mexican tropical montane cloud forest (TMCF). We studied spores diversity, structure and colonization by arbuscular mycorrhizal fungi (AMF) within the roots of the Alsophila firma in rainy and dry season. Eighteen species of the genera Acaulospora (5), Gigaspora (4), Glomus (4), Funneliformis (2), Sclerocystis (2) and Scutellospora (1) were identified. The species F. constrictum, F. geosporum, Gigaspora albida, G. decipiens, Glomus microaggregatum and Sclerocystis coremioides are reported for the first time in TMCF. The dominant genera were Funneliformis and Acaulospora. In rainy season, a higher richness (H′ t0.005(2)9 = 4.78) and evenness (E) of AMF spores was recorded, compared to the dry season. However, the degree of colonization was statistically significant higher in the dry season. This study is the first to estimate the species richness of AMF associated with the rhizosphere of a fern in Mexico as well as for A. firma.

Present and future potential distribution of the endemic Perote ground squirrel (Xerospermophilus perotensis) under different climate change scenarios

Abstract The current distribution of the endemic Perote ground squirrel (Xerospermophilus perotensis) and its future potential response to climate change have not been addressed. Thus, in this work, we focus on both aspects of this species by means of ecological niche modeling, using different general circulation models and Intergovernmental Panel on Climate Change emission scenarios. Because the species’ life history includes a hibernation period, we performed two different sets of analysis: one considering the whole annual cycle and another considering only the species’ active season. According to our results, the current potential distribution of X. perotensis extends further out of the Oriental Basin, to which the species is endemic. Future projections vary among different climatic scenarios and data sets used in the modeling process, but virtually all of them project a substantial encroachment of the species’ potential distribution area by 2050. Our models suggest that, compared with species that are active throughout the year, X. perotensis, being a seasonal species, could be affected by climate change, increasing the risk of extinction. This may pose a serious threat to the Perote ground squirrel’s persistence throughout the following decades.

Insecticidal activity of raw ethanolic extracts from Magnolia dealbata Zucc on a tephritid pest

Ethanolic extracts from Magnolia dealbata (Zucc.) (Magnoliaceae); leaves, bark, seeds, sarcotesta and flowers were evaluated for insecticidal activity against adults of the Mexican fruit fly, Anastrepha ludens (Loew) (Diptera: Tephritidae). Using feeding bioassays composed from sugar-extract mixtures, only the extract from sarcotesta indicated insecticidal activity against the flies. The extracts from the other four plant tissues (leaves, bark, seeds and flowers) did not manifest any biological activity. The most effective extract was obtained from oven-dried sarcotesta, whereas extracts from fresh sarcotesta were inactive. Our results suggest that M. dealbata sarcotesta contains secondary metabolites with insecticidal activity against A. ludens adults. These metabolites are as potent as natural pyrethins and represent a potential substance for controlling this type of pest.

Altitudinal Record of Dendroctonus approximatus Dietz (Coleoptera: Curculionidae) in Veracruz, Mexico

Among bark beetles, the genus Dendroctonus Erichson causes the most damage to trees in forests around the world (Six and Bracewell 2015), attacking trees of the genera Pinus L., Picea A. Dietr., Pseudotsuga Carrière, and Larix (Mill.) (all Pinaceae) (Wood 1963; Six and Bracewell 2015). The group comprises 20 species (ArmendárizToledano et al. 2015), of which 13 are found in the forests of Mexico. In Mexico, 40.5% of pest control reports are attributed to damage by Dendroctonus species (Pérez-Camacho et al. 2013). Species in this genus have been classified into two groups according to the order of colonization of the host, with six species (D. mexicanus Hopkins, D. frontalis Zimmermann, D. adjunctus Blandford, D. rhizophagus Thomas and Bright (Salinas-Moreno et al. 2010), D. pseudotsugae Hopkins, and D. ponderosae Hopkins) considered as primary pests and the remaining seven as secondary pests, including D. approximatus Dietz (Ruiz et al. 2009; Salinas-Moreno et al. 2010; Vı́ctor and Zúniga 2016). Dendroctonus approximatus attacks 17 species of Pinus, of which the following species are known to occur in Veracruz: P. ayacahuite C. Ehrenb. ex Schltdl., P. hartwegii Lindl., P. montezumae Lamb., P. patula Schltdl. and Cham., P. pseudostrobus Lindl., and P. teocote Schltdl. and Cham. (Salinas-Moreno et al. 2010), practically all of which are economically important species in Mexico. Dendroctonus approximatus usually has one generation per year but can have two generations in years with warmer conditions. The species’ pheromone system is unknown (Six and Bracewell 2015). This report offers the first geo-referenced data on the altitudinal distribution of D. approximatus in the northwestern region of the volcano Cofre de Perote, Veracruz, Mexico. The specimens were collected by means of eight-cone Lindgren traps baited with generalist bait composed of frontalin, alphaand beta-pinene, and endo-brevicomine (Sistema Injecthor De Mexico) from June 2014 to July 2016 in coniferous ecosystems of the communities of El Conejo and Los Pescados (Perote), El Rosario (Xico), and El Zapotal (Acajete) in Veracruz (Table 1). Four traps (three baited and one unbaited) were placed at intervals of 100 m per site. The sites occurred at altitude intervals of 250 m from 2,000 to 3,500 m elevation (Table 1). Beetles caught in traps were collected and transferred to 70% ethyl alcohol every 15 days. Specimens were identified to genus using Wood (1982), and species identification was made by Thomas Atkinson (University of Texas, Austin, TX). Genitalia of collected insects were compared to those of D. approximatus specimens from the Entomological Collection of the Institute of Plant Health of the Colegio de Postgraduados (CEAM) in Texcoco, Mexico, following Vı́ctor and Zúniga (2016). Genitalia were dissected by separating the abdomen from the rest of the body and immersing it in 10% potassium hydroxide at 80° C for 20 minutes to macerate the tissue. Once extracted, the genitalia were immersed in 70%

Influence of season and organ on antibacterial activity ofMagnolia dealbataZucc. against two phytopathogenic bacteria

As an alternative to reduce the use of agrochemicals, plant extracts can be a better choice in the control of phytopathogens. In this study, we tested the effects of Magnolia dealbata Zucc. crude extracts on the bacterial growth of Pectobacterium carotovorum and Pseudomonas cichorii, both micro-organisms of phytopathogenic relevance. In addition, our other aim was to explain the influence of the seasons and source organs at different maturing stages in the bioactivity of the extracts. Several ethyl acetate and ethanol crude extracts obtained from leaves, bark, flowers, polyfollicles and seeds were tested using the disk-diffusion method. The ethyl acetate extract of M. dealbata polyfollicle collected in summer inhibited the development of P. carotovorum and P. cichorii to the same extent as the tetracycline positive control (Z=1.0690, p=.285 and Z=1.278, p=.201, respectively) while the ethyl acetate seed extract inhibited the growth of P. carotovorum, but did not equal the effect of tetracycline (Z=2.022, p=.043). It can be concluded that the extracts obtained during summer showed the highest inhibition of these bacteria.