Seed and endocarp traits as markers of the biodiversity of regional sources of germplasm of tejocote ( Crataegus spp.) from Central and Southern Mexico

Properties of the subduction system in Mexico

Tejocote (Crataegus spp.) is a genus of fruit-bearing trees distributed widely throughout Mexico; 13 species are reported for the north and central zones and two or more species may be present in southern Mexico. Accessions of this genus are safeguarded in the Germplasm Bank of Tejocote at the Autonomous University of Chapingo, mainly from three regional sources, i.e. the states of Puebla, Mexico, and Chiapas, including five different species that belong to series Mexicanae and series Crus-galli. They can be morphologically characterized by leaves from different shoot types, flowers and fruits. Multivariate statistical methods were used to elucidate patterns of variation in each of these regional sources. The sources displayed very low intra-source variability. The source from Chiapas showed significant statistical differences in all morphological variables evaluated, as a result, this genetic pool is considered as different from the other two sources. The sources from the states of Puebla and Mexico only differed by 22.79% (with P ≤ 0.05), and thus they could be considered as components of a single genetic pool. The most highly discriminant variables were from the leaf, such as basal angle, petiole length/major axis length ratio, minor axis length/major axis length ratio, and number of veins.

Central and southern Mexico represents a strategic place to understand the dynamics of Pangaea break-up and its influences on the evolution of the Pacific margin of North America. Lower–Middle Jurassic volcano-sedimentary successions, and scarce magmatic rocks, crop out discontinuously across this region and have been interpreted either as a vestige of a continental arc or as several deposits of syn-rift magmatism. At present, their origin is controversial. Available geochemical data on these igneous rocks suggest that they represent almost pure crustal melts produced in a rift environment rather than in an arc. In fact, the studied rocks exhibit the high silica contents and moderate to strong peraluminous character typical of sediment melts. The enriched isotopic composition (high86Sr/87Sr and low143Nd/144Nd) and the age distributions of inherited zircon grains readily identify the widespread Upper Triassic metasedimentary sequences presently exposed in southwestern and central Mexico as the most likely crustal source of these Jurassic igneous rocks. Accordingly, we argue that these Early–Middle Jurassic magmas originated in a syn-rift igneous province associated with extensional-driven crustal attenuation in the context of Pangaea fragmentation. Our findings also constrain post-Pangaea subduction initiation to be younger than Middle Jurassic time in central and southern Mexico.

Lumnitzera littorea (Jack) Voigt. is a species of mangrove plant belonging to the family Combretaceae. Natural reproduction of L. littorea is extremely difficult due to its seed abortion in China. To reveal the molecular mechanism of seed abortion, we performed transcriptome to analyze the seeds of L. littorea-T (normal seeds) and L. littorea-S (abortive seeds). After analysis of the raw data, 64,868 transcripts (mean length = 658 bp) were assembled. Among these transcripts, 39,779 were functionally annotated. Then, differentially expressed genes (DEGs) were screened, and 23,513 transcripts were identified that were likely involved in seed abortion. About 207 DEGs assigned to Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, and approximately 12.1% fell into reproduction categories. Genes involved in response to sucrose and starch metabolism, and phytohormone biosynthesis showed significant different expression levels between normal and abortive seeds of L. littorea. Further expressions patterns of key genes contribute to seed development were analyzed using quantitative real-time PCR, and the results were consistent with high-throughput sequencing data. The information obtained in this study will aid in the research of the mechanism of seed abortion in further molecular studies of L. littorea. © 2021 Friends Science Publishers

This volume furthers our understanding of key basins in central and southern Mexico, and establishes links to exhumed sediment source areas in a plausible paleogeographic framework. Authors present new data and models on the relations between Mexican terranes and the assembly and breakup of western equatorial Pangea, plate-tectonic and terrane reconstructions, uplift and exhumation of source areas, the influence of magmatism on sedimentary systems, and the provenance and delivery of sediment to Mesozoic and Cenozoic basins. Additionally, authors establish relationships between basement regions (sediment source) in the areas that supplied sediment to Mesozoic rift basins, Late Cretaceous foreland systems, and Cenozoic basins developed in response to Cordilleran events.

Distribution of hydrous minerals in the subduction system beneath Mexico

Biomass burning from grassland, forests, and agricultural waste results in large amounts of gases and particles emitted to the atmosphere, which affect air quality, population health, crop development, and natural vegetation. Regional atmospheric circulations can transport those plumes of pollutants over hundreds of kilometers, affecting vulnerable environments such as those considered protected natural areas (PNAs). This study evaluates the spatiotemporal distribution of active fires detected, and associated emissions, in central and southern Mexico from satellite data between March and June 2017, to assess the impact of the smoke plumes on protected ecosystems. The arrival of smoke plumes to selected PNAs (both near large urban centers and in remote areas) is assessed using airmass forward trajectories from selected emission sources. The spatial distribution of the remotely derived aerosol optical depth confirms the regional impact of particle emissions from the observed fires on PNAs, particularly in central Mexico. The identified areas of high fire density are also associated with large coarse particle concentrations at the surface. Moreover, there is a significant contribution of organic carbon to the total coarse particle mass, 60% on average. Finally, while most of the impact in ambient pollution is observed in PNAs located close to the regions with active fires in southern Mexico and Central America, the long-range transport of smoke plumes reaching the USA was also confirmed.

A major provenance change in sandstones from the Tezoatlán basin, southern Mexico, controlled by Jurassic, sinistral normal motion along the Salado River fault: Implications for the reconstruction of Pangea

In Mexico, ultramafic complexes are present in different regions from the northwest (Baja California Norte) to the southeast (Chiapas). In this paper, we present the results of the exploration of three ultramafic (serpentine) habitats in central and southern Mexico: Cuicatlán–Concepción Pápalo (Oaxaca), Tehuitzingo–Tecomatlán (Puebla), and San Juan de Otates (Guanajuato). Previous geology studies showed that these complexes are mainly made up of serpentinized peridotites. Soil analyses demonstrated typical ultramafic characteristics such as high content of Mg in relation to Ca, and high concentrations of Fe, Cr, Co, and Ni. Soil samples from Oaxaca and Puebla had similar Ni contents around 2300 mg kg−1, while samples of Guanajuato showed the lowest Ni levels with an average of 200 mg kg−1 as well as for other metals such as Co, Cr, Mn, and Zn. During this study, 83 plant specimens were collected, of which 52 were identified at genus level and 40 at species level. The collected plants belong to 19 different families such as Anacardiaceae, Fabaceae, Acanthaceae, Asteraceae, Sterculiaceae, and Verbenaceae which are also widely present in other ultramafic areas in Iran, Brazil, Sri Lanka, and Costa Rica. Only two Mexican endemic species are included in the collection. Ni hyperaccumulators were not detected at any of the studied sites. Therefore, hyperaccumulation, as a tolerance mechanism of the flora in response to ultramafic geochemical stress, does not seem to be developed in Central Mexico, as observed in the close Costa Rican site of Santa Elena.

In July-August 2019, seven Armillaria isolates (derived from rhizomorphs and mycelial fans of infected roots) were collected in association with woody hosts in the central Mexico: states of Guanajuato (MEX204), Jalisco (MEX206, MEX208, MEX209), and Michoacan (MEX211, MEX214, MEX216). All seven isolates were identified as Armillaria gallica based on translation elongation factor 1α (tef1) gene sequences (GenBank accession Nos.: MN839636 - MN839642 for MEX204, MEX206, MEX208, MEX209, MEX211, MEX214, and MEX216) and somatic pairing tests against known tester isolates. GenBank nucleotide BLAST results showed tef1 similarity for all isolates was highest for with A. gallica (≥ 97%; GenBank Accession Nos. KF156775 and KF156772). In replicated pairings against three tester isolates each for A. gallica, A. mellea, and A. mexicana, all isolates showed the highest compatibility with A. gallica (67-100%), with lower compatibility against A. mellea and A. mexicana, with 3-11% and 2-11%, respectively. Variations in compatibility among different tester isolates could reflect cryptic speciation within A. gallica (Klopfenstein et al., 2017). In Tarimoro, Guanajuato, MEX204 was isolated from infected Quercus jonesii (20°13'46.2"N 100°42'51.1"W, elevation 2286 m) that displayed root disease symptoms/signs (wilting/defoliation and mycelial fans within the roots). In a forested area of Mazamitla, Jalisco, MEX206 was isolated from infected Quercus laevis (19°54´52"N 103°00´07"W, elevation 2564 m) with root disease symptoms/signs (e.g., wilting, foliar chlorosis, and mycelial fans within the root crown); MEX208 was isolated from infected Pinus pseudostrobus (19°54´53"N 102°59´54"W, elevation 2554 m) with basal resinosis and mycelial fans; and MEX209 was collected from a symptomless P. devoniana (19°54'13.1"N 103°00'14.1"W, elevation 2566 m). In Zinapecuaro, Michoacan, MEX211 (19°53'28.8"N 100°39'44.0"W, elevation 2587 m) was isolated from infected Malus domestica with root disease that resulted in mortality; in Hidalgo, Michoacan, MEX214 (19°46'49"N 100°39'25.2"W, elevation 2961 m) and MEX216 (19°46'58"N 100°39'24"W, elevation 2958 m) were isolated from infected P. devoniana and P. teocote, respectively, which both displayed root disease symptoms/signs (basal resinosis and mycelial fans). Previously, A. gallica was reported in the State of Mexico, Veracruz, Oaxaca, Mexico (Elías-Román et al. 2013; Klopfenstein et al. 2014), but this represents the first report of A. gallica in Guanajuato, Jalisco, and Michoacan, Mexico. In contrast to other regions of North America (e.g., Bruhns et al. 2000), A. gallica was demonstrated to be a virulent pathogen on peach (Prunus persica) in central Mexico (Elías-Román et al. 2013). Unfortunately, tree seedlings cannot be used for Armillaria pathogenicity tests in a greenhouse or nursery; however, all root-diseased trees in this report showed Armillaria mycelial fans under the bark of a living tree, which are reliable indicators of pathogenicity, and no other root diseases were found. This report demonstrates that A. gallica is distributed across central Mexico, where it is associated with disease on Quercus, Pinus, and Malus. Such information is critical to increase our understanding of Armillaria root disease across diverse geographic regions and climates.

Histological and anatomical characteristics of parthenocarpic and normal pear fruits

Birches are generally known for their high genetic and morphological variability, which has resulted in the description of many species. Ojców birch was described in 1809 by Willibald Suibert Joseph Gottlieb Besser in Poland. Since then, several studies assessing its taxonomy were conducted. Today, various authors present Ojców birch at different taxonomic ranks. In Czechia, the Ojców birch is classified a critically endangered taxon and confirmed at one locality consisting of several tens of individuals. However, before a strategy for its conservation can be applied, we consider it necessary to assess the taxonomic position of the endangered Czech population and to evaluate its relationship to the original Polish population. This study aimed to evaluate the morphometric and genetic variability between populations of B. ×oycoviensis in Poland and the Czechia and their relationship to regional populations of B. pendula, one of the putative parental species of the Ojców birch. Altogether, 106 individuals were sampled, including the holotype of B. szaferi, the second putative parental species of B. ×oycoviensis, received from the herbarium of W. Szafer, which is deposited at the Institute of Botany in Kraków. Morphological analyses identified differences in leaves between B. ×oycoviensis and B. pendula. However, no significant differences were found in genome size between selected taxa/working units except for B. pendula sampled in Czechia. The identified difference of the Czech population of B. pendula is probably caused by population variability. Genetic variability between all the taxa under comparison, regardless of their origin, was also very low; only the benchmark taxa (B. nana and B. humilis) clearly differed from all samples analyzed. The results indicate minute morphological and negligible genetic variability between the Czech and Polish populations of B. ×oycoviensis. In light of our results, the classification of B. ×oycoviensis as B. pendula var. oycoviensis seems more accurate than all hitherto presented alternatives (e.g. B. ×oycoviensis as a separate species).

Birches are generally known for their high genetic and morphological variability, which has resulted in the description of many species. Ojców birch was described in 1809 by Willibald Suibert Joseph Gottlieb Besser in Poland. Since then, several studies assessing its taxonomy were conducted. Today, various authors present Ojców birch at different taxonomic ranks. In Czechia, the Ojców birch is classified a critically endangered taxon and confirmed at one locality consisting of several tens of individuals. However, before a strategy for its conservation can be applied, we consider it necessary to assess the taxonomic position of the endangered Czech population and to evaluate its relationship to the original Polish population. This study aimed to evaluate the morphometric and genetic variability between populations of B. ×oycoviensis in Poland and the Czechia and their relationship to regional populations of B. pendula, one of the putative parental species of the Ojców birch. Altogether, 106 individuals were sampled, including the holotype of B. szaferi, the second putative parental species of B. ×oycoviensis, received from the herbarium of W. Szafer, which is deposited at the Institute of Botany in Kraków. Morphological analyses identified differences in leaves between B. ×oycoviensis and B. pendula. However, no significant differences were found in genome size between selected taxa/working units except for B. pendula sampled in Czechia. The identified difference of the Czech population of B. pendula is probably caused by population variability. Genetic variability between all the taxa under comparison, regardless of their origin, was also very low; only the benchmark taxa (B. nana and B. humilis) clearly differed from all samples analyzed. The results indicate minute morphological and negligible genetic variability between the Czech and Polish populations of B. ×oycoviensis. In light of our results, the classification of B. ×oycoviensis as B. pendula var. oycoviensis seems more accurate than all hitherto presented alternatives (e.g. B. ×oycoviensis as a separate species).

Several and diverse native populations of wild grapevines have been reported growing in the States of Puebla, Mexico and Morelos, Central Mexico. After collection, successfully rooted vines were planted in Zumpahuacán, State of Mexico, and since 2013, their fruit were analyzed, mainly in relation to berry-weight and sweetness. Recently, the seed oil content was analyzed. Most berries harvested in 2013, 2014 and 2015 weighted less than 1 g and only berries of accession Puebla-41 (P-41) weighted nearly 2.5 g. On the other hand, most berries had lower than 18°B. Four accessions, three native of Puebla and one from Morelos had the higher fruit production (2.5, 1.5 and 1.4; and 0.68 kg per plant) and might be the genetic material proposed to be planted in Zumpahuacán, Mexico. Seed oil analysis confirmed the presence of linoleic acid as the main fatty acid in Central Mexico wild grape seed oil. Nowadays, the extraction of seed oil in Central Mexico native grapes seems to be the better alternative to interest locals and agro-industrial related companies in conserving and cropping this plant genetic resource.

Several and diverse native populations of wild grapevines have been reported growing in the States of Puebla, Mexico and Morelos, Central Mexico. After collection, successfully rooted vines were planted in Zumpahuacán, State of Mexico, and since 2013, their fruit were analyzed, mainly in relation to berry-weight and sweetness. Recently, the seed oil content was analyzed. Most berries harvested in 2013, 2014 and 2015 weighted less than 1 g and only berries of accession Puebla-41 (P-41) weighted nearly 2.5 g. On the other hand, most berries had lower than 18°B. Four accessions, three native of Puebla and one from Morelos had the higher fruit production (2.5, 1.5 and 1.4; and 0.68 kg per plant) and might be the genetic material proposed to be planted in Zumpahuacán, Mexico. Seed oil analysis confirmed the presence of linoleic acid as the main fatty acid in Central Mexico wild grape seed oil. Nowadays, the extraction of seed oil in Central Mexico native grapes seems to be the better alternative to interest locals and agro-industrial related companies in conserving and cropping this plant genetic resource.