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Because of its wide distribution and adaptation, the maize Ratón race (Zea mays L.) is an important component of the diversity in the state of Coahuila, Mexico. The objective of the present research was to perform a morphological characterization of 83 native populations of the Ratón race and identify a subset that will represent diversity. Populations were evaluated in replicated experiments at two different locations with two planting dates per location. Twentysix quantitative characters of the plant, tassel, ear and grain were recorded, and 14 additional characters (indices) were calculated as relationships among characters. Phenotypic diversity was examined by principal component and cluster analyses. Differences (p ≤ 0.01, p ≤ 0.05) among environments were found for 28 characters and (p ≤ 0.01) among populations for all characters, due to variation in environments and diversity among populations, respectively. Also, differences were found (p ≤ 0.01, p ≤ 0.05) in 38 of the 40 characters in the populations × environments interaction, as a differential response of the populations in the environments. Based on the repeatability index (r > 1.0), 10 characters and nine indices less influenced by the environment were selected for classification. The first two components explained 53.3 % of the total variation and it was established that the vegetative, ear and tassel characters were the most important in describing the variation; this allowed to identify a pattern of diversity associated with the area of adaptation of populations in low - intermediate - transition areas, which reveals that maize variation is closely related to altitude, and temperature and humidity gradients. Based on the dendrogram, a representative subset of the diversity of the Ratón race in Coahuila was obtained, made up of 13 of 83 populations (15.7 %). [ABSTRACT FROM AUTHOR]

Chickpea (Cicer arietinum L.) breeding programs in Northwestern Mexico have focused in developing extra-largeseeded Kabuli cultivars, but additional efforts are required to generate genotypes with better grain quality traits. Information about molecular genetic diversity of Mexican chickpea germplasm and other genotypes from international collections may be valuable sources to improve nutritional properties. The aim of this study was to determine the genetic diversity based on microsatellite markers and the variation in grain quality traits of 14 Kabuli genotypes from Mexico and nine Desi genotypes from other countries. The hypothesis was that the genetic variation detected allows the differentiation of the genotypes according to their origin. DNA was extracted and analyzed with 31 markers distributed across the chickpea genome. A total of 164 alleles were obtained (average of 5.3 alleles per locus) and a total gene diversity of 0.72, which demonstrated a broad genetic base of the chickpeas analyzed. The UPGMA-cluster analysis, modelbased population structure and principal component analysis revealed two major groups, one formed by Desi chickpeas and the other by Kabuli genotypes. The chickpeas also showed a wide variability in seed coat color, seed weight, seed coat proportion, and starch, protein and phenolics content, which was significantly associated with 12 microsatellite markers. These genetic materials represent a broad source of variation for improving chickpea grain quality. [ABSTRACT FROM AUTHOR]

The predominant criteria for defining and identifying races of the genetic complex of Zea mays L. are based on morphological and agronomic attributes along with geographic distribution. In some occasions these present inconsistencies with respect to the authentic genetic identity of the populations. The molecular methods can reveal in detail the identity and variability of individuals and populations through genetic footprints, thus their application in the identification and characterization of races offers advantages. The objective of the present study was to determine the genetic diversity of maize landraces of northern Mexico through microsatellites. The diversity, allelic profile and genetic structure of eight maize landraces of northern Mexico (Apachito, Azul, Cónico Norteño, Cristalino de Chihuahua, Ratón and Tuxpeño Norteño) and one of teosinte (Zea mays ssp. parviglumis Iltis and Doebley)) were determined by means of analysis of microsatellites (SSR). Twenty-five individuals of 63 accessions of the abovementioned races were evaluated using 31 loci of SSR. The parameters of genetic diversity estimated were total number of alleles, number of alleles per locus, proportion of polymorphic loci, expected heterozygosity and genetic structure of the populations using the Wright's F-statistics. The distribution of diversity was determined through principal coordinates and cluster analyses. In total 570 alleles were found, with an average of 18.3 per locus and 87.9 % of polymorphic loci. A 75.6 % of the genetic diversity resides within the populations of the maize races cultivated in northern Mexico and the remaining 24.4 % among populations of these races. The molecular markers grouped the accessions in races in a form that was only partially concordant with respect to the traditional classification. [ABSTRACT FROM AUTHOR]

Tomato’s (Solanum lycopersicum L.) narrow genetic background limits its genetic improvement. The tomato genetic base may be broaden with the use of its native and wild populations as they are a source of useful alleles, to increase yield, quality, and resistance to biotic and abiotic factors that cause stress. Native tomato collections from Mexico have a greater genetic diversity than that of elite germplasm; this implies that genotypes with agronomic, morphological and allelic characteristics different from such elite germplasm may be selected. Therefore, our objective was to evaluate the genetic diversity of 26 accessions of native Mexican tomatoes and identify the best ones for their use in tomato breeding. An agromorphological characterization with 20 traits in a completely randomized experimental design with three replications was performed along with a study with molecular SSR markers. The principal components analysis and hierarchical grouping allowed to identifying four groups with outstanding yield, size and internal fruit quality characteristics. The molecular markers were used to calculate the Shannon index, Nei index and Roger genetic distance, from which they generated seven groups, whose inbreeding and fixation coefficients were close to 1. This indicated the presence of inbreeding and wide differences within of the identified groups. With both characterizations and the Gower distance, the separation of S. lycopersicum L. and S. pimpinellifolium L. species was determined. The native Mexican tomato genotypes possess great genetic diversity and allelic variability that would allow their use in different breeding programs to incorporate alleles for yield and yield components, size and sugars content in the cultivated tomatoes. [ABSTRACT FROM AUTHOR]

Foxtail millet (Setaria italica), which originated in China, is an important crop with high genetic diversity. In recent years, several cultivars were developed, but parental cultivars resources are still limited. Inter-simple sequence repeat (ISSR) markers can be used with a high degree of automation and are advantageous tools for genetic diversity analysis. The objective of this study was to analyze genetic diversity in 30 cultivars of foxtail millet using the fluorescent ISSR technique. Eight ISSR markers were used to analyze the genetic diversity in 13 cultivars in Shanxi (SX), 7 in Hebei (HE), 4 in Inner Mongolia (IM), 2 in Shaanxi (SN), 2 in Henan (HA) and 2 in Liaoning (LN), respectively. A total of 122 bands, of which 105(84.5%) were polymorphism bands, were obtained. The average number of polymorphic information content (PIC), marker index (MI) and resolving power (RP) of eight ISSR primers in this study was 0.9, 12.04 and 5.54, respectively. Nei's genetic distance varied from 0.56 to 0.93. Cluster analysis classified the 30 cultivars into three groups. The cultivars from SX province could be placed together in Group II, but SN, HE and IM were placed in Group I. Group III contained germplasms from different regions (SX, HE, HA and IM), In conclusion, our results indicate high genetic diversity among 30 Chinese foxtail millet cultivars, which could contribute to future breeding programs and functional genomic research. [ABSTRACT FROM AUTHOR]

Pholisma culiacanum is a root holoparasitic plant, endemic to the Mexican states of Sinaloa and Sonora that has cultural, nutritious, biological, and evolutionary importance. This plant is an adequate agricultural model as an alternative source of nutrients and as a tool for understanding photosynthesis’ molecular changes, from autotrophism to parasitism. The aim of this study was to analyze the genetic diversity of seven populations of P. culiacanum in Sinaloa and Sonora. Sequences from a chloroplast DNA (TrnL-F) fragment were analyzed in 70 samples, in order to calculate the genetic variation within (86.51 %) and between (13.49 %) populations. Correlation and simple linear regression analysis were performed for the genetic and geographic distances data. Haplotype and nucleotide diversity was detected at 0.85 and 0.27; 11 haplotypes were identified as well. The relationship between genetic and geographic distances was not significant (p>0.05); therefore, no evidence of isolation due to distance was found. Based on the analyzed information, areas of in situ exploitation and genetic resources conservation are proposed. [ABSTRACT FROM AUTHOR]

Genetic variability with mutagenic agents has been employed in plant breeding due to its significant contribution to the improvement of the existing rice genotypes by using genetically diverse parents. This study evaluated the genetic variability and diversity of mutant rice using quantitative traits and inter-simple sequence repeats (ISSR) molecular markers. A field experiment was carried out on M5 generation of 31 developed mutant lines and their parent (control). Morphological traits and 25 ISSR molecular markers were used as tools for determining cultivar identities and genetic diversity. The selected primers generated 443 clear polymorphic bands with an average number of 18 per primer. The bands were 85.10 % polymorphic. Un-weighted Pair Group of Arithmetic Means (UPGMA) with similarity coefficients were used for cluster analysis. Through this, all the genotypes were grouped into six clusters. It was shown that crosses between MR219-ML8 and MR219-ML22 could be done for development of high yielding varieties. Also, these mutants could be used as donor parents in rice breeding programs and some can be recommended as new rice varieties suitable for rice cultivation in Malaysia. [ABSTRACT FROM AUTHOR]