Genetic variability and structure of an important wild steppe grass Psathyrostachys juncea (Triticeae: Poaceae) germplasm collection from north and central Asia

Environmental Niche Dynamics of Blue Grama (Bouteloua gracilis) Ecotypes in Northern Mexico: Genetic Structure and Implications for Restoration Management

Understanding the genetic structure adopted by natural populations and its relation to environmental adaptation is critical for the success of restoration programs. We evaluated the genetic structure and temporal environmental niche dynamics of blue grama (Bouteloua gracilis) in 48 populations. The genetic evaluation was performed through amplified fragment length polymorphism (AFLP) molecular markers. The maximum entropy method was used to model the past, present, and future environmental niches of the three clusters derived from the genetic analysis. The environmental niches of the three genetic clusters showed dynamic overlaps and isolations during the last interglacial and glacial maximum. The paleoclimatic events, which occurred during those periods, may have reinforced genetic exchange among populations and affected their genetic structure. Genetic clusters also presented different environmental niches in the present. Thus, they can be considered as three distinct ecotypes and restoration programs must be carried out using local germplasm from each environmental niche to increase their chance of success. Based on the environmental niches of the genetic clusters, changes are expected in the near and mid-century future. Therefore, climate change must be considered for species conservation management and future restoration programs.

EST-SSR Primer Development and Genetic Structure Analysis of Psathyrostachys juncea Nevski

Psathyrostachys juncea is a perennial forage grass which plays an important role in soil and water conservation and ecological maintenance in cold and dry areas of temperate regions. In P. juncea, a variety of biotic and abiotic stress related genes have been used in crop improvement, indicating its agronomic, economic, forage, and breeding value. To date, there have been few studies on the genetic structure of P. juncea. Here, the genetic diversity and population structure of P. juncea were analyzed by EST-SSR molecular markers to evaluate the genetic differentiation related to tillering traits in P. juncea germplasm resources. The results showed that 400 simple sequence repeat (SSR) loci were detected in 2,020 differentially expressed tillering related genes. A total of 344 scored bands were amplified using 103 primer pairs, out of which 308 (89.53%) were polymorphic. The Nei's gene diversity of 480 individuals was between 0.092 and 0.449, and the genetic similarity coefficient was between 0.5008 and 0.9111, with an average of 0.6618. Analysis of molecular variance analysis showed that 93% of the variance was due to differences within the population, and the remaining 7% was due to differences among populations. Psathyrostachys juncea materials were clustered into five groups based on population genetic structure, principal coordinate analysis and unweighted pair-group method with arithmetic means (UPGMA) analysis. The results were similar between clustering methods, but a few individual plants were distributed differently by the three models. The clustering results, gene diversity and genetic similarity coefficients showed that the overall genetic relationship of P. juncea individuals was relatively close. A Mantel test, UPGMA and structural analysis also showed a significant correlation between genetic relationship and geographical distribution. These results provide references for future breeding programs, genetic improvement and core germplasm collection of P. juncea.

Erianthus germplasm collection in Thailand: genetic structure and phylogenetic aspects of tetraploid and hexaploid accessions

BACKGROUND

The genus Erianthus, which belongs to the "Saccharum complex", includes C₄ warm-season grasses. Erianthus species are widely distributed throughout Southeast Asia, East Asia and South Asia. Erianthus arundinaceus (Retz.) Jeswiet is highly adaptable to the environment, has a high percentage of dry matter, and is highly productive. Recently, this species has attracted attention as a novel bioenergy crop and as a breeding material for sugarcane improvement. Such interest in E. arundinaceus has accelerated the collection and conservation of its genetic resources, mainly in Asian countries, and also evaluation of morphological, agricultural, and cytogenetic features in germplasm collections. In Thailand, genetic resources of E. arundinaceus have been collected over the past 20 years and their phenotypic traits have been evaluated. However, the genetic differences and relatedness of the germplasms are not fully understood.

RESULTS

A set of 41 primer pairs for nuclear simple sequence repeats (SSRs) developed from E. arundinaceus were used to assess the genetic diversity of 121 Erianthus germplasms collected in Thailand; of these primer pairs, 28 detected a total of 316 alleles. A Bayesian clustering approach with these alleles classified the accessions into four main groups, generally corresponding to the previous classification based on phenotypic analysis. The results of principal coordinate analysis and phylogenetic analysis of the 121 accessions on the basis of the SSR markers showed the same trend as Bayesian clustering, whereas sequence variations of three non-coding regions of chloroplast DNA revealed eight haplotypes among the accessions. The analysis of genetic structure and phylogenetic relationships, however, found some accessions whose classification contradicted the results of previous phenotypic classification.

CONCLUSIONS

The molecular approach used in this study characterized the genetic diversity and relatedness of Erianthus germplasms collected across Thailand. This knowledge would allow efficient maintenance and conservation of the genetic resources of this grass and would help to use Erianthus species as breeding materials for development of novel bioenergy crops and sugarcane improvement.