Genetic variation of mangrove species Avicennia marina in Iran revealed by microsatellite markers

Mangroves play an essential role in ecosystem dynamics but are reported to be regressing as human pressure increases on coastal zones. In order to ensure conservation of mangroves, genetic diversity in remaining population must be explored. Since Avicennia marina is an environmentally susceptible species, such studies including examination of its genetic variation is done in a worldwide range.During the present study the level of genetic variation of mangrove trees (A. marina) in three coastlines of Bushehr province (Southwest regions of Iran) was examined using microsatellite markers. Threemicrosatellite loci which were applied in the last large-scale study, detected high levels of allelic diversity here (14 alleles in total), essential for an accurate estimation of population genetic parameters.The levels of heterozygosity detected for each population, over all loci, ranged from 0.451 to 0.667 with an average of 0.589, indicating relatively appropriate level of genetic variation. The expectedheterozygosity was larger than the observed heterozygosity leading to positive inbreeding coefficients in all three populations. Highly significant departures from Hardy-Weinberg Equilibrium were detectedin populations. Reduced level of genetic variation was found in the central population indicating strong genetic structure among the other populations with larger area and less exploitation

Development and Application of Image-Based High-Throughput Phenotyping Methodology for Salt Tolerance in Lentils

Soil salinity is a major abiotic stress in Australian lentil-producing areas. It is therefore imperative to identify genetic variation for salt tolerance in order to develop lentil varieties suitable for saline soils. Conventional screening methods include the manual assessment of stress symptoms, which can be very laborious, time-consuming, and error-prone. Recent advances in image-based high-throughput phenotyping (HTP) technologies have provided unparalleled opportunities to screen plants for a range of stresses, such as salt toxicity. The current study describes the development and application of an HTP method for salt toxicity screening in lentils. In a pilot study, six lentil genotypes were evaluated to determine the optimal salt level and the growth stage for distinguishing lentil genotypes using red–green–blue (RGB) images on a LemnaTec Scanalyzer 3D phenomics platform. The optimized protocol was then applied to screen 276 accessions that were also assessed earlier in a conventional phenotypic screen. Detailed phenotypic trait assessments, including plant growth and green/non-green color pixels, were made and correlated to the conventional screen (r = 0.55; p < 0.0001). These findings demonstrated the improved efficacy of an image-based phenotyping approach that is high-throughput, efficient, and better suited to modern breeding programs

Small urban stands of the mangrove Avicennia marina are genetically diverse but experience elevated inbreeding

Anthropogenic impacts contribute to the fragmentation of urban mangrove forests, and in the Sydney region of Australia, Avicennia marina is commonly found in small stands of However, genetic diversity may not vary with stand size because insufficient time has passed since stands were established or pollen and propagule dispersal are sufficient to overwhelm the effects of genetic drift and founder events. We tested the predictions that, despite the potential of mangroves for dispersal of propagules by water and long distance dispersal of pollen by honeybees, fragmentation and localized foraging by honeybees causes small stands of A. marina to display reduced genetic diversity and elevated inbreeding. Using four microsatellite markers, we quantified the genetic and genotypic diversity present within samples of 20 adults taken from three large (\u3e1500 trees), intermediate (300-500 trees) and small (\u3c50 \u3etrees) stands within each of two urbanized estuaries and estimated mating system parameters using progeny arrays for sets of five adults within the large and small stands. We detected no significant effect of stand size on levels of single-locus genetic diversity. There were low, although significant, levels of allelic differentiation within (F SE = 0.021, P = 0.003) and among (F ET = 0.055, P = 0.005) estuaries but no evidence of isolation by distance. In contrast, our analysis of progeny arrays revealed that, while all stands displayed high levels of biparental inbreeding, an expected consequence of pollination by honeybees, current outcrossing rates (t m ) were significantly lower in small (0.55) as compared to large (0.75) stands. The genetic makeup of the adult populations imply that stands are interconnected and suggest little impact of habitat fragmentation, while the progeny arrays suggest that plants within small stands may display reduced fitness