Studies of potato resistance to Globodera rostochiensis revealed novel alleles for 57R marker.

Globodera rostochiensis resistance has been an important trait in potato (Solanum tuberosum) breeding for decades. Our aim was to complement phenotypic testing with genetic marker analysis. We analysed the results of G. rostochiensis resistance greenhouse testing in 4601 tubers of 2918 breeding clones from 11 years. Applicability of H1 gene markers TG689 and 57R was compared. We implemented the latter with the positive predictive value of 99.1% and negative predictive value of 60.0% into the breeding scheme. The 57R marker alleles of 22 Estonian cultivars and 470 breeding clones were determined. Two unique 57R alleles, 57R-887 and 57R-1155, were found in Estonian cultivar 'Anti'. The 887 bp allele has two deletions (14 bp and 490 bp) accompanied by several other indels and SNPs within the 57R marker region. The 1155 bp allele has three deletions (7 bp, 20 bp and 210 bp) accompanied by several other indels and SNPs within the same region. Partial resistance to G. rostochiensis in 'Anti' suggests that the newly described alleles could affect the H1-mediated resistance directly or indirectly.

Are stomata in ferns and allies sluggish? Stomatal responses to CO2 , humidity and light and their scaling with size and density.

Fast stomatal reactions enable plants to successfully cope with a constantly changing environment yet there is an ongoing debate on the stomatal regulation mechanisms in basal plant groups. We measured stomatal morphological parameters in 29 fern and allied species from temperate to tropical biomes and two outgroup angiosperm species. Stomatal dynamic responses to environmental drivers were measured in 16 ferns and the two angiosperms using a gas-exchange system. Principal components analyses were used to further reveal the structure-function relationships in stomata. We show a > 10-fold variation for stomatal opening delays and 20-fold variation for stomatal closing delays in ferns. Across species, stomatal responses to vapor pressure deficit (VPD) were the fastest, while light and [CO2 ] responses were slower. In most cases the outgroup species' reaction speeds to changes in environmental variables were similar to those of ferns. Correlations between stomatal response rate and size were apparent for stomatal opening in light and low [CO2 ] while not evident for closing reactions and changes in VPD. No correlations between stomatal density and response speed were observed. Together, this study demonstrates different mechanisms controlling stomatal reactions in ferns at different environmental stimuli, which should be considered in future studies relating stomatal morphology and function.