Association of single nucleotide polymorphisms in LpIRI1 gene with freezing tolerance traits in perennial ryegrass

Perennial ryegrass is an important agricultural species, however, susceptible to winterkill. Freezing injury is caused primarily by ice formation. The LpIRI1 protein has the potential to inhibit ice recrystallization, thus minimize the damage. An association study was conducted using single nucleotide polymorphisms obtained through allele sequencing of the LpIRI1 gene and phenotypic data were collected using two phenotyping platforms in a perennial ryegrass association mapping population of 76 diverse genotypes. Winter survival (FWS) was evaluated under field conditions, while tiller survival (PTS) and electrolyte leakage (EL) at -8 °C and -12 °C were determined under controlled-environment conditions. Proline content (PC) in cold-acclimated plants was measured prior the freezing test. Significant variation in FWS, PTS, EL and PC was observed among genotypes in our panel. EL and PTS revealed significant negative correlations at -8 °C (rs = -0.40) and -12 °C (rs = -0.49). PC, however, did not show significant correlations with any of the measured traits, while FWS was correlated (rs = -0.48) with EL at -12 °C. The LpIRI1 gene was found to be highly polymorphic with an average SNP frequency of 1 SNP per 16 bp. Association analysis revealed two non-synonymous SNPs being associated with increased EL, both being located in the LpIRI1 leucine-rich repeat. The results indicate that allelic variation in the LpIRI1 gene plays an important role in the cell membrane integrity of perennial ryegrass during freezing, and can be exploited for developing more freezing tolerant cultivars

Mating type idiomorphs of Pyrenophora teres in Turkey

Pyrenophora teres f. maculata (Ptm) and Pyrenophora teres f. teres (Ptt) causes spot form and net form of net blotch diseases of barley, respectively. Although both forms of P. teres are morphologically similar, their symptoms and genetic background differ. In this study, 175 single spore (109 Ptm and 66 Ptt) isolates obtained from different regions of Turkey were evaluated for their mating type distribution and prevalence. Fungal isolates of both forms were verified using species-speci.c polymerase chain reaction (PCR) primers. For mating type determination studies, duplex PCR was performed using MAT-specific single nucleotide polymorphism primers. Sixty and 49 of 109 Ptm isolates were found as MAT1-1 and MAT1-2 types, respectively and 43 and 23 of 66 Ptt isolates were found as MAT1-1 and MAT1-2 types, respectively. These results show the possibility of sexual reproduction among the Ptm isolates in Turkey and Ptt population of Central Anatolia, Turkey. However, the overall pattern of Ptt isolates did not support the sexual reproduction hypothesis in Turkey. Sexual reproduction in the life cycle of P. teres is important since it could lead to genetic and pathogenic variation. As a result of new sexual combinations more virulent pathotypes of P. teres may occur

Association of single nucleotide polymorphisms in LpIRI1 gene with freezing tolerance traits in perennial ryegrass

Perennial ryegrass is an important agricultural species, however, susceptible to winterkill. Freezing injury is caused primarily by ice formation. The LpIRI1 protein has the potential to inhibit ice recrystallization, thus minimize the damage. An association study was conducted using single nucleotide polymorphisms obtained through allele sequencing of the LpIRI1 gene and phenotypic data were collected using two phenotyping platforms in a perennial ryegrass association mapping population of 76 diverse genotypes. Winter survival (FWS) was evaluated under field conditions, while tiller survival (PTS) and electrolyte leakage (EL) at -8 °C and -12 °C were determined under controlled-environment conditions. Proline content (PC) in cold-acclimated plants was measured prior the freezing test. Significant variation in FWS, PTS, EL and PC was observed among genotypes in our panel. EL and PTS revealed significant negative correlations at -8 °C (rs = -0.40) and -12 °C (rs = -0.49). PC, however, did not show significant correlations with any of the measured traits, while FWS was correlated (rs = -0.48) with EL at -12 °C. The LpIRI1 gene was found to be highly polymorphic with an average SNP frequency of 1 SNP per 16 bp. Association analysis revealed two non-synonymous SNPs being associated with increased EL, both being located in the LpIRI1 leucine-rich repeat. The results indicate that allelic variation in the LpIRI1 gene plays an important role in the cell membrane integrity of perennial ryegrass during freezing, and can be exploited for developing more freezing tolerant cultivars.This is a post-peer-review, pre-copyedit version of an article published in Euphytica. The final authenticated version is available online at: http://dx.doi.org/10.1007/s10681-014-1330-y.</p