A landscape-scale field survey demonstrates the role of wheat volunteers as a local and diversified source of leaf rust inoculum.

Deploying disease-resistant cultivars is one of the most effective control strategies to manage crop diseases such as wheat leaf rust, caused by Puccinia triticina. After harvest, this biotrophic fungal pathogen can survive on wheat volunteers present at landscape scale and constitute a local source of primary inoculum for the next cropping season. In this study, we characterised the diversity of P. triticina populations surveyed on wheat volunteer seedlings for six consecutive years (2007-2012) at the landscape scale. A total of 642 leaf rust samples classified in 52 virulence profiles (pathotypes) were collected within a fixed 5-km radius. The pathotype composition (identity and abundance) of field-collected populations was analyzed according to the distance between the surveyed wheat plots and to the cultivars of origin of isolates. Our study emphasised the high diversity of P. triticina populations on wheat volunteers at the landscape scale. We observed an impact of cultivar of origin on pathogen population composition. Levels of population diversity differed between cultivars and their deployment in the study area. Our results suggest that wheat volunteers could provide a significant though highly variable contribution to the composition of primary inoculum and subsequent initiation of leaf rust epidemics.

Multilocus Genotypes of the Wheat Leaf Rust Fungus Puccinia triticina in Worldwide Regions Indicate Past and Current Long-Distance Migration.

Many plant pathogenic fungi have a global distribution across diverse ecological zones and agricultural production systems. Puccinia triticina, the wheat leaf rust fungus, is a major pathogen in many wheat production areas of the world. The objective of this research was to determine the genetic relatedness of P. triticina in different worldwide regions. A total of 831 single-uredinial isolates collected from 11 regions were characterized for multilocus genotype at 23 simple sequence repeat loci and for virulence to 20 lines of wheat with single genes for leaf rust resistance. A total of 424 multilocus genotypes and 497 virulence phenotypes were found. All populations had high heterozygosity and significant correlation between virulence and molecular variation, which indicated clonal reproduction. The populations from North America and South America, Central Asia and Russia, and the Middle East and Europe were closely related for multilocus genotypes and many individual isolates from other continental regions were closely related. Twenty-seven multilocus genotypes were found in more than one continental region, and 13 of these had isolates with identical virulence phenotypes. The wide geographic distribution of identical and highly related multilocus genotypes of P. triticina indicated past and more recent migration events facilitated by the spread of clonally produced urediniospores.

Glycaemic control and hypoglycaemia with insulin glargine 300U/mL versus insulin glargine 100U/mL in insulin-naïve people with type 2 diabetes: 12-month results from the EDITION 3 trial.

AIM: To explore if efficacy and safety findings for insulin glargine 300U/mL (Gla-300) versus insulin glargine 100U/mL (Gla-100), observed over 6 months in insulin-naïve people with type 2 diabetes, are maintained after 12 months. METHODS: EDITION 3 was a phase 3a, randomized, multicentre, open-label, parallel-group, treat-to-target study of once-daily Gla-300 versus Gla-100 (target fasting self-monitored plasma glucose, 4.4-5.6mmol/L [80-100mg/dL]). Participants completing the initial 6-month treatment phase continued their previously allocated basal insulin. RESULTS: Of 878 participants randomized, 337/439 (77%) and 314/439 (72%) assigned to Gla-300 and Gla-100, respectively, completed 12 months of treatment. Improved glycaemic control was sustained until 12 months in both treatment groups, with similar reductions in HbA1c from baseline to month 12 (difference: -0.08 [95% confidence interval (CI): -0.23 to 0.07] % or -0.9 [-2.5 to 0.8] mmol/mol). Relative risk of experiencing≥1 confirmed (≤3.9mmol/L [≤70mg/dL]) or severe hypoglycaemic event with Gla-300 versus Gla-100 was 0.86 (95% CI: 0.69 to 1.07) at night and 0.92 (0.82 to 1.03) at any time of day. For events with a glycaemic threshold of<3.0mmol/L (<54mg/dL) these numbers were 0.76 (0.49 to 1.19) and 0.66 (0.50 to 0.88). A similar pattern was seen for documented symptomatic events. No between-group differences in adverse events were identified. CONCLUSION: Over 12 months, Gla-300 treatment was as effective as Gla-100 in reducing HbA1c in insulin-naïve people with type 2 diabetes, with lower overall risk of hypoglycaemia at the<3.0mmol/L threshold.

New insulin glargine 300 U/ml compared with glargine 100 U/ml in insulin-naïve people with type 2 diabetes on oral glucose-lowering drugs: a randomized controlled trial (EDITION 3).

AIMS: To compare the efficacy and safety of new insulin glargine 300 U/ml (Gla-300) with that of glargine 100 U/ml (Gla-100) in insulin-naïve people with type 2 diabetes using oral glucose-lowering drugs. METHODS: The EDITION 3 study was a multicentre, open-label, parallel-group study. Participants were randomized to Gla-300 or Gla-100 once daily for 6 months, discontinuing sulphonylureas and glinides, with a dose titration aimed at achieving pre-breakfast plasma glucose concentrations of 4.4-5.6 mmol/l (80-100 mg/dl). The primary endpoint was change in glycated haemoglobin (HbA1c) from baseline to month 6. The main secondary endpoint was percentage of participants with ≥1 nocturnal confirmed [≤3.9 mmol/l (≤70 mg/dl)] or severe hypoglycaemia from week 9 to month 6. Other measures of glycaemia and hypoglycaemia, weight change and insulin dose were assessed. RESULTS: Randomized participants (n = 878) had a mean (standard deviation) age of 57.7 (10.1) years, diabetes duration 9.8 (6.4) years, body mass index 33.0 (6.7) kg/m(2) and HbA1c 8.54 (1.06) % [69.8 (11.6) mmol/mol]. HbA1c levels decreased by equivalent amounts with the two treatments; the least squares mean difference in change from baseline was 0.04 [95% confidence interval (CI) -0.09 to 0.17] % or 0.4 (-1.0 to 1.9) mmol/mol. Numerically fewer participants reported ≥1 nocturnal confirmed (≤3.9 mmol/l) or severe hypoglycaemia from week 9 to month 6 [relative risk (RR) 0.89 (95% CI 0.66 to 1.20)] with Gla-300 versus Gla-100; a significantly lower risk of hypoglycaemia with this definition was found over the 6-month treatment period [RR 0.76 (95% CI 0.59 to 0.99)]. No between-treatment differences in adverse events were identified. CONCLUSIONS: Gla-300 is as effective as Gla-100 in reducing HbA1c in insulin-naïve people with type 2 diabetes, with lower hypoglycaemia risk.

Virulence in Puccinia triticina for Durum Wheat Cultivar Creso and Other Durum Wheat Cultivars Carrying Resistance Gene Lr14a in France.

Durum wheat cv. Creso has been mentioned as having durable resistance to leaf rust (2-4). However, an average final disease level of 70S on the modified Cobb scale was scored on Creso across three locations in inoculated field trials in France during 2009. A mixture of two durum wheat leaf rust isolates commonly found in France was used for the inoculation, one was virulent on Lr23 and the other was avirulent on this gene, their identical avirulence/virulence formula for other genes was Lr1, 2a, 2b, 3, 3bg, 3ka, 9, 11, 13, 15, 16, 17, 19, 24, 25, 26, 27+31/Lr2c, 10, 14a, 14b, 20, 21, 33, and 44. On cv. Llareta Inia and breeding line Somateria, both of which carry the resistance gene Lr14a, the average final disease level was, respectively, 95S and 80S. Creso, Llareta Inia, and Somateria displayed average final disease levels of, respectively, 0, 10S, and 1 in field trials inoculated with race CBG/BP in 2009 at two locations in Mexico (Ciudad Obregon and El Batan). Race CBG/BP, virulent on Lr3, 10, 11, 14b, 20, 23, 27 + 31, and 33, is the most widely virulent race identified so far in Mexico where Lr14a remains effective for durum wheat. Virulence for Lr14a in durum wheat leaf rust populations was already mentioned to be present in France since 2000 (1). It has been suggested that the resistance of Creso, which has remained durable in Italy since 1975 (4), could be due to a gene close to but different from Lr14a. Alternatively, the fact that Creso's reaction was significantly lower than those of Llareta Inia or Somateria could indicate the presence of another gene, of minor effect, in addition to Lr14a. Whatever the genetic basis of the Creso resistance may be, it has been overcome by common French pathotypes and its usefulness in breeding, at a regional if not global level, has become questionable. References: (1) H. Goyeau et al. Phytopathology 96:264, 2006. (2) S. A. Herrera-Foessel et al. Plant Dis. 92:469, 2008. (3) M. Maccaferri et al. Theor. Appl. Genet. 117:1225, 2008. (4) D. Marone et al. Mol. Breed. 24:25, 2009.

Molecular markers linked to the leaf rust resistance gene Lr24 in different wheat cultivars.

The aim of this study was to find molecular markers (RAPD and SCAR) for the wheat leaf rust resistance gene Lr24. A backcross line, RL 6064, possessing a single resistance gene to leaf rust (Lr24) and its recurrent parent 'Thatcher' were used to find RAPD markers linked to the Lr24 gene. Among 125 RAPD primers tested, only one (OP-H5) detected an additional band in the resistant line RL 6064. The genetic linkage of this molecular marker to Lr24 was tested on a segregating F2 population derived from a cross between the leaf rust resistant line RL 6064 and the susceptible line 'Chinese Spring'. This marker showed complete linkage to the Lr24 resistance gene. A more reliable and specific marker for this resistance gene was made by converting it into a sequence characterized amplified region (SCAR). The presence of a single amplification product allowed direct detection of the gene in the test tube by the addition of ethidium bromide. This SCAR marker linked to the leaf rust resistance gene Lr24 could be used easily in a practical breeding program.