Allelic heterogeneity and trade-off shape natural variation for response to soil micronutrient. PLOS Genetics 8: e1002814. doi

Abstract As sessile organisms, plants have to cope with diverse environmental constraints that may vary through time and space, eventually leading to changes in the phenotype of populations through fixation of adaptive genetic variation. To fully comprehend the mechanisms of evolution and make sense of the extensive genotypic diversity currently revealed by new sequencing technologies, we are challenged with identifying the molecular basis of such adaptive variation. Here, we have identified a new variant of a molybdenum (Mo) transporter, MOT1, which is causal for fitness changes under artificial conditions of both Mo-deficiency and Mo-toxicity and in which allelic variation among West-Asian populations is strictly correlated with the concentration of available Mo in native soils. In addition, this association is accompanied at different scales with patterns of polymorphisms that are not consistent with neutral evolution and show signs of diversifying selection. Resolving such a case of allelic heterogeneity helps explain species-wide phenotypic variation for Mo homeostasis and potentially reveals trade-off effects, a finding still rarely linked to fitness

Evaluación de la reacción de líneas puras de girasol y sus híbridos F1 a las condiciones de sequía mediante diversos índices de tolerancia al estrés

In this study, 21 genotypes of sunflower ( Helianthus annuus L.) derived from a half diallel cross between six inbred lines were evaluated in both water-stressed and well-watered environments. In each environment, the genotypes were evaluated using a randomized complete block design with three replications. From the grain yield data, drought tolerance indices comprising of stability tolerance index (STI), mean productivity (MP), geometric mean productivity (GMP), harmonic mean (HM), stress susceptibility index (SSI), tolerance index (TOL), yield index (YI) and yield stability index (YSI) were calculated for every genotype. The resulting data were analyzed as obtained from a randomized complete block design. Significant differences among genotypes were observed for all drought tolerance indices except for SSI and YSI. High yield value in non-stress and stress environments was exhibited by genotypes ‘LR4 × LR25’ (14.02 g) and ‘LR25 × C100’ (3.84 g) respectively. The maximum value of STI (0.93), MP (8.72), GMP (6.91) and HM (5.48) indices was by genotype ‘LR4 × LR25’. Correlation coefficients revealed that TOL, MP, GMP, STI, HM, and YI indices could effectively be used for screening of drought tolerant genotypes. Using MP, GMP, HM, TOL, YI and STI indices, genotypes UPGMA classification was done and three clusters were established that paralleled the biplot analysis results. According to results in this study, ‘LR4 × LR25’ is the most drought tolerant genotype which was clustered as group A. We suggest that tolerance indices including MP, GMP and HM are suitable for sunflower drought tolerant genotypes selection.En este estudio, 21 genotipos de girasol ( Helianthus annuus L.) derivados de un cruce medio dialélico entre seis líneas puras se evaluaron con y sin estrés hídrico. Para cada ambiente, los genotipos se evaluaron usando un diseño de bloques completos al azar con tres repeticiones. De los datos de rendimiento de grano se calcularon los índices de tolerancia a la sequía para cada genotipo: índice de estabilidad de la tolerancia sexual (ITS), productividad media (MP), productividad media geométrica (GMP), media armónica (HM), índice de susceptibilidad al estrés (SSI), índice de tolerancia (TOL), índice de rendimiento (YI) e índice de estabilidad del rendimiento (YSI). Los datos resultantes se analizaron como obtenidos a partir de un diseño de bloques completos al azar. Se observaron diferencias significativas entre los genotipos en todos los índices de tolerancia a la sequía a excepción de SSI y YSI. Los genotipos ‘LR4 × LR25’ y ‘LR25 × C100’ exhibieron un alto rendimiento en ambos ambientes (14,02 y 3,84 g, respectivamente); ‘LR4 × LR25’ presentó el valor máximo de los índices STI (0,93), MP (8,72), GMP (6,91) y HM (5,48). Los coeficientes de correlación revelaron que los índices TOL, MP, GMP, STI, HM y YI podrían ser utilizados para la selección de genotipos tolerantes a la sequía. Utilizando los índices MP, GMP, HM, TOL, YI y STI, se hizo una  clasificación UPGMA de los genotipos y se establecieron tres grupos análogos a los resultados del análisis biplot. De acuerdo a los resultados de este estudio, ‘LR4 × LR25’, del grupo A, es el genotipo más tolerante a la sequía. Se concluye que los índices de tolerancia MP, GMP y HM son adecuados para la selección de genotipos tolerantes a la sequía en girasol

Evaluation of the reaction of sunflower inbred lines and their F1 hybrids to drought conditions using various stress tolerance indices

In this study, 21 genotypes of sunflower (Helianthus annuus L.) derived from a half diallel cross between six inbred lines were evaluated in both water-stressed and well-watered environments. In each environment, the genotypes were evaluated using a randomized complete block design with three replications. From the grain yield data, drought tolerance indices comprising of stability tolerance index (STI), mean productivity (MP), geometric mean productivity (GMP), harmonic mean (HM), stress susceptibility index (SSI), tolerance index (TOL), yield index (YI) and yield stability index (YSI) were calculated for every genotype. The resulting data were analyzed as obtained from a randomized complete block design. Significant differences among genotypes were observed for all drought tolerance indices except for SSI and YSI. High yield value in non-stress and stress environments was exhibited by genotypes �LR4 × LR25� (14.02 g) and �LR25 × C100� (3.84 g) respectively. The maximum value of STI (0.93), MP (8.72), GMP (6.91) and HM (5.48) indices was by genotype �LR4 × LR25�. Correlation coefficients revealed that TOL, MP, GMP, STI, HM, and YI indices could effectively be used for screening of drought tolerant genotypes. Using MP, GMP, HM, TOL, YI and STI indices, genotypes UPGMA classification was done and three clusters were established that paralleled the biplot analysis results. According to results in this study, �LR4 × LR25� is the most drought tolerant genotype which was clustered as group A. We suggest that tolerance indices including MP, GMP and HM are suitable for sunflower drought tolerant genotypes selection.En este estudio, 21 genotipos de girasol (Helianthus annuus L.) derivados de un cruce medio dialélico entre seis líneas puras se evaluaron con y sin estrés hídrico. Para cada ambiente, los genotipos se evaluaron usando un diseño de bloques completos al azar con tres repeticiones. De los datos de rendimiento de grano se calcularon los índices de tolerancia a la sequía para cada genotipo: índice de estabilidad de la tolerancia sexual (ITS), productividad media (MP), productividad media geométrica (GMP), media armónica (HM), índice de susceptibilidad al estrés (SSI), índice de tolerancia (TOL), índice de rendimiento (YI) e índice de estabilidad del rendimiento (YSI). Los datos resultantes se analizaron como obtenidos a partir de un diseño de bloques completos al azar. Se observaron diferencias significativas entre los genotipos en todos los índices de tolerancia a la sequía a excepción de SSI y YSI. Los genotipos �LR4 × LR25� y �LR25 × C100� exhibieron un alto rendimiento en ambos ambientes (14,02 y 3,84 g, respectivamente); �LR4 × LR25� presentó el valor máximo de los índices STI (0,93), MP (8,72), GMP (6,91) y HM (5,48). Los coeficientes de correlación revelaron que los índices TOL, MP, GMP, STI, HM y YI podrían ser utilizados para la selección de genotipos tolerantes a la sequía. Utilizando los índices MP, GMP, HM, TOL, YI y STI, se hizo una clasificación UPGMA de los genotipos y se establecieron tres grupos análogos a los resultados del análisis biplot. De acuerdo a los resultados de este estudio, �LR4 × LR25�, del grupo A, es el genotipo más tolerante a la sequía. Se concluye que los índices de tolerancia MP, GMP y HM son adecuados para la selección de genotipos tolerantes a la sequía en girasol