Seven corn inbred lines previously shown to differ in response to soil residues of chlorsulfuron were characterized as to the target-enzyme acetolactate synthase (ALS) specific activity and to its susceptibility to the herbicide. ALS from plantlets at the five-leaf stage of growth was similarly susceptible to chlorsulfuron in all lines and its specific activity in the shoots was not significantly correlated with in vivo tolerance to the herbicide. By contrast, differences in ALS specific activity in roots of plants both at the five- and three-leaf stages of growth were significantly correlated (r = 0.96∗∗ and r = 0.93∗∗, respectively) with in vivo tolerance. Correlation was also noted in extracts from cultured excised root tips (r = 0.94∗∗). Callus tissue of a chlorsulfuron-tolerant line was less affected by the herbicide and had a significantly higher ALS specific activity than callus from a chlorsulfuron susceptible line, whereas inhibition of ALS by the herbicide was similar in both lines. These results indicate that the naturally occurring differences in ALS levels in the roots of the investigated inbred lines contribute largely to the differential in vivo response observed to chlorsulfuron.

In this study, a forward-genetics analysis was performed on a portion of TILLMore, a chemically mutagenized population of barley cv. ‘Morex’ (http://www.distagenomics.unibo.it/TILLMore/), to identify root morphology alterations by comparison with ‘Morex’ wild-type. For this purpose, a simple paper-roll approach was performed to identify phenotypic variants at the seedling stage. The analysis of c. 1000 M4 families allowed us to identify c. 70 lines with altered root morphology. A more accurate phenotypic characterization of a portion of the mutant lines has been performed using stereomicroscopy and a scanning electron microscopy approach.

In this study, the targetting-induced local lesions in genomes approach was used to identify mutants for genes related to starch metabolism in barley. Starch is the major reserve of plants and serves as primary carbohydrate component in human and livestock diets and has also numerous industrial applications. Mutants for biosynthetic or regulatory genes of starch metabolism often produce starch granules with abnormal morphological and molecular features that could be of interest for technological applications. We report the identification of 29 mutations in five starch-related barley genes (Bmy1, GBSSI, LDA1, SSI and SSII) through the molecular screening of TILLMore, a sodium azide-mutagenized population. Almost all the mutations detected were CG–TA transitions and several (c. 60%) implied a change in amino-acid sequence and therefore possible phenotypic effects. Four mutants showed non-sense or splice-junction alterations, which could drastically affect the protein function.

The effectiveness of association mapping (AM) based on linkage disequilibrium (LD) is currently being tested in a number of crops. An important prerequisite for the application of AM is the availability of collections of accessions with a suitable level of genetic variation for target traits and with limited spurious LD due to the presence of population structure. Herein, the results of a genome-wide molecular characterization of a collection of elite durum wheat accessions well-adapted to Mediterranean environments are presented. Ninety-seven highly polymorphic simple sequence repeats and 166 amplified fragment length polymorphism markers were used to characterize 189 durum accessions, mainly cultivars and advanced breeding lines. Genome-wide significant and sizeable LD indices at a centimorgan scale were observed, while LD mainly decayed within 10 cM. On the other hand, effects due to spurious LD were notably lower than those previously observed in a durum wheat collection sampling durum gene pools of more diverse origin. These results, coupled with the high level of genetic variability detected for a number of important morpho-physiological traits and their high heritability, indicate the suitability of this collection for AM studies targeting agronomically important traits.