Biochemical and molecular characterisation of Glu-1 loci in Argentinean wheat cultivars

The high molecular weight glutenin subunit (HMW-GS) composition of acollection of 107 Argentinean bread wheat cultivars was analysed bysodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE).Allelic variation at the Glu-1 loci was identified and its frequencycalculated. Eleven alleles were detected, three encoded at the Glu-A1locus, six at the Glu-B1 locus and two at the Glu-D1 locus. Alow frequency of the null allele at the Glu-A1 locus and a highfrequency of subunits 5+10 at the Glu-D1 locus were observed.Reversed phase-high performance liquid chromatography (RP-HPLC)analysis was used to further characterise HMW-GS. Two different types ofBx subunit 8 (named subunits 8 and 8) were detected, the latterhaving shorter elution time. Subunit 8 was not identifiable bySDS-PAGE. According to quantification by RP-HPLC analysis, two groupsof subunit 7 were observed. One group, with a relatively high proportionof subunit 7 (approximately 39% of the total amount of HMW-GS)appeared in cultivars with allele 7+8 at the Glu-B1 locus; asecond group of subunit 7 (around 24% of the total amount ofHMW-GS), was found in alleles 7+8, 7+8 and 7+9. Restrictionfragment length polymorphisms (RFLP) analyses of HMW-GS genes werealso carried out after digestion of genomic DNA with HindIII andTaqI restriction enzymes. The relationship between DNA fragment sizeand glutenin subunits, as estimated by electrophoretic mobility inSDS-PAGE, was also examined. The restriction enzyme TaqIdemonstrated to be a useful tool to detect homozygous plants in selectionprograms against the Glu-A1 null allele.     

Propanil tolerance in Echinochloa crus‐galli (L.) Beauv

Abstract

Two morphological variants of Echinochloa crus‐galli were collected from rice fields of an area in Greece where rice has been grown for over a decade and growers have recently been complaining about reduced effectiveness of propanil. Seedling response of the two variants to propanil was compared with that of E. crus‐galli collected from vegetable fields in another area where rice has never been grown. Initial contact toxicity of propanil was similar in all collections. Growth inhibition thereafter was clearly different, resulting in death of the E. crus‐galli from vegetables but not of the E. crus‐galli from rice. The latter could overcome initial toxicity and resume growth at 8 kg/ha of propanil, whereas the former was killed at 2–4 kg/ha. Prevalence of E. crus‐galli forms of higher tolerance resulting from selection through rice husbandry and/or repeated use of propanil may account for the reduced effectiveness of propanil in the area of intensive rice growing.