Identification of QTLs associated with metribuzin tolerance in field pea (<Emphasis Type="Italic">Pisum sativum</Emphasis> L.)

Competition with weeds is a major constraint to production of field pea in Australia, exacerbated by limited herbicide control options. Metribuzin is considered to be a safe herbicide, but may be phytotoxic to both weeds and target crop. A preliminary glasshouse-based assay was used to identify the optimal concentration required for discrimination between tolerant and sensitive field pea genotypes as 10 ppm metribuzin. This dosage was subsequently used to screen the Kaspa × PBA Oura recombinant inbred line genetic mapping population of 185 individuals for tolerance to metribuzin in three individual controlled environment assays. After two weeks of metribuzin treatment, plants were assessed on the basis of both a numerical score for symptoms such as chlorosis and necrosis, and plant damage as a percentage of necrosis. The two phenotypic parameters showed a high level of correlation (r = 0.85–0.97). The locations and magnitudes of effect of quantitative trait loci (QTLs) were determined for metribuzin tolerance (based on both symptom score and plant damage) as well as several related morphological traits. Analysis of all characters detected a single genomic region located on linkage group (LG) Ps IV (LOD scores 3.5–5.7), accounting for proportions of phenotypic variance for plant symptom score and percentage of plant necrosis varying from 12 to 21%. Genetic markers based on genic sequences that closely flank the metribuzin tolerance QTL are suitable for implementation in field pea breeding programs. In addition, comparative genomics between field pea and Medicago truncatula identified a cytochrome P450 monooxygenase gene in the vicinity of the QTL, potentially involved in non-target-site metabolism-based herbicide tolerance.     

QTL detection for flowering time in faba bean and the responses to ambient temperature and photoperiod

Faba bean (Vicia faba L.) is a grain legume primarily used for animal feed and human food grown in a range of environments, globally. Time of flowering in faba bean is critical for adaptation to specific environments and is controlled largely by factors such as ambient temperature and photoperiod. The aim of this study was to investigate the genetic control of flowering time and the responses of flowering time to ambient temperature and photoperiod in faba bean. A bi-parental recombinant inbred line population (Icarus × Ascot) was evaluated over three years in field trials and three different controlled environments with varying temperatures and photoperiods. QTL analysis identified eight regions of co-localised QTLs associated with days to flowering, thermal time to flowering and node of first flower; on Chr-I.A/III/V, Chr-I.B.3, Chr-III.1, Chr-III.2, Chr-V.1 and Chr-V.2. Two of the detected regions are common with previously detected QTLs, up to two more are possibly common and the remaining four appear to be novel. For the first time, the associations of these QTLs with ambient temperature and photoperiod response were described. Candidate genes for some of the QTLs were identified using the associations with ambient temperature and photoperiod response together with knowledge extended from other legumes that have a syntenic relationship with faba bean.     

Morpho-physiological evaluation of Elymus semicostatus (Nees ex Steud.) Melderis as potential donor for drought tolerance in Wheat (Triticum aestivum L.)

Genetic Resources and Crop Evolution - Gradual deterioration in water resources and unpredictable distribution pattern of annual precipitation amount are major threats having drastic effects on...