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Pyrethrum seed has an important role in the transmission of Stagonosporopsis tanaceti, the cause of ray blight disease of pyrethrum. A TaqMan probe based polymerase chain reaction (PCR) assay was developed to quantify the level of S. tanaceti inocula in pyrethrum seed and seedlings. Primer pair (St_qF3, St_qR2) was designed based on the intergenic spacer (IGS) region of S. tanaceti, which produced a 125 bp amplicon specific to S. tanaceti. TaqMan PCR assay using St_qF3, St_qR2 and a probe St_qP was highly specific against the genomic DNA of S. tanaceti, but did not amplify DNA of 14 related Stagonosporopsis species or other foliar pathogens of pyrethrum. The sensitivity limit of this assay was measured using the cycle threshold (Ct) value which ranged from 17.59 for 10 nanograms (ng) to 36.34 for 100 femtograms (fg) genomic DNA of S. tanaceti. There was a significant negative correlation (r = −0.999, P < 0.001) between the Ct value and the percent of S. tanaceti infected seed. In addition, this TaqMan PCR assay detected latent infection within seedlings. This assay could be applied to test commercial seed and seedlings before deciding on the appropriate management practices.

Two new pathogens of pyrethrum, described as Paraphoma chlamydocopiosa and Paraphoma pye, isolated from necrotic leaf lesions on pyrethrum plants in northern Tasmania, Australia, were identified using morphological characters, phylogenetic analysis of the internal transcribed spacer (ITS), elongation factor 1â α (EF1â α) and βâ tubulin (TUB) genes, and pathogenicity bioassays. Bootstrap support in the combined and individual gene region phylogenetic trees supported the two species that were significantly different from the closely related P. chrysanthemicola and P. vinacea. Morphological characteristics also supported the two new species, with conidia of P. chlamydocopiosa being considerably longer and wider than either P. chrysanthemicola or P. vinacea, and P. pye being distinct in forming bilocular pycnidia. Glasshouse pathogenicity tests based on root dip inoculation resulted in P. chlamydocopiosa and P. pye infecting the crown and upper root tissues of pyrethrum plants, and significant reduction in biomass 2 months after inoculation. Both of these Paraphoma species caused leaf lesions during in vitro and in vivo bioassays 2 weeks after foliar spray inoculation. Although P. chlamydocopiosa and P. pye were shown to be crown rot pathogens, they were also commonly isolated from leaves of diseased plants in pyrethrum fields of northern Tasmania.

Ray blight disease of pyrethrum (Tanacetum cinerariifolium) is caused by Stagonosporopsis tanaceti, with infected seed being a major means of transmission of this fungal pathogen. The infection process of S. tanaceti in pyrethrum seed and seedlings was determined. Infection hyphae only infected the outer and inner layers of the seed coat and not the embryo of naturally infected pyrethrum seed. During the process of germination of infected seed, S. tanaceti from the seed coat infected the developing embryo and cotyledon, resulting in pre‐ and post‐emergence death, depending on the level of infection in the seed coat. Pre‐emergence death occurred due to disintegration of the infected embryo, which was replaced by hyphae and extracellular anthocyanin‐like material (EAM) at 7 days after incubation (dai). Post‐emergence death occurred after both epidermal and cortical tissues of infected cotyledons at the crown/hypocotyl region disintegrated due to colonization by hyphae. Moreover, most of the tissues of the vascular bundles and cortical tissues contained heavy depositions of EAM at 10–14 dai. In 6‐week‐old infected seedlings, hyphae were confined to the epidermis and the cortical tissues at the crown/hypocotyl regions; the vascular bundles of both infected and uninfected regions, and cortical tissues of the uninfected regions of the seedlings were completely free from infection hyphae and EAM. These findings provide a better understanding of the early stages of the disease cycle of S. tanaceti and will lead to improved control measures for seedborne infection using seed treatments.

Fusarium species were isolated from roots, crowns, basal petioles but rarely from the leaves of infected pyrethrum (Tanacetum cinerariifolium) plants showing poor growth and stunting in yield-decline sites of northern Tasmania and the Ballarat region of Victoria, Australia. Multigene phylogenetic analyses using the internal transcribed spacer (ITS), the polymerase II second largest subunit (RPB2) and the partial translation elongation factor 1-α (EF1) sequences, identified F. oxysporum and F. avenaceum as the most frequently isolated species associated with root and crown diseases of pyrethrum, and F. equiseti and F. venenatum at a low incidence. Pathogenicity trials confirmed that F. oxysporum and F. avenaceum significantly affected growth of pyrethrum plants causing Fusarium crown rot; however, F. avenaceum was less pathogenic than F. oxysporum. Fusarium oxysporum and F. avenaceum may be part of a complex of pathogens that are involved in pyrethrum yield-decline.

Two glasshouse and two field experiments were conducted in 2013 and 2014 to compare the relative importance of four physiological traits: osmotic adjustment (OA), leaf proline concentration, canopy temperature depression (CTD) and root depth on drought performance of canola quality B. juncea (juncea canola). Glasshouse experiments were conducted at The University of Melbourne, Parkville, and field experiments were conducted at Horsham, Victoria. The experiments used juncea canola hybrids and their parental lines and were laid out in a randomised complete block design with three replications. The glasshouse experiments consisted of two treatments, well watered and water deficit from first open flower to maturity, whereas the field experiments were sown at a site that received 266 mm annual rainfall in 2014. In the glasshouse, canopy temperature depression was the only trait to show a positive and consistent association with drought performance of juncea canola. Cooler canopy temperature was also associated with improved yield in field experiments. Root depth was positively correlated with CTD in 2014 in glasshouse, whereas no correlation of root depth with OA and leaf proline was observed. The results indicated that CTD was the only reliable trait among those tested to screen juncea canola for drought tolerance. Root depth of juncea canola hybrids was a constitutive trait and probably was a result of hybrid vigour.

BACKGROUND: Field pea (Pisum sativum L.) is a self-pollinating, diploid, cool-season food legume. Crop production is constrained by multiple biotic and abiotic stress factors, including salinity, that cause reduced growth and yield. Recent advances in genomics have permitted the development of low-cost high-throughput genotyping systems, allowing the construction of saturated genetic linkage maps for identification of quantitative trait loci (QTLs) associated with traits of interest. Genetic markers in close linkage with the relevant genomic regions may then be implemented in varietal improvement programs. RESULTS: In this study, single nucleotide polymorphism (SNP) markers associated with expressed sequence tags (ESTs) were developed and used to generate comprehensive linkage maps for field pea. From a set of 36,188 variant nucleotide positions detected through in silico analysis, 768 were selected for genotyping of a recombinant inbred line (RIL) population. A total of 705 SNPs (91.7%) successfully detected segregating polymorphisms. In addition to SNPs, genomic and EST-derived simple sequence repeats (SSRs) were assigned to the genetic map in order to obtain an evenly distributed genome-wide coverage. Sequences associated with the mapped molecular markers were used for comparative genomic analysis with other legume species. Higher levels of conserved synteny were observed with the genomes of Medicago truncatula Gaertn. and chickpea (Cicer arietinum L.) than with soybean (Glycine max [L.] Merr.), Lotus japonicus L. and pigeon pea (Cajanus cajan [L.] Millsp.). Parents and RIL progeny were screened at the seedling growth stage for responses to salinity stress, imposed by addition of NaCl in the watering solution at a concentration of 18 dS m-1. Salinity-induced symptoms showed normal distribution, and the severity of the symptoms increased over time. QTLs for salinity tolerance were identified on linkage groups Ps III and VII, with flanking SNP markers suitable for