No abstract

Summary The physiological and molecular bases of glyphosate resistance in one susceptible (S) and four resistant (R) Conyza bonariensis biotypes (sampled in orchards from Andalusia, Spain) were investigated. Resistance index (RI) values of the four R biotypes ranged between 2.9 and 5.6. The main physiological difference between S and R biotypes was the dissimilar mobility of glyphosate in the whole plant. In R biotypes, the herbicide was translocated less from leaves to culm and root, and more from culm to leaves compared with the S biotype. The upward mobility of glyphosate via xylem suggests that the herbicide may be sequestered to the apoplast or the vacuole. The hypothesis of an insensitive 5‐enolpyruvylshikimate‐3‐phosphate synthase (EPSPS) was provisionally discarded on the basis of shikimate accumulation in R plant tissues after glyphosate treatment. At the molecular level, the relative abundance of EPSPS mRNA prior to glyphosate treatment was approximately double in two R biotypes compared with the S standard and the other R biotypes. Moreover, the two R biotypes having both no translocation and doubled EPSPS mRNA levels had also the highest RI. These results suggest that two factors may be related to glyphosate resistance in the R biotypes: (i) impaired translocation and (ii) high basal EPSPS transcript levels. The comparison between these findings and earlier results on glyphosate resistance mechanism in Conyza canadensis biotypes from the USA, suggests that similar agronomic factors (repeated application of glyphosate, no crop and herbicide rotation, no tillage) have selected similar traits on different genetic pools of the resistance‐prone Conyza genus.

No abstract

Trials were carried out to study the germination and dormancy of Cuscuta campestris Y. (dodder) seeds and factors influencing the success of early parasitisation of sugarbeet. Primary dormancy can be removed by seed scarification. Germination was negligible at 10°C and optimal at 30°C, while it was not influenced by light. Seed burial induced a cycle of induction and breaking of secondary dormancy. Seedling emergence was inversely proportional to the depth of seed burial and only seed buried within 5 cm of the soil surface emerged. Storage of C. campestris seeds in a laboratory for 12 years resulted in the loss of primary dormancy, enabling the germination of all viable seeds. Host infection (i.e. protrusion of parasite haustoria from host tissue) was heavily influenced by host growth stage. Tropism towards a host was due to the perception of light transmitted by green parts of sugarbeet plants. Insertion of a transparent glass sheet between host leaves and parasite seedlings did not modify this response. This phototropism permitted Cuscuta to identify host plants with high chlorophyll content as a function of the lower red/far red ratio of transmitted light.

Among health-promoting phytochemicals in whole grains, phenolic compounds have gained attention as they have strong antioxidant properties and can protect against many degenerative diseases. Aim of this study was to profile grain phenolic extracts of one modern and five old common wheat (Triticum aestivum L.) varieties and to evaluate their potential antiproliferative or cytoprotective effect in different cell culture systems.Wheat extracts were characterized in terms of antioxidant activity and phenolic composition (HPLC/ESI-TOF-MS profile, polyphenol and flavonoid contents). Results showed that antioxidant activity (FRAP and DPPH) is mostly influenced by flavonoid (both bound and free) content and by the ratio flavonoids/polyphenols. Using a leukemic cell line, HL60, and primary cultures of neonatal rat cardiomyocytes, the potential antiproliferative or cytoprotective effects of different wheat genotypes were evaluated in terms of intracellular reactive oxygen species levels and cell viability. All tested wheat phenolic extracts exerted dose-dependent cytoprotective and antiproliferative effects on cardiomyocytes and HL60 cells, respectively. Due to the peculiar phenolic pattern of each wheat variety, a significant genotype effect was highlighted. On the whole, the most relevant scavenging effect was found for the old variety Verna. No significant differences in terms of anti-proliferative activities among wheat genotypes was observed. Results reported in this study evidenced a correspondence between the in vitro antioxidant activity and potential healthy properties of different extracts. This suggests that an increased intake of wheat grain derived products could represent an effective strategy to achieve both chemoprevention and protection against oxidative stress related diseases.