Examination of latent infection in raspberry canes with Phytophthora rubi and P. idaei and transmission in micropropagation

Buds of raspberry canes from naturally and artificially infected root stocks were tested by nested PCR for the latent presence of Phytophthora rubi and P. idaei to establish the risk of introducing these pathogens into micropropagation. Fifteen out of 201 buds tested positive for P. rubi and only 1 out of 176 for P. idaei. These infections were not restricted to buds in the lower part of the cane and mostly do not appear to spread systemically up from the rootstock but seem to be caused by secondary infections of the canes. Buds from symptomless canes from infected root stocks were used for micropropagation and P. rubi could be detected in 5.8% of the obtained microplants after ten generations in one of the two trials. This indicates that micropropagation procedures are not absolutely infallible in eliminating infection and underlines the necessity of a zero tolerance towards diseases in the starting material.     

Influence of beta-carotene supplementation on carotene content of ovaries of heifers

Carotene is stored as a tissue reserve in the corpus luteum. With different carotene supplementations in heifers (0, 100, 200 and 300 mg/animal and day) it could be clearly seen that the carotene concentration in the corpus luteum (2.3, 27, 50 and 81 micrograms/g) was directly dependent on it. On the other hand, the weight of corpus luteum (3.8 to 4.6 g) was not influenced (P greater than 0.05) by carotene supplementation. Apart from corpus luteum carotene was also stored in orange coloured pigment corpuscles of ovary. The carotene concentration of the pigments was 6 to 70 times higher (158, 150, 334 and 487 micrograms/g) than in the corpus luteum. Weights of the pigments rose with increased carotene doses. However, the weights amounted to merely 4 to 11% of the corpus luteum's mass. The amount of carotene in corpus lutea of animals added with carotene contained was higher than that of pigments. Further investigations are necessary to characterize the physiological importance of the pigment corpuscles.     

The destructive invasive pathogen Phytophthora lateralis found on Chamaecyparis lawsoniana across the UK

In 2010–2011, Phytophthora lateralis was isolated from diseased Chamaecyparis lawsoniana exhibiting dieback and mortality at eight geographically separate forest, parkland and shelterbelt locations in England, Scotland and Northern Ireland. In 2011, P. lateralis was also isolated from young symptomatic nursery plants of C. lawsoniana and Thuja occidentalis recently imported into Scotland from mainland Europe. These are the first findings of P. lateralis in the UK. At six of the field sites, only collar and root lesions were observed. However, at two sites, large stem and branch lesions unconnected to the collar region were also observed. Phytophthora lateralis was readily isolated from both aerial and basal lesions. In artificial inoculation experiments, two Scottish isolates of the pathogen caused lesions on C. lawsoniana shoots and were readily reisolated from the lesions, their pathogenicity being comparable to that of P. lateralis isolates originating from outside the UK. Isolates from six field sites and the two nursery interceptions exhibited ITS and cox II sequences identical to published sequences of French and North American isolates. However, the isolates from two field sites shared an ITS sequence with Taiwanese isolates and differed from North American, French and Taiwanese isolates by a single‐base substitution in cox II, suggesting a separate evolutionary history. It is clear that P. lateralis now presents a significant threat to C. lawsoniana in Britain. The main source of the outbreaks is likely to be imported infested nursery stock.