The potential of AFLPs in biosystematics: A first application inSolanum taxonomy(Solanaceae)

Using the AFLP technique highly informative DNA fingerprints were generated from 19 taxa ofSolanum sect.Petota (potatoes) and three taxa ofSolanum sect.Lycopersicum (tomatoes). Both phenetic and cladistic analyses were conducted from the individual genotypic level to the species level. An AFLP fingerprint, using a combination of suitable AFLP primers, generated 12 to 71 scorable fragments per genotype which was sufficient for taxonomic interpretation. The classifications based on the molecular markers were generally in agreement with current taxonomic opinions. Unexpectedly,S. microdontum was associated with ser.Megistacroloba rather than with ser.Tuberosa, andS. demissum (ser.Demissa) and species of ser.Acaulia appeared closely affiliated. AFLP is an efficient and reliable technique to generate biosystematic data and therefore a promising tool for evolutionary studies.     

Infectibility and sensitivity of UK raspberry, blackberry and hybrid berry cultivars to Rubus viruses

Six blackberry or hybrid berry cultivars and 19 raspberry cultivars were assessed for their infectibility with, and sensitivity to, graft inoculation with 10 distinct viruses found infecting Rubus in the UK. Cultivars were grafted with each of, two isolates of the pollen borne raspberry bushy dwarf virus (RBDV), five aphid borne viruses: black raspberry necrosis, raspberry leaf mottle (RLMV), raspberry leaf spot (RLSV), rubus yellow net and raspberry vein chlorosis (RVCV); and isolates of the nematode transmitted nepoviruses, arabis mosaic, raspberry ringspot, strawberry latent ringspot and tomato black ring. All tested cultivars were infectible with a resistance breaking isolate of RBDV but only about half of that number with the Scottish type isolate of the virus. The raspberry cvs Autumn Bliss, and occasionally Glen Garry and Glen Prosen, developed leaf yellowing symptoms following infection with RBDV, but none of the other infected cultivars showed obvious leaf symptoms when kept in a heated glasshouse during the growing season. All tested cultivars were infectible with each of the four viruses transmitted in nature by the aphid, Amphorophora idaei. Most were infected symptomlessly, but seven cultivars developed severe leaf spotting symptoms due to infection with RLMV or RLSV. All but one of the raspberry cultivars were infectible with RVCV, which is transmitted in nature by the aphid Aphis idaei, and almost all infected plants developed leaf symptoms; only one of the hybrid berry or blackberry cultivars tested was infected with RVCV. In tests with the four nepoviruses, all tested cultivars, except Tummelberry, were infectible with at least one or more of these viruses. However, cultivars responded differently to challenge inoculation with different isolates of individual nepoviruses. Several cultivars developed chlorotic leaf mottling following infection with some nepovirus isolates. The implications of these results for virus control are discussed in the light of the changing pattern of virus and virus vector incidence in the UK.     

甘薯根腐病菌侵染对甘薯内源激素水平的影响

甘薯根腐病病原菌[Fusarium solani(Mart.)Sacc.f.sp.batatas McClure,简称FSB]侵染及其培养液滤液处理高敏感性甘薯品种‘胜利百号’后,引起甘薯叶片、茎尖和根部组织内源ABA含量大幅升高。其中在根部出现最早,但茎尖中积累浓度最高。侵染后甘薯叶片、茎尖和根部组织内源GA1/3含量显著低于对照。甘薯组培苗经FSB培养滤液处理9h后,ABA含量显著上升,处理15h,ABA含量呈下降趋势,而GA1/3含量在101和102稀释液处理15h(103稀释液处理12h)时出现显著上升。这些结果有助于解释甘薯根腐病株矮小不产生藤蔓,并在秋季大量现蕾开花的生理现象。     

Prey preference and egg production of the carabid beetleAgonum dorsale

In order to elucidate whether the aphidRhopalosiphum padi is low quality food for the carabid beetleAgonum dorsale, as it has previously been found to be for cereal spiders, we performed a series of experiments using fruit fliesDrosophila melanogaster as a standard alternative prey (‘control prey’): 1) Prey preference, 2) Aphid consumption for satiated and starved beetles, 3) Egg production on different diets and 4) Preference experiments with fruit flies coated with a taste of different prey types. Other alternative prey types used were earthworms and sciarid midges, all potential prey in the field.A. dorsale has a low preference for aphids compared to fruit flies. Apparently there is an upper limit to the consumption of aphids independent of hunger and much below the beetles' total food demand. Egg production on a pure diet of aphids is lower than on a pure diet of fruit flies; it is extremely low on a pure diet of earthworms; the highest fecundity is found on a mixed diet. As fruit flies coated with a taste of aphids or sciarid midges are less prefered than flies covered with a taste of fruit flies there may be a chemical factor, acting through taste, involved in determining prey preference.     

马铃薯遗传转化体系的优化及玉米淀粉分支酶基因SBEⅡb的导入

以马铃薯脱毒试管苗茎段为转化受体材料,建立并优化了农杆菌介导的马铃薯遗传转化体系。通过农杆菌介导法将玉米淀粉分支酶基因(Starch branching enzyme b,SBEⅡb)的过表达载体转化马铃薯,接种762个茎段,共获得35株抗性植株。经PCR检测获得了4株转基因阳性植株;对转基因植株进一步进行GUS活性组织化学染色,发现转基因植株的茎段与试管薯均被染上蓝色,表明外源SBEⅡb基因已整合到马铃薯基因组,且正常表达。     

Detection of hatching inhibitors and hatching factor stimulants for golden potato cyst nematode, Globodera rostochiensis, in potato root leachate

In a comparison of four potato varieties, in-soil hatch of the golden potato cyst nematode (Globodera rostochiensis) was positively correlated to in vitro hatch in response to potato root leachate (PRL). The in-soil hatch of cysts of G. rostochiensis to two of the four varieties was significantly less than that of the control (cysts in gravel without potato plants) in the first 2 wk after plant emergence, suggesting the production of hatching inhibitors (HIs) by young potato plants. The hatching factor: hatching inhibitor ratio of PRL was positively associated with the net hatching activity of the PRL. Four zones of HI activity were resolved following gel permeation chromatography of PRL on Sephadex G-10. Hatch-inactive chemicals, which stimulated the activity of hatching factors (HFs) in PRL (hatching factor stimulants, HSs), were also isolated from PRL, hatch levels induced by individual HFs responding differently to the same HS preparation. The complex interactions between individual HFs and other hatching chemicals in PRL was illustrated when addition of the hatch-active potato glycoalkaloid α-solanine caused both inhibition and stimulation of PRL-induced hatch, depending on the α-solanine concentration.     

Host plant adaptability and proteomic differences of diverse Rhopalosiphum maidis (Fitch) lineages

Corn leaf aphid Rhopalosiphum maidis (Fitch) can feed on various cereal crops and transmit viruses that may cause serious economic losses. To test the impact of both host plant species and age on R. maidis, as well as the proteomic difference of diverse populations, we first investigated the survival and reproduction of six R. maidis populations (i.e., LF, HF, GZ, DY, BJ, and MS) via a direct observation method in the laboratory on 10 and 50 cm high maize seedlings, and 10 cm high barley seedlings. Then a proteomic approach was implemented to identify the differentially expressed proteins from both aphids and endosymbionts of BJ and MS populations. Results indicated that the BJ population performed significantly better than the others on both barley and 50 cm high maize seedlings, while no population could survive on 10 cm high maize seedlings. The proteomic results demonstrated that the expression levels of myosin heavy chain (muscle isoform X12) (spot 781) and peroxidase (spot 1383) were upregulated, while ATP-dependent protease Hsp 100 (spot 2137) from Hamiltonella defensa and protein SYMBAF (spot 2703) from Serratia symbiotica were downregulated in the BJ population when compared to expression levels of the MS population. We hypothesize that the fatalness observed on 10 cm high maize seedlings may be caused by secondary metabolites that are synthesized by the seedlings and the MS population of R. maidis should be more stress-resistant than the BJ population. Our results also provide insights for understanding the interaction between host plants and aphids.     

Pea lectin is correctly processed,stable and active in leaves of transgenic potato plants

A gene encoding the preproprotein of the pea (Pisum sativum) lectin was expressed in transgenic potato plants using a cauliflower mosaic virus (CaMV) 35S promoter or a tobacco ribulose bisphosphate carboxylase small subunit (ssRubisco) promoter. Presence of the pea lectin to levels greater than 1% of total soluble leaf protein was detected by radioimmunoassay (RIA). The pattern of expression derived from the two promoters was established using both RIA and a squash-blot immunolocalisation technique. Western blotting demonstrated that the preproprotein was correctly processed, generating and subunits that assembled to give an isolectin form observed in pea seeds and roots. It was also found that the haemagglutination activity and specificity of pea lectin synthesised in transgenic potato leaves was comparable to purified lectin from pea cotyledons.