Specificity of Interactions Between Wild Lactuca spp. and Bremia lactucae Isolates from Lactuca serriola

Specificity of interactions between eight Lactuca species and 8 Bremia lactucae isolates was studied in seedlings and adult plants of 36 Lactuca accessions plus one L. serriola × L. sativa hybrid. Pathogenicity of the isolates and/or plant susceptibility was expressed by sporulation intensity. A highly compatible relationship was observed in all of L. serriola accession/isolate interactions tested. A differential reaction was found in numerous cases testifying to physiological specialization of the pathogen in a wild pathosystem. Nonspecific nondifferential compatibility (quantitative resistance) can be expected in L. serriola PI 281876. Age dependent resistance (seedlings versus adult plants, and vice versa) and heterogeneity of reactions were also recorded. The comparisonof B. lactucae isolates from L. sativa and L. serriola has shown a significant shift of pathogenicity in favour of L. serriola accessions. A high level of resistance was found in the L. serriola × L. sativa hybrid. The existence of basic incompatibility can be expected in L. saligna and L. virosa as well as in such taxonomically remote species as L. viminea, L. squarrosa and L. biennis. Other taxonomically remote species, i.e. L. dentata and L. alpina, exhibited a compatible reaction, although the reaction of the former was differential. A high level of sporulation was recorded in all accession/isolate interactions of L. alpina.     

21种野生百合亲缘关系的ISSR分析

该研究选用7条ISSR标记引物对百合属21种野生百合的亲缘关系进行分析,使用POPGEN1.32和MEGA5.1数据处理软件分析数据。结果表明：7条引物扩增出149条条带,其中136条为多态性条带,多态性条带比率为91.06％,平均有效等位点数为1.7624,平均Nei’ s基因多样度为0.4214,平均Shanon信息指数0.6085。遗传距离变化范围为0.3075~0.8873,紫脊百合和尖被百合的遗传距离最大,均值为0.8873,表明21份材料中二者亲缘关系最远;紫脊百合和宜昌百合遗传距离最小,均值为0.3075,表明二者亲缘关系最近。聚类结果与形态学分类大致吻合,21个供试材料可被分成5个类群,大理百合、宝兴百合、卷丹百合、紫斑百合、乳头百合、川百合、兰州百合、山丹百合、绿花百合和毛百合为第Ⅰ类群;紫脊百合、宜昌百合、岷江百合、通江百合和淡黄花百合为第Ⅱ类群;野百合和百合为第Ⅲ类群;青岛百合为第Ⅳ类群;第Ⅴ类群包括玫红百合、有斑百合和尖被百合。毛百合与卷瓣组百合亲缘关系较近,钟花组百合与卷瓣组百合存在基因交流,说明不能仅仅依靠形态学对野生百合进行分类。聚类分析结果中野百合与百合单独聚为一类,这说明是否具叶柄对野生百合的分类是一个重要的形态学特性。 ISSR分子标记适合用于百合属植物的亲缘关系分析。     

Crossing experiments of lettuce cultivars and species (Lactuca sect.Lactuca,Compositae)

The degree of relationships withinLactuca sativa and three wild relativesL. serriola, L. saligna, andL. virosa was studied by observing the performance, vigour and fertility of the F 1 hybrids obtained from crosses made in and between the four species. The crosses ofL. saligna ×L. virosa and the reciprocal crosses produced no hybrids.L. saligna andL. virosa are the least related of the four species.L. sativa ×L. serriola and the reciprocal crosses were successful and produced fertile hybrids These two species are genetically very closely related.L. saligna is known to produce, as a female parent, hybrids withL. sativa andL. serriola. Now the reciprocal cross was successful for the first time, so the unability to obtain hybrids in the past was based on the choice of accessions and not caused by unilateral incompatibility.L. virosa ×L. sativa and the reciprocal combination produced hybrids. The combinationL. serriola ×L. virosa produced hybrids with very limited fertility. In contrast to earlier reports (sterile hybrids) one combination of the reciprocal cross too produced hybrids with very limited fertility.—Some of theL. saligna ×L. sativa (and reciprocal) hybrids were found to look strikingly likeL. serriola. This adds evidence for the descent ofL. serriola andL. sativa:L. saligna also made part of the ancestral complex of the cultivated lettuce.     

Effect of bacteriocinogenic Lactobacillus spp. on the shelf life of fufu, a traditional fermented cassava product

Quantitative determination of antimicrobial compounds produced by the Lactobacillus strains under test was carried out. L. plantarum F1 produced the highest quantity of lactic acid (16.4 g/l) while the lowest amount (0.3 g/l) was produced by L. jensenii F9. All the test organisms produced hydrogen peroxide, with L. brevis OG1 having the highest yield of 0.037 g/l. Diacetyl was also produced by all the organisms, with L. plantarum F1 and L. brevis OG1 having the highest yield of 1.7 g/l, while the lowest producer was L. jensenii F9 (0.86 g/l). Determination of bacteriocin activity was carried out. L. plantarum F1 exhibited 6400 AU/ml bacteriocin activity, while L. brevis OG1 had the lowest activity of 3200 AU/ml using E. coli NCTC10418 as indicator organism. However, L. fermentum F5 and L. jensenii F9 did not produce any detectable bacteriocin. The pH value in the culture supernatant of L. plantarum F1 reached 3.1 within 48 h of incubation, while that of L. jensenii F9 was 5.2. Fufu was prepared using both bacteriocin-producing (BP) L. plantarum F1 and L. brevis OG1, and non-bacteriocin producing L. fermentum F5 and L. jensenii F9. No viable cells of Salmonella typhimurium ATCC13311 and Shigella flexneri AP23498 were detected after 12 h in the cassava products fermented with mixed starter culture of L. plantarum F1 and L. brevis OG1. The rate of survival of enteropathogens in cassava fermented with mixed starter cultures of L. plantarum F1 and L. brevis OG1 was much lower when compared to cassava fermented with mixed starter culture of L. fermentum F5 and L. jensenii F9. At 12 h, the viable count of E. coli NCTC10418 in cassava fermented with mixed starter cultures of L. plantarum F1 and L. brevis OG1 was 1.1 log₁₀ c.f.u./g whereas in cassava fermented with mixed starter cultures of L. fermentum F5 and L. jensenii F9, 8.5 log₁₀ c.f.u./g was obtained The study revealed that fufu produced with BP mixed starter cultures had a better shelf life and kept for 13 days before spoilage occurred, relative to 5 days observed for fufu produced using non-bacteriocin-producing starter cultures, and 6 days for the traditional fermented fufu.     

Morphological variation inLolium (Poaceae) as a measure of species relationships

Analysis of morphological and phenological data for determining the genetic variation within sevenLolium species led to the recognition of two groups within this genus. One group, containing the two inbreeding speciesL. temulentum andL. persicum, was clearly distinct from all other species. Strong morphological and phenological intergradation was found between both species. The cross-breeding species,L. perenne, L. rigidum, andL. multiflorum, formed another group. Little differentiation was found between these species, though they were distinct. Two inbreeding species,L. loliaceum andL. remotum, were clearly distinct from each other and the two groups.L. loliaceum had an isolated position and was most related toL. rigidum. L. remotum had an intermediate position between the cross-breeding and inbreeding species, and was almost equally distant from all three cross-breeding species.Genetic variation inLolium spp. I.     

B-CHROMOSOMES,THEIR ORIGIN AND RELATION TO MEIOSIS IN INTERSPECIFIC LOLIUM HYBRIDS

The following Lolium species were shown to have 14 chromosomes: L. canariensis Steud. (= L. gracile Parl.), L. loliaceum (Bory and Chaub.) Hand.-Mazz., L. multiflorum Lam., L. perenne L., and L. temulentum L. B-chromosomes in addition to the normal complement were observed during metaphase I and anaphase I for L. persicum Boiss. and Hohen., L. remotum Schrank, L. rigidum Gaud., L. strictum Presl. (= L. rigidum?), and for several synthesized interspecific hybrids. General absence of B-chromosomes in diakinesis suggested that they originated by misdivision of A-chromosomes during prometaphase I. The B-chromosomes reached a maximum of eight but the number varied for microsporocytes of the same plant. B-chromosomes appeared spontaneously in progenies from sibbing of hybrid plants without supernumeraries but were also eliminated in the F₂ from other sibbings. Degree of chromosome pairing during meiosis was unrelated to the subsequent presence of B-chromosomes. Normal pairing of seven bivalents was typical for L. perenne × L. multiflorum, L. perenne × L. rigidum, L. multiflorum × L. loliaceum, and L. rigidum × L. loliaceum. Between five and seven bivalents were recorded for L. multiflorum × L. persicum, L. multflorum × L. remotum, L. multiflorum × L. strictum, L. rigidum × L. persicum, L. rigidum × L. remotum, L. rigidum × L. strictum, and L. rigidum × L. temulentum. The results indicated that these Lolium species have a common and generally undifferentiated genome suggesting relatively recent speciation.     

Anaerobic Induction of Adherence to Laminin in Lactobacillus gasseri Strains by Contact with Solid Surface

The effect of growth conditions on adhesion was studied in six species belonging to Lactobacillus acidophilus homology groups. Namely, 17 strains including 6 fresh isolates of L. gasseri from human feces were assessed for their adherence to immobilized fibronectin, laminin, and type IV collagen. These extracellular matrix proteins were used as a model of damaged intestinal mucosa. When the bacteria were grown on MRS agar under anaerobic conditions, all eight L. gasseri strains and one L. johnsonii strain showed strong adhesiveness to laminin, but not when grown in static MRS broth. A similar pattern was observed in four L. gasseri strains in terms of adherence to fibronectin. No L. gasseri or L. johnsonii strains exhibited adhesion to type IV collagen under either growth condition. Adhesion of L. acidophilus, L. crispatus, L. amylovorus, and L. gallinarum was not affected by the growth conditions. Although protease treatment of L. gasseri cells abolished the adhesion, periodate oxidation of the cells increased it except in one strain. The adherence of L. gasseri cells was diminished by periodate and α-mannosidase treatments of immobilized laminin. The above results suggest that mannose-specific proteinaceous adhesion can be induced in L. gasseri by contact with a mucosal surface in the anaerobic intestinal lumen.     

A potential species-specific molecular marker suggests interspecific hybridization between sibling species Littorina arcana and L. saxatilis (Mollusca, Caenogastropoda) in natural populations

Three sister species of rough periwinkles, viz. Littorina saxatilis (Olivi 1792), L. arcana (Hannaford Ellis 1978) and L. compressa (Jeffreys 1865) from the Barents Sea (Russia), the White Sea (Russia) and the Norwegian Sea (Norway) were studied. The identification of two sibling species L. saxatilis and L. arcana is often difficult as both species have extremely similar shell morphology and reproductive systems. Only mature females can be unambiguously distinguished, with a jelly gland present in female L. arcana, but which is replaced by a brood pouch containing developing embryos in L. saxatilis. No clear-cut diagnostic features have been found to discriminate between males or juveniles of the two species. The very first diagnostic DNA marker (DNA fragment A2.8, 271 bp length) for L. arcana and L. saxatilis separation was developed. The marker was derived from apparently species-specific L. arcana DNA fragments obtained via Random Amplified Polymorphic DNA (RAPD) analysis. This fragment was cloned and sequenced, whereupon specific primers were designed and the amplification was surveyed in a large number of morphologically well-identified females of both species. Subsequently, the specific DNA marker was used for the identification of male L. arcana and partners in copulating pairs. In this way, we obtained evidence of possible interspecific hybridization between the sibling species L. arcana and L. saxatilis living in sympatry in natural populations: the presence of A2.8 fragment in 12% of morphologically well identified L. saxatilis females and its absence in 14% of morphologically well identified L. arcana females. The A2.8 fragment never amplified in L. saxatilis from sites without L. arcana. The A2.8 fragment did not amplify in L. compressa, not even in microsympatric populations, and we did not observe interspecific copulations between L. arcana and L. compressa.     

Chloroplast-DNA variation in the genus Lotus (Fabaceae) and further evidence regarding the maternal parentage of Lotus corniculatus L.

 To resolve the maternal parentage of the tetraploid Lotus corniculatus, restriction-site variation of chloroplast DNA (cpDNA) was studied in several accessions of that species, in the four putative parental diploid species, L. tenuis, L. alpinus, L. japonicus and L. uliginosus, and in four phylogenetically more distant diploid species, L. hispidus, L. edulis, L. ornithopodoides and Tetragonolobus maritimus var. siliquosus. Evidence of cpDNA maternal inheritance was obtained by using reciprocal controlled crosses between plants of L. corniculatus and natural tetraploid individuals of L. alpinus showing very distinct restriction patterns. Interspecific cpDNA variation in the eight Lotus species and T. siliquosus was analysed by comparing cpDNA fragment patterns produced by five restriction endonucleases and totalling 304 distinct fragments. Genetic differentiation in cpDNA was very high between the L. corniculatus group and L. hispidus on the one hand, and the three other species on the other hand. Sixteen restriction-site mutations and eight length polymorphisms were identified among the five species of the L. corniculatus group and L. hispidus, Lotus uliginosus, L. alpinus and L. japonicus showed at least six DNA changes with regard to the molecule of L. corniculatus. Accordingly, these species should be excluded as maternal progenitors of L. corniculatus. Conversely, the cpDNA of L. tenuis differed from that of L. corniculatus by only two small-length mutations. As also suggested previously from an analysis of several nuclear markers, the results reported here show decisively that L. tenuis may be considered as the most probable maternal ancestor of L. corniculatus. Received: 23 February 1997/Accepted: 28 February 1997     

An isoenzyme study in the genus Lotus (Fabaceae)

Summary Segregation of the cytosolic Pgi2 locus was studied among progeny of the synthetic allotetraploid (L. japonicus × L. alpinus)², the synthetic autotetraploid (L. alpinus)², and the cultivated tetraploid species L. corniculatus L. Evidence of an original diploid duplication found within the interspecific hybrid L. japonicus × L. alpinus was also found within the synthetic allotetraploid (quadruplication of loci). Evidence suggesting quadruplication of loci was also found in the tetraploid L. corniculatus, but not in the synthetic autotetraploid (L. alpinus)². It is suggested that the original duplication resulted from unequal crossing-over between homoeologues and that it provides evidence that L. corniculatus is a segmental allotetraploid. Quadruplication of loci in L. corniculatus could explain previously reported distorted tetrasomic ratios for segregation of qualitative characters in this species.     

Displacement in two invasive species of leafminer fly in different localities

Liriomyza sativae was displaced by L. trifolii in the USA probably due to the lower insecticide susceptibility of L. trifolii, but L. trifolii was displaced by L. sativae in Japan. To know the possible causes of the species displacement observed in Japan, differences in the insecticide susceptibility, fecundity, effects of natural enemies, and reproductive interference between L. trifolii and L. sativae were evaluated. As a result, the higher fecundity of L. sativae and differential effects of parasitoids on the two Liriomyza species are considered to be contributing factors.     

Studies on the Pyruvate and Carbohydrate Metabolisms by Lactic Acid Bacteria

The formation of ketopentoses from aldopentoses was demonstrated by six strains of hetero-fermentative lactic acid bacteria (heterofermenters). The dried bacterial cells harvested on malt extract and their cell-free extracts were found to reveal isomerization of d-xylose or l-arabinose to corresponding ketopentoses in the presence of borate, while any formation of ketopentose was never observed with the enzyme preparations of homofermenters except L. xylosus and Pc. lindneri. The ketopentoses were isolated by a Dowex-l borate column, and identified by paper-chromatography. Results obtained were as follows: xylulose was formed from xylose by six strains of heterofermenters (L. fermentum, Leuc. mesenteroides, L. brevis, L. buchneri, L. gayonii and L. fermenti) and by L. xylosus. Ribulose was obtained from arabinose by L. brevis, L. pento-aceticus, L. gayonii, L. buchneri and Pc. linderi.     

PHYTOCHROME CONTROL OF ROOT GROWTH RATE IN LEMNA SPECIES

Root growth rate was studied in Lemna gibba L. (strains Gl and G3) and L. minor L. in relation to low energy red and far-red light treatments. Far-red treatments inhibited growth rate; inhibition was abolished upon subsequent treatment with red light. These effects can be observed after an 18-hr growth period. This red/far-red photoreversible response suggests that root growth in L. gibba L. and L. minor L. is under phytochrome control.     

Assessment of the potential for hybridisation between Laricobius nigrinus (Coleoptera: Derodontidae) and Laricobius osakensis,predators of the hemlock woolly adelgid (Hemiptera: Adelgidae)

In 2003, Laricobius nigrinus Fender was introduced into the eastern United States as a biological control agent of the hemlock woolly adelgid (Adelges tsugae Annand). Following its release, it was discovered that L. nigrinus was hybridising and producing viable progeny with Laricobius rubidus LeConte, a species native to eastern North America. Recently, Laricobius osakensis Montgomery and Shiyake was imported from Japan into the USA as a potential biological control agent of hemlock woolly adelgid. Hybridisation between L. nigrinus and L. rubidus led to interest in the outcome of interactions between L. osakensis and the other two Laricobius spp. The purpose of this study was to determine if L. osakensis could mate with L. nigrinus, if they could produce hybrid progeny, and whether mating interferes with reproductive output. Laricobius spp. were observed mating directly following emergence and found to be capable of producing sterile eggs in the absence of a mating event. Laboratory and confined field studies found no evidence that L. osakensis and L. nigrinus could produce hybrid progeny and the interaction between the two species did not result in a lower reproduction associated with interspecific mating attempts. Interbreeding should therefore not have an impact on biological control using these species. Fecundity experiments showed that L. osakensis produced eggs earlier in the season and at a higher rate than L. nigrinus, suggesting that L. osakensis may have the potential to be an even more successful biological control agent than L. nigrinus.     

Molecular Identification of Potentially Probiotic Lactobacilli

The rRNA-targeted oligonucleotide probes are useful for the identification of Lactobacillus acidophilus, L. gasseri, L. johnsonii, L. crispatus, and L. amylovorus. However, the oligonucleotide probe designed for L. helveticus hybridized with nucleic acids of type strains of L. gallinarum and L. helveticus. Hence, the similarity among the 73 strains of lactobacilli was evaluated on the basis of their randomly amplified polymorphic DNA (RAPD) profiles derived from five single-primer reactions. These strains were grouped into seven clusters at a similarity level of 30%, which corresponded to six separate species of the L. acidophilus complex (L. johnsonii, L. gallinarum, L. amylovorus, L. crispatus, L. acidophilus, and L. gasseri, respectively) and L. helveticus. For the first time, strains of L. gallinarum were characterized by RAPD and PFGE analyses. The genome length in that species was estimated to be near 1.45 Mb with the summation of ApaI fragments, and near 1.95 Mb with the summation of SmaI fragments. Received: 1 July 1999 / Accepted: 2 August 1999     

Molecular Discrimination of Lactobacilli Used as Starter and Probiotic Cultures by Amplified Ribosomal DNA Restriction Analysis

Lactic acid bacteria such as Lactobacillus helveticus, L. delbrueckii subsp. delbrueckii, L. delbrueckii subsp. lactis, L. delbrueckii subsp. bulgaricus, L. acidophilus, and L. casei related taxa which are widely used as starter or probiotic cultures can be identified by amplified ribosomal DNA restriction analysis (ARDRA). The genetic discrimination of the related species belonging to these groups was first obtained by PCR amplifications by using group-specific or species-specific 16S rDNA primers. The numerical analysis of the ARDRA patterns obtained by using CfoI, HinfI, Tru9I, and ScrFI was an efficient typing tool for identification of species of the L. acidophilus and L. casei complex. ARDRA by using CfoI was a reliable method for differentiation of L. delbrueckii subsp. bulgaricus and L. delbrueckii subsp. lactis. Finally, strains ATCC 393 and ATCC 15820 exhibited unique ARDRA patterns with CfoI and Tru9I restriction enzymes as compared with the other strains of L. casei, L. paracasei, and L. rhamnosus. Received: 30 August 2000 / Accepted: 2 October 2000     

Some cultural characteristics of mycelia of a mycorrhizal fungus,Lyophyllum shimeji

Cultural characteristics of 45 strains ofLyophyllum shimeji and 10 strains of three related species were determined. The average optimum temperature for mycelial growth ofL. shimeji on a medium consisting of rye grains was 24.9°C, slightly higher than those forL. fumosum andL. decastes. The average mycelial growth rate of theL. shimeji strains, each at its optimum temperature, was 2.0 mm/day, almost the same as that ofL. decastes and 2 times greater than those ofL. semitale andL. fumosum. All strains ofL. shimeji could grow on beech and pine sawdust, but none could significantly decompose beech wood blocks. Of the 45 strains ofL. shimeji, 3 strains had ability to form primordia on the rye grain medium without the host plant.This study was supported in part by the Forestry Agency, Japan.     

Comparison of learning in related generalist and specialist eucoilid parasitoids

Effects of learning in two microhabitat specialists, Leptopilina boulardia Barbotin et al. and L. fimbriata Kieffer were compared to previous and new results of learning in the microhabitat generalist L. heterotoma Thomson. Females were given one or more oviposition experiences on hosts in different types of substrate. In all species oviposition experience affected the choice for a substrate, although this effect of learning was considerably less in L. fimbriata compared to the other two species. Patch times, known to be highly determined by experience in the generalist L. heterotoma, were much less flexible in the specialists. L. boulardi and L. fimbriata have fixed patch times on their natural substrate and have variable patch times on other substrates only. In all three species one oviposition affected the choice for a substrate. Additional ovipositions showed no different effect. An accumulative effect of the number of ovipositions on patch times was found in L. heterotoma only. Retention of the learning effect was only studied in L. boulardi, and was shown to be similar to that reported for L. heterotoma, i.e. two to three days. Although learning was found in both the generalist and the specialist species studied, it seems to affect their foraging behaviour differently.     

Limited genetic variation in Lacerta mixta and its parthenogenetic daughter species: evidence from cytochrome b and ATPase 6 gene DNA sequences

Little mtDNA variation was observed among populations of the bisexual Caucasian rock lizard Lacerta mixta and unisexual L. dahli and L. armeniaca. Three haplotypes were detected in L. mixta and the maximum pairwise difference among the samples was 0.67%. No intra- and interspecific variation was found among populations of either L. armeniaca or L. dahli. Moreover, both unisexual species were identical to one of the three haplotypes of L. mixta. The limited variation in L. mixta is likely the result of bottleneck effect, although the small sample size may also be responsible. The lack of variation in the unisexuals was attributed to the restricted variation among the maternal parents, limited involvement of females in the hybridization, and recent origin. This revised version was published online in July 2006 with corrections to the Cover Date.     

Effects of acetic and formic acid on ABE production by <Emphasis Type="Italic">Clostridium acetobutylicum</Emphasis> and <Emphasis Type="Italic">Clostridium beijerinckii</Emphasis>

The effect of acetic acid and formic acid on acetone-butanol-ethanol (ABE) production by solventogenic Clostridia was investigated. The ABE concentration in Clostridium acetobutylicum was found to have increased slightly on addition of 3.7 ∼ 9.7 g/L acetic acid, but was found to have drastically reduced in the presence of 11.7 g/L acetic acid. However, the solvent production of C. beijerinckii was not affected by addition of acetic acid in the range of 3.7 ∼ 11.7 g/L. C. acetobutylicum was more vulnerable to formic acid than C. beijerinckii. In C. acetobutylicum, the total ABE production decreased to 77% on addition of 0.4 g/L formic acid and 25% with 1.0 g/L formic acid. The total ABE production by C. acetobutylicum was also noted to have decreased from 15.1 to 8.6 g/L when 8.7 g/L acetic acid and 0.4 g/L formic acid co-existed. The solvent production by C. beijerinckii was not affected at all under the tested concentration range of formic acid (0.0 ∼ 1.0 g/L) and co-presence of acetic acid and formic acid. Therefore, C. beijerinckii is more favorable than C. acetobutylicum when the ABE is produced using lignocellulosic hydrolysate containing acetic and formic acid.