Differences in the Sensitivity to UVB Radiation of Two Cultivars of Rice (Oryza sativa L.)

The effects of UVB radiation on the growth of two cultivarsof Japanese lowland rice (Oryza sativa L.), Sasanishiki andNorin 1, were examined in a phytotron. Supplementation of visibleradiation with UVB radiation reduced plant length, tiller number,the fresh and dry weights of the aboveground parts of plants,and the amounts of total leaf nitrogen, chlorophyll, solubleprotein and ribulose-1,5-bisphosphate carboxylase/oxygenase(Rubisco) in the eighth leaf, the youngest fully expanded leaf.By contrast, UVB radiation significantly increased the accumulationof UV-absorbing compounds. There was a difference between thetwo cultivars in the resistance to the effects of UVB radiation.The reduction in the amounts of Rubisco was smaller in Sasanishiki,while the increase in the accumulation of UV-absorbing compoundswas greater in Sasanishiki. Parameters of plant growth, withthe exception of the amount of Rubisco, decreased in directproportion to decreases in total leaf nitrogen in plants grownunder lower or higher doses of UVB radiation. However, the decreasein the Rubisco content of Norin 1 grown under a high dose ofUVB radiation was exceptionally marked, and was not observedsimilarly in Sasanishiki. These results suggest that the remarkablereduction in Rubisco content in Norin 1 might have been dueto the specific effects of UVB radiation. It is also suggestedthat the difference between cultivars in the resistance to UVBradiation might be due to the differences in the levels of Rubiscoand in UV-absorbing compounds that are induced by UVB radiation. (Received January 29, 1996; Accepted May 31, 1996)     

Effects of supplemental UV-B radiation on growth and leaf photosynthetic reactions of soybean (Glycine max)

Experiments were conducted under greenhouse conditions to investigate the effects of enhanced UV-B radiation (280 to 320 nm) on height, fresh and dry weights, leaf chlorophyll and carotenoids, CO₂ uptake rates, and Hill activity in soybean ( Glycine max L. cv. Bragg). Plants were exposed for 6 h continuously from midmorning to midafternoon each day to UV-B radiation which was provided by Westinghouse FS-40 sun lamps filtered with 0.127-mm cellulose acetate film (UV-B enhanced) or 0.127-mm Mylar S film (UV-B Mylar control). Three different UV-B enhanced radiation levels were tested: 1.09 (treatment T₁), 1.36 (treatment T₂), and 1.83 (treatment T₃) UV-B sun equivalent units (UV-B_sec) where 1 UV-B_sec= 15.98 mW·m⁻² of solar UV-B obtained by applying EXP -[(α-265)/21]², a weighting function that simulates the DNA absorption spectrum, to the UV-B lamp systems. These UV-B levels correspond to a calculated decrease in stratospheric ozone content of 6%, 21%, and 36% for treatment T₁, T₂, and T₃, respectively.
Daily exposure of soybean plants to UV-B radiation significantly decreased height, fresh and dry weights, leaf chlorophyll and carotenoid contents, and CO₂ uptake rates. Leaf pigment extracted in 80% acetone from UV-B-treated soybean plants showed considerable increase in absorption in the wavelength region of 330 to 400 nm with increased UV-B radiation levels. Chloroplast preparations from leaves of T₂ and T₃ plants showed significant reductions in Hill reaction measurements.     

Electron transfer reactions for the reduction of NADP+ in Methanosphaera stadtmanae

Abstract Methanosphaera stadtmanae , a member of the Methanobacteriales reduces methanol, but not CO₂ with H₂ or 2-propanol to produce methane. In cell-free extracts of M. stadtmanae the activities of several enzymes involved in electron transfer were measured. The activities of an F₄₂₀-nonreactive hydrogenase, NADP⁺: F₄₂₀ oxidoreductase, NADP⁺-dependent 2-propanol dehydrogenase, and a methyl viologen dependent F₄₂₀ dehydrogenase were observed. Based on the presence of these particular enzyme activities, their cofactor requirements and the absence of F₄₂₀-dependent hydrogenase activity, a model of the electron transport pathway through the coenzyme F₄₂₀ to provide electrons for biosynthesis, was formulated.     

The ATP-dependent synthesis of factor 390 by cell-free extracts of Methanobacterium thermoautotrophicum (strain ΔH)

Abstract Cell-free extracts of Methanobacterium thermoautotrophicum (strain ΔH) converted the 8-OH-5-deazaflavin coenzyme F₄₂₀ to factor 390, a 8-adenylyl derivative (F₄₂₀-AMP). Activity was only observed upon exposure of the crude cell-free extract to oxygen. The ability to synthesize F₃₉₀ was lost when crude cell-free extract was subsequently brought to an anaerobic reducing environment. The enzymatic reaction used ATP and oxidized coenzyme F₄₂₀ as substrates and inorganic pyrophosphate was formed next to F₃₉₀. GTP could be used instead of ATP resulting in a guanylylated derivative. The crude cell-free extract showed K _m values of 154 μM for coenzyme F₄₂₀ and 2.4 mM for ATP. A partially purified enzyme preparation exhibited a K _eq of 0.32. In accordance, coenzyme F₄₂₀ and ATP could be synthesized from F₃₉₀ and PPi by the reverse reaction.     

Serum albumin polymorphism and its relationship to economic traits in crossbred cattle

The serum albumin genotypes of 65 Jersey × Hariana (F₁), 75 Holstein Friesian × Hariana (F₁) and 47 Brown Swiss × Hariana (F₁) crossbred cows were determined by starch gel electrophoresis. Two albumin alleles Alb^F and Alb^s , but only either as Alb^F homozygotes or Alb^Fs heterozygotes, were observed amongst these animals. There were no Alb^S homozygotes or other genotypes. Highly significant relationships between albumin genotypes and both birth weights and first-lactation milk yields of these cows were observed. The Alb^F allele was associated with increased milk yield and greater birth weights.     

Peroxidase and polyphenol oxidase activities in Cyperus esculentus leaves following glyphosate applications

Following a 2-week treatment with glyphosate [N-(phosphonomethyl)glycine] changes in peroxidase (EC 1.11.1.7) and polyphenol oxidase (PPO; EC 1.14.18.1) activities of yellow nutsedge ( Cyperus esculentus L.) plants, were determined. Glyphosate caused significant increases of both activities. Isoelectric focusing gave 3 species (F₁, F₂ and F₃) of peroxidase activity, at pl 3.8, 4.4 and 4.8, and 4 species (F_a, F_b, F_c and F_d) of PPO activity at pl 7.0, 7.5, 7.8 and 9.5. The activity of the 4 active forms of PPO increased with increasing glyphosate dose up to 10⁻² M . The effect of the herbicide on the 3 fractions with peroxidase activity was to change their relative activities. Highest F₁ activity was found in control plants whereas the F₂ fraction was the predominant form in the plants treated with glyphosate at 10⁻² M and the highest F₃ activity occurred in plants treated with 5 × 10⁻³ M glyphosate. The increased PPO activity could produce phytotoxic o -quinones, and variations in peroxidase isoenzymes activity could enhance isoperoxidases with lignin biosynthetic activity.     

Inheritance of Anthracnose Resistance in the Common Bean Differential Cultivar G 2333 and Identification of a New Molecular Marker Linked to the Co-42 gene

The inheritance of anthracnose resistance of the common bean ( Phaseolus vulgaris L.) differential cultivar G 2333 to Colletotrichum lindemuthianum races 73 and 89 was studied in crosses with the susceptible cultivar Rudá. The segregation ratios of 15 : 1 in the F₂ and 3 : 1 in the backcrosses to Rudá indicate that for each of the races tested there are two independent resistance loci in G 2333. A random amplified polymorphic DNA (RAPD) molecular marker (OPH18_1200C) linked in resistance to race 73 was identified in a BC₃F_2:3 population derived from crosses between Rudá and G 2333. A RAPD molecular marker OPAS13_950C, previously identified as linked to gene Co-4² , was also amplified in this population. Co-segregation analyses showed that these two markers are located at 5.6 (OPH18_1200C) and 11.2 (OPAS13_950C) cM of the Co-4² gene. These markers were not present in BC₁F_2:3 plants resistant to race 89 indicating that this population carries a different resistance gene. DNA amplification of BC₁F_2:3 plants with RAPD molecular marker OPAB_450C, previously identified as linked to gene Co-5 , indicated that this gene is present in this population.     

Evidence for coadaptation in geographic populations of Drosophila bipectinata

In order to test whether there is genetic coadaptation in geographic populations of Drosophila bipectinata with respect to body size, reciprocal crosses were made among five strains derived from ecogeographically different localities in India. Wing length was used as an index of body size, and was measured in all the five strains, and their crosses in F and F₂ generations. The statistical analysis of the data show that there is significant interpopulation variation in body size and in all the crosses, there is an increase in body size in F₁ generation when compared with mid-parent value. Further, there is a decrease in body size in F₂ generation as compared to F₁ in most of the crosses with increased variability. These results provide evidence for genetic coadaptation in geographic populations of D. bipectinata .     

Effect of carbon dioxide enrichment on chlorophyll content, starch content and starch grain structure in Trifolium subterraneum leaves

Trifolium subterraneum (cv. Dinninup) responds to enriched atmospheric CO₂ in a manner similar to that described by Madsen (1968 and 1976) for tomato. In immature leaves, the total chlorophyll content per unit dry weight and the chlorophyll a:b ratio are significantly lower in plants grown at 0.10 vol% CO₂. Although fully expanded mature leaves partially overcome the deficit in chlorophyll content, the chlorophyll a:b ratio remains substantially lower in these high CO₂ grown plants. The large amount of starch accumulated as irregularly shaped grains appears to disrupt normal chloroplast structure in clover plants grown in enriched atmospheric CO₂. These results indicate the chlorotic appearance of leaves from high CO₂ grown clover plants is due to a decrease in chlorophyll content per dry weight possibly resulting from large starch grains and starch accumulation altering normal chloroplast structure and function.     

The F1FO ATP synthase genes in Methanosarcina acetivorans are dispensable for growth and ATP synthesis

There is a long-standing discussion in the literature, based on biochemical and genomic data, whether some archaeal species may have two structurally and functionally distinct ATP synthases in one cell: the archaeal A₁A_O together with the bacterial F₁F_O ATP synthase. To address a potential role of the bacterial F₁F_O ATP synthase, we have exchanged the F₁F_O ATPase gene cluster in Methanosarcina acetivorans against a puromycin resistance cassette. Interestingly, the mutant was able to grow with no difference in growth kinetics to the wild type, and cellular ATP contents were identical in the wild type and the mutant. These data demonstrate that the F₁F_O ATP synthase is dispensable for the growth of M. acetivorans .     

RAPD and SCAR Markers Linked to a Gene Conferring Resistance to Angular Leaf Spot in Common Bean

Angular leaf spot, caused by the fungus Phaeoisariopsis griseola , is one of the most important bean diseases in Brazil. The objectives of this study were to determine the inheritance of angular leaf spot resistance and to identify random amplified polymorphic DNA (RAPD) and sequence-characterized amplified region (SCAR) markers linked to the resistance gene present in cv. Cornell 49-242, in a cross between this cultivar and susceptible cv. Rudá. The parents, F₁, F₂ and backcross-derived plants were inoculated with P. griseola pathotype 31-17 under environmentally controlled greenhouse conditions. The results indicate that one single dominant gene controls the resistance in Cornell 49–242. Two RAPD markers, OPN 02_890c and OPE 04_650c, were found to be linked in the coupling phase, at 3.2 and 12.5 c m of the resistance gene, respectively. To increase the reproducibility of the detection of marker OPN02_890c it was converted into a SCAR marker. It is proposed that the designation of Phg-2 be used for the angular leaf spot resistant gene present in Cornell 49-242.     

Isolation of photorespiratory mutants from Lotus japonicus deficient in glutamine synthetase

A mutagenesis programme using ethyl methanesulphonate (EMS) was carried out on Lotus japonicus (Regel) Larsen cv. Gifu in order to isolate photorespiratory mutants in this model legume. These mutants were able to grow in a CO₂-enriched atmosphere [0.7% (v/v) CO₂] but showed stress symptoms when transferred to air. Among them, three mutants displayed low levels of glutamine synthetase (GS; EC 6.3.1.2) activity in leaves. The mutants accumulated ammonium in leaves upon transfer from 0.7% (v/v) CO₂ to air. F₁ plants of back crosses to wild type were viable in air and F₂ populations segregated 3 : 1 (viable in air : air-sensitive) indicative of a single Mendelian recessive trait. Complementation tests showed that the three mutants obtained were allelic. Chromatography on DEAE-Sephacel used to separate the cytosolic and plastidic GS isoenzymes together with immunological data showed that: (1) mutants were specifically affected in the plastidic GS isoform, and (2) in L. japonicus the plastidic GS isoform eluted at lower ionic strength than the cytosolic isoform, contrary to what happens in most plants. The plastidic GS isoform present in roots of wild type L. japonicus was also absent in roots of the mutants, indicating that this plastidic isoform from roots was encoded by the same gene than the GS isoform expressed in leaf tissue. Viability of mutant plants in high-CO₂ conditions indicates that plastidic GS is not essentially required for primary ammonium assimilation. Nevertheless, mutant plants did not grow as well as wild type plants in high-CO₂ conditions.     

Spiral growth and cell wall properties of the gibberellin-treated first internodes in the seedlings of a wheat cultivar tolerant to deep-sowing conditions

The Hong Mang Mai wheat cultivar is tolerant to deep-sowing conditions because it has an elongated first internode that is sensitive to gibberellin (GA₃). The cells in the GA-treated first internodes were approximately 4.2 mm long, twice as long as the untreated Hong Mang Mai first internode cells. The elongation of the first internode of Hong Mang Mai, particularly when treated with GA₃, was accompanied by remarkable spiral growth. In contrast, the first internodes of the GA-insensitive cultivar Norin 10 did not exhibit GA₃-induced elongation or spiral growth. The walls of the first internode cells of GA₃-treated Hong Mang Mai seedlings showed increased extensibility and higher (1→3), (1→4)- β - d -glucanase activity, autolysis and glucan contents than the cell walls of untreated Hong Mang Mai first internodes. The changes in the cell wall extensibility due to GA₃ treatment correlated strongly with the GA₃-induced changes in cell wall glucan content, autolysis, and glucanase activity. GA₃-treated Hong Mang Mai seedlings showed elevated expression of Glucanase EI gene in the first internode compared to GA₃-treated Norin 10. Thus, GA aids first internode elongation in Hong Mang Mai by enhancing glucan turnover and thus increasing cell wall loosening. The spiral growth of the first internode also helps the plant elongate against soil resistance, thereby promoting the deep-sowing tolerance of this cultivar.     

Spectrophotometric identification of 8-hydroxy-5-deazaflavin: NADPH oxidoreductase activity in streptomycetes producing tetracyclines

Abstract Cell-free extracts of vegetative mycelia of Streptomyces aureofaciens and Streptomyces rimosus were found to reduce streptomycete-origin 8-hydroxy-5-deazaisoalloxazine derivatives (SF₄₂₀) using NADPH as a dnor of hydrogen and electrons. 7,8-didemethyl-8-hydroxy-5-deazariboflavin (F₀) also was a substrate, although with a lower reaction rate than that for SF₄₂₀. NADH could not substitute for NADPH. The F₄₂₀-reductase activity was also observed in homogenates of S. aureofaciens spores.     

Gametophyte-specific transposition of the maize Ds element in transgenic tobacco

To assess the potential advantages of a transposon-tagging system based on gametophyte-specific transposition a fusion between the anther-specific Arabidopsis thaliana apg promoter and the maize Ac transposase gene was constructed and introduced into tobacco. The ability of this transposase source to activate Ds transposition in a developmentally controlled manner was monitored by crossing to plants harbouring the cell autonomous excision marker gene construct, Ds —SPT. A number of fully green, streptomycin-resistant seedlings resulting from germinal transposition events were observed in the progeny of apg -TPase x Ds —SPT F1 plants. Streptomycin-resistant sectors were not observed in either F₁ seedlings or F₂ progeny, indicating a complete lack of somatic excision. Further crosses of apg —TPase sources to plants containing Ds—bar herbicide selection excision marker constructs gave reproducible gametophytic excision frequencies of up to 0.3%. Sequencing of Ds excision sites from F₂ seedlings derived from single F₁ plants revealed various sequence alterations in the original Ds insertion 'footprint' indicative of independent Ds excision events. Independent re-insertion was confirmed by Southern analysis of F₂ siblings. It is concluded that apg -controlled Ac transposase expression activates male gametophyte-specific Ds transposition.     

A comprehensive analysis of QTL for abdominal fat and breast muscle weights on chicken chromosome 5 using a multivariate approach

Quantitative trait loci (QTL) influencing the weight of abdominal fat (AF) and of breast muscle (BM) were detected on chicken chromosome 5 (GGA5) using two successive F₂ crosses between two divergently selected 'Fat' and 'Lean' INRA broiler lines. Based on these results, the aim of the present study was to identify the number, location and effects of these putative QTL by performing multitrait and multi-QTL analyses of the whole available data set. Data concerned 1186 F₂ offspring produced by 10 F₁ sires and 85 F₁ dams. AF and BM traits were measured on F₂ animals at slaughter, at 8 (first cross) or 9 (second cross) weeks of age. The F₀, F₁ and F₂ birds were genotyped for 11 microsatellite markers evenly spaced along GGA5. Before QTL detection, phenotypes were adjusted for the fixed effects of sex, F₂ design, hatching group within the design, and for body weight as a covariable. Univariate analyses confirmed the QTL segregation for AF and BM on GGA5 in male offspring, but not in female offspring. Analyses of male offspring data using multitrait and linked-QTL models led us to conclude the presence of two QTL on the distal part of GGA5, each controlling one trait. Linked QTL models were applied after correction of phenotypic values for the effects of these distal QTL. Several QTL for AF and BM were then discovered in the central region of GGA5, splitting one large QTL region for AF into several distinct QTL. Neither the 'Fat' nor the 'Lean' line appeared to be fixed for any QTL genotype. These results have important implications for prospective fine mapping studies and for the identification of underlying genes and causal mutations.     

INHERITANCE OF RESISTANCE TO CYHALOTHRIN IN THE HOUSEFLY (DIPTERA: MUSCIDAE)

Abstract The genetic inheritance of resistance to cyhalothrin in housefly, Musca domstica (L) was investigated.
Reciprocal crosses between susceptible (S) and resistant (R) strains were used to determine the characteristics of resistance. Analysis of probit line from the F₁ generation and F₂ generation obtained by inbreeding the F₁ hybrids indicated that cyhalothrin resistance was controlled by more than one factors and degree of resistance dominance to cyhalothrin was -0.10, indicating cyhalothrin resistance is conferred by incompletely recessive gene(s). The realized heritability of resistance to cyhalothrin cyhalothrin calculated from data collected routinely from laboratory selection was 0.12.     

The consequences of freezing temperatures followed by high irradiance on in vivo chlorophyll fluorescence and growth in Picea abies

Picea abies (L.) Karst. plants, propagated by cuttings, were subjected to one night of freezing temperatures (-5°C), high irradiance (1 200 or 1 800 μmol m⁻² s⁻¹), or freezing temperatures followed by high irradiance. The treatments were applied at bud burst, at time of shoot elongation, and when the shoots had ceased to elongate. The maximum quantum yield of photosynthesis, F_v/F_m, dry weight of branches and needles, and length and survival of shoots were measured. F_v/F_m and growth decreased after a night of freezing temperatures followed by high irradiance, at the time of bud burst and shoot elongation. High irradiance alone influenced F_v/F_m, but not growth. Freezing temperatures affected F_v/F_m, and growth at the time of shoot elongation. F₀ increased after a night of freezing temperatures and decreased with age of the current-year needles. It was concluded that the use of short-term measurements of chlorophyll fluorescence induction to predict changes in growth after a night of frost and subsequent high light was not a reliable method.