Epigenetics’ Role in the Common Bean (Phaseolus vulgaris L.) and Soybean (Glycine max (L.) Merr.) Nodulation: a Review

Plant Molecular Biology Reporter - Nitrogen-fixing bacteria establish symbiosis with legumes for the biological nitrogen fixation process in specific root structures called nodules. Among these...     

How much genetic variation in fern populations is stored in the spore banks? A study of Athyrium filix-femina (L.) Roth

The genetic variation within spore banks of Athyrium filix-femina (L.) Roth from three sites in north-eastern Switzerland was investigated. At two sites spore banks were located beneath sporophyte populations. One collection site was 10Om away from a sporophyte population. The gametophytes grown from the soil samples, the dimensions of which were 4 × 4 × 1.5 cm, and sporophytes from each site were analysed electrophoretically for either three or four variable allozyme loci. The spore banks from the different soil samples within and between populations revealed a considerable amount of genetic diversity. The most frequent alleles within the two sporophyte populations were, with a few exceptions, also the most frequent within the spore banks. The influence of single sporophytic individuals on the genetic composition of microsites seems to be considerably reduced by stochastic processes such as soil movement or the action of earthworms, which promote the mixing of spores from different spatial and temporal origins. It was shown that spores remain viable after passing through the gut of earthworms and that spore banks from even small soil samples revealed genetic diversity and could lead to a large number of genetically distinct sporophytes. The results suggest that fertilization seems to be close to random because the sporophyte populations sampled were in Hardy-Weinberg equilibrium and had fixation index ( F _is) close to zero.     

Factors Affecting the Radiosensitivity of Hexaploid Wheat to γ-Irradiation: Radiosensitivity of Hexaploid Wheat (Triticum aestivum L.)

Understanding the radiosensitivity of plants, an important factor in crop mutation breeding programs, requires a thorough investigation of the factors that contribute to this trait. In this study, we used the highly radiosensitive wheat (Triticum aestivum L.) variety HY1 and J411, a γ-irradiation-insensitive control, which were screened from a natural population, to examine the factors affecting radiosensitivity, including free radical content and total antioxidant capacity, as well as the expression of TaKu70 and TaKu80 (DNA repair-related genes) as measured by real-time PCR. We also investigated the alternative splicing of this gene in the wild-type wheat ecotype by sequence analysis. Free radical contents and total antioxidant capacity significantly increased upon exposure of HY1 wheat to γ-irradiation in a dose-dependent manner. By contrast, in J411, the free radical contents exhibited a similar trend, but the total antioxidant capacity exhibited a downward trend upon increasing γ-irradiation. Additionally, we detected dose-dependent increases in TaKu70 and TaKu80 expression levels in γ-irradiated HY1, while in J411, TaKu70 expression levels increased, followed by a decline. We also detected alternative splicing of TaKu70 mRNA, namely, intron retention, in HY1 but not in J411. Our findings indicate that γ-irradiation induces oxidative stress and DNA damage in hexaploid wheat, resulting in growth retardation of seedlings, and they suggest that TaKu70 may play a causal role in radiosensitivity in HY1. Further studies are required to exploit these factors to improve radiosensitivity in other wheat varieties.     

Regulation of α-galactosidase activity and the hydrolysis of galactomannan in the endosperm of the fenugreek (Trigonella foenum-graecum L.) seed

When endosperms were isolated from fenugreek seeds 5 h after sowing and incubated in a small volume of water, the development of α-galactosidase activity and the breakdown of the galactomannan storage polysaccharide were both inhibited relative to control endosperms incubated in larger volumes. The inhibition could be relieved by pre-washing the endosperms, and reimposed by the wash-liquors. If the endosperms were isolated 24 h after sowing, no inhibition was observed. Removal of the embryonic axis from germinating fenugreek seeds and from germinated seedlings also inhibited the development of α-galactosidase activity and galactomannan breakdown in the endosperms; the inhibition was more pronounced the earlier the axis was removed. Axis excision 5 h after sowing caused a delay in the onset of galactomannan breakdown and of the appearance of α-galactosidase activity in the endosperms. It also led to a decrease in the rates of galactomannan breakdown and α-galactosidase production. Axis excision 24 h after sowing caused only a slowing of the rates of galactomannan breakdown and α-galactosidase increase. The inhibition caused by axis removal at 5 h could be relieved partially by gibberellin (10^-4 M), benzyladenine (10^-5 M), mixtures of these and by the herbicide SAN 9789 [4-chloro-5-(methylamine)-2-(α,α,α-trifluoro-m-tolyl)-3-(2H)-pyridazinone]. These substances had no effect on the inhibition caused by axis-removal at 24 h. Excision of the cotyledons at 5 h-leaving the separated axis and the endosperm-also caused inhibition of galactomannan breakdown and α-galactosidase development. The results are consistent with the presence in the fenugreek seed endosperm of diffusible inhibitors of galactomannan mobilisation which are removed or inactivated during normal germination and early seedling development. They are also consistent with a role for the seedling axis in the control of galactomannan breakdown in the endosperm. Initially the axis appears to have a regulatory function (via gibberellins and/or cytokinins?) in determining the onset of α-galactosidase production in the endosperm. Thereafter its continued presence is necessary to ensure maximal rates of α-galactosidase production and galactomannan hydrolysis. The role of the axis may be initially to counteract the endogenous inhibitors in the endosperm and then to act as a sink for the galactomannan breakdown products released in the endosperm and taken up by the cotyledons.     

A Bayesian analysis of gene flow from crops to their wild relatives: cultivated (Lactuca sativa L.) and prickly lettuce (L. serriola L.) and the recent expansion of L. serriola in Europe

Interspecific gene flow can lead to the formation of hybrid populations that have a competitive advantage over the parental populations, even for hybrids from a cross between crops and wild relatives. Wild prickly lettuce (Lactuca serriola) has recently expanded in Europe and hybridization with the related crop species (cultivated lettuce, L. sativa) has been hypothesized as one of the mechanisms behind this expansion. In a basically selfing species, such as lettuce, assessing hybridization in natural populations may not be straightforward. Therefore, we analysed a uniquely large data set of plants genotyped with SSR (simple sequence repeat) markers with two programs for Bayesian population genetic analysis, STRUCTURE and NewHybrids. The data set comprised 7738 plants, including a complete genebank collection, which provided a wide coverage of cultivated germplasm and a fair coverage of wild accessions, and a set of wild populations recently sampled across Europe. STRUCTURE analysis inferred the occurrence of hybrids at a level of 7% across Europe. NewHybrids indicated these hybrids to be advanced selfed generations of a hybridization event or of one backcross after such an event, which is according to expectations for a basically selfing species. These advanced selfed generations could not be detected effectively with crop‐specific alleles. In the northern part of Europe, where the expansion of L. serriola took place, the fewest putative hybrids were found. Therefore, we conclude that other mechanisms than crop/wild gene flow, such as an increase in disturbed habitats and/or climate warming, are more likely explanations for this expansion.     

The Fine Structural Observation on the Development of Embryo and Endosperm in the Intergene- rfc Crosses of Fadish ♀ (Raphanus sativus L.) Cabbageo ♂ (Brassica oleracea L.)

The present report deals with the structural abnormalities and abortion of the endosperm, and the related abnormal development of the embryos in the intergeneric crosses of radish (Raphanus sativus L.) ♀ with cabbage (Brassica oleracea L.) ♂. The weak development of ER, the occurence of starch grains in chloroplasts, the curious distribution of chloroplasts around the nuclei, and the earlier formation of cellular endosperm are some primary structure abnormalities of endosperm and they may indicate the poor development, low metabolic activities, and precocious growth in the hybrid endosperm. The endosperm abortion, which starts from chalazal end endosperm, comprises the damage of both structure and function of ER membrane, and the disintegration of nuclei and organelles, or even death. The hybrid embryos degenerated very early in 2-cell stage or even zygote stage in case the endosperm Aborted early. In case of endosperm late-aborted, the hybrid embryos grew for quite a long period of time but become slow down as the endosperm showed abnormal development and started to abort. As the results, the embryos were smaller, the embryo propers and the suspensors showed no growth in step with one another, and the embryo cells appeared structural abnormalities, and finally degenerated and aborted.     

Inheritance and mapping of the ore gene controlling the quantity of β-carotene in cucumber (Cucumis sativus L.) endocarp

The metabolic precursor of vitamin A, ??-carotene, is essential for human health. The gene(s) controlling ??-carotene quantity (Q??C) has been introgressed from Xishuangbanna gourd (XIS, possessing ??-carotene; Cucumis sativus L. var. xishuangbannanesis Qi et Yuan; 2n?=?2x?=?14) into cultivated cucumber (no ??-carotene; Cucumis sativus L.). To determine the inheritance of Q??C in cucumber fruit endocarp, F1 progeny and a set of 124 F7 recombinant inbred lines (RILs) derived from the cultivated cucumber line CC3 and XIS line SWCC8 were evaluated for Q??C during 2009 and 2010 in Nanjing, China. Segregation analysis revealed that endocarp Q??C of greenhouse-grown fruit was controlled by a single recessive gene. Further, marker analysis indicated the gene controlling Q??C was linked to seven SSR markers on linkage group 3, where their order was SSR20710?CSSR19511?CSSR15419?CSSR07706?Core?CSSR23231?CSSR11633?CSSR20270. These markers and the putative candidate gene were mapped to cucumber chromosome 3DS. An evaluation of 30 genetically diverse cucumber lines indicated that marker SSR07706 has utility in further genetic analyses of the Q??C orange endocarp gene, designated ore. Moreover, the markers defined herein may have utility for marker-assisted selection directed towards the development of cucumber germplasm with high fruit ??-carotene content.     

N-β-alanyldopamine and N-acetyldopamine occurrence and synthesis in the central nervous system of Manduca sexta (L.)

N-β-Alanyldopamine (NBAD), N-acetyldopamine (NADA), dopamine (DA), and 3,4-dihydroxyphenylalanine (DOPA) were detected in the brain and ganglia of the central nervous system of larval and adult tobacco hornworms, Manduca sexta, by reversed phase HPLC with electrochemical detection. NBAD predominated in larval neural tissue during development of the fifth instar and increased to peak concentrations of 936, 650 and 263 nmol g⁻¹ in the abdominal ganglia, subesophageal plus thoracic ganglia and brain, respectively, at the wandering stage of development. Concentrations of all catecholamines decreased in the pharate pupa and were generally lowest in the adult nerve cord. DA was the second most abundant catecholamine in larval ganglia, but the primary catecholamine in adult ganglia. Relatively high levels of DOPA also occurred in the ganglia of wandering larvae but not at other times. NADA was detected only in the abdominal ganglia of day 3 larvae. N-Acyltransferases that catalyze synthesis of NBAD and NADA from DA also were present in abdominal ganglia, as demonstrated by analysis of in vitro cultures in which exogenous DA stimulated synthesis of both N-acylated catecholamines. Maximal NBAD synthesis occurred in ganglia removed from wandering stage larvae (9.3 nmol g⁻¹ day⁻¹), whereas NADA synthesis was highest in ganglia from pharate pupae (7.3 nmol g⁻¹ day⁻¹). Thus, N-β-alanylation and N-acetylation are competing metabolic reactions for DA in the hornworm's nervous system. The role played by the N-acylated catecholamines in M. sexta neurophysiology is unknown, but these compounds may be storage or inactive forms of the putative neurotransmitter DA.     

Trace metals in the common mussel,Mytilus edulis (L.), and in the alga Fucus vesiculosus (L.) from the region of the sound (Öresund)

Concentrations of zinc, cadmium, lead and iron were determined in whole soft parts of mussels, Mytilus edulis (L.), and in growing tips of the alga Fucus vesiculosus (L.) from a total of 20 locations in the area of the Sound between Sweden and Denmark. Pollution profiles produced for each metal were similar in any one of the species studied but the profiles for metals in M. edulis were distinct from those for metals in F. vesiculosus. Results for mussels agreed broadly with those reported previously for this region, indicating a northward decrease in available metal concentrations. By contrast, results for algae showed few differences in metal availability throughout the study area, although some local effects were evident.The differences in the pollution profiles exhibited by these two organisms depend on their response to different portions of the total trace metal load of ambient waters. Results from the alga agree well with available data on the concentrations of trace metals in solution in waters of the Sound. The alga thus appears to be responding only to metals in solution, as suggested by previous authors. By contrast, the major proportion of the total body load of metals in mussels is derived from ingested phytoplankton. The pollution profiles exhibited by mussels may be explained if phytoplankton from the Baltic Sea contain higher concentrations of trace metals than do those from Kattegat. Possible mechanisms for the production of such differences in the metal contents of the two phytoplankton populations, and the ecological implications of these differences, are briefly discussed.     

Testing the enemy release hypothesis: a comparison of foliar insect herbivory of the exotic Norway maple (Acer platanoides L.) and the native sugar maple (A. saccharum L.)

Norway maple (Acer platanoides) is a Eurasian introduced tree species which has invaded the North American range of its native congener, sugar maple (A. saccharum). One hypothesis used to explain the success of an invasive species is the enemy release hypothesis (ERH), which states that invasive species are often particularly successful in their new range because they lack the enemies of their native range. In this study, we hypothesized that Norway maple would have less insect damage than sugar maple due to such enemy release. Autumn 2005 and summer 2006 leaves of Norway and sugar maple were collected from six sites in New Jersey and Pennsylvania to compare percent leaf area loss, gall damage, fungal damage, and specific leaf area (cm²/g). Although both species had low overall mean levels of leaf damage (0.4–2.5%), in both years/seasons Norway maple had significantly less leaf damage than sugar maple. Insects were also collected to compare insect assemblies present on each tree species. The numbers of insect taxa and individuals found on each species were nearly equivalent. Overall, the results of this study are consistent with the enemy release hypothesis for Norway maple. In addition, sugar maples when surrounded by Norway maples tended to show reduced herbivory. This suggests that the spread of Norway maple in North America, by reducing amounts of insect herbivory, may have further ecosystem-wide impacts.     

Characterisation of the cDNA clones of two β-tubulin genes and their expression in the potato plant (Solanum tuberosum L.)

The cDNA clones of two potato -tubulin genes were isolated from a tuberising stolon tip library. Analysis of 20 positive clones showed that they represented one or another of two different but very similar -tubulin genes, designated TUBST1 and TUBST2. The expression pattern of -tubulin genes in the potato plant was investigated by RNA blot analysis and by RT-PCR. Southern analysis of potato genomic DNA with coding and non-coding -tubulin probes revealed that there are multiple -tubulin genes in the potato genome and that there is likely to be considerable divergence in the 3 non-coding sequences. Phylogenetic analysis of plant -tubulin genes is described.     

Ecdysone 20-monooxygenase in mitochondria and microsomes of Manduca sexta (L.) Midgut: Is the dual localization real?

The dual localization of ecdysone 20-monooxygenase in mitochondria and microsomes of Manduca sexta larval midgut was investigated. Cosubstrate requirements and response to osmolarity of the microsomal ecdysone 20-monooxygenase system were found to be different from those previously reported for the mitochondrial enzyme system. The microsomal monooxygenase utilized NADPH and, less efficiently, NADH as cosubstrates. NADPH and NADH effects were neither additive nor synergistic. NADPH yielded identical activities in isotonic and hypotonic incubations. Mitochondria and microsomes showed no synergistic interaction for ecdysone 20-hydroxylation. After washing of the mitochondria, a large proportion of their ecdysone 20-monooxygenase activity was lost. The extent of the loss was inversely correlated to the concentration of mitochondria in the incubation mixture. The addition of bovine serum albumin to the incubations (2 mg/ml) largely restored the original activities. The microsomal contamination in mitochondrial pellets after each of three successive washings was determined by measuring the activity of a microsomal marker enzyme, NADPH-cytochrome c reductase. At each step of the purification, the ecdysone 20-monooxgenase activity of the mitochondrial preparations far exceeded the activity attributable to the microsomal contamination. These results confirm the existence of two independent ecdysone 20-monooxygenase systems in the midgut of M. sexta larvae.     

Effects of photoperiod and of ultraviolet radiation on the incidence of diapause in the Horn Fly, “Haematobia Irritans (L.) (Diptera: Muscidae)”

The horn fly, HAEMATOBIA IRRITANS (L.), is a bloodsucking pest of cattle found in almost all cattle-raising areas of the northern hemisphere.Predisposition to diapause in the pupal stage was determined in the adult parent. The predisposition was influenced by photoperiod which may have its effect either directly on the insect or indirectly by influencing the host blood. The percentage of the pupae that entered diapause varied inversely with the length of the photoperiod between 12 and 20 hours. Light in the visible range (7,800 to 4,000 A.U.) was provided byCool-whitefluorescent tubes. The addition of ultraviolet radiation (3,900 to 2,800 A.U.) in the 16- and 20-hour photoperiods further decreased the percentage of diapause.

---

Zusammenfassung Die Hornfliege, HAEMATOBIA IRRITANS (L.), ist ein blutsaugender Parasit in fast allen Rinderzuchtgebieten der nördlichen Hemisphäre.Die Prädisposition zur Diapause im Puppenstadium wurde in den erwachsenen Eltern determiniert.Sie wurde durch Belichtung beeinflusst, die entweder direkt auf das Insekt oder indirekt über das Blut des Wirtes wirkte. Die Prozentzahl an Puppen in Diapause fiel ab, wenn die periodischen Belichtungszeiten von 12 bis 20 Stunden verlängert wurden. Das sichtbare Licht (7800–4000 Å) stammte von cool-white fluoreszierenden Röhren. Durch die periodische Zugabe einer Ultraviolett- (3900 – 2800 Å) Bestrahlung fiel der Anteil an Diapausen noch weiter.

---

Résumé La mouche, HAEMATOBIA IRRITANS (L.), est un parasite hématophage du bétail répandu dans presque toutes les zones d'élevagê de l'hémisphère nord. La prédisposition à la diapause au stade de pupe a été déterminée chez les parents adultes. La prédisposition est influencée par une période d'éclairage qui peut agir soit directement sur l'insecte soit indirectement par l'intermédiaire du sang de l'hôte. Le pourcentage des pupes entrant en diapause varie inversement à la durée d'un éclairage de 12 à 20 heures. La lumière blanche (7800 – 4000 Å) est produite par des tubes fluorescents froids. L'addition de rayonnement ultra-violet (3900 à 2800 Å) dans les périodes d'éclairage de 16 et de 20 heures réduit encore le pourcentage de diapauses.

     

Biomass and primary production of Cladophora glomerata (L.) Kütz. in the Neva Estuary

The dynamics of the biomass, primary production, and P/B ratio of floating and attached forms of green filamentous alga Cladophora glomerata (L.) Kütz. was studied for the shallow water littoral area of the Neva Estuary in 2003–2006. The biomass of the floating algae constituted up to 70% of the total biomass, and the primary production reached up to 90% of the total for the depths of 0–1 m from the middle of July to the end of August.     

Species, dynamics and population composition of phthirapteran in free-range chickens (Gallus gallus L.) in São Luis Island, State of Maranhão

The objective of this work was to identify the phthirapteran species, to determine the prevalence according to the anatomical region of the body and to know the dynamics and composition of the population of these ectoparasites in free-range chicken in S?o Luis Island, state of Maranh?o. Inspection was performed in 40 chickens and feathers were collected from the head, neck, wing, thigh, dorsal and ventral regions and cloacae. The phthirapteran species identified were: Menopon gallinae L., Menacanthus stramineus Nitzsch, Menacanthus pallidulus Neumann, Menacanthus cornutus Schommer (Menoponidae), and Lipeurus caponis L., Goniodes dissimilis Denny and Goniocotes gallinae De Geer (Philopteridae). L. caponis was collected from all regions sampled, including the head, which was the least infested region. The dorsum was the most infested, especially in the dry period of the year and where the greater parasitic diversity was observed, the wing and the head were the least infested regions. Considering the dynamics and the composition of the population the phthirapteran presented a prevalence of 85% of the sampled chickens, the mean intensity of infestation was 45.3 varying from <1 to 453. The egg stage was superior to the others life stages followed by nymphs and female adults, independent of the phthirapteran species.     

Production of γ-Aminobutyric Acid and Its Supplementary Role in the TCA Cycle in Rice (Oryza sativa L.) Seedlings

Journal of Plant Growth Regulation - Germination of rice (Oryza sativa L.) results in rapid accumulation of γ-aminobutyric acid (GABA), but its precise role in the process remains unclear. In...     

N-β-Alanyldopamine levels and synthesis in integument and other tissues of Manduca sexta (L.) during the larval-pupal transformation

N-β-Alanyldopamine (NBAD) and other diphenols in tissues of the fifth larval instar of the tobacco hornworm, Manduca sexta (L.), were analyzed by HPLC with electrochemical detection. NBAD accumulated in the integument during the intermolt feeding period, with maximal levels in the wandering stage (6 mmol/g). It then declined to a low level during apolysis and endocuticle digestion, while hemolymph NBAD increased during the same interval to a peak concentration (3 mM) shortly before pupal ecdysis. Trachea and foregut contained lesser amounts of NBAD (0.5 mmol/g), perhaps associated with cuticle, whereas fat body, muscle, midgut and hindgut had 0.1 mmol/g or less. Dopamine (DA), N-acetyldopamine and 3,4-dihydroxyphenylalanine (DOPA) were at least 10-fold less abundant than NBAD in the integument. NBAD synthase, which catalyzes the formation of NBAD from DA and β-alanine, was assayed in both integument and fat body. Highest activity was detected in the integument, where two peaks were observed, one at day 3 near the end of larval feeding and the other at day 9 as pupal cuticle tanning was initiated. Fat body enzyme was substantially less and was detected only in the pharate pupa. Maximal NBAD synthesis by integument cultured in vitro was dependent upon DA supplementation of at least 1.4 mM. 20-Hydroxyecdysone did not alter NBAD synthesis in vitro in either the integument or the fat body, even though injection of this hormone into isolated larval abdomens induced synthesis and/or transport of integumental NBAD back into the hemolymph. The rate-limiting steps in the NBAD biosynthetic pathway appear to be the production of DOPA and DA, because β-alanine occurs in the hemolymph at relatively high levels throughout larval-pupal development.