Carbohydrates and resistance to <Emphasis Type="Italic">Phytophthora infestans</Emphasis> in potato plants

Plants generally deal with biotic or abiotic stresses by altering components as for example cell wall constituents and metabolites. Infection by Phytophthora infestans, the causal agent of late blight, constitutes a stress condition for the plants and they react to it with changes arising in their metabolism depending on the resistance level of the plants. The present work compares two potato hybrids differing in their level of horizontal resistance to late blight. Carbohydrate content in stems and leaves of infected and uninfected plants was determined by HPLC. Some carbohydrates accumulated in the stems of the resistant hybrid infected by P. infestans, whereas they remained unchanged in the susceptible hybrid. On the other hand, in the leaves, these carbohydrates accumulated only in the infected susceptible hybrid.     

Evolving digital circuits using hybrid particle swarm optimization and differential evolution

This paper presents the evolution of combinational logic circuits by a new hybrid algorithm known as the Differential Evolution Particle Swarm Optimization (DEPSO), formulated from the concepts of a modified particle swarm and differential evolution. The particle swarm in the hybrid algorithm is represented by a discrete 3-integer approach. A hybrid multi-objective fitness function is coined to achieve two goals for the evolution of circuits. The first goal is to evolve combinational logic circuits with 100% functionality, called the feasible circuits. The second goal is to minimize the number of logic gates needed to realize the feasible circuits. In addition, the paper presents modifications to enhance performance and robustness of particle swarm and evolutionary techniques for discrete optimization problems. Comparison of the performance of the hybrid algorithm to the conventional Karnaugh map and evolvable hardware techniques such as genetic algorithm, modified particle swarm, and differential evolution are presented on a number of case studies. Results show that feasible circuits are always achieved by the DEPSO algorithm unlike with other algorithms and the percentage of best solutions (minimal logic gates) is higher.     

Transient expression of<Emphasis Type="Italic"> Arabidopsis thaliana</Emphasis> ascorbate peroxidase 3 in<Emphasis Type="Italic"> Nicotiana benthamiana</Emphasis> plants infected with recombinant potato virus X

We have explored the transient over-expression of Arabidopsis thaliana ascorbate peroxidase 3 (APX3) in Nicotiana benthamiana using a viral vector based on the potato virus X (PVX). Plants infected with a PVX:APX3 hybrid had a similar progression of viral particles compared to control plants infected with a PVX:GFP hybrid, indicating that infection was not affected by the over-expression of heterologous APX3. Our results also showed that in PVX:APX3-infected plants, the hybrid virus directed a high level of APX3 expression and the recombinant protein was functional, as inferred from the higher APX activity compared to mock and PVX:GFP hybrid-infected plants. The PVX recombinant expression system used is a simple and quick method for transient expression of heterologous APXs, which are expected to suffer specific processing in plant cells.     

Cytological,morphological and molecular analyses of controlled progenies from meiotic mutants of alfalfa producing unreduced gametes

A program of sexual polyploidization was carried out in alfalfa using plants from wild diploid species that produced male or female unreduced gametes. Sixteen progenies from 2x-4x and 2x-2x crosses were examined with a combination of morphological, cytological and molecular analyses. The chromosome counts revealed diploid, tetraploid and aneuploid plants. Plants with B chromosomes were also detected. The leaf area of the plants was a useful characteristic for distinguishing tetraploid from diploid plants obtained by unilateral or bilateral sexual polyploidization. Leaf shape and leaf margin were not correlated with the ploidy levels. Plants with supernumerary chromosomes displayed obovate or elliptic leaves which differed markedly from the range of forms typical of diploid and tetraploid alfalfa plants. RAPD markers were investigated in all progeny plants to determine maternal and paternal amplification products. Three alfalfa-specific primers proved to be effective in revealing the hybrid origin of the plants. A combination of cytological, morphological and molecular analyses is essential for a detailed genetic characterization of progenies in programs of sexual polyploidization.     

Broccoli plants with pyramided cry1Ac and cry1C Bt genes control diamondback moths resistant to Cry1A and Cry1C proteins

This study was undertaken to determine the effects of pyramiding two Bacillus thuringiensis (Bt) genes in the same plant on the production of Bt proteins and the control of diamondback moths (DBM, Plutella xylostella) resistant to one or the other protein. Broccoli lines carrying both cry1Ac and cry1C Bt genes were produced by sexual crosses of cry1Ac- and cry1C-transgenic plants. Plants containing both genes were selected by tests for resistance to kanamycin and hygromycin, and confirmed by PCR analysis for the Bt genes. Both cry1Ac and cry1C mRNAs were detected in the hybrid lines, and Cry1Ac and Cry1C proteins were stably produced at levels comparable to the parental plants. Plants producing both Cry1Ac and Cry1C proteins caused rapid and complete mortality of DBM larvae resistant to Cry1A or Cry1C, and suffered little or no leaf damage. These plants, in combination with the resistant DBM populations available, will allow greenhouse or field studies of resistance management strategies involving gene pyramiding.     

Plant behaviour and communication

Plant behaviours are defined as rapid morphological or physiological responses to events, relative to the lifetime of an individual. Since Darwin, biologists have been aware that plants behave but it has been an underappreciated phenomenon. The best studied plant behaviours involve foraging for light, nutrients, and water by placing organs where they can most efficiently harvest these resources. Plants also adjust many reproductive and defensive traits in response to environmental heterogeneity in space and time. Many plant behaviours rely on iterative active meristems that allow plants to rapidly transform into many different forms. Because of this modular construction, many plant responses are localized although the degree of integration within whole plants is not well understood. Plant behaviours have been characterized as simpler than those of animals. Recent findings challenge this notion by revealing high levels of sophistication previously thought to be within the sole domain of animal behaviour. Plants anticipate future conditions by accurately perceiving and responding to reliable environmental cues. Plants exhibit memory, altering their behaviours depending upon their previous experiences or the experiences of their parents. Plants communicate with other plants, herbivores and mutualists. They emit cues that cause predictable reactions in other organisms and respond to such cues themselves. Plants exhibit many of the same behaviours as animals even though they lack central nervous systems. Both plants and animals have faced spatially and temporally heterogeneous environments and both have evolved plastic response systems.     

SEGREGATION AND RECOMBINATION OF CHEMICAL CONSTITUENTS IN A HYBRID SWARM OF BAPTISIA LAEVICAULIS × B. VIRIDIS AND THEIR TAXONOMIC IMPLICATIONS

Turner , B. L. (U. Texas, Austin), and Ralph Alston . Segregation and recombination of chemical constituents in a hybrid swarm of Baptisia laevicaulis × B. viridis and their taxonomic implications. Amer. Jour. Bot. 46(9): 678–686. lllus. 1959.—Selected plants from a hybrid population of Baptisia laevicaulis × B. viridis and individuals from “pure” populations of the parental species were examined chromatographically. The resulting patterns were then compared with the respective phenotypes by the use of hybrid indices. Although the parental type individuals yielded nearly uniform patterns, hybrid-type plants showed a striking recombination of chemical components and there was an excellent correlation between chromatographic patterns and hybrid expression. Of particular interest was the detection of a new and distinctive compound in 2 of the hybrid-type plants which was not observed in either parent. Chromatograms of 3 other Baptisia species also showed distinctive patterns, and their relationship to each other, as indicated by morphological features, was accompanied by similarities in the biochemical pattern. The segregation and recombination of biochemical constituents are discussed with respect to their evolutionary and taxonomic implications. It is suggested that an extension of the techniques utilized might provide for the establishment of “biochemical profiles” which should prove of considerable value to the systematist.     

Parallel formation of hybrid swarms of ground beetles in the genus Carabus (Coleoptera: Carabidae) in adjacent river basins

Populations of forms intermediate between Carabus (Ohomopterus) insulicola and Carabus (Ohomopterus) arrowianus occur at the boundaries between the two species in the Kiso Valley, Nagano Prefecture, central Honshu, Japan. Morphological and mitochondrial DNA analyses revealed that these populations are derived from a hybrid swarm established as a result of secondary contact between the two species. A similar hybrid swarm has been reported in the Ina Valley, an adjacent river basin separated by the Kiso Mountain Range, where the two species are distributed parapatrically. The hybrid swarm individuals in the two valleys show parallelism in the morphological evolution of the male genitalia upon secondary contact and subsequent formation of hybrid swarms between the two Carabus species.     

Insect-resistant plants with improved horticultural traits from interspecific potato hybrids grown in vitro

Summary Plants were regenerated from petiole calli of interspecific hybrids of Solanum tuberosum x S. berthaultii, an insect-resistant wild species. Callus culture was used to generate genetic changes to overcome the restricted recombination between the two genomes. Two plants out of 58 (3.5%) from calli of hybrid J114-1 showed stable and heritable differences from the hybrid over two cycles of evaluations in the field. Replicated trials were conducted in 1987 and 1988, using two populations of plants propagated by nodal cuttings from the original regenerates maintained in vitro. One regenerate showed insect resistance and increased marketable yield (approximately two fold) in the field. The other had higher levels of phenolic exudate in one of the two types of foliar trichomes associated with the insect resistance mechanism. Some desirable changes were discernible only in sexual progeny of regenerates, not in the regenerates themselves. In a backcross to S. tuberosum, 7 of 14 (50%) regenerates from hybrid F743-4 showed more progeny (up to 15-fold) with improved trichome traits and horticultural characteristics than the original hybrid. The variations were not associated with changes in ploidy. Fifteen plants obtained from these crosses are currently being incorporated into breeding lines. These results suggest that a period of callus culture followed by plant regeneration may aid in the introgression of desirable traits from wild species into crop plants.     

Introgressive hybridization between a native and an introduced species:Viola lutea subsp.Sudetica versusV. Tricolor

A hybrid swarm betweenViola lutea subsp.sudetica (2n=50, native species) andViola tricolor (2n=26, introduced species) originated in the 1970’s in the Krkono?e Mts. Analyses of chromosome numbers, reproductive biology, morphology, and ecology gave the following results: (1) Compared to the plants found in the 1970’s, the number of colour morphs have decreased and the types now prevailing in the field are morphologically closer toV. lutea subsp.sudetica, forming a continuum. (2) In the field, hybrids having approximately the same chromosome number as the primary hybrids are most common. Some plants of the hybrid swarm have certain characters unknown to their parents. (3) In the field, autogamous types similar toV. tricolor were found. (4) A limited number of plants from the field and culture have higher somatic chromosome numbers thanV. lutea subsp.sudetica; there was a tendency towards increasing chromosome numbers in their progeny (up to 2n=62). These plants have some new morphological characters (a small proportion of hexacolpate pollen) not found in the parents (nor in the other hybrids with prevailing tetracolpate and pentacolpate pollen grains) and higher pollen fertility in comparison to the other hybrids. These plants also have the highest germination rate. (5) There is a tendency for chromosome numbers to decline in the progeny of open pollinated hybrid plants in the lowland experimental graden. (6) The phenology of the plants in the mountain grasslands and the lowland garden is different; the parents behave in a totally contrasting manner. (7) In the field at least some hybrids extend outside the geographical and ecological ranges of the parental species, invading new communities. (8) Seeds ofV. tricolor do not show any dormancy and germinate in the year of production; most of theV. lutea subsp.sudetica seeds germinate during the spring of the following year. Hybrids with intermediate chromosome numbers had both types of germination strategy. The germination rate of intermediates with high chromosome numbers was even higher than that ofV. tricolor.     

植物与土壤微生物在调控生态系统养分循环中的作用

陆地生态系统的地上、地下是相互联系的。植物与土壤微生物作为陆地生态系统中的重要组成部分, 它们之间的相互作用是生态系统地上、地下结合的重要纽带。该文首先介绍了植物在养分循环中对营养元素的吸收、积累和归还等作用, 阐述了土壤微生物对养分有效性及土壤质量具有重要的作用。其次, 重点综述了植物与土壤微生物之间相互依存、相互竞争的关系。植物通过其凋落物与分泌物为土壤微生物提供营养, 土壤微生物作为分解者提供植物可吸收的营养元素, 比如共生体菌根真菌即可使植物根与土壤真菌达到互惠。然而, 植物的养分吸收与微生物的养分固持同时存在, 因而两者之间存在对养分的竞争。通过植物多样性对土壤微生物多样性的影响分析, 以及土壤微生物直接或间接作用于植物多样性和生产力的分析, 探讨了植物物种多样性与土壤微生物多样性之间的内在联系。针对当前植物与土壤微生物对养分循环的调控机制的争论, 提出植物凋落物是调节植物与土壤微生物养分循环的良好媒介, 植物与土壤微生物的共同作用对维持整个生态系统的稳定性具有重要意义。也指出了目前在陆地生态系统地上、地下研究中存在的不足和亟待解决的问题。     

Comparison of essential oils and genetic relationship of Origanum × intercedens to its parental taxa in the island of Crete

Plants of the taxa Origanum onites and Origanum vulgare were allowed to cross-pollinate under natural open field conditions and to produce a mixed population of putative hybrid Origanum × intercedens and parent genotypes. Randomly collected plants were classified as putative hybrids or parent genotypes by inspection of their inflorescence. They were then subjected to analysis of their essential oil composition and were fingerprinted by randomly amplified polymorphic DNA (RAPD) fragments. DNA primers identifying the genotype as well as showing the distance of a particular putative hybrid plant from the parent genotypes were found. Alone or in combination with the essential oil composition they can be used as reliable tools for the genetic identification of the two parental taxa and the putative hybrid plants in natural populations.     

Calmodulin‐related CML24 interacts with ATG4b and affects autophagy progression in Arabidopsis

Plants encounter environmental stress challenges that are distinct from those of other eukaryotes because of their relative immobility. Therefore, plants may have evolved distinct regulatory mechanisms for conserved cellular functions. Plants, like other eukaryotes, share aspects of both calcium‐ and calmodulin‐based cellular signaling and the autophagic process of cellular renewal. Here, we report a novel function for an Arabidopsis calmodulin‐related protein, CML24, and insight into ATG4‐regulated autophagy. CML24 interacts with ATG4b in yeast two‐hybrid, in vitro pull‐down and transient tobacco cell transformation assays. Mutants with missense mutations in CML24 have aberrant ATG4 activity patterns in in vitro extract assays, altered ATG8 accumulation levels, an altered pattern of GFP–ATG8‐decorated cellular structures, and altered recovery from darkness‐induced starvation. Together, these results support the conclusion that CML24 affects autophagy progression through interactions with ATG4.     

SOMATIC EMBRYOGENESIS AND PLANT REGENERATION FROM TISSUE CULTURES OF PENNISETUM AMERICANUM,AND P. AMERICANUM x P. PURPUREUM HYBRID

Immature embryos as well as explants obtained from young inflorescences of Pennisetum americanum (pearl millet) give rise to callus tissues on nutrient media containing 2,4-dichlorophenoxyacetic acid (2,4-D). A compact and pale-yellow callus that arises from the peripheral cells of the scutellum, and from the young inflorescences, undergoes further organized growth. When transferred to a 2,4-D-free medium, supplemented with indole-acetic acid or kinetin, or both, embryoids are formed in the organized areas of the callus. Embryoids show a bipolar organization with a shoot-coleorhiza (root) axis and have a coleoptile-like structure surrounded at the base by a cup-shaped structure that resembles the scutellum in texture and morphology. Embryoids show bilateral or radial symmetry and “germinate” in vitro to form plants that have been grown to maturity in soil. Similar embryogenic callus cultures have been produced from young inflorescence tissues of hybrid Pennisetum, a triploid sexually sterile hybrid of P. americanum x P. purpureum. Plants derived from these have also been transferred to soil. The regenerated plants showed normal chromosome numbers.     

Morphological and phytochemical variation, genetic structure and phenology in an introgressive hybrid swarm of Senecio hercynicus and S. ovatus (Compositae, Senecioneae)

Introgressive hybridisation between Senecio hercynicus and Senecio ovatus (Compositae, Senecioneae) was studied in a mixed stand of the two species on the S- and SW-facing slopes of the German part of the Bohemian Forest (SE Germany). Morphological variation based on multivariate analysis of 14 diagnostic characters, along with genetic data from an amplified fragment length polymorphism (AFLP) fingerprinting analysis, indicates that the surveyed stand forms an intensively introgressed hybrid swarm. The majority of individuals were found to be intermediate between the two parental taxa, and strong statistical correlation between phenetic and genetic distances was observed. In contrast to that, flowering time of individuals (expressed as the time when 50% of the capitula of a plant were in flower) was found to follow a bimodal distribution in the hybrid swarm and lacked any correlation with the genetic and morphological relationships among plants. The same was true for the spectra of pyrrolizidine alkaloids (PA) revealed by a gas-chromatographic survey: most of the 142 individuals surveyed fell into one of two main chemotypes, only a few plants exhibited an intermediate and additive PA spectrum, and no correlation with the genetic and morphological relationships among plants was observed. Assuming that most of the AFLP markers are neutral, we conclude that the correlation of morphology with the genetic pattern may argue for the neutrality of morphological features analysed. Consequently, we interpret the lack of correlation between phenological and phytochemical data with the neutral genetic markers as evidence that both phenology and phytochemistry may be either under selection or that these features are genetically or biosynthetically constrained.     

The effects of cytoplasmic male sterility on cytonuclear disequilibria in hybrid zones

Male sterility is studied in hybrid zones by different measures of cytonuclear disequilibria, D, D₁, D₂, and D₃. Of particular interest are the dynamics of disequilibria as the system evolves to equilibrium. Our first model, the hybrid swarm model, yields equilibrium results identical to those observed in a model with random mating. In our second model of a hybrid zone, predictions of the sign pattern of disequilibrium values can be made based on migration values. A characteristic sign pattern may help to distinguish cytoplasmic male sterility (CMS) from other mechanisms of selection. Our simple CMS model with migration is successfully fit to cytonuclear data on a hybrid population of cottonwoods.     

The use of genetic markers selected in vitro for the isolation and genetic verification of intraspecific somatic hybrids of Nicotiana tabacum L.

Summary A scheme employing genetic markers obtained by in vitro selection was developed for the stringent isolation of hybrid somatic cells of Nicotiana tabacum. Mesophyll protoplasts that carried two dominant alleles of nuclear genes conferring resistance to the herbicide picloram (pmR1) and the ability to utilize glycerol as the sole source of carbon (Gut) were fused with suspension-culture protoplasts that were marked with the dominant nuclear allele (HuR9) conferring resistance to hydroxyurea. Putative somatic hybrid cell lines were identified by selecting for the Gut and HuR9 markers, followed by an assay for the unselected marker PmR1. Plants regenerated from six of these cell lines were proved to be true somatic hybrids by demonstrating the segregation of each of the three parental markers in the progeny of crosses of those plants with normal seed-derived plants.     

The hypothesis of hybrid origin of Poa jemtlandica supported by morphometric and isoenzyme data

Morphometric and isozyme data were used to test the hypothesis that the pseudoviviparous Poa jemtlandica has originated as a hybrid between the sexual P flexuosa and the facultative apomict P alpina. Plants were sampled from three localities in southern Norway. In addition, some Icelandic plants were included. Both morphometric and isozyme data clearly support the hybrid hypothesis. Poa jemtlandica was morphologically intermediate between its supposed parents in several individual characters as well as in a discriminant analysis. Seven enzyme systems were analysed. Eight areas of activity were interpreted as "loci", each of which certainly represented several duplicated genes in these plants which all are polyploid. A total of 27 different multilocus phenotypes was observed: ten phenotypes in P alpina var. vivipara, eight phenotypes in I. alpina var. alpina, seven phenotypes in P jemtlandica, and three phenotypes in P flexuosa. The phenotype of Icelandic P jemtlandica was identical to that of P. jemtlandica from one of the Norwegian localities. Additive electrophoretic patterns were observed for P jemtlandica at four individual "loci". At the remaining "loci" some phenotypes of P. jemtlandica were most similar to P. flexuosa, others to P alpina. The data also suggest that P jemtlandica has originated several times, but there is no indication of frequent or recent hybridization where the species coccur today.     

Ontogenetic events in androgenesis of Brazilian barley genotypes

This paper describes a simple procedure for obtention of barley (Hordeum vulgare L.) doubled haploid plants from Brazilian hybrid genotypes. Anatomical and histological examinations showed the reversion of barley pollen to an sporophytic mode of development. A sequence of mitosis led to the formation of multicellular pollen grains. Regeneration of plants occurred either by direct embryogenesis or callus formation followed by differentiation through direct embryogenesis or organogenesis. Plants were formed in the same medium used for induction dispensing an additional regeneration step. This procedure makes doubled haploid production simpler and faster. Plantlets were transferred to another medium for rooting and after that planted in pots with vermiculite and nutrient solution.     

EVOLUTIONARY SORTING OF CHARACTERS IN A HYBRID SWARM. I: DIRECTION OF SLOPE

Quercus Douglasii and Quercus turbinella subsp. californica intergrade in California in a belt about 250 miles long. In the area of each parental taxon and near Lebec, in the middle of the zone where hybrids are common and where the gene pool is about evenly divided as to origin, the phenotypes were scored on a six-point scale to establish hybrid indices. At Lebec populations on slopes facing at intervals of one-eighth the distance around the compass were scored. The composition of each population was heterogeneous but restricted markedly according to exposure to the sun. Plants on northeast-facing slopes approached but did not equal the high score of Quercus Douglasii in Madera County; those on southwest-facing slopes approached but did not equal the extreme low score of subsp. californica near Victorville. Evolutionary sorting must be very rapid, for it is correlated with slopes of the same hills, and the hybrid swarm must be very sensitive to the environment.