Combining ability for the traits of stem branching and plant height in linseed lines

Combining ability for the traits of stem branching and plant height has been studied in ten pure lines of flax under complete and incomplete diallel crosses. High heritability of the traits "plant height", "the number of lateral stems" and "the number of lateral shoots" and essential role of genes with dominant effects of interaction in genetic control of the traits of stem branching and plant height have been shown. On the basis of combining ability indexes the ways for usage of certain genotypes and crossing combinations in flax breeding were defined. As a result of individual selection from hybrid combinations some new complexes of habit traits and agriculturally valuable plant characteristics were obtained.     

Genetic control systems of stem branching and plant height in linseed

A diallel analysis of the traits “plant height”, “number of lateral stems”, and “number of lateral shoots” was carried out using Hayman’s method in three self-pollinated lines and one linear cultivar of linseed. A similarity was demonstrated between the inheritance of the studied traits and the additive-dominant model without any nonallelic interactions. The recessive nature of inheritance of increased plant height and high numbers of shoots together with dominant inheritance of increased numbers of lateral stems was revealed. The number of blocks of polymeric genes responsible for the variability in the studied traits was also estimated. The lines of linseed were ranged according to their contents of dominant alleles.     

The systems of genetic control of the traits of branching and plant height in linseed

The genetic control of the traits "plant height", "the number of lateral shoots" and "the number of lateral stems" has been studied in 3 pure lines and 1 variety of linseed according to the model 1 of Hayman method. It has been shown that the traits under investigation are inherited according to the additive-dominant model of genetic control in the absence of any interloci interactions. The higher plant height and numerous lateral shoots are recessive traits controlled by 2 blocks of polymeric genes, whereas the trait of numerous lateral stems is a dominant trait influenced by 1 to 3 blocks of genes. The linseed lines have been ranked according to the number of dominant alleles they have. Suggestions for selection using these parental genotypes have been made.     

Combining ability of tropical maize lines for seed quality and agronomic traits

Studies of genetic effects of early selection of maize based on seed quality traits are rare, especially those that use materials from different heterotic groups. These studies are also useful in tropical environments and for the advancement of sustainable agriculture with cropping during seasons not commonly used for cultivation. We estimated, through diallel crosses, the predominant genetic effects on the expression of agronomic traits and seed quality and on the general combining ability of nine maize lines from commercial hybrids and the specific combining ability of hybrid combinations among them. In the evaluation of seed quality, seven tests were used: first count and final count of seed germination, seedling vigor classification, cold tolerance, seedling emergence rate in a sand seedbed, speed of emergence in a sand seedbed, and speed of emergence index. Plant height, first ear height and grain yield were the estimated agronomic traits. In the diallel analysis, method 3 (model I) proposed by Griffing was used. There was a greater significance of non-additive genetic effects in the genetic control of seed quality of the various lines. The Flash, Dekalb 350 and P 30F80 lines combined high seed quality and high grain yield. For growth during the normal planting season, the combinations CD 3121-1 x P 30F80, Speed x CD 3121-2, Dow 8330 x AG 8080 and Dekalb 350 x CD 3121-2 were the most promising for both seed quality and agronomic traits.     

Combining plant and animal traits to assess community functional responses to disturbance

There is a general consensus that functional traits are reliable indicators of adaptation of organisms to particular environmental characteristics. In this study we relate the combined distributions of species traits of plants and animals to disturbance regimes in chestnut forests of southern Switzerland affected by regular winter fires. We used co‐inertia analysis for combining the trait response of 471 invertebrate species (117 001 individuals) and 81 plant species at 23 sites with different fire and cutting histories. Trait response was assessed by calculating the variation in weighted mean traits averaged over the communities and by using mean traits in multivariate analyses. The analysis showed a strong association between plant and animal traits under fire constraints (Monte‐Carlo test, p=0.0045). Plants and animal distributions show parallel trends in responses to fire which selects traits relating to persistence (ability to survive), resilience (ability to recover) and mobility. Warmth‐demanding insects, herbivores, flying carnivores and pollinators were associated with recent fires, as were annual, ruderal and light‐demanding plant species with long flowering duration. Small arthropods feeding on dead wood and those with narrow habitat requirements were associated with low fire frequency and unburnt sites, as were competitive plants with large seeds favoring moist sites. The spatial association between plant and animal traits reflected adaptations that promote survival in the disturbance regime, while the disturbance acts as an environmental filter on the distribution and assemblage of the trait values within communities. This combined analysis of plant and invertebrate traits distributions illustrates how community and ecosystem responses can be monitored and the results generalized across localities and disturbance types. Analyses of traits that cross trophic levels provide powerful and promising tools for validating management procedures and controlling ecosystem functions.     

Combining ability analysis over environments in diallel crosses of linseed (Linum usitatissimum L.)

Summary This paper reports on combining ability studies for yield and its component traits in diallel crosses involving ten ecogeographically and genetically diverse linseed (Linum usitatissimum L.) cultivars in the F₂ generation over three locations. The general combining ability (GCA) and specific combining ability (SCA) mean squares were significant at all three locations for all traits. Combined analysis over locations showed the same trend of significance. The ratio of GCA to SCA mean squares was significant for all the traits in individual location analysis as well as in combined analysis. This indicated the predominant role of additive gene effects in the inheritance of these characters. The GCA mean squares were several times larger than SCA mean squares for all the traits, indicating the presence of considerable magnitude of additive genetic variance and the additive x additive components of the epistatic variance. Consequently, effective selection should be possible within these F₂ populations for all characters. Significant genotype-location and GCA-location interactions indicated that more than one test location is required to obtain reliable information. The inexpensive and reliable procedure used for making the choice of parents was the determination of breeding values of the parents on the relative performance of their F₂ progeny bulks.Part of the thesis submitted by the senior author in partial fulfillment of the requirements for the Ph. D. degree of the Marathwada Agricultural University, Parbhani, 431 402, India     

Combining ability of summer-squash lines with different degrees of parthenocarpy and PRSV-W resistance

The aim was to assess heterosis in a set of 16 summer-squash hybrids, and evaluate the combining capacity of the respective parental lines, which differed as to the degree of parthenocarpy and resistance to PRSV-W (Papaya Ringspot Virus-Watermelon strain). The hybrids were obtained using a partial diallel cross design (4 × 4). The lines of parental group I were 1 = ABX-037G-77-03-05-01-01-bulk, 2 = ABX-037G-77-03-05-03-10-bulk, 3 = ABX-037G-77-03-05-01-04-bulk and 4 = ABX-037G-77-03-05-05-01-bulk, and of group II, 1' = ABX-037G-77-03-05-04-08-bulk, 2' = ABX-037G-77-03-05-02-11-bulk, 3' = Clarice and 4' = Caserta. The 16 hybrids and eight parental lines were evaluated for PRSV-W resistance, parthenocarpic expression and yield in randomized complete-block designs, with three replications. Parthenocarpy and the resistance to PRSV-W were rated by means of a scale from 1 to 5, where 1 = non-parthenocarpic or high resistance to PRSV-W, and 5 = parthenocarpic or high susceptibility to PRSV-W. Both additive and non-additive gene effects were important in the expression of parthenocarpy and resistance to PRSV-W. Whereas estimates of heterosis in parthenocarpy usually tended towards a higher degree, resistance to PRSV-W was towards higher susceptibility. At least one F(1) hybrid was identified with a satisfactory degree of parthenocarpy, resistance to PRSV-W and high fruit-yield.     

Tradeoffs between height growth rate, stem persistence and maximum height among plant species in a post-fire succession

One way species of low maximum height can accrue sufficient light income to persist in vegetation is via rapid height growth immediately following disturbance. By surveying patches of known time since fire, we reconstructed height–growth trajectories for 19 post-fire recruiting species from fire-prone vegetation in south-eastern Australia. Cross-species patterns of height growth were compared to several plant traits thought to influence height strategy, including leaf mass per area, stem tissue density, stem diameter and capacity to resprout. Shorter species were found to temporarily outpace taller species, both as resprouters and within reseeders. Among reseeders, a single axis of variation summarised patterns of height–growth, time to onset of reproduction and longevity. This axis was tightly correlated with maximum height, leaf mass per area and stem diameter at a given height. These results illustrate how a range of height strategies can coexist in fire-prone vegetation, via the time-process initiated by disturbance.     

Predicting the limits to tree height using statistical regressions of leaf traits

Leaf morphology and physiological functioning demonstrate considerable plasticity within tree crowns, with various leaf traits often exhibiting pronounced vertical gradients in very tall trees. It has been proposed that the trajectory of these gradients, as determined by regression methods, could be used in conjunction with theoretical biophysical limits to estimate the maximum height to which trees can grow. Here, we examined this approach using published and new experimental data from tall conifer and angiosperm species. We showed that height predictions were sensitive to tree-to-tree variation in the shape of the regression and to the biophysical endpoints selected. We examined the suitability of proposed end-points and their theoretical validity. We also noted that site and environment influenced height predictions considerably. Use of leaf mass per unit area or leaf water potential coupled with vulnerability of twigs to cavitation poses a number of difficulties for predicting tree height. Photosynthetic rate and carbon isotope discrimination show more promise, but in the second case, the complex relationship between light, water availability, photosynthetic capacity and internal conductance to CO(2) must first be characterized.     

Tomato psyllid behavioral responses to tomato plant lines and interactions of plant lines with insecticides

Adult tomato psyllid, Bactericerca (Paratrioza) cockerelli (Sulc) (Homoptera: Psyllidae), behavioral responses were evaluated for five tomato plant lines and for the interactions of insecticides with four commercial cultivars. Plant lines tested included the commercial 'Shady Lady', 'Yellow Pear', '7718 VFN', 'QualiT 21', and the plant introduction line PI 134417. Insecticides included a kaolin particle film, pymetrozine, pyriproxyfen, spinosad, and imidacloprid. Psyllids spent significantly more time feeding on 'Yellow Pear' than all other plant lines except '7718 VFN'. In comparisons among plant lines, psyllids exposed to the wild accession PI 1.34417 showed a 98% reduction in feeding, a significant increase in jumping behavior, and a significant tendency to abandon the leaves, thereby demonstrating repellency, not just an antixenosis response. Interactions between plant lines and insecticides influenced behavioral responses. All insecticides tested significantly reduced feeding durations on all cultivars except the preferred 'Yellow Pear'. However, nonfeeding activities such as walking, probing, resting, and jumping varied substantially with chemical and cultivar combination. The behavior assay results offered insight into host resistance mechanisms, provided a useful technique for measuring effects of interaction of plant lines with insecticides, and generated information for selecting insecticides for specific cultivars used in integrated pest management program for the tomato psyllid.     

HDC细胞与MESPU—13细胞形成嵌合鼠能力的比较研究

ＥＳ细胞嵌合能力的强弱是人们利用ＥＳ细胞获得转基因小鼠时十分关心的问题。本言语通过囊胚显微注射法将１５个左右ＥＳ细胞注入Ｃ５７ＢＬ／６Ｊ品系小鼠３．５天囊胚的囊胚腔中观察嵌合鼠毛色嵌合情况。统计嵌合鼠的出生率;以及用葡萄糖磷酸异构酶（ＧＰＩ）电泳地检测ＥＳ细胞在嵌合鼠体内各种组织和器官的嵌合情况,对于ＨＰＲＴ缺陷（ＨＤＣ）细胞和ＭＥＳＰＵ－１３细胞的嵌合能力我们作了较详细的研究,结果表明ＭＥＳＰＵ     

Leaf physiological traits in relation to resprouter ability in the Mediterranean Basin

In Mediterranean ecosystems, fire is a strong selective agent among plants, and the different post-fire regeneration strategies (e.g. resprouting and non-resprouting) have implications for other plant traits. Because young plants of non-resprouters need to grow quickly and mature well before the next fire, we predict that they should possess leaf traits related to increased efficiency in growth and resource acquisition compared with resprouter species. To test this hypothesis, we measured specific leaf area, leaf nitrogen and carbon concentrations and leaf physiological traits, including gas exchange parameters and chlorophyll fluorescence, in 19 Mediterranean species cultivated in a common garden. Both cross-species and phylogenetically informed analyses suggest that non-resprouters have better physiological performance at the leaf level (i.e. higher photosynthetic capacity) than resprouters. All these results suggest that non-resprouter species are able to take greater advantage for vegetative growth and carbon fixation than resprouters during periods when water is readily available. The contrasted physiological differences between resprouters and non-resprouters reinforce the idea that these two syndromes are functionally different (i.e. they are functional types).     

QTL mapping of combining ability and heterosis of agronomic traits in rice backcross recombinant inbred lines and hybrid crosses

Background

Combining ability effects are very effective genetic parameters in deciding the next phase of breeding programs. Although some breeding strategies on the basis of evaluating combining ability have been utilized extensively in hybrid breeding, little is known about the genetic basis of combining ability. Combining ability is a complex trait that is controlled by polygenes. With the advent and development of molecular markers, it is feasible to evaluate the genetic bases of combining ability and heterosis of elite rice hybrids through QTL analysis.

Methodology/Principal Findings

In the present study, we first developed a QTL-mapping method for dissecting combining ability and heterosis of agronomic traits. With three testcross populations and a BCRIL population in rice, biometric and QTL analyses were conducted for ten agronomic traits. The significance of general combining ability and special combining ability for most of the traits indicated the importance of both additive and non-additive effects on expression levels. A large number of additive effect QTLs associated with performance per se of BCRIL and general combining ability, and dominant effect QTLs associated with special combining ability and heterosis were identified for the ten traits.

Conclusions/Significance

The combining ability of agronomic traits could be analyzed by the QTL mapping method. The characteristics revealed by the QTLs for combining ability of agronomic traits were similar with those by multitudinous QTLs for agronomic traits with performance per se of BCRIL. Several QTLs (1–6 in this study) were identified for each trait for combining ability. It demonstrated that some of the QTLs were pleiotropic or linked tightly with each other. The identification of QTLs responsible for combining ability and heterosis in the present study provides valuable information for dissecting genetic basis of combining ability.     

Deterministic cellular descendance and its relationship to the branching of plant organ axes

Summary. A double-wall map L-system, designated as S_5-5, was developed to simulate the cellular pattern found at the summit of shoot apices of Psilotum nudum. Commencing from a 3-sided autoreproductive founder cell, fives steps of simulation established a basic set of ten different cell types. Continuing the simulation beyond the fifth step revealed that, in addition to the regular production of new 3-sided cells, a group of autoreproductive 5-sided cells came into being. A close correspondence exists between the cells of the two-dimensional simulation and the two-dimensional cellular patterns found on the epidermis of the apices of Psilotum species. The 3-sided cells produced during the simulation correspond to the potentially organogenetic 3-sided cells that can be seen upon the apical surfaces. Successive generations of these 3-sided apical cells (which are actually 4-sided tetrahedral cells when viewed in three dimensions) and their immediate descendants are thought to be selected to organise the successive pairs of apices that bring about the repeated bifurcation of the Psilotum shoots. The 5-sided cells contribute to the cellular pavements which separate these pairs of organogenetic centres, each with their 3-sided apical cells. The cellular patterns simulated by the S_5-5 system may also correspond to the cellular patterns found on the surfaces of some other pteridophyte apices, including that of the rhizophores of Selaginella species. Tritiated-thymidine labelling of rhizophore apices revealed a group of nonproliferating cells that was associated with rhizophore bifurcation and which may correspond to a group of pavement cells. Nonproliferating cells, by regulating the siting of new organogenetic centres, may have evolved as an accompaniment to branching events such as the bifurcation of root and organ axes.Correspondence and reprints: School of Biological Sciences, University of Bristol, Woodland Road, Bristol BS8 1UG, United Kingdom.     

不同木本植物功能型当年生小枝功能性状差异

为探讨不同植物功能型之间小枝功能特征的差异,在重庆金佛山和缙云山分别采集20和26个木本植物,选择当年生的小枝测定其叶片和枝条性状。结果表明:1)叶片厚度表现为:落叶植物<常绿植物,乔木<灌木;单叶面积和叶片总面积表现为:落叶植物>常绿植物,乔木>灌木;不同植物功能型间小枝的叶片数量均无显著差异。2)落叶植物和乔木的小枝横截面积、小枝长度和小枝干重均显著高于常绿植物和灌木,不同植物功能型间小枝密度无显著差异。3)与常绿植物和灌木相比,落叶植物和乔木有较高的展叶效率(单位长度小枝支撑的叶片面积),小枝的出叶强度(单位长度小枝支撑的叶片数)无显著差异。4)在小枝水平上,常绿植物比落叶植物投入更多的生物量到叶片。     

Responses to competition effects of two anuran tadpoles according to life-history traits

Experimental manipulations of the densities of two larval anurans, Pelodytes punctatus and Bufo bufo , showed that these species compete asymmetrically in semi-natural conditions. Growth, mass at metamorphosis, date of metamorphosis, and survival were used as measures of response to interspecific competition. A mechanistic approach was used to collect information on the behaviour of the two species in different conditions. The competitive superiority of Pelodytes at individual level was correlated with a larger body, faster growth rate, increased per capita competitive impact on conspecifics, and greater reduction in the availability of trophic and spatial resources. In the presence of Pelodytes, Bufo showed slower growth, smaller size at metamorphosis and reduced survival. In the interspecific treatments Bufo individuals modified their behaviour by increasing activity and use of the water column while Pelodytes did not change their foraging activity or space use in the aquaria. However, the presence of Bufo resulted in a reduced larval period and smaller size at metamorphosis. We hypothesise that the presence of Bufo act as a signal of environmental degradation and shorten the larval period of Pelodytes, a typical temporal pond breeder . The smaller Bufo tadpoles are potentially stronger competitors at population level because they use relatively large amounts of energy (greater densities and higher metabolic rates). Consequently, they use larger proportions of the shared resources than their larger competitor. A possible evolutionary response for larger tadpoles is the development of interference mechanisms or "escaping" from ephemeral ponds where mortality by drying represent a high risk.     

Combining ability and heterosis in diallel crosses of maize

Summary The present investigation involved crosses among 20 elite yellow maize populations. These were evaluated in four environments in a randomized block design with four replications in each environment. Variety Cuba was observed to be the best general combiner for grain yield, followed by St Croix and Prolific. No clear association could be discerned between general combining ability (GCA) effects for grain yield and its components, and mean grain yield performance and GCA effects. Heterosis was observed in general and all the crosses involving Cuba yielded better than the midparent. The five hybrids, Kisan × Cuba, Antigua 3D × St Croix, Prolific × St Croix, Vijay × Antigua Gr. I and A 23 × Cuba, yielded more than the standard check. Significant yield superiority of these varietal hybrids over the best commercial composite (Jawahar) suggested the possibility of their commercial exploitation.Part of the thesis submitted by the senior author in the partial fulfilment of the requirements for the Ph.D. degree