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Leaf Trait-Environment Relationships in a Subtropical Broadleaved Forest in South-East China  [PDF]
Wenzel Kr?ber, Martin B?hnke, Erik Welk, Christian Wirth, Helge Bruelheide
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0035742
Abstract: Although trait analyses have become more important in community ecology, trait-environment correlations have rarely been studied along successional gradients. We asked which environmental variables had the strongest impact on intraspecific and interspecific trait variation in the community and which traits were most responsive to the environment. We established a series of plots in a secondary forest in the Chinese subtropics, stratified by successional stages that were defined by the time elapsed since the last logging activities. On a total of 27 plots all woody plants were recorded and a set of individuals of every species was analysed for leaf traits, resulting in a trait matrix of 26 leaf traits for 122 species. A Fourth Corner Analysis revealed that the mean values of many leaf traits were tightly related to the successional gradient. Most shifts in traits followed the leaf economics spectrum with decreasing specific leaf area and leaf nutrient contents with successional time. Beside succession, few additional environmental variables resulted in significant trait relationships, such as soil moisture and soil C and N content as well as topographical variables. Not all traits were related to the leaf economics spectrum, and thus, to the successional gradient, such as stomata size and density. By comparing different permutation models in the Fourth Corner Analysis, we found that the trait-environment link was based more on the association of species with the environment than of the communities with species traits. The strong species-environment association was brought about by a clear gradient in species composition along the succession series, while communities were not well differentiated in mean trait composition. In contrast, intraspecific trait variation did not show close environmental relationships. The study confirmed the role of environmental trait filtering in subtropical forests, with traits associated with the leaf economics spectrum being the most responsive ones.
Mapping Quantitative Trait Loci Associated with Leaf Senescence During Maturation of Rice (Oryza sativa L.)  [PDF]
Dongzhi Lin,Junzhi Zhang,Hailong Zuo,Jianlong Xu
Asian Journal of Plant Sciences , 2010,
Abstract: In this study, the Recombinant Inbred (RI) population derived from Asominori (japonica)/ IR24 (indica) were employed to identify Quantitative Trait Loci (QTLs) for six leaf-senescence associated traits during maturation in rice, viz., the flag Leaf Chlorophyll-Content (LCC) at heading (FCH) and maturity (FCM), the second-leaf LCC at heading (SCH) and maturity (SCM), the reduction-speed of flag-leaf LCC (RFC) and the second-leaf LCC (RSC). Resultantly, all continuous variations and transgressive segregations in the RI population were observed, indicating that the six traits were quantitatively inherited. A total of eighteen QTLs for the six traits were mapped to chromosome 2 (four QTLs), 3 (four QTLs), 4 (two QTLs), 6 (two QTLs), 8 (two QTLs), 9 (two QTLs), 11, 12, which could explained 11.0 to 27.8% of the phenotypic variation. Interestingly, most LCC QTLs varied with leaf order and growth stage in rice. Among them, four QTLs for RFC and three ones for RSC, conferring the speed of flag- and the second leaf senescence, respectively, did not share the common genomic region each other and the all former alleles from japonica Asominori delayed leaf senescence and two of the latter alleles also from indica IR24, whereas the remaining one from Asominori, showing that genetic basis of leaf senescence was different between flag- and the second leaf during maturation of rice. The results and the tightly linked molecular markers that flank the QTLs detected in this study may be beneficial for selection of rice varieties with late leaf senescence.
Quantitative trait loci associated with resistance to gray leaf spot and grain yield in corn
Veiga, Adriano Delly;Pinho, Renzo Garcia Von;Resende, Luciane Vilela;Pinho, édila Vilela de Resende Von;Balestre, Márcio;Pereira, Laís Andrade;
Ciência e Agrotecnologia , 2012, DOI: 10.1590/S1413-70542012000100004
Abstract: the main objectives of hybrid development programs include incorporating genetic resistance to diseases and increasing grain yield. identification of quantitative trait loci (qtl) through the statistical analysis of molecular markers allows efficient selection of resistant and productive hybrids. the objective of this research was to identify qtl associated with resistance to gray leaf spot and for grain yield in the germplasm of tropical corn. we used two strains with different degrees of reaction to the disease; the genotypes are owned by geneseeds ltda, their f1 hybrid and the f2 population. the plants were evaluated for gray leaf spot resistance, for grain yield and were genotyped with 94 microsatellite markers. association of the markers with the qtl was performed by single marker analysis using linear regression and maximum likelihood analysis. it was observed that the additive effect was predominant for genetic control of resistance to gray leaf spot, and the dominant effect in that of grain yield. the most promising markers to be used in studies of assisted selection are: umc2082 in bins 4.03 and umc1117 in bins 4.04 for resistance to gray leaf spot; for grain yield umc1042 in bins 2.07 and umc1058 in bins 4.11.
Complex bioclimatic and soil gradients shape leaf trait variation in Embothrium coccineum (Proteaceae) among austral forests in Patagonia
Revista chilena de historia natural , 2009, DOI: 10.4067/S0716-078X2009000200004
Abstract: patterns of trait variation may be adaptive when vary in relation to an environmental gradient. in particular, leaf traits can affect productivity and competitive ability. we identify patterns of leaf size and shape variation with environmental heterogeneity in one of the most widespread tree species within temperate south america: embothrium coccineum (proteaceae). we collected leaf specimens and composite soil samples from 35 populations between 38° and 55° s latitude in patagonia, covering a wide range of mean annual precipitation (map) and mean annual temperature (mat). at each location, we measured nine morphological traits, some of which were cross correlated hence we focus on a smaller number of representative traits. we hypothesized that leaf area (la), dry mass (dm), and specific leaf area (sla) would increase, and that leaf shape (sf) would be more elongated, with increasing temperature, precipitation, and soil nutrient availability. we also expected growing season climate to be more closely associated with leaf traits than mean annual metrics. we used bivariate and backward stepwise multiple regressions to analyse the dependence of morphological traits with climatic and edaphic metrics. la and dm increased with increasing summer rainfall or winter temperature, as hypothesized. opposite to our hypothesis, la and dm decreased with increasing summer temperature suggesting that in terms of leaf size, e. coccineum may sense summer conditions largely as an increasing aridity stressful gradient. surprisingly, sla increased with increasingly warm or dry summers. sf was related positively to mat and negatively to map, suggesting that under more benign western climate regimes e. coccineum leaves tend to be elongated. across sites, la and dm increased with soil organic carbon and available phosphorus, and decreased with soil nitrogen and exchangeable cations. the opposite pattern was observed for sla. biologically meaningful climate metrics and soil nutrient conditi
Quantitative trait loci for leaf chlorophyll content at two developmental stages of rice (Oryza sativa L.)
Yanjun Dong,Zhongnan Yang,Jianlong Xu,Dongzhi Lin
Communications in Biometry and Crop Science , 2007,
Abstract: Knowledge of the genetics of leaf chlorophyll content (LCC) at tillering and heading stages should help develop rice varieties with high photosynthetic ability. In this study, 182 backcross-recombinant inbred lines (BIL), derived from Koshihikari (japonica)/Kasalath (indica)//Koshihikari, were used to identify quantitative trait loci (QTL) for LCC at the tillering and heading stages of rice. Continuous variation and transgressive segregation for LCC were observed in the BIL population, indicating that LCC was a quantitatively inherited trait. Seven QTL for LCC were identified and mapped to chromosomes 1 (two QTL), 2, 3, 4, 6, and 8, which individually accounted for 5.1 to 14.8% of the total phenotypic variation. Three QTL (qLCC-1-1, qLCC-1-2 and qLCC-4) were common between the tillering and heading stages. The alleles at four QTL (qLCC-1-1, qLCC-1-2, qLCC-2, and qLCC-8) from Koshihikari and the alleles at the other three QTL (qLCC-3, qLCC-4 and qLCC-6) from Kasalath increased LCC. The tightly linked molecular markers flanking the QTL detected in this study should be useful in improving photosynthetic ability in rice.
Plastic Traits of an Exotic Grass Contribute to Its Abundance but Are Not Always Favourable  [PDF]
Jennifer Firn, Suzanne M. Prober, Yvonne M. Buckley
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0035870
Abstract: In herbaceous ecosystems worldwide, biodiversity has been negatively impacted by changed grazing regimes and nutrient enrichment. Altered disturbance regimes are thought to favour invasive species that have a high phenotypic plasticity, although most studies measure plasticity under controlled conditions in the greenhouse and then assume plasticity is an advantage in the field. Here, we compare trait plasticity between three co-occurring, C4 perennial grass species, an invader Eragrostis curvula, and natives Eragrostis sororia and Aristida personata to grazing and fertilizer in a three-year field trial. We measured abundances and several leaf traits known to correlate with strategies used by plants to fix carbon and acquire resources, i.e. specific leaf area (SLA), leaf dry matter content (LDMC), leaf nutrient concentrations (N, C:N, P), assimilation rates (Amax) and photosynthetic nitrogen use efficiency (PNUE). In the control treatment (grazed only), trait values for SLA, leaf C:N ratios, Amax and PNUE differed significantly between the three grass species. When trait values were compared across treatments, E. curvula showed higher trait plasticity than the native grasses, and this correlated with an increase in abundance across all but the grazed/fertilized treatment. The native grasses showed little trait plasticity in response to the treatments. Aristida personata decreased significantly in the treatments where E. curvula increased, and E. sororia abundance increased possibly due to increased rainfall and not in response to treatments or invader abundance. Overall, we found that plasticity did not favour an increase in abundance of E. curvula under the grazed/fertilized treatment likely because leaf nutrient contents increased and subsequently its' palatability to consumers. E. curvula also displayed a higher resource use efficiency than the native grasses. These findings suggest resource conditions and disturbance regimes can be manipulated to disadvantage the success of even plastic exotic species.
Quantitative trait loci (QTLs) for resistance to gray leaf spot and common rust diseases of maize
J Danson, M Lagat, M Kimani, A Kuria
African Journal of Biotechnology , 2008,
Abstract: Gray leaf spot and common rust diseases can greatly reduce grain yield of maize in susceptible genotypes by between 10 and 70% on average. Control of these diseases through conventional measures has been quite ineffective and difficult to sustain. The most feasible way to control them is by breeding and deploying resistant maize genotypes. This study was carried out to evaluate germplasm for QTLs associated with resistance to GLS and common rust diseases by use of microsatellite markers and artificial inoculation with the two pathogens. A total of 41 genotypes comprising 23 recombinant inbred lines, 14 parental inbred lines and 4 hybrid checks were screened using 28 SSR markers and disease pressure by artificial inoculation (Tables 1 and 2). Out of the 14 parental inbred lines, only 4 were found to carry the QTL associating positively for the two diseases, and 10 out of the 23 recombinant inbred lines with possible lineage from any of the 14 parents, were positively associated with the traits and seven of the markers used (Table 3). GLS QTLs were significant for two markers; bnlg1258 with a LOD score of 16.0 and umc2019 with a LOD score of 17.9 from regions 2.06 and 2.08 of chromosome 2, respectively. Significant QTLs for common rust resistance were identified in three regions of chromosome 10, corresponding to markers phi054 with a LOD score of 14.0 at bin 10.00, umc1319 with a LOD score of 4.0 at bin 10.02 and bnlg1451 with a LOD score of 14.3 at bin 10.03. The effects of these QTLs were different from genotype to genotype. The disease severity scores (scale of 1-5) of artificial inoculation ranged from 1.5 to 2.5 for gray leaf spot with a mean of 1.88 and a range of 1.5 to 3.0 with a mean of 1.74 for common rust. All the inbred lines scored better for the two diseases than the four hybrid checks which scored 3.5. The most resistant genotypes showed a score of 1.5 for gray leaf spot and common rust. All parents showed a score of less than 2.5 for GLS and common rust. Parental genotypes MAL40, MAL9, MAL13, MAL41, MAL11, MAL19, MAL23-2, MAL24, and MAL19-1, carried QTLs associated with resistance to grey leaf spot and common rust and thus were identified as sources of resistance conferred to the inbred lines. The selected lines are being used to make single hybrids, double crosses, three way hybrids and synthetics resistant to diseases. The marker data was also used to analyze the diversity of the genotypes studied, with relevance to immune/resistant, tolerant or susceptible to the two diseases. Using the GLS genotypic data, 13 genotypes clustered into 11 groups, and using the common rust data, the 13 genotypes clustered into 12 clusters. This indicates that almost each of these genotypes was grouped in a cluster that contained lines that did not have positive association of marker and trait data. These results indicated that the putative QTLs for GLS are associated with the 13 genotypes and two markers in chromosome 2 (bnlg1258 and umc2019), wher
Vyacheslav Trachevskyi,Katerina Molozovenko,Marina Zinchenko
Proceedings of National Aviation University , 2012,
Abstract: Показано вплив антип рен в на горюч сть пол мерних матер ал в. Розглянуто вплив фосфоровм сних сполук на горюч сть та ф зико-механ чн властивост епоксидних пол мер в. Приведено методи зменшення х горючост без зм ни ф зико-механ чних характеристик. Presents the influence of flame retardant on the flammability of polymeric materials. The influence of phosphorus compounds on flammability and physical and mechanical properties of epoxy polymers. Experimentally shows the possible methods of reducing their combustibility without changing the physical and mechanical characteristics. Показано влияние антипиренов на горючесть полимерных материалов. Рассмотрено влияние фосфорсодержащих соединений на горючесть и физико-механические свойства эпоксидных полимеров. Приведены методы уменьшения их горючести без изменения физико-механических характеристик.
Two alternative recessive quantitative trait loci influence resistance to spring black stem and leaf spot in Medicago truncatula
Lars G Kamphuis, Judith Lichtenzveig, Richard P Oliver, Simon R Ellwood
BMC Plant Biology , 2008, DOI: 10.1186/1471-2229-8-30
Abstract: Macroscopically, the resistant response of accession SA27063 was characterised by small, hypersensitive-like spots following inoculation while the susceptible interaction with accessions A17 and SA3054 showed necrotic lesions and spreading chlorosis. No unique cytological differences were observed during early infection (<48 h) between the resistant and susceptible genotypes, except pathogen growth was restricted to one or a few host cells in SA27063. In both interactions reactive oxygen intermediates and phenolic compounds were produced, and cell death occurred. Two F2 populations segregating for resistance to spring black stem and leaf spot were established between SA27063 and the two susceptible accessions, A17 and SA3054. The cross between SA27063 and A17 represented a wider cross than between SA27063 and SA3054, as evidenced by higher genetic polymorphism, reduced fertility and aberrant phenotypes of F2 progeny. In the SA27063 × A17 F2 population a highly significant quantitative trait locus (QTL, LOD = 7.37; P < 0.00001) named resistance to the necrotroph Phoma medicaginis one (rnpm1) genetically mapped to the top arm of linkage group 4 (LG4). rnpm1 explained 33.6% of the phenotypic variance in the population's response to infection depicted on a 1–5 scale and was tightly linked to marker AW256637. A second highly significant QTL (LOD = 6.77; P < 0.00001), rnpm2, was located on the lower arm of LG8 in the SA27063 × SA3054 map. rnpm2 explained 29.6% of the phenotypic variance and was fine mapped to a 0.8 cM interval between markers h2_16a6a and h2_21h11d. rnpm1 is tightly linked to a cluster of Toll/Interleukin1 receptor-nucleotide binding site-leucine-rich repeat (TIR-NBS-LRR) genes and disease resistance protein-like genes, while no resistance gene analogues (RGAs) are apparent in the genomic sequence of the reference accession A17 at the rnpm2 locus.The induction of defence responses and cell death in the susceptible interaction following infection by P. med
The Performance of Random Forests in an Operational Setting?for Large Area Sclerophyll Forest Classification  [PDF]
Andrew Mellor,Andrew Haywood,Christine Stone,Simon Jones
Remote Sensing , 2013, DOI: 10.3390/rs5062838
Abstract: Mapping and monitoring forest extent is a common requirement of regional forest inventories and public land natural resource management, including in Australia. The state of Victoria, Australia, has approximately 7.2 million hectares of mostly forested public land, comprising ecosystems that present a diverse range of forest structures, composition and condition. In this paper, we evaluate the performance of the Random Forest (RF) classifier, an ensemble learning algorithm that has recently shown promise using multi-spectral satellite sensor imagery for large area feature classification. The RF algorithm was applied using selected Landsat Thematic Mapper (TM) imagery metrics and auxiliary terrain and climatic variables, while the reference data was manually extracted from systematically distributed plots of sample aerial photography and used for training (75%) and accuracy (25%) assessment. The RF algorithm yielded an overall accuracy of 96% and a Kappa statistic of?0.91 (confidence interval (CI) 0.909–0.919) for the forest/non-forest classification model, given a Kappa maximised binary threshold value of 0.5. The area under the receiver operating characteristic plot produced a score of 0.91, also indicating high model performance. The framework described in this study contributes to the operational deployment of a robust, but affordable, program, able to collate and process large volumes of multi-sourced data using open-source software for the production of consistent and accurate forest cover maps across the full spectrum of Victorian sclerophyll forest types.
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