Adult Leaf Research Articles

Mass production of Diglyphus isaea (Hymenoptera: Eulophidae), a biological control agent of a Korean population of potato leaf miner Liriomyza huidobrensis (Blanchard) (Diptera: Agromyzidae)

AbstractThe potato leaf miner, Liriomyza huidobrensis (Blanchard), is an important pest of potato throughout the world, including Korea. A method was developed for mass rearing the parasitoid Diglyphus isaea (Walker) using faba bean, Vicia faba L. (Fabaceae), as the host‐plant and L. huidobrensis as the insect host. Faba bean plants were planted in pots and maintained in a greenhouse for about 15 d. Pots were then exposed to adult leaf miners in oviposition cages for 4 h. Plants containing late second to early third instar larvae were exposed to adult D. isaea in parasitoid cages for 24 h. The leaf area per pot after 15 d was 597.9 cm2, which produced 103.33 larvae per pot. The number of adult parasitoids emerging per pot was 72.5; about 41% of these were female. The daily cost of parasitoid production was USD20.95 per 1000 individual parasitoids. The methodology developed for D. isaea could be used to rear other ectoparasitoids such as Hemiptarsenus spp. and Pnigalio sp. with different insect hosts like L. trifolii. This is why this mass‐rearing information is important for securing test insect materials for ecological and biological study of Liriomyza species, and also for developing a biological control for Liriomyza species other than L. huidobrensis by mass production of associated natural enemies. We are facing rapid agro‐ecosystem changes including pest systems. Continuous monitoring of Liriomyza in solanaceous crops is needed.

Predicting spillover risk to non-target plants pre-release: Bikasha collaris a potential biological control agent of Chinese tallowtree (Triadica sebifera)

Quarantine host range tests accurately predict direct risk of biological control agents to non-target species. However, a well-known direct effect of biological control of weeds releases is spillover damage to non-target species. Spillover damage may occur when the population of agents achieves outbreak densities, depletes the target weed, and some feeding occurs on non-target species. Similar to the assessment of direct risks to non-target species, we assessed the risk of spillover damage to non-target species pre-release. Quarantine experiments were conducted on the flea beetle Bikasha collaris (Coleoptera: Chrysomelidae), a potential biological control agent of Chinese tallowtree, Triadica sebifera, a weed of wetlands, forests, and natural areas in the southeastern U.S.A. Recently emerged, naïve B. collaris adults were fed leaves of T. sebifera (target species), three close relatives that are non-target species (Ditrysinia fruticosa, Gymnanthes lucida, Hippomane mancinella), or water. Adult longevity, egg production, and leaf damage were greatest on the weed and near zero or zero on the non-target species and water control. A spillover event was simulated by transferring adults to non-target species or water after feeding on T. sebifera for 2 or 4weeks and found similar longevity and egg production as those fed only non-target species or water. These results indicated pre-release that when adults that have fed on T. sebifera are forced to spillover onto the non-target species, there is no risk of damage and that B. collaris will only be able to sustain populations on the target weed.

Convergent repression of miR156 by sugar and the CDK8 module of Arabidopsis Mediator

In Arabidopsis, leaves produced during the juvenile vegetative phase are simple, while adult leaves are morphologically complex. The juvenile to adult transition is regulated by miR156, a microRNA that promotes juvenility by impeding the function of SPL transcription factors, which specify adult leaf traits. Both leaf derived sugars, as well as the Mediator Cyclin Dependent Kinase 8 (CDK8) module genes CENTER CITY (CCT)/MED12 and GRAND CENTRAL (GCT)/MED13, act upstream of miR156 to promote the juvenile to adult transition. However, it is not known whether sugar, CCT and GCT repress miR156 independently, as part of the same pathway, or in a cooperative manner. Here we show that sugar treatment can repress MIR156 expression in the absence of CCT or GCT. Both cct and the photosynthetic mutant chlorina1 (ch1) (which decreases sugar synthesis) exhibit extended juvenile development and increased MIR156A and MIR156C expression. Compared to ch1 and cct single mutants, the ch1 cct double mutant has a stronger effect on juvenile leaf traits, higher MIR156C levels, and a dramatic increase in MIR156A. Our results show that sugar and the CDK8 module are capable of regulating MIR156 independently, but suggest they normally act together in a synergistic manner.

Influence of no‐tillage practices and later planting date on the pea leaf weevil, Sitona lineatus, in pea, Pisum sativum

AbstractThe pea leaf weevil, Sitona lineatus (L.) (Coleoptera: Curculionidae), is a periodic pest of pea, Pisum sativum L. (Fabaceae), in the Palouse region of northern Idaho and eastern Washington, USA. Previous work on‐station and in commercial pea fields showed initial adult weevil colonization was greater in conventional‐tillage than in no‐tillage fields. Increased surface residue of no‐tillage systems results in cooler soils with greater available moisture typically resulting in later planting dates for conventional‐tillage fields. Cereal residue, a characteristic of the region's no‐tillage systems, and planting date were investigated as potential inhibitors of adult pea leaf weevil colonization and feeding on peas via field experiments in 2005 and 2006. Plots without cereal residue and early‐planted plots had greater weevil abundance. Early‐planted peas had greater weevil feeding injury compared to late‐planted peas. The presence of cereal residue did not significantly impact injury levels. A laboratory choice‐test with peas grown in conventional‐tillage and no‐tillage fields indicated greater adult weevil feeding damage on conventional‐tillage‐grown peas. A separate laboratory choice‐test using peas planted 10 days apart demonstrated greater adult weevil feeding injury on early‐planted peas. However, adjusting for available leaf edge resulted in no differences between treatments in either choice test, indicating crop availability and plant apparency during peak weevil colonization rather than plant factors resulting from growing conditions likely explain greater injury on peas planted early and under conventional‐tillage in the field.

Overexpression of a Hevea brasiliensis ErbB-3 Binding protein 1 Gene Increases Drought Tolerance and Organ Size in Arabidopsis.

Rubber trees are economically important tropical tree species and the major source of natural rubber, which is an essential industrial material. This tropical perennial tree is susceptible to cold stress and other abiotic stresses, especially in the marginal northern tropics. Recent years, the genome sequencing and RNA-seq projects produced huge amount of sequence data, which greatly facilitated the functional genomics study. However, the characterization of individual functional gene is in urgent demands, especially for those involved in stress resistance. Here we identified and characterized the rubber tree gene ErbB-3 binding protein 1, which undergoes changes in expression in response to cold, drought stress and ABA treatment. HbEBP1 overexpression (OE) in Arabidopsis increased organ size, facilitated root growth and increased adult leaf number by delaying the vegetative-to-reproductive transition. In addition, HbEBP1 OE enhanced the resistance of the Arabidopsis plants to freezing and drought stress, demonstrating that this gene participates in the regulation of abiotic stress resistance. RD29a, RD22 and CYCD3;1 expression was also greatly enhanced by HbEBP1 OE, which explains its regulatory roles in organ size and stress resistance. The regulation of drought stress resistance is a novel function identified in plant EBP1 genes, which expands our understanding of the roles of EBP1 gene in response to the environment. Our results provide information that may lead to the use of HbEBP1 in genetically engineered crops to increase both biomass and abiotic stress resistance.

Tree diversity promotes generalist herbivore community patterns in a young subtropical forest experiment.

Stand diversification is considered a promising management approach to increasing the multifunctionality and ecological stability of forests. However, how tree diversity affects higher trophic levels and their role in regulating forest functioning is not well explored particularly for (sub)tropical regions. We analyzed the effects of tree species richness, community composition, and functional diversity on the abundance, species richness, and beta diversity of important functional groups of herbivores and predators in a large-scale forest biodiversity experiment in south-east China. Tree species richness promoted the abundance, but not the species richness, of the dominant, generalist herbivores (especially, adult leaf chewers), probably through diet mixing effects. In contrast, tree richness did not affect the abundance of more specialized herbivores (larval leaf chewers, sap suckers) or predators (web and hunting spiders), and only increased the species richness of larval chewers. Leaf chemical diversity was unrelated to the arthropod data, and leaf morphological diversity only positively affected oligophagous herbivore and hunting spider abundance. However, richness and abundance of all arthropods showed relationships with community-weighted leaf trait means (CWM). The effects of trait diversity and CWMs probably reflect specific nutritional or habitat requirements. This is supported by the strong effects of tree species composition and CWMs on herbivore and spider beta diversity. Although specialized herbivores are generally assumed to determine herbivore effects in species-rich forests, our study suggests that generalist herbivores can be crucial for trophic interactions. Our results indicate that promoting pest control through stand diversification might require a stronger focus on identifying the best-performing tree species mixtures.

First Draft Assembly and Annotation of the Genome of a California Endemic Oak Quercus lobata Née (Fagaceae).

Oak represents a valuable natural resource across Northern Hemisphere ecosystems, attracting a large research community studying its genetics, ecology, conservation, and management. Here we introduce a draft genome assembly of valley oak (Quercus lobata) using Illumina sequencing of adult leaf tissue of a tree found in an accessible, well-studied, natural southern California population. Our assembly includes a nuclear genome and a complete chloroplast genome, along with annotation of encoded genes. The assembly contains 94,394 scaffolds, totaling 1.17 Gb with 18,512 scaffolds of length 2 kb or longer, with a total length of 1.15 Gb, and a N50 scaffold size of 278,077 kb. The k-mer histograms indicate an diploid genome size of ∼720–730 Mb, which is smaller than the total length due to high heterozygosity, estimated at 1.25%. A comparison with a recently published European oak (Q. robur) nuclear sequence indicates 93% similarity. The Q. lobata chloroplast genome has 99% identity with another North American oak, Q. rubra. Preliminary annotation yielded an estimate of 61,773 predicted protein-coding genes, of which 71% had similarity to known protein domains. We searched 956 Benchmarking Universal Single-Copy Orthologs, and found 863 complete orthologs, of which 450 were present in > 1 copy. We also examined an earlier version (v0.5) where duplicate haplotypes were removed to discover variants. These additional sources indicate that the predicted gene count in Version 1.0 is overestimated by 37–52%. Nonetheless, this first draft valley oak genome assembly represents a high-quality, well-annotated genome that provides a tool for forest restoration and management practices.

Changes in tarsal morphology and attachment ability to rough surfaces during ontogenesis in the beetle Gastrophysa viridula (Coleoptera, Chrysomelidae)

Insects live in a three-dimensional space, and need to be able to attach to different types of surfaces in a variety of environmental and behavioral contexts. Adult leaf beetles possess great attachment ability due to their hairy attachment pads. In contrast, their larvae depend on smooth pads to attach to the same host plant. We tested friction forces generated by larvae and adults of dock leaf beetles Gastrophysa viridula on different rough surfaces, and found that adults generate much higher attachment to various substrates than larvae, but are more susceptible to completely losing attachment ability on surfaces with “critical” roughness. Furthermore, sex-specific setal morphology has the effect that attachment forces of male adults are generally higher than those of females when adjusted for body weight. The results are discussed in the context of development, ecology, and changing behavioral strategies of successive life stages.

Effect of Contact Insecticides Against the Invasive Goldspotted Oak Borer (Coleoptera: Buprestidae) in California.

The goldspotted oak borer, Agrilus auroguttatus Schaeffer (Coleoptera: Buprestidae), was linked in 2008 to ongoing tree mortality in oak woodlands of southern California. Mortality of coast live oak, Quercus agrifolia Née, and California black oak, Q. kelloggii Newb., continues as this exotic phloem borer spreads in southern California. Management options are needed to preserve high-value oaks and maintain management objectives. From 2009 to 2012, we tested four contact insecticide formulations in four experiments against A auroguttatus in California. The impact of contact insecticides was evaluated ∼<1, 8, and 12 mo postapplication against A auroguttatus adults in no-choice leaf-feeding or walking bioassays. At <1 mo postapplication, bifenthrin, carbaryl, lambda-cyhalothrin, and permethrin all reduced adult survival and feeding in leaf-feeding and walking bioassays. At 8 mo postapplication, only bifenthrin reduced adult feeding, but had no effect on survivorship. At 12 mo postapplication, adult A auroguttatus survived fewer days and fed less in leaf-feeding bioassays with bifenthrin, carbaryl, and permerthin. These results support the annual application of contact insecticides prior to A auroguttatus' flight period to reduce adult leaf maturation feeding and activity on the bark surface (e.g., oviposition), but additional studies are needed to show these contact treatments can prevent tree mortality from this invasive species.

Characterization of Lr75: a partial, broad-spectrum leaf rust resistance gene in wheat.

Here, we describe a strategy to improve broad-spectrum leaf rust resistance by marker-assisted combination of two partial resistance genes. One of them represents a novel partial adult plant resistance gene, named Lr75. Leaf rust caused by the fungal pathogen Puccinia triticina is a damaging disease of wheat (Triticum aestivum L.). The combination of several, additively-acting partial disease resistance genes has been proposed as a suitable strategy to breed wheat cultivars with high levels of durable field resistance. The Swiss winter wheat cultivar 'Forno' continues to show near-immunity to leaf rust since its release in the 1980s. This resistance is conferred by the presence of at least six quantitative trait loci (QTL), one of which is associated with the morphological trait leaf tip necrosis. Here, we used a marker-informed strategy to introgress two 'Forno' QTLs into the leaf rust-susceptible Swiss winter wheat cultivar 'Arina'. The resulting backcross line 'ArinaLrFor' showed markedly increased leaf rust resistance in multiple locations over several years. One of the introgressed QTLs, QLr.sfr-1BS, is located on chromosome 1BS. We developed chromosome 1B-specific microsatellite markers by exploiting the Illumina survey sequences of wheat cv. 'Chinese Spring' and mapped QLr.sfr-1BS to a 4.3cM interval flanked by the SSR markers gwm604 and swm271. QLr.sfr-1BS does not share a genetic location with any of the described leaf rust resistance genes present on chromosome 1B. Therefore, QLr.sfr-1BS is novel and was designated as Lr75. We conclude that marker-assisted combination of partial resistance genes is a feasible strategy to increase broad-spectrum leaf rust resistance. The identification of Lr75 adds a novel and highly useful gene to the small set of known partial, adult plant leaf rust resistance genes.

Strategies to Combat Mycosphaerella Leaf Disease in Eucalyptus globulus Plantations in Northern Spain

Eucalyptus globulus is widely planted in temperate regions to produce pulp for its high performance but few studies of the impact of Mycosphaerella Leaf Disease (MLD) have been documented. This study aimed to explore and provide knowledge on disease in the management of young Eucalyptus globulus stands in the north of Spain. The influences of subspecies, cloning, and fertilization on the degree of severity of the disease were analyzed. The study was conducted with different material plants of Eucalyptus globulus, of Australian origin, from other sources, open-pollinated families, clones, and families of controlled pollination. Each series tested different vegetal material, except for a number of control codes that were used as reference samples for MLD evaluation. Severity, height at which foliage changes from juvenile to adult, total height, and volume were all measured. There were significant correlations in the average MLD severity of families and provenances obtained from the different trials. ANOVA revealed important differences between subspecies of E. globulus. A correlation was found between the percentage of adult leaf and the severity. There were differences in the impact of MLD between plant material non-selected and selected by its tolerance (p &lt; 0.0001). There was a significant effect on the severity between mature cuttings and families from seed non-selected in their tolerance to MLD. Their tolerance was lower than that achieved from seed selected by its tolerance to MLD. Genetic selection was shown as the best strategy since there are individuals exceptionally tolerant to MLD.

Expression Profiles of Pathogenesis-Related Gene, TaLr35PR1, as it Relate to Lr35-Mediated Adult Plant Leaf Rust Resistance

Plants have developed sophisticated mechanisms to combat pathogen infection. One of the acquired modes in response to pathogen attack is the production of the pathogenesis-related (PR) proteins. Our earlier studies reported that TaLr35PR1, a PR1 gene encoding a protein with conserved serine carboxypeptidase (SCP) domain, has been cloned from wheat near-isogenic line TcLr35. However, the involvement of TaLr35PR1 in wheat growth and Lr35-mediated adult resistance to Puccinia triticina remains unclear. Here, we showed that TaLr35PR1 was strongly induced by P. triticina in wheat plant containing Lr35 (TcLr35), in which the expression level of TaLr35PR1 significantly increased and reached the maximum at 12 hpi. The accumulations of TaLr35PR1 increased stably and showed significant peak challenged by P. triticina at different growth and development periods of TcLr35 wheat while it maintained similar level and changed little in mock inoculated. Western blotting was conducted to confirm that TaLr35PR1 protein was increasingly accumulated in the TcLr35 adult plants after P. triticina inoculation and maintained at a similar level from 120 to 168 h post-inoculation. Similar to the expression patterns of TaLr35PR1 at RNA levels, the accumulations of TaLr35PR1 protein were weak in the seedling stage and then increased to the peak and kept constant levels at the mature stage which is consistent with the expression feature of Lr35 gene as an adult plant resistance gene. All these findings suggest that TaLr35PR1 is involved in wheat growth and Lr35-mediated adult wheat defense response to leaf rust pathogen attack.

Genetic analysis of an ephemeral intraspecific hybrid zone in the hypervariable tree, Metrosideros polymorpha, on Hawai'i Island.

Intraspecific hybrid zones involving long-lived woody species are rare and can provide insights into the genetic basis of early-diverging traits in speciation. Within the landscape-dominant Hawaiian tree, Metrosideros polymorpha, are morphologically distinct successional varieties, incana and glaberrima, that dominate new and old lava flows, respectively, below 1200 me on volcanically active Hawai'i Island, with var. glaberrima also extending to higher elevations and bogs. Here, we use morphological measurements on 86 adult trees to document the presence of an incana-glaberrima hybrid zone on the 1855 Mauna Loa lava flow on east Hawai'i Island and parent-offspring analysis of 1311 greenhouse seedlings from 71 crosses involving 72 adults to estimate heritabilities and genetic correlations among vegetative traits. Both the variation in adult leaf pubescence at the site and the consistency between adult and offspring phenotypes suggest the presence of two hybrid classes, F1s and var. incana backcrosses, as would be expected on a relatively young lava flow. Nine nuclear microsatellite loci failed to distinguish parental and hybrid genotypes. All four leaf traits examined showed an additive genetic basis with moderate to strong heritabilities, and genetic correlations were stronger for the more range-restricted var. incana. The differences between varieties in trait values, heritabilities and genetic correlations, coupled with high genetic variation within but low genetic variation between varieties, are consistent with a multi-million-year history of alternating periods of disruptive selection in contrasting environments and admixture in ephemeral hybrid zones. Finally, the contrasting genetic architectures suggest different evolutionary trajectories of leaf traits in these forms.

Molecular markers for adult plant leaf rust resistance gene Lr48 in wheat

Leaf rust of wheat, caused by Puccinia triticina, is an important disease throughout the world. The adult plant leaf rust resistance gene Lr48 reported in CSP44 was previously mapped in chromosome 2B, but the marker–gene association was weak. In this study, we confirmed the location of Lr48 to be in the short arm of chromosome 2B and identified closely linked markers suitable for use in breeding. The CSP44/WL711 recombinant inbred line (RIL) population (90 lines) showed monogenic segregation for Lr48. Twelve resistant and 12 susceptible RILs were used for selective genotyping using an iSelect 90K Infinium SNP assay. Closely linked SNPs were converted into Kompetitive allele-specific primers (KASP) and tested on the parental lines. KASP markers giving clear clusters for alternate genotypes were assayed on the entire RIL population. SNP markers IWB31002, IWB39832, IWB34324, IWB72894 and IWB36920 co-segregated with Lr48 and the marker IWB70147 was mapped 0.3 cM proximal to this gene. Closely linked KASP markers were tested on a set of Australian and Nordic wheat genotypes. The amplification of SNP alleles alternate to those linked with Lr48 in the majority of the Australian and Nordic wheat genotypes demonstrated the usefulness of these markers for marker-assisted pyramiding of Lr48 with other rust resistance genes.

Plant Regeneration from Leaf-derived Callus Cultures of Primrose (Primula vulgaris)

Efficient micropropagation of Primula species is important both for fundamental scientific studies and commercial applications. Primula vulgaris (Huds), along with other Primulaceae species, exhibits floral heteromorphy with two distinct forms of hermaphroditic flower. Studies to identify genes that control heteromorphic flower development require propagation of floral mutants, and efficient regeneration is a key requirement for plant transformation. Several species, including P. vulgaris cultivars and P. ×polyantha hybrids, are important horticultural crops in Europe, United States, and Japan and semidouble/double Primula varieties offer a high-end product. Vegetative propagation of sterile double forms, and as a means to increase numbers of inbred parent plants for F1 seed production is, however, slow. Micropropagation offers the most efficient way of increasing these varieties quickly and efficiently. To date, most Primula micropropagation protocols require explant material derived from in vitro grown seedlings or use floral parts as donor material with seasonal limitations. Therefore, an effective and efficient protocol was developed for in vitro regeneration of P. vulgaris via indirect organogenesis from adult leaf–derived explants. Exposure of leaf explants of P. vulgaris to media containing synthetic cytokinin, thidiazuron (TDZ), and auxin [1-naphthylacetic acid (NAA) or 2,4-dichlorophenoxyacetic acid (2,4-D)] resulted in undifferentiated cell proliferation and followed by differentiated growth as shoot organogenesis. Silver nitrate improved in vitro callus growth and increased shoot regeneration further, with up to 72% of explants producing shoots. Regenerated plants developed normally and produced normal fertile flowers within 7 months. The system was also successfully applied for the micropropagation of sterile double-flowered P. vulgaris ‘Sue Jervis’. The protocol reported here enables propagation of P. vulgaris without seasonal limitation or destruction of valuable parent donor material. The protocol, with further development, has the potential to underpin development of a transformation system for Primula, which would be of value in studies on flower development and disease resistance in laboratory grown plants.

Seasonal activity of adult leaf beetles (Coleoptera: Chrysomelidae, Orsodacnidae) occuring in Kovada Lake and Kızıldağ National Parks in Isparta Province (Turkey)

AbstractLeaf beetles were studied in the Kovada Lake National Park (KL) and Kızıldağ National Park (KD) in Isparta province (Turkey) during April–October in 2009 and 2010. A total of 131 leaf beetle species were collected. In total, 88 species were detected from KL and 95 species from KD. Adult activity periods of the collected leaf beetle species were determined and their frequency and dominancy values were provided. The results showed slight differences in terms of the seasonal activity of the species in the two national parks. According to Shannon-Wiener index, the highest leaf beetle diversity among the studied months was found in early June (H’: 4.23) and late May (H’: 4.17). Sørensen similarity index of the species according to different seasonal periods showed three distinct seasonal periods: a) early April, b) late April to early July, c) late July to late October. Almost all leaf beetles showed a seasonal distribution, with the highest dominance during spring and early summer. The main reason for these different seasonal activities is that leaf beetle species are related to the quality and availability of host-plants.

Inheritance of Leaf Rust and Stripe Rust Resistance in the Brazilian Wheat Cultivar 'Toropi'.

Leaf rust (Puccinia triticina) and stripe rust (P. striiformis f. tritici) affect wheat production worldwide. Brazilian 'Toropi' wheat has demonstrated durable leaf rust resistance in South America since its release in 1965. It was previously found to have up to two adult plant leaf rust resistance genes. The leaf and stripe rust resistance of Toropi were studied by analyzing a doubled-haploid population made by crossing with susceptible 'Thatcher'. Toropi expressed good resistance to leaf rust in Canada, Brazil, and New Zealand. Based on field and greenhouse testing, the leaf rust resistance of Toropi is conferred by two race-nonspecific complementary adult plant genes and a race-specific adult plant gene. The stripe rust resistance of Toropi analyzed in New Zealand and in Canada is based on up to two resistance genes. Toropi should provide an important contribution to rust resistance because it expressed good leaf rust and stripe rust resistance in different parts of the world.

Studies on Occurrence Ecological Factors and Management Strategies of Ambrostoma quadriimpressum in Harbin City

This paper investigated effects of four ecological variables on the damage levels of elm leaf beetle (different effects of minimum and maximum values, relations between each two variables were also explored) and discussed current management measures. The results showed that among these factors, interval between elm trees significantly affected damage level by this leaf beetle species, and perimeter of elm trunk could change this effect. On the other side, while middle values for each index were deleted, effects comparison between minimum and maximum parts showed that good root soil as overwintering was related with more damage; more severe damages on elm tree would result in more control measures used; on elm tree with bigger trunk, more damages were observed; and if other elm tree was closer, more damages would occur. Secondly, good root soil was related with more measures used; good root soil was correlated with smaller perimeter; good root soil was associated with bigger interval. Thirdly, more measures were correlated with bigger perimeter; more measures were also correlated with good root soil. Fourthly, bigger perimeter was correlated with worse root soil. Current dominant control measures included chemical pesticide application preventing adult insects from descending or climbing up along trunk before and after overwintering. These results suggested that we should focus on elm leaf beetle management on all the elm trees instead of only on bigger elm trees at proper period simultaneously because occurrence on these elm trees were related intensively although this adult elm leaf beetle species could not fly and had limited movement ability.

Genome Wide Association Study of Seedling and Adult Plant Leaf Rust Resistance in Elite Spring Wheat Breeding Lines.

Leaf rust is an important disease, threatening wheat production annually. Identification of resistance genes or QTLs for effective field resistance could greatly enhance our ability to breed durably resistant varieties. We applied a genome wide association study (GWAS) approach to identify resistance genes or QTLs in 338 spring wheat breeding lines from public and private sectors that were predominately developed in the Americas. A total of 46 QTLs were identified for field and seedling traits and approximately 20–30 confer field resistance in varying degrees. The 10 QTLs accounting for the most variation in field resistance explained 26–30% of the total variation (depending on traits: percent severity, coefficient of infection or response type). Similarly, the 10 QTLs accounting for most of the variation in seedling resistance to different races explained 24–34% of the variation, after correcting for population structure. Two potentially novel QTLs (QLr.umn-1AL, QLr.umn-4AS) were identified. Identification of novel genes or QTLs and validation of previously identified genes or QTLs for seedling and especially adult plant resistance will enhance understanding of leaf rust resistance and assist breeding for resistant wheat varieties. We also developed computer programs to automate field and seedling rust phenotype data conversions. This is the first GWAS study of leaf rust resistance in elite wheat breeding lines genotyped with high density 90K SNP arrays.

Patchy distribution and varied habitats of Macrozamia lucida cycads explained by constancy in a key environmental variable

Identifying the influence of environmental variables on the spatio-temporal distribution of organisms remains a central goal of ecology. Although environmental limits to the geographic range of species have been investigated, less information is available regarding the influence of environmental variables limiting species to discrete patches within their geographic range. Identifying environmental variables of importance to the species in question is further complicated where the patches appear to be distributed across a variety of outwardly dissimilar habitats. We assessed the influence of environmental variables on the patchy distribution of Macrozamia lucida L.A.S. Johnson (Zamiaceae) cycads endemic to south-east Queensland, Australia. Here we show that patches of M. lucida are consistently associated with elevated moisture, despite the patches being located in contrasting habitats and topographic positions. Our survey results across five field sites demonstrate that both cycad abundance and adult cycad condition (estimated from measures of adult cycad leaf production and reproductive output) are positively correlated with elevated moisture, as measured by mean minimum relative humidity at the plant–soil interface. The historical biogeography of the genus Macrozamia may be intimately linked with the contraction and fragmentation of Australia’s mesic biomes during the Miocene. It is plausible that current distribution pattern of M. lucida, restricted to discrete patches that meet the species’ environmental requirements, reflects a contraction and fragmentation within its range from a more regular historical distribution under more favourable climatic regimes.