Progeny Populations Research Articles

Identification and genetic diversity analysis of specific walnut F1 progeny based on SSR molecular markers: taking heart-shaped walnuts and Jinghong 1 as examples.

To gain a deeper understanding of the genetic diversity and authenticity of natural pollinated F1 progeny populations of specific walnuts (heart-shaped walnuts and Jinghong 1), as well as the genetic relationship between F1 offspring and their maternal parent. 32 heart-shaped walnut F1 offspring, 45 Jinghong 1 F1 offspring, and their maternal parent were selected as materials, and14 pairs of SSR markers were used for genetic diversity and parent-child relationship analysis. The results showed that Jr05, Jr11, Jr29, Jr44, Jr45, Jr52, Jr53, Jr55, and Jr56 could be used as SSR markers for the identification of hybrid offspring in heart-shaped walnuts. Jr35, Jr40, Jr45, Jr50, Jr52, and Jr53 could be used as SSR markers for the identification of hybrid offspring of Jinghong 1. XX21 had the closer genetic relationship with heart-shaped walnuts, and HR20 had the closer genetic relationship with Jinghong 1. Besides, the classification results of F1 offspring based on UPGMA clustering and STRUCTURE were different. This study not only laid the foundation for parental identification of specific walnut F1 progeny, but also provided theoretical reference for fixing hybrid advantages, germplasm innovation, and new variety breeding.

Characterization of genetic resistance to cucumber mosaic virus (CMV) in spinach (Spinacia oleracea L.).

Cucumber mosaic virus (CMV) is a significant pathogen causing quality loss in spinach. Although host genetic resistance is the primary method of managing CMV infection in this crop, CMV resistance genes are not widely utilized in spinach breeding programs as the genetic and molecular mechanisms underlying resistance are not yet fully understood. CMV infections were therefore studied in different lines of spinach plants, and their progeny, to develop a model of the genetic basis of CMV resistance. Visual observations and RT-PCR assays revealed that three monoecious lines (03-258, 03-263, and 03-336) were susceptible to CMV, while three traditional resistant cultivars and a near-isogenic line (NIL-M) exhibited resistance. A dioecious line (03-009) consisted of susceptible and resistant plants. Notably, resistant plants did not exhibit the lesions typical of the hypersensitive response. Genetic analysis of progeny from the cross NIL-M × 03-336 indicated that a single dominant allele (designated SRCm1, standing for Spinach Resistance to CMV 1) controlled CMV resistance; analysis of sib-cross progeny populations derived from line 03-009 supported this conclusion. These results offer a valuable model for CMV resistance in spinach and will enhance future breeding programs.

Advancements in Cold-Region Rice Breeding: The 4S Phenotypic-Design Breeding System and Its Applications in Heilongjiang.

Heilongjiang, located in the cold region, is China's largest rice-producing and commercializing province. The variety selection of rice in cold regions (RCR) is indispensable in promoting the rice industry's development, and technological innovation in breeding theory plays a significant role in breeding breakthrough. Based primarily on long-term research, contemplation, and breeding practices, the 4S (selected topic, selected breeding, selected progenies, and selected promotion) phenotypic-design breeding technical system for RCR, which has revolutionized the theoretical basis and deepened the conceptual model, has been developed through systematic analyses and generalization. The system covers several key aspects such as scientific question formulation, breeding objective optimization, parental taxa hybridization, progeny population selection, and innovation dissemination, aiming to improve the foresight, precision, and efficiency of breeding. Furthermore, the system has demonstrated successful cases of rice variety breeding over the past 20 years, such as for Suijing 3, Suijing 4, Suijing 18, and a series of other rice varieties, providing theoretical and technical supports for cold-region rice breeding.

Genetic mapping and molecular marker development for white flesh color in tomato.

Fruit color significantly influences the quality of horticultural crops, which affects phytochemical diversity and consumer preferences. Despite its importance, the genetic basis of the white-colored fruit in tomatoes remains poorly understood. In this study, we demonstrate that white-fleshed tomato varieties accumulate fewer carotenoids than yellow-fleshed varieties. We developed various segregating populations by hybridizing red, yellow, and white fruit tomato cultivars. Genetic analysis revealed that the white fruit color trait is controlled by a single gene that dominates both red and yellow fruits. Bulk segregant RNA sequencing provided a preliminary map of a 3.17 Mb region on chromosome 3 associated with the white color trait. Based on kompetitive allele-specific PCR (KASP) markers, we narrowed the candidate gene region to 819 kb. Within this region, we identified a 4906-bp sequence absence variation near Phytoene Synthase 1 (SlPSY1) specific to white-colored tomatoes. Genotyping of the progeny and natural populations using a single nucleotide polymorphism adjacent to this absence of variation confirmed its key role in white fruit formation. Collectively, our findings provide insights into white fruit trait formation in tomatoes, enabling tomato breeders to precisely introduce white fruit traits for commercial exploitation.

Genetic diversification of allohexaploid Brassica hybrids (AABBCC) using a fertile octoploid with excessive C genome set (AABBCCCC).

Using octoploid somatic hybrids with excessive C genome sets, AABBCCCC, a diverse allohexaploid, AABBCC, was produced by C genome reduction through subsequent crossing with various AABB cultivars. Even when somatic hybrids are produced, the plants that are produced are rarely in themselves an innovative crop. In this study, we used somatic hybrids of Brassica juncea (AABB) and B. oleracea (CC) as model cases for the genetic diversification of the somatic hybrids. One cell of 'Akaoba Takana' (B. juncea) and two cells of 'Snow Crown' (B. oleracea) were fused to create several somatic hybrids with excessive C genomes, AABBCCCC. Using AABBCCCC somatic hybrids as mother plants and crossing with 'Akaoba Takana', the AABBCC progenies were generated. When these AABBCC plants were self-fertilized, and flow cytometric (FCM) analysis was performed on the next generations, differences in the relative amount of genome size variation were observed, depending on the different AABBCCCC parents used for AABBCC creation. Further self-progeny was obtained for AABBCC plants with a theoretical allohexaploid DNA index by FCM. However, as the DNA indices of the progeny populations varied between plants used and aneuploid individuals still occurred in the progeny populations, it was difficult to say that the allohexaploid genome was fully stabilized. Next, to obtain genetic diversification of the allohexaploid, different cultivars of B. juncea were crossed with AABBCCCC, resulting in diverse AABBCC plants. Genetic diversity can be further expanded by crossbreeding plants with different AABBCC genome sets. Although genetic stability is necessary to ensure in the later generations, the results obtained in this study show that the use of somatic hybrids with excess genomes is an effective strategy for creating innovative crops.

Advancements in Research on Cichlid: Reproductive Biology, Social Structure, and Communication

The social behavior of cichlid fish emerged as a captivating subject within the realm of ichthyological research. The sociality of these aquatic organisms often encompasses a wealth of intricate elements. Within this complexity, the reproductive biology of cichlids was observed to mirror the characteristics pivotal for progeny propagation and population development. Their social structures were characterized by stringent hierarchies and occupational specialization among individuals. Communication mechanisms were found to be instrumental in ensuring the timely exchange of information across members of the species. Furthermore, population behaviors served as vital conduits, maintaining the cohesion of the aforementioned elements and securing the seamless operation of this organic system. Given these aspects, this study chose these topics as entry points for inquiry, synthesizing recent scholarly work on cichlid sociality to retrace the trajectory of research in this field. This retrospective analysis was conducted to distill clear future directions based on the examined data. The research undertaken provided a scientific reference poised to enhance further inquiry into the enigmatic subject of cichlid sociality, laying a robust foundation for both advancing the study of these fishes and fostering their conservation.

Analysis of genetic diversity by the SLAF-seq among the farmed Onychostoma macrolepis populations

ObjectiveThe objective of this study was to examine the genetic diversity within and between farmed populations of Onychostoma macrolepis, and to establish a foundation for enhancing the genetic resources of breeding groups through the introduction of new individuals and crossbreeding. A total of 49 individuals were subjected to sequencing using Specific-Locus Amplified Fragment Sequencing (SLAF-seq), one of the restriction site-associated DNA sequencing technologies. The single nucleotide polymorphisms(SNPs)were identified to conduct the analyzation of phylogeny population structure, principal component and genetic diversity.ResultsA total of 853,067 SNPs were identified. The results of the phylogenetic analysis revealed that each sample was genetically clustered into three distinct groups: ZhenPing (ZP), LanGao parents (LG), and their progeny population (LG-F1). Each population was observed to be clustered together. Analysis of population genetic diversity revealed that the observed heterozygosity (Ho) ranged from 0.200 to 0.230, the expected heterozygosity (He) ranged from 0.280 to 0.282, and the polymorphic information content (PIC) ranged from 0.228 to 0.230. These results indicate that the genetic diversity of the population is low and the signs of long-term interbreeding are obvious, but there are differences between the populations, and the genetic diversity of the population can be improved by hybridization in different regions.

Compost-Derived Bacterial Communities Offer Promise as Biocontrol Agents against Meloidogyne javanica and Promote Plant Growth in Tomato

Meloidogyne nematodes, commonly known as root-knot nematodes, pose a considerable threat to crop yields, resulting in significant economic losses due to their intricate biology and limited control methods. In line with the European Union’s focus on promoting organic farming and soil health to encourage sustainable agricultural practices, this study explores the efficacy of two characterized bacterial communities obtained from compost against M. javanica in tomato plants. Through pot experiments, it was demonstrated that both bacterial communities, namely SC1 and SC2, effectively suppressed nematode reproduction and root invasion, which was reflected by a reduction in the number of egg masses per root (by 63% and 28%, respectively) and a reduction in the total progeny population (by 68% and 28%, respectively), with various simultaneously enhanced growth parameters in tomatoes, i.e., aerial part fresh weight increased by 74% and 58%, aerial part dry weight increased by 90% and 55%, and plant height increased by 86% and 53%, respectively. These findings underscore the potential of compost bacterial communities as promising tools for organic or integrated pest management, thereby supporting sustainable agricultural practices and contributing to improved crop yields.

Influence of single-species and species-species competitive interactions, in a food limited environment, among certain stored-grain beetles on population size and grain weight losses

Resource competition is a common biotic factor that affects progeny production and population size of stored-grain beetles. Larvae of the external feeding competitors, Tribolium, Oryzaephilus, and Trogoderma have almost identical habits, all developing and feeding outside grains Trogoderma larvae therefore are likely to face the competition of both competitors that share the same habitat, with the possibility of displacement of one or both of these species from the habitat. A series of trials of the single-, two-, and three-species competitive interactions among Trogoderma granarium, Tribolium castaneum, and Oryzaephilus surinamensis beetles were performed in 20g cracked-wheat grains at 30 ± 1 °C and 65 ± 5% r.h. Population sizes of living individuals, total populations (living + dead), and grain losses in all combinations were estimated after 30 and 60 days. This was to understand the role of external competitors in T. granarium establishment and vice versa. The population size of Trogoderma benefited more from coexisting with Oryzaephilus than with Tribolium, whereas that of Oryzaephilus did not benefit from coexisting with either species. Each of Trogoderma and Tribolium inhibited development of Oryzaephilus with more suffering in the treatment containing the two, which eventually led to greater collapse in Oryzaephilus populations. However, path analysis of the population growth rates of each species in pure and mixed infestations indicates coexistence is possible between all species and mixed infestations are more harmful to the grains than pure ones, since there are positive associations among them.

Evaluation of downy mildew resistance in spinach (Spinacia oleracea)

Spinach (Spinacia oleracea) is an economically important leafy vegetable grown in the United States and world-wide. The downy mildew pathogen, Peronospora effusa (Pfs), is a major biotic constraint impacting spinach production and quality. The use of resistant cultivars is an economical and environmentally-friendly management option especially in organic production systems. As new races of the pathogen continue to appear, there is a need to continue to select for resistance to the emerging races. The objectives of this study were to evaluate a set of spinach hybrids and F2 breeding populations for resistance to Pfs race 5 to develop a better understanding of the genetics of downy mildew resistance. Also, we screened 39 commercial spinach cultivars for resistance to a recently identified race, Pfs race 19. The genetics of resistance to Pfs 5 was determined by greenhouse inoculations of F1 progeny (individual crosses between near isogenic lines, NIL3 or NIL1 and susceptible genotype, Viroflay) and F2 population progeny (cross between Califlay and susceptible Viroflay). Two hybrids were examined for resistance to Pfs 5. The results indicated that resistance conferred at the RPF1 or the RPF3 loci in a heterozygous (Rr) condition to Pfs 5 was completely dominant. Also, Chi-square analysis of the segregation pattern in the F2 population showed that resistance to Pfs race 5 was conferred by a single dominant gene. A total of 22 out of 39 spinach commercial cultivars were resistant to the newly reported Pfs race 19 and could be used in breeding programs to develop new cultivars with resistance to Pfs 19.

Mitotic kinase inhibitors as Therapeutic Interventions for Prostate Cancer: Evidence from In vitro Studies.

Prostate cancer is one of the devastating diseases characterized by genetic changes leading to uncontrolled growth and metastasis of the cells of the prostate gland and affects men worldwide. Conventional hormonal and chemotherapeutic agents are effective in mitigating the disease if diagnosed at an early stage. All dividing eukaryotic cells require mitotic progression for the maintenance of genomic integrity in progeny populations. The protein kinases, upon activation and de-activation in an ordered fashion, lead to spatial and temporal regulation of the cell division process. The entry into mitosis along with the progression into sub-phases of mitosis is ensured due to the activity of mitotic kinases. These kinases include Polo-Like-Kinase 1 (PLK1), Aurora kinases, and Cyclin-Dependent-Kinase 1 (CDK1), among others. The mitotic kinases, among others, are usually overexpressed in many cancers and can be targeted using small molecule inhibitors to reduce the effects of these regulators on mechanisms, such as regulation of genomic integrity and mitotic fidelity. In this review, we attempted to discuss the appropriate functions of mitotic kinases revealed through cell culture studies and the impact of their respective inhibitors derived in pre-clinical studies. The review is designed to elucidate the growing field of small molecule inhibitors and their functional screening or mode of action at the cellular and molecular level in the context of Prostate Cancer. Therefore, studies performed specifically on cells of Prostatic-origin are narrated in this review, culminating in a comprehensive view of the specific field of mitotic kinases that can be targeted for therapy of Prostate cancer.

Comparing modeling methods of genomic prediction for growth traits of a tropical timber species, Shorea macrophylla.

Shorea macrophylla is a commercially important tropical tree species grown for timber and oil. It is amenable to plantation forestry due to its fast initial growth. Genomic selection (GS) has been used in tree breeding studies to shorten long breeding cycles but has not previously been applied to S. macrophylla. To build genomic prediction models for GS, leaves and growth trait data were collected from a half-sib progeny population of S. macrophylla in Sari Bumi Kusuma forest concession, central Kalimantan, Indonesia. 18037 SNP markers were identified in two ddRAD-seq libraries. Genomic prediction models based on these SNPs were then generated for diameter at breast height and total height in the 7th year from planting (D7 and H7). These traits were chosen because of their relatively high narrow-sense genomic heritability and because seven years was considered long enough to assess initial growth. Genomic prediction models were built using 6 methods and their derivatives with the full set of identified SNPs and subsets of 48, 96, and 192 SNPs selected based on the results of a genome-wide association study (GWAS). The GBLUP and RKHS methods gave the highest predictive ability for D7 and H7 with the sets of selected SNPs and showed that D7 has an additive genetic architecture while H7 has an epistatic genetic architecture. LightGBM and CNN1D also achieved high predictive abilities for D7 with 48 and 96 selected SNPs, and for H7 with 96 and 192 selected SNPs, showing that gradient boosting decision trees and deep learning can be useful in genomic prediction. Predictive abilities were higher in H7 when smaller number of SNP subsets selected by GWAS p-value was used, However, D7 showed the contrary tendency, which might have originated from the difference in genetic architecture between primary and secondary growth of the species. This study suggests that GS with GWAS-based SNP selection can be used in breeding for non-cultivated tree species to improve initial growth and reduce genotyping costs for next-generation seedlings.

Breeding design in wheat by combining the QTL information in a GWAS panel with a general genetic map and computer simulation

A large amount of genome-wide association study (GWAS) panels together with quantitative-trait locus (QTL) information associated with breeding-targeted traits have been described in wheat (Triticum aestivum L.). However, the application of mapping results from a GWAS panel to conventional wheat breeding remains a challenge. In this study, we first report a general genetic map which was constructed from 44 published linkage maps. It permits the estimation of genetic distances between any two genetic loci with physical map positions, thereby unifying the linkage relationships between QTL, genes, and genomic markers from multiple genetic populations. Second, we describe QTL mapping in a wheat GWAS panel of 688 accessions, identifying 77 QTL associated with 12 yield and grain-quality traits. Because these QTL have known physical map positions, they could be mapped onto the general map. Finally, we present a design approach to wheat breeding by using known QTL information and computer simulation. Potential crosses between parents in the GWAS panel may be evaluated by the relative frequency of the target genotype, trait correlations in simulated progeny populations, and genetic gain of selected progenies. It is possible to simultaneously improve yield and grain quality by suitable parental selection, progeny population size, and progeny selection scheme. Applying the design approach will allow identifying the most promising crosses and selection schemes in advance of the field experiment, increasing predictability and efficiency in wheat breeding.

Variability in germination fractions of Amaranthus albus in response to weed management and abiotic maternal conditions

Understanding the effects of abiotic, biotic, and management factors on weed germination is vital for optimizing weed control in agricultural fields. Nevertheless, the considerable variability among weed populations may undermine the reliability of these efforts. This study explores the intra-specific variability of Amaranthus albus populations obtained from agricultural fields across a climate gradient, ranging from semi-arid to Mediterranean. We explore the influence of temperature on germination, characterize A. albus seed morphology and assess seedling growth rate, while considering maternal effects. Nine populations were collected in northern Israel, and F2 generation seeds were produced under uniform conditions. Seed traits, germination patterns and growth rate of both maternal and progeny populations were characterized and compared. The estimated parameters of time-to-event models of populations and generations were compared using a meta-analytic approach. There were significant seed weight differences among the F1 populations, with eastern populations having the highest mean weights (28.6–38.5 mg per 50 seeds). Overall, F1 populations had higher seed weight than F2 populations (25.5 vs. 23.4 mg; p < 0.001). Two distinct germination patterns were observed in F1 populations: For the early-season planting areas, germination was rapid and uniform, with higher germination percentages at lower temperatures; in contrast, for the late-planting areas, germination was delayed and variable, with higher percentages under more favorable conditions (30 °C). F2 populations exhibited nearly identical germination patterns in response to temperature. The initial growth rate over time was similar across populations and generations, indicating that maternal conditions had no effect beyond the germination phase. The plasticity in the germination response to temperature suggests that modeling A. albus behavior is possible but requires a thorough understanding of underlying system components. The study emphasizes the importance of incorporating location-specific factors into weed management strategies, considering both natural processes and anthropogenic influences shaping weed populations.

Sex-specific responses of Ruditapes philippinarum to ocean acidification following gonadal maturation

Ocean acidification (OA) can seriously affect marine bivalves at different levels of biological organization, generating widespread consequences on progeny recruitment and population maintenance. Yet, few effort has been devoted to elucidating whether female and male bivalves respond differentially to OA in their reproductive seasons. Here, we estimated differences in physiological responses of female and male Manila clams (Ruditapes philippinarum) to OA during gonadal maturation. In comparison to OA-stressed male clams, females significantly depressed activities in enzymes related to energy metabolism (NKA, T-ATP), antioxidant defence (SOD and MDA), and non-specific immune function (ACP), and downregulated expression of AMPK that plays a key role in cellular metabolism, indicating that sex did significantly affect responses of R. philippinarum to OA. Such sex-based differences can be likely couched in energetic terms, given the much more energetically expensive cost of egg production than that of sperms. These results indicate that sex-specific responses to OA during reproductive seasons do exist in marine bivalves, and therefore accounting for such sex specificity is of paramount importance when projecting population sustainability and formulating conservation strategies in an acidifying ocean.

Comparison of stress tolerance of hybrid and selfed offspring of two populations of Litopenaeus vannamei

In recent years, as the marine environment has been deteriorated, the aquaculture water environment has also been negatively affected to varying degrees. Negative environmental factors make extremely damaging to organisms, resulting in stress-induced diseases and high mortality rates of cultured shrimp. Therefore, stress resistance breeding of Litopenaeus vannamei and evaluating the stress tolerance of the breeding population are urgently needed now. Litopenaeus vannamei collected from Thailand (T) and the United States (M) were used as parents, while four progeny populations of TT, MM, TM, and MT were constructed by diallel cross, with a total of 20 families. The tolerance of young shrimp to high ammonia-N, high pH, and low salt was compared through a 96-h acute toxicity test; the heterosis of each mating combination was analyzed; and the tolerance of parents and offspring was evaluated. Here we show that under 96 h of high ammonia-N, high pH, and low salt stress, the mortality rates of each family were 19.52%–92.22%, 23.33%–92.22%, and 19.33%–80.00%, respectively. There were significant differences in the tolerance of different families to ammonia-N, pH, and salinity stress (P &amp;lt; 0.05). The population with a female parent from the United States had stronger tolerance to ammonia-N, pH, and low salt stress than the population with a female parent from Thailand. The population with a male parent from Thailand had weaker tolerance to pH and low salt stress than the population with a male parent from the United States, but it was superior to the population with a male parent from the United States under ammonia-N stress. The heterosis rates of the hybrid population TM in acute high ammonia-N, high pH and low salinity were 81.67%, 44.58% and −10.13%, respectively; However, the heterosis rates of the MT population were 14.89%, 38.89%, and −8.96%, respectively. The overall resistance of the four populations showed MM &amp;gt; MT &amp;gt; TT &amp;gt; TM. The population TM had obvious heterosis in high ammonia-N and high pH tolerance traits, and the family MM7 had a strong low salt tolerance, so it can be considered a candidate family for subsequent breeding work. Moreover, variability in stress resistance and heterosis of stress resistance of different populations obtained by family selection was discussed in this paper. The experimental results provide a basis for screening new strains of vannamei shrimp with strong stress resistance through family breeding.

Genetic evaluation of F2 and F3 interspecific hybrids of mung bean (Vigna radiata L. Wilczek) using retrotransposon‐based insertion polymorphism and sequence‐related amplified polymorphism markers

Mung bean (Vigna radiata L. Wilczek) is a self‐pollinating and indispensable pulse crop in Indonesia. While low yield productivity is a major concern, genetic improvement is possible through interspecific hybridization. However, interspecific hybridization is relatively infrequent and produces low recombination exchanges, significantly limiting crop breeding efficiency. Thus, a comprehensive study is needed of the selection and genetic diversity evaluation of progenies in advanced generations derived from interspecific hybridization using a specific molecular marker. This study aims to confirm the heterozygosity in the F2 population and assess the genetic diversity in F3 mung bean populations resulting from interspecific hybridization between the mung bean and common bean. We designed the retrotransposon‐based insertion polymorphism (RBIP) marker by identifying the syntenic regions in the flanking sequences of retrotransposon insertion in common bean and mung bean. The RBIP marker can be applied to distinguish the heterozygote progenies from the homozygote progenies. Six combinations of sequence‐related amplified polymorphism (SRAP) primers were used in the genotyping of F3 mung bean progenies. The SRAP marker showed a high degree of polymorphism of up to 100%, while high genetic variation was observed within the population (71%) of mung bean progenies. The F3.4 population had the greatest number of genotypes and displayed the highest number of effective alleles, private alleles, and percentage of polymorphic loci, suggesting the existence of high genetic diversity within this population. These genetic diversity data are exceptionally critical for future genetic research since it has potentially high yield production. The genomic and marker‐assisted selection studies will support the major goals of the mung bean breeding program.

Influenza virus transcription and progeny production are poorly correlated in single cells

The ultimate success of a viral infection at the cellular level is determined by the number of progeny virions produced. However, most single-cell studies of infection quantify the expression of viral transcripts and proteins, rather than the amount of progeny virions released from infected cells. Here, we overcome this limitation by simultaneously measuring transcription and progeny production from single influenza virus-infected cells by embedding nucleotide barcodes in the viral genome. We find that viral transcription and progeny production are poorly correlated in single cells. The cells that transcribe the most viral mRNA do not produce the most viral progeny and often represent aberrant infections that fail to express the influenza NS gene. However, only some of the discrepancy between transcription and progeny production can be explained by viral gene absence or mutations: there is also a wide range of progeny production among cells infected by complete unmutated virions. Overall, our results show that viral transcription is a relatively poor predictor of an infected cell’s contribution to the progeny population.

Influenza virus transcription and progeny production are poorly correlated in single cells.

The ultimate success of a viral infection at the cellular level is determined by the number of progeny virions produced. However, most single-cell studies of infection quantify the expression of viral transcripts and proteins, rather than the amount of progeny virions released from infected cells. Here, we overcome this limitation by simultaneously measuring transcription and progeny production from single influenza virus-infected cells by embedding nucleotide barcodes in the viral genome. We find that viral transcription and progeny production are poorly correlated in single cells. The cells that transcribe the most viral mRNA do not produce the most viral progeny and often represent aberrant infections that fail to express the influenza NS gene. However, only some of the discrepancy between transcription and progeny production can be explained by viral gene absence or mutations: there is also a wide range of progeny production among cells infected by complete unmutated virions. Overall, our results show that viral transcription is a relatively poor predictor of an infected cell's contribution to the progeny population.

Using Transferable Eucalypt Microsatellite Markers to Identify QTL for Resistance to Ceratocystis Wilt Disease in Eucalyptus pellita F. Muel. (Myrtales, Myrtaceae)

The deployment of Eucalyptus pellita trees that are resistant to Ceratocystis manginecans is essential for the commercial plantations and therefore the sustainability of forest industries in Southeast Asia that utilize this resource. Current screening procedures are time-consuming and expensive but could be expedited with the aid of marker-assisted selection and breeding. The identification of genotypes with resistance to the disease may be facilitated if microsatellite markers developed in other Eucalyptus species are transferable and can be linked to quantitative trait loci (QTL) for disease resistance. This possibility was tested in 111 full-sib progenies and their parents by genotyping with 49 microsatellite markers developed in other Eucalyptus species. Disease development was assessed after stem inoculation with C. manginecans isolate Am60C. The disease index (DI) varied from 0 to 20% of stem length. There was a continuous distribution of resistant and susceptible seedlings with 60% in the resistant category. Of the 30 acceptable markers, 17 (56%) defined two linkage groups (LG). In each LG, one QTL with a significant logarithm of odds (LODs &gt; 13) was identified. The transferability of microsatellite markers developed in other Eucalyptus species facilitated the rapid identification of LGs and QTLs in E. pellita. To further refine the linkage map, the testing of more microsatellite markers and a larger population of progenies are required.