Progeny Populations Research Articles

Evaluation of diatomaceous earth formulations enhanced with natural products against stored product insects

The insecticidal effect of prepared insecticide formulations labelled as Natural P, Inert Natural P and Py EC on Sitophilus oryzae, Rhyzopertha dominica and Tribolium castaneum have been evaluated on wheat grains. Formulation Natural P contains diatomaceous earth (DE), amorphous silica gel (3%), pyrethrin, flax oil, lavandin essential oil (EO) and un-activated yeast. Formulation Inert Natural P contains DE, amorphous silica gel, lavandin EO and food grade bait whereas formulation Py EC contains pyrethrin, piperonyl butoxide (PBO), flax oil, polysorbate, methyl oleate and amorphous silica gel (5%). Celatom® MN-51 (diatomaceous earth – DE) was used as a standard insecticide. Inert Natural P and Natural P were applied as dust at four different doses and Py EC was applied as emulsions on grain by spraying. All three formulations showed higher insecticidal efficacy and higher progeny inhibition on all three tested insect species and had lower impact on wheat bulk density reduction compared with Celatom® MN-51. The LD50 and LD90 values of Inert Natural P were 48.7 and 163.7 ppm respectively for S. oryzae, 15.2 and 178.0 ppm for R. dominica and 115.2 and 171.3 ppm for T. castaneum. The LD50 and LD90 values of Natural P were 83.6 and 97.9 ppm respectively for S. oryzae, 19.5 and 97.9 ppm for R. dominica and 75.4 and 105.6 ppm for T. castaneum. Applied Py EC at concentration of 2.0 ppm a.i. pyrethrin exhibited 100% mortality after 2 d of S. oryzae and T. castaneum and after 6 d of R. dominica. In addition, all three formulations caused significant reduction of progeny (F1) population compared to control, providing promising approach of integrated pest management strategy.

Phenotypic traits of two boring giant clam (Tridacna crocea) populations and their reciprocal hybrids in the South China Sea

The boring giant clam, Tridacna crocea, is distributed along coasts in the South China Sea, and has formed several geographic populations. These populations represent potentially different genetic resources for aquaculture, and the evaluation of their genetic and production characteristics is important. To determine these performance characteristics, complete diallel crosses between two geographical populations with about 600 km distance, Zhaoshu Island and Huangyan Island, were conducted using pooled gametes at an experimental station in Sanya, Hainan Island Province. Two intra-population crosses (ZZ and HH) and two reciprocal inter-population crosses (ZH and HZ) were carried out successfully three times. High fertilization rates and D larvae rate were observed in all the experimental groups, suggesting that there was no sperm-egg recognition barrier between the two geographic populations. Reciprocal hybrids had a higher survival rate than the pure populations, but with the exception of metamorphosis rate there were no significant differences between the inter- and intra-population crosses. Growth heterosis was evident in both the spat and adult stages, and was mainly influenced by egg origin and mating strategy in the adult stage. In view of the growth differences between the two pure populations' progeny, the Huangyan Island population's progeny was more suitable for giant clam aquaculture than the Zhaoshu Island population's progeny. Our results demonstrate that crossbreeding between the Huangyan Island and Zhaoshu Island populations of boring giant clams can produce considerable heterosis, which has promising prospects for application in the giant clam aquaculture industry in the South China Sea.

Breeding new sweetpotato genotypes combining elevated content of two antagonistic traits of high dry matter and beta-carotene content in a high root yield background

This study was embarked upon to stack two key but inversely associated sweetpotato traits (dry matter and beta-carotene content) through conventional breeding methods. Thirty-seven elite sweetpotato genotypes were evaluated for both traits, and 15 parents comprising five orange-, five yellow- and five white-fleshed genotypes were selected from the 37 for hybridization. Using bi-parental mating fashion, an F1 progeny population for both traits was developed. Of the 13 families developed, eight families had above 30% of the progenies made of orange-fleshed (high beta-carotene) genotypes with three families having at least 50% of the progenies as OFSP. All the families (except two) showed wide variation for beta-carotene content (range 0.15–12.39 mg/100gFW) with some progenies exhibiting transgressive segregation. For dry matter content, most of the progenies across families had dry matter content > 30%. Overall, 17 high yielding F1 genotypes that combined elevated beta-carotene and dry matter content were identified. These 17 genotypes showed that although a strong inverse relationship exists between dry matter and beta-carotene, the relationship does not make the development of genotypes expressing both traits totally impossible through conventional breeding. These 17 superior genotypes that combine both traits will also serve as elite genetic background for many African sweetpotato breeding platforms in their quest to develop OFSP genotypes that meet the food culture of many African societies.

Динаміка популяцій короїдів у соснових лісах Житомирської області

Установлено, що у всиханні соснових насаджень Житомирської області відіграють роль короїди, які заселяють дерева, ослаблені внаслідок посух і надмірного антропогенного навантаження. Висловлено гіпотезу, що після посухи 2009 р. відбулося два спалахи різних угруповань короїдів. Для підтвердження цієї гіпотези проаналізовано динаміку за 2013-2019 рр. популяційних показників найпоширеніших видів під час їхнього масового розмноження у лісах Житомирської області: великого (Tomicus piniperda) та малого (T. minor) соснових лубоїдів, а також верхівкового (Ips acuminatus) й шестизубчастого (I sexdentatus) короїдів. Під час аналізу даних стосовно поширеності, щільності поселення, продукції й енергії розмноження цих видів, одержаних на 550 палетках із 61 модельного дерева, з'ясовано, що в комплексі короїдів в осередках всихання до 2014 р. переважали соснові лубоїди, а з 2015 р. – верхівковий і шестизубчастий короїди, які мають декілька поколінь на рік. Показано, що основні тенденції розвитку комплексу короїдів у соснових насадженнях Житомирської області в роки досліджень визначала динаміка популяцій домінантного виду – верхівкового короїда. Значення показників поширеності, щільності поселень, продукції та енергії розмноження короїдів свідчать про посилення з 2016 р. внутрішньовидової конкуренції в популяції верхівкового короїда, а у 2018-2019 рр. – також міжвидової конкуренції. З огляду на дію конкуренції та накопиченням ентомофагів в осередках всихання варто очікувати згасання спалахів масового розмноження короїдів.

Comparison of Genetic Diversity in Naturally Regenerated Norway Spruce Stands and Seed Orchard Progeny Trials

Forest ecosystems in Europe are expected to experience changes in temperature and water regimes associated with increased risks of extreme environmental events and disasters. Genetic diversity and relatedness has been linked to resilience of forest stands and landscapes. Genetic diversity indicators were compared between a Norway spruce population naturally regenerated after extensive windthrow and Norway spruce progeny populations derived from two seed orchards. In addition, genetic diversity in an undisturbed stand in a long established national park and a spruce genetic resource stand were analyzed. Populations were genotyped at 11 simple sequence repeat (SSR) loci. Average genetic diversity indicators were similar across populations. However, the total number of alleles, average number of alleles over all loci, effective number of alleles, average gene diversity, and average allelic richness were highest in the naturally regenerated population and lowest in one of the seed orchard progeny populations. The genetic diversity in progeny from seed orchards used for stand renewal is comparable to the genetic diversity in naturally regenerated stands. However, fluctuations in seed production between years can have a large impact on genetic diversity in seed orchard progeny. The use of improved Norway spruce germplasm deployed via clonal seed orchards for forest renewal can maintain similar levels of genetic diversity compared to naturally regenerated stands, while also increasing production and timber quality.

Illegitimacy Testing of Elaeis guineensis Population Based on Simple Sequence Repeat Markers

Illegitimacy is a factor negatively affecting controlled pollination in Elaeis guineensis breeding programs and it may happen in any step of hybridization processes, starting from early stages of parent selection and labeling to the last stage of the replicated field trial. Availability of method for testing the existence of illegitimacy among progenies of oil palm is beneficial. Four half-sib family populations consisted of 83 individuals were evaluated. Sixteen loci of SSR markers were utilized to genotype plant materials and identify illegitimate individuals. The legitimate parents and illegitimate progenies were evaluated using CERVUS and COLONY softwares. The results showed that the 16 SSR marker loci evaluated were having medium to high PIC values and they were both informative and suitable for parent-offspring analysis. The results also showed that the 16 SSR markers were sufficient for the illegitimacy testing using the COLONY software. Moreover, this study did not find any illegitimate individual among the four progeny populations. The generated SSR marker data were also successfully used to assign and to reconstruct the expected pedigree of the progenies. This can be used as an example of molecular marker utilization to improve the integrity of breeding program of oil palms.

Fine mapping of an up-curling leaf locus (BnUC1) in Brassica napus

BackgroundLeaf shape development research is important because leaf shapes such as moderate curling can help to improve light energy utilization efficiency. Leaf growth and development includes initiation of the leaf primordia and polar differentiation of the proximal-distal, adaxial-abaxial, and centrolateral axes. Changes in leaf adaxial-abaxial polarity formation, auxin synthesis and signaling pathways, and development of sclerenchyma and cuticle can cause abnormal leaf shapes such as up-curling leaf. Although many genes related to leaf shape development have been reported, the detailed mechanism of leaf development is still unclear. Here, we report an up-curling leaf mutant plant from our Brassica napus germplasm. We studied its inheritance, mapped the up-curling leaf locus BnUC1, built near-isogenic lines for the Bnuc1 mutant, and evaluated the effect of the dominant leaf curl locus on leaf photosynthetic efficiency and agronomic traits.ResultsThe up-curling trait was controlled by one dominant locus in a progeny population derived from NJAU5734 and Zhongshuang 11 (ZS11). This BnUC1 locus was mapped in an interval of 2732.549 kb on the A05 chromosome of B. napus using Illumina Brassica 60 K Bead Chip Array. To fine map BnUC1, we designed 201 simple sequence repeat (SSR) primers covering the mapping interval. Among them, 16 polymorphic primers that narrowed the mapping interval to 54.8 kb were detected using a BC6F2 family population with 654 individuals. We found six annotated genes in the mapping interval using the B. napus reference genome, including BnaA05g18250D and BnaA05g18290D, which bioinformatics and gene expression analyses predicted may be responsible for leaf up-curling. The up-curling leaf trait had negative effects on the agronomic traits of 30 randomly selected individuals from the BC6F2 population. The near-isogenic line of the up-curling leaf (ZS11-UC1) was constructed to evaluate the effect of BnUC1 on photosynthetic efficiency. The results indicated that the up-curling leaf trait locus was beneficial to improve the photosynthetic efficiency.ConclusionsAn up-curling leaf mutant Bnuc1 was controlled by one dominant locus BnUC1. This locus had positive effects on photosynthetic efficiency, negative effects on some agronomic traits, and may help to increase planting density in B. napus.

The genetic assessment of the natural regeneration capacities of black poplar populations in the modern river valley landscapes

Black poplar (Populus nigra L.) is an economically and ecologically important tree species which in the past was widely distributed along riversides in vast areas of Europe. Currently, it deserves conservation with a view of serious threats resulting from the species habitat reduction and progressive introgressive hybridization. Here we examined the regeneration capacities of black poplar populations from the Vistula River in Poland in a region which has been influenced by man-made disturbance regimes. Using both nuclear (nDNA) and chloroplast (cpDNA) genetic markers and spatial location data we: (1) evaluated the susceptibility of the studied populations to introgression, (2) determined genetic diversity of the analyzed offspring and compared it with their maternal stands, and (3) assessed the level of gene flow among populations and generations. Nine hybrid individuals were identified in the examined groups of one-year poplar seedlings. Both molecular variance and clustering analyses showed that the gene pool of black poplar populations was homogenous (FST = 0.004, p = 0.623). Heterozygosity and allelic richness were comparable between adult and their progeny populations, and there were also no strong disturbances in a random distribution of genotypes in the study area. Low spatial genetic structure was observed in two seedling groups and among all black poplar individuals from the Wysoczyn population. The results are discussed in the context of natural regeneration capacities of the remaining black poplar populations and protection of the species genetic resources along the landscapes of the river valleys.

Effects of sublethal fumigation with phosphine on the reproductive capacity of Liposcelis entomophila (End.) (Psocoptera: Liposcelididae)

The goal of our study was to determine if phosphine exposure changed the fecundity of the surviving Liposcelis entomophila, and the fitness of resulting offspring. Two strains of L. entomophila, were tested. One (F0) that had not been exposed to phosphine in the laboratory, and a second (F4) that had been exposed to the LC50 dose of phosphine for 4 successive generations. The daily egg production, rate of growth, hatching rate, sex ratio, and adult emergence rate were measured after exposures to phosphine at the LC20 and LC50 doses. LC20 fumigation did not affect peak oviposition and fumigation at LC50 dose delayed peak oviposition peak in F0. Females fumigated at LC20 dose had higher fecundity in the first oviposition peaks from 3rd day. The accumulated egg production of F4 fumigated at LC20 and LC50 was significantly higher than that of F0 in the first and second weeks. All the results indicated that long term fumigation with sublethal LC20 could stimulate the surviving females to lay more eggs. Fumigation at LC50 dose could inhibit female fecundity and progeny population growth. The results suggested that long-term fumigation with LC20 could induce strong population growth and lead to L. entomophila infestations.

KERAGAMAN GENETIK, HERITABILITAS DAN KEMAJUAN GENETIK KARAKTER AGRONOMI PADA POPULASI GALUR F2 HASIL PERSILANGAN

Genetic variability, heritability estimate and expected genetic advance may be useful to provide the basis for planning of more efficient in selection program. The objectives of this study were to determine genetic variability, heritability and genetic advance of agronomic characters that could be realized through selection of segregation progenies. The F2 soybean progenies derived from two cross combinations and their three parent varieties were evaluated for their genetic variability, heritability and expected genetic advance of agronomic traits at Muneng Experimental Station, Probolinggo, East Java, during dry season of 2016. The experiment was arranged in a randomized block design, with three replications. Seeds of each F2 progenies and their parents were sown in four rows of 4 m length of plots. Plant spacing was 40 cm x 20 cm, with one plant per hill. Plant population of each F2 progenies and their parents were 80 plants in each replication. Among the character observed, number of pods per plant, seed yield per plant and days to maturity had the highest coefficient of variability, with the means of 53.1%, 48.2% and 42,5% respectively. Plant height and seed size had a moderate coefficient of variability, with the means of 33.5% and 35.7%. While the days to flowering, number of branches and number of nodes per plant had the lowest coefficient of variability, and the means were only 19.9%, 14.1% and 15.8% respectively. The heritability estimate of the eight agronomic traits ranged from 18.9%-53.6%. Number of pods per plant and plant height had the highest heritability estimates for the two crosses, and the means were 53.6% and 41.5% respectively. The days to maturity, seed size and days to flowering were also had high heritability estimate of 38.8%, 36.8% and 36.6%. The mean heritability estimates for seed yield per plant, number of nodes and number of branches per plant were the lowest of only 20.6%, 19.7% and 18.9% respectively. Based on the F2 data, selection on the number of pods per plant had the highest expected genetic advance of 44.7%, followed by the days to maturity (41.0%) and the plant height (40.4%). Seed yield per plant, seed size and the days to flowering had a moderate expected genetic advance of 34.8%, 33.4% and 26.8%. The means of expected genetic advance for number of branches and number of nodes per plant were the lowest of 13.8% and 13.9% respectively. In relation to grain yield, the mean heritability estimate for seed yield per plant was low, of only 20.8%. However, considerable high genetic heritability (48.2%) and genetic advance (34.8%) was present on the seed yield per plant.

Occurrence, Seasonal Abundance, and Superparasitism of Ooencyrtus kuvanae (Hymenoptera: Encyrtidae) as an Egg Parasitoid of the Spotted Lanternfly (Lycorma delicatula) in North America

The occurrence of egg parasitoid Ooencyrtus kuvanae (Howard) (Hymenoptera: Encyrtidae) on its new host, the spotted lanternfly (Lycorma delicatula (White) (Hemiptera: Fulgoridae)), was surveyed at 4 study plots in 2016 and 10 additional plots in 2017 in Pennsylvania through field collection and laboratory incubation. O. kuvanae adults were found on L. delicatula egg mass surfaces at two plots (ODSouth and Lutz) in 2016, but at none in 2017. The results of laboratory incubation showed that O. kuvanae adults were only recovered from host eggs collected at plot ODSouth in 2016, with adults emerging between 22 April and 2 May 2016 at 22 ± 1 °C, 40% ± 5% relative humidity (RH), and a 16:8 h photoperiod (light/dark). The overall parasitism at this study plot was 6.0% by egg mass and 1.2% by egg. Two oviposition sites contained parasitized L. delicatula eggs, with 12.3% (9.5–15.0%) host egg masses and 3.1% (1.3–5.0%) host eggs utilized by the parasitoid. O. kuvanae parasitism by egg was significantly higher on oviposition site ODSouth #7 than on ODSouth #8. No O. kuvanae adults were reared out of field-collected host eggs from the 10 plots in 2017. Seasonal abundance and superparasitism of O. kuvanae was examined at plot ODSouth in 2017. O. kuvanae-parasitized L. delicatula eggs were found on all four oviposition sites based on field monitoring of parasitoid adult emergence, resulting in a parasitism of 35.4% (18.8–55.6%) by egg mass and 2.2% (0.5–3.9%) by egg. No significant difference in parasitism by egg was observed among oviposition sites. O. kuvanae adults emerged in the field between 2 May and 1 June 2017. Superparasitism was confirmed for O. kuvanae on L. delicatula eggs based on parasitoid production (1.0–3.3 adults/parasitized egg) and adult exit holes (1–3 exit holes/parasitized egg). As the first parasitoid recorded from L. delicatula in North America, O. kuvanae has the potential to become an important biological control agent for L. delicatula in North America, with its well-synchronized life history in the spring, century-long field establishment, superparasitism, and female-biased progeny population. L. delicatula complements the gypsy moth well as an alternative host for O. kuvanae in the field.

Reciprocal Translocation Analysis with Whole Chromosome Painting for FISH.

Ionizing radiation can produce many chromosome aberrations; however, a number of aberrations are not readily detectable with a conventional Giemsa staining and require special staining methods. Moreover, an easy method to identify nondetectable chromosomal aberrations, such as symmetrical inter-chromosomal translocations, is available: whole chromosome fluorescence in situ hybridization (FISH) staining. Asymmetrical translocations such as dicentric chromosomes are known to be lethal but cells with symmetrical translocations may survive and persist in the progeny population for years. Chromosome banding techniques can also detect inter-chromosomal translocations but understanding banding patterns requires professional training and experience. Due to its clear detection by a discernible painting color, whole chromosome painting method is superior in identifying chromosome fragmentation, loss, and amplification of chromosomes. This chapter introduces whole chromosome FISH painting method to detect chromosomal aberrations such asfragments and translocations.

Correlation and genetic analysis of seed shell thickness and yield factors in Tartary buckwheat (Fagopyrum tataricum (L.) Gaertn.).

In order to solve the difficult problem of the outer shell covering in the processing of Tartary buckwheat, we conducted a genetic analysis in segregating F2 and F3 populations derived from a hybrid between ‘Yunqiao No. 1’ and ‘Rice buckwheat’, and the F3 population was used to analyze the phenotypic and genetic correlation among the traits. The results showed that the variety with a value of trait for seed shell thickness over 0.20 mm is a hard-shelled type (The thick shell type = seed shell rate > 20%), and that with a value of trait for seed shell thickness below 0.15 mm is a easily-shelled type (The thin shell type = seed shell rate < 20%), while that with a value of trait for seed shell thickness ranging from 0.15 mm to 0.20 mm is a hard-shelled type or easily-shelled type. In addition, alleles for traits of number of seed per plant and total seed weight per plant have larger dominance variance relative to their additive variance, indicating that genes controlling these traits have larger dominant effects, it is not suitable for the selection of single plant in offspring plants at the early stage of development, because these traits do not show up then. The alleles for traits of 1000 kernel weight and seed shell thickness have larger additive variance relative to their dominant variance, indicating that genes governing these traits have greater additive effects, with which the single plant can be selected in the progeny at the early stage of development. Although, the value of seed shell thickness has been shown to correlated positively with that of 1000 kernel weight, almost all the seeds of easily-shelled type are those with thin shell. However, ideal single plants with easily-shelled trait are those with intermediate phenotypes of seed shell thickness and 1000 kernel weight, by which the traits of large number of seeds per plant and total seed weight per plant could be selected. In the progeny population of this study, there were excellent single plants with high-yield and easily-shelled traits, of which the value of seed shell thickness was 0.17 mm (0.15 mm to 0.20 mm), the value of 1000 kernel weight was 14 g, the value of number of seeds per plant was 1137 and value of total seed weight per plant was 15.9 g. The results showed that taking the hybrid combinations of easily-shelled trait with the trait of seed shell thickness was the most effective selection indexes to breed the high-yield buckwheat varieties with the trait of easy shelling.

Genetska varijabilnost unutar i između generativnih potomstava divlje ruže (Rosa sp.)

Dog rose (Rosa canina L.) is a cosmopolitan plant species that due to its nutritional, medical and cosmetic values deserves more attention. Dog roses are cultivated in Croatia on very small scale and most of the rose hip used in the domestic processing industry is imported. In this study, three dog rose F1 progeny populations developed from selected plants collected in Korcula, Malesnica and Prigorje Brdovecko, originating from two climatic regions (P1 - Mediterranean and P2 and P3 - continental) have been studied as a part of a field experiment for two growing seasons, in order to assess the level of genetic variability for pomological and agronomic traits. In addition, genetic variation within and among examined three dog rose populations has been assessed using 6 polymorphic SSR markers. The highest variability, as well as the most desirable agronomic traits were found within the P3 population, while the lowest ones were present in the P1 population. Most desirable properties and highest values for commercially important traits were detected in the genotype RC29 (P3). Molecular data was sufficient to separate three studied populations but not all individuals within the populations. Through selection and hybridization of perspective genotypes of dog roses from Croatia, it would be possible to create clonally propagated varieties suitable for commercial cultivation.

A new DNA marker CafLess-TCS1 for selection of caffeine-less tea plants.

A clonal line of Camellia taliensis, ‘Taliensis-akeme’ has a recessive caffeine-less gene. To accelerate breeding of caffeine-less tea cultivars using this gene, DNA markers are indispensable for selecting heterozygotes that do not show a caffeine-less phenotype as parental lines. Therefore, we tried to determine the sequence of the six tea caffeine synthase (TCS) genes to search for polymorphisms and to prepare one of the TCS genes as a selection marker. Six TCS genes and the caffeine-less trait were mapped on the reference linkage map of tea. Strong linkage between the caffeine-less phenotype and TCS1 indicate that it is a promising candidate as a causative gene of the caffeine-less trait. We decided to use a three-nucleotide insertion in TCS1 that can be distinguished by sequencing as a selection marker named ‘CafLess-TCS1’. Caffeine-less individuals appeared in the progeny population of caffeine-less heterozygous individuals selected using ‘CafLess-TCS1’. These results confirmed that the developed ‘CafLess-TCS1’ will be an effective selection marker for breeding of caffeine-less tea cultivars.

Toxicity and Sublethal Effects of Flupyradifurone, a Novel Butenolide Insecticide, on the Development and Fecundity of Aphis gossypii (Hemiptera: Aphididae).

The cosmopolitan pest Aphis gossypii (Glover) causes considerable economic losses on various crops by its feeding damage and transmitting diseases around the world. Flupyradifurone is a novel butenolide pesticide; its toxicity on A. gossypii parent generation (F0) was estimated following treatment with LC25 concentration for 48 h. The adult longevity and fecundity of the F0 individuals treated by flupyradifurone showed no significant decrease in comparison with the control. Life table method was used to evaluate the sublethal effects on progeny population (F1). Results showed that the development time of the fourth instar and the preadult as well as the total pre-reproductive period were significantly prolonged, while their fecundity was significantly decreased compared with the control. Additionally, the intrinsic rate of increase (r), the finite rate of increase (λ), and the net reproductive rate (R0) of F1 were all significantly lower in the group treated by LC25 than in the control group. These results reveal that the sublethal concentration of flupyradifurone could suppress the population growth of A. gossypii and indicate that this novel insecticide may be as a useful tool in pest management.

Genome-wide association study discovered favorable single nucleotide polymorphisms and candidate genes associated with ramet number in ramie (Boehmeria nivea L.)

BackgroundRamie (Boehmeria nivea L.) is one of the most important natural fiber crops and an important forage grass in south China. Ramet number, which is a quantitative trait controlled by multigenes, is one of the most important agronomic traits in plants because the ramet number per plant is a key component of grain yield and biomass. However, the genetic variation and genetic architecture of ramie ramet number are rarely known.ResultsA genome-wide association study was performed using a panel of 112 core germplasms and 108,888 single nucleotide polymorphisms (SNPs) detected using specific-locus amplified fragment sequencing technology. Trait-SNP association analysis detected 44 significant SNPs that were associated with ramet number at P < 0.01. The favorable SNP Marker20170–64 emerged at least twice in the three detected stages and was validated to be associated with the ramie ramet number using genomic DNA polymerase chain reaction with an F1 hybrid progeny population. Comparative genome analysis predicted nine candidate genes for ramet number based on Marker20170–64. Real-time quantitative polymerase chain reaction analysis indicated that six of the genes were specific to upregulation in the ramie variety with high ramet number. These results suggest that these genes could be considered as ramet number-associated candidates in ramie.ConclusionsThe identified loci or genes may be promising targets for genetic engineering and selection for modulating the ramet number in ramie. Our work improves understanding of the genetics of ramet number in ramie core germplasms and provides tools for marker-assisted selection for improvement of agricultural traits.

Predicting segregation of multiple fruit-quality traits by using accumulated phenotypic records in citrus breeding.

In the breeding of citrus (Citrus spp.), suitable fruit quality is essential for consumer acceptance of new cultivars. To identify parental combinations producing F1 progeny with fruit-quality traits exceeding certain selection criteria, we developed a simple and practical method for predicting multiple-trait segregation in an F1 progeny population. This method uses breeding values of parental genotypes and an additive genetic (co)variance matrix calculated by the best linear unbiased prediction method to construct a model for trait segregation in F1 progeny. To confirm the validity of our proposed method, we calculated the breeding values and additive genetic (co)variances based on phenotypic records on nine fruit-quality traits in 2122 genotypes, and constructed a trait segregation model. Subsequently, we applied the trait segregation model to all pairs of the 2122 genotypes (i.e., 2,252,503 combinations), and predicted the most promising combinations and evaluated their probabilities of producing superior genotypes exceeding the nine fruit-quality traits of satsuma mandarin (Citrus unshiu Marcow.) or ‘Shiranuhi’ (‘Kiyomi’ × ‘Nakano No. 3’ ponkan), two popular citrus cultivars in Japan. We consider these results to be useful not only for selecting good parental combinations for fruit quality or other important traits but also for determining the scale of breeding programs required to achieve specific breeding goals.

Effects of sublethal herbicides on offspring germination and seedling growth: Redroot pigweed (Amaranthus retroflexus) vs. velvetleaf (Abutilon theophrasti)

The effects of sublethal doses of herbicides on plants cannot be ignored, yet little is known about the effects of sublethal doses of herbicides on the F1 generation of plants. Seed germination and seedling growth of native and invasive plants following the sublethal exposure of parent plants to herbicides were comparatively analyzed in this study. Sublethal atrazine and tribenuron-methyl had carry-over effects on the germination and seedling growth of the F1 generation of invasive redroot pigweed (Amaranthus retroflexus L.) and native velvetleaf (Abutilon theophrasti Medicus), both of which had different responses to the carry-over effects of sublethal herbicide. The germination percentage of the F1 redroot pigweed (decreased) was greater than that of the F1 velvetleaf (increased or not significantly changed) following parental exposure to atrazine or tribenuron-methyl. Atrazine reduced the radical growth of 7-day-old velvetleaf seedlings and decreased the difference in seedling length between velvetleaf and redroot pigweed, while tribenuron-methyl had no significant effects on the growth of 7-day-old velvetleaf seedlings. The herbicide inhibition effect on the germination and growth of F1 velvetleaf and redroot pigweed did not increase as the sublethal dose increased. This study suggests that carry-over effects of sublethal herbicides weaken the growth advantage of the F1 velvetleaf at the seedling stage and may have a more negative influence on progeny population development of native velvetleaf compared with invasive redroot pigweed.

Genomic Prediction Accounting for Genotype by Environment Interaction Offers an Effective Framework for Breeding Simultaneously for Adaptation to an Abiotic Stress and Performance Under Normal Cropping Conditions in Rice.

Developing rice varieties adapted to alternate wetting and drying water management is crucial for the sustainability of irrigated rice cropping systems. Here we report the first study exploring the feasibility of breeding rice for adaptation to alternate wetting and drying using genomic prediction methods that account for genotype by environment interactions. Two breeding populations (a reference panel of 284 accessions and a progeny population of 97 advanced lines) were evaluated under alternate wetting and drying and continuous flooding management systems. The predictive ability of genomic prediction for response variables (index of relative performance and the slope of the joint regression) and for multi-environment genomic prediction models were compared. For the three traits considered (days to flowering, panicle weight and nitrogen-balance index), significant genotype by environment interactions were observed in both populations. In cross validation, predictive ability for the index was on average lower (0.31) than that of the slope of the joint regression (0.64) whatever the trait considered. Similar results were found for progeny validation. Both cross-validation and progeny validation experiments showed that the performance of multi-environment models predicting unobserved phenotypes of untested entrees was similar to the performance of single environment models with differences in predictive ability ranging from -6–4% depending on the trait and on the statistical model concerned. The predictive ability of multi-environment models predicting unobserved phenotypes of entrees evaluated under both water management systems outperformed single environment models by an average of 30%. Practical implications for breeding rice for adaptation to alternate wetting and drying system are discussed.