To send content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about sending content to .
To send content items to your Kindle, first ensure firstname.lastname@example.org
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about sending to your Kindle.
Note you can select to send to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
Nipa (Nypa fruticans Wurmb.), aside from being part of the mangrove forest ecosystem that has been under assault at an alarming rate, lacks information on its genetic variation at the population level for conservation planning purposes. Microsatellites, or simple sequence repeats (SSRs), are molecular markers employed to detect genetic variations in population studies. Here, the primers for this palm were identified through whole-genome sequencing using the Illumina® Sequencing Technology platform. Over half (52.4%) of SSRs consisted of mononucleotide repeats, whereas the remainder mostly consisted of dinucleotide (22.7%) and trinucleotide (22.4%) repeats. The frequencies of longer repeats (tetranucleotides, pentanucleotides and hexanucleotides) were exceptionally rare (2.5%). At least 18 out of 75 genomic loci were polymorphic, based on 37 randomly selected samples assayed for screening. Polymorphic loci (P) reached a mean of 72% across the Indo-West Pacific region. Estimates of genetic diversity showed a lower mean observed heterozygosity (Ho) (0.195) than expected (He) (0.316), suggesting evolutionary forces were acting across nipa populations. The fixation (F) index (0.388) supported this result, which indicates considerable genetic differentiation among populations in the region. An average of 2.111 alleles (Na) was obtained. In conclusion, these microsatellite markers are promising tools for genetic evaluation of nipa populations to facilitate characterization of this species in its distribution range.
Epilobium belongs to the family Onagraceae, which consists of approximately 200 species distributed worldwide, and some species have been used as medicinal plants. Epilobium nankotaizanense is an endemic and endangered herb that grows in the high mountains in Taiwan at an elevation of more than 3300 m. Alpine herbs are severely threatened by climate change, which leads to a reduction in their habitats and population sizes. However, only a few studies have addressed genetic diversity and population genetics. In the present study, we developed a new set of microsatellite markers for E. nankotaizanense using high-throughput genome sequencing data. Twenty polymorphic microsatellite markers were developed and tested on 30 individuals collected from three natural populations. These loci were successfully amplified, and polymorphisms were observed in E. nankotaizanense. The number of alleles per locus (A) ranged from 2.000 to 3.000, and the observed (Ho) and expected (He) heterozygosities ranged from 0.000 to 0.929 and from 0.034 to 0.631, respectively. The developed polymorphic microsatellite markers will be useful in future conservation genetic studies of E. nankotaizanense as well as for developing an effective conservation strategy for this species and facilitating germplasm collections and sustainable utilization of other Epilobium species.
Mile-a-minute (Mikania micrantha Kunth) is a tropical American species and has become a worldwide invasive weed. It was first introduced to mainland China in 1983 in Yingjiang City, Dehong State, Yunnan Province. To assess the origins of populations from Dehong State, Yunnan Province, the genetic structure of 427 individuals from 11 M. micrantha populations from Yunnan, Guangxi, Hainan, and Guangdong provinces were analyzed. A total of 28 alleles were detected in 12 nuclear microsatellite loci. Genetic diversity at the population level was relatively high. An analysis of molecular variance showed that most of the variation occurred within populations (82.73%), and only 18.27% occurred among populations. The genetic differentiation coefficient (FST) was 0.183. The estimated gene flow (Nm) from FST was 1.116. The independent origins of four populations collected from Dehong State, Yunnan Province, was determined by the unweighted pair-group method with arithmetic means clustering and STRUCTURE analysis. Three gene clusters and one admixture gene cluster were found. A Mantel test of pairwise Nei’s genetic distances and pairwise geographic distances revealed no evidence for isolation by distance (r = 0.068, P = 0.343). These results suggest that the post-introduction admixture caused by multiple introductions and high gene flow might contribute to the evolutionary adaptation of M. micrantha. These results could provide a scientific basis for the management of invasive M. micrantha.
Khasi mandarin (Citrus reticulata Blanco) is a commercial mandarin variety grown in northeast India and one of the 175 Indian food items included in the global first food atlas. The cultivated plantations of Khasi mandarin grown prominently in the lower Brahmaputra valley of Assam, northeast India, have been genetically eroded. The lack in the efforts for conservation of genetic variability in this mandarin variety prompted diversity analysis of Khasi mandarin germplasm across the region. Thus, the study aimed to investigate genetic diversity and partitioning of the genetic variations within and among 92 populations of Khasi mandarin collected from 10 cultivated sites in Kamrup and Kamrup (M) districts of Assam, India, using Inter-Simple Sequence Repeat (ISSR) markers. The amplification of genomic DNA with 17 ISSR primers yielded 216 scorable DNA amplicons of which 177 (81.94%) were polymorphic. The average polymorphism information content was 0.39 per primer. The total genetic diversity (HT = 0.28 ± 0.03) was close to the diversity within the population (HS = 0.20 ± 0.01). A high mean coefficient of gene differentiation (GST = 0.29) reflected a high level of gene flow (Nm = 1.22), indicating high genetic differentiation among the populations. Analysis of Molecular Variance (AMOVA) showed 78% of intra-population differentiation, 21% among the population and 1% among the districts. The obtained results indicate the existence of a high level of genetic diversity in the cultivated Khasi mandarin populations, indicating the need for preservation of each existing population to revive the dying out orchards in northeast India.
Mexico has a wealth of plant genetic resources, including Capsicum species. In southern Mexico, specifically in the western part of the Yucatan Peninsula, Maya farmers have preserved a great diversity of chilli pepper landraces of C. annuum, C. frutescens and C. chinense. However, the morphological diversity, capsaicinoid content, conservation status and potential use of these species have not been studied. To fill this gap and generate information to support the conservation and use of these species, we characterized the phenotypic diversity and capsaicinoid content for nine chilli pepper landraces from the western Yucatan Peninsula by assessing 15 quantitative and 39 qualitative traits for 10 plants of each landrace. For quantitative variables, two groups of chilli pepper landraces were obtained by principal component analysis and cluster analysis. Group I was formed by Rosita, Bobo, Dulce, Xcat'ik1, Xcat'ik2 and Verde landraces; Group II included the Maax, Bolita and Pico Paloma landraces. For qualitative variables, three groups of chilli pepper landraces were obtained; Group I included Dulce, Bobo, Xcat'ik1, Xcat'ik2 and Verde landraces, Group II only included the Rosita landrace, and Group III included Maax, Bolita and Pico Paloma landraces. Ultra-performance liquid chromatography–photodiode array (UPLC-PDA) quantification of capsaicinoids indicated higher values in landraces Rosita (14,062.3 μg/g D.W), Bolita (5928.1 μg/g D.W), Maax (3438.4 μg/g D.W) and Pico Paloma (3138.9 μg/g D.W). The Yucatan chilli pepper landraces provide valuable diverse germplasm for morphological characteristics and capsaicinoid content that can be used in breeding and conservation programmes.
Interspecific hybrids between pearl millet (Pennisetum glaucum) and napier grass (Pennisetum purpureum) give rise to perennial fodder crops characterized by high biomass, broad clumps and good palatability. These hybrids are triploid and developed by hand pollination of napier grass pollen on pearl millet panicles. The progeny shows a high percentage of pearl millet genotype due to self-pollination in the female parent. Identification of hybrids at a young stage based on morphological characters is difficult. DNA-based molecular markers have high discriminating power and were used to assess genetic differences between hybrids and their parents. Genetic diversity was studied in 18 pearl millet × napier grass hybrids along with their parents and two released national checks using inter simple sequence repeat (ISSR) markers. Eight ISSR primers gave rise to 125 bands, of which 120 bands were polymorphic. Polymorphic information content and ISSR primer index ranged from 0.40 to 0.49 and 8.88 to 11.14, respectively. The hybrids showed the presence of unique bands, besides those shared with male and female parents. Female (pearl millet) parents formed a separate group in the dendrogram constructed based on ISSR polymorphism. The male (napier grass) parents formed a separate group along with hybrids, indicating a higher similarity of hybrids with the male parents. Principal component analysis and STRUCTURE analyses showed a similar grouping. The close resemblance of hybrids to the male parents confirmed their interspecific origin. The study revealed that ISSR marker analysis could be a quick and reliable method to identify interspecific hybrids at an early stage of growth.
A field experiment was carried out for over two seasons (autumn and spring) as a split–split plot scheme based on a randomized complete block design with three replications. The main plots included two irrigation levels of the maximum available water depletion (maximum allowable depletion (MAD)) of 55 and 85% as non-stress and drought-stress environments, respectively, and the subplot accommodated two levels of nitrogen (0 and 62.5 kg N/ha, urea fertilizer); also, 20 barley genotypes were assigned to the sub-subplots. The biplot analysis of both sowing seasons showed that grain yield (GY) had a high positive correlation with total biomass (TB), whereas it had a high negative correlation with proline and total soluble carbohydrate as drought-tolerance-determinant characteristics. The genotypes which had the lowest and highest GY ranked significantly (P ≤ 0.01) different with changing the sowing season under each irrigation level, indicating a larger plant interaction and non-stability in response to the season change (about two-fold), as compared to the change in the irrigation conditions. It could also be concluded that barley genotypes might experience a higher decrease in GY and sensitivity to water deficit in the autumn sowing season, as compared to the spring planting season, which was also intensified by nitrogen application. However, the response to nitrogen application depends on the plant genotype.
In this study of Metagonimus suifunensis (M. suifunensis) in the Russian Southern Far East, the variability of the full-length sequences of the cytochrome b (cytb) mtDNA gene was assessed for the first time. In addition, the cox1 mtDNA gene sequences were also obtained for this species from new localities. In total, 87 and 81 sequences of the cytb and cox1 genes, respectively, were used in the current study. The cytb gene proved more promising and revealed two haplogroups that are associated with the spatial distribution of the species: geographical isolation caused the fixation of differences between northern and southern populations. In addition, the results obtained for the cytb gene opened up new perspectives in the analysis of sequences of the cox1 gene, which was not sufficiently effective as a sole marker. Based on data for both mitochondrial genes, molecular processes influencing the formation of the modern population were analysed for M. suifunensis. The new data confirmed the previously expressed opinion that this species colonized the study territory from north to south and will form the basis for determining possible ways of its further expansion, which is important for predicting the emergence of new foci of metagonimosis.
Knowledge of the genetic diversity and relationships among maize inbred lines can facilitate germplasm management and plant breeding programmes. The study investigated the level of genetic diversity among S6 lines developed from a tropical-adapted shrunken-2 (sh-2) maize population and their relationship with normal endosperm tropical inbred lines of known heterotic groups. Ninety-one sh-2 maize inbred lines (UI1-UI91) developed in the University of Ibadan super-sweet Maize Breeding Programme were genotyped at 30 simple sequence repeat (SSR) loci, alongside five normal endosperm maize inbred lines viz. TZi3, TZi4, TZi10, TZi12 and TZi15, four of which belong to two heterotic groups. Twenty-three SSR markers were polymorphic and detected a total of 61 alleles, with a range of 2–7 and an average of 2.65 alleles per locus. The polymorphic information content ranged from 0.12 in bnlg1937 to 0.77 in phi126, with an average of 0.36. The gene diversity (He) averaged 0.43. Cluster analysis resulted in five groups consisting of 16, 36, 17, 23 and 3 inbred lines, with one sh-2 line ungrouped. TZi 12 and TZi 15, both of which are of the same heterotic group, clustered with TZi 3 of another heterotic group. Considerable genetic diversity exists among the 96 inbred lines. Only two of the five normal endosperm lines shared clusters with the sh-2 lines. The clustering of the normal endosperm inbred lines is not related to their established heterotic patterns. Inbred lines in two clusters offer the possibility of guiding the exploitation of heterosis among the sh-2 lines.
Asian palmyrah palm (Borassus flabellifer L.) is a multipurpose, economically important tree widely distributed in the Indian subcontinent and Southeast Asia. The multifaceted uses (~800 uses) of the tree as food, wood and medicine make it a viable industrial crop. However, the dioecious nature of the tree coupled with long juvenile phase (12–20 years to initiate flowering), long stature and considerable variations in the productivity of male and female trees necessitates the application of new biotechnological tools for crop improvement. This review provides comprehensive information on the extent of genetic diversity of the crop, problems associated with palmyrah cultivation along with its multifaceted application and research gaps to be addressed for the effective utilization and conservation of palmyrah palm genetic resources.
Iron walnut, Juglans sigillata Dode, restricted to southwestern China, has its centre of distribution in Yunnan Province which has a varied climate, geography and rich plant diversity. Yunnan contains abundant J. sigillata germplasm. In this study, a provincial-scale set of walnut germplasm resources (14 populations comprising 1122 individuals) was evaluated for genetic diversity based on 20 simple sequence repeat (SSR) loci. The number of SSR alleles per locus ranged from 7 to 27, with an average of 17.55. Mean allelic richness and mean private allelic richness ranged from 3.40 to 4.62 and 0.11 to 0.36, with average of 3.93 and 0.30, respectively. Expected heterozygosity (He) varied from 0.26 to 0.78, with an average of 0.57. Polymorphism information content ranged from 0.22 to 0.79, with an average of 0.57. Genetic differentiation (FST) was 0.05, indicating that only 5% of total genetic variability was inter-populational, a finding supported by an analysis of molecular variance and STRUCTURE analysis. Relatively high gene flow (Nm = 6.70) was observed between populations. A unweighted pair-group method with arithmetic analysis classified the 14 populations into two major groups. Mantel testing uncovered a significant correlation between geographic distance and genetic distance (r = 0.33, P = 0.04). Overall, the research revealed a moderately high level of genetic diversity in the germplasm and low genetic differentiation among populations, which showed great potential for further development and exploitation of this resource.
Cysticercosis caused by the metacestode larval stage of Taenia hydatigena formerly referred to as Cysticercus tenuicollis is a disease of veterinary importance that constitutes a significant threat to livestock production worldwide, especially in endemic regions due to condemnation of visceral organs and mortality rate of infected young animals. While the genetic diversity among parasites is found to be potentially useful in many areas of research including molecular diagnostics, epidemiology and control, that of T. hydatigena across the globe remains poorly understood. In this study, analysis of the mitochondrial DNA (mtDNA) of adult worms and larval stages of T. hydatigena isolated from dogs, sheep and a wild boar in China showed that the population structure consists of two major haplogroups with very high nucleotide substitutions involving synonymous and non-synonymous changes. Compared with other cestodes such as Echinococcus spp., the genetic variation observed between the haplogroups is sufficient for the assignment of major haplotype or genotype division as both groups showed a total of 166 point-mutation differences between the 12 mitochondrial protein-coding gene sequences. Preliminary analysis of a nuclear protein-coding gene (pepck) did not reveal any peculiar changes between both groups which suggests that these variants may only differ in their mitochondrial makeup.
Breeding for resistance to biotic stress and higher yield is a continuous process. Thus, the identification of desirable parents with good combining ability and nature of gene action for the target trait is of utmost importance. Hence, in this present investigation, 10 lines and three testers of Okra were crossed in line × tester mating design to generate 30 testcross progenies and their evaluation along with parents and check in a randomized complete block design with three replications. To depict the true picture of genetic variation among the parental genotypes, molecular diversity analysis was also carried out using genomic-simple sequence repeats before crossing to ascertain that sufficient variability is present among the parents. The molecular analysis grouped the parental genotypes into four clusters (I–IV). The analysis of variance revealed that all the treatments were significant for most of the traits. The combining ability analysis suggested Pusa A-4 as the best general combiner for earliness, Pusa Bhindi-5 for high yield, and DOV-92 for fruit length, plant height, yield per plant, and coefficient of infection for Yellow Vein Mosaic Virus Disease resistance. Similarly, the specific combining ability analysis suggested that the cross combinations DOV-92 × Pusa Bhindi-5 followed by DOV-92 × Pusa A-4 and DOV-92 × Pusa Sawani exhibit high economic heterosis for yield per plant as well as for disease resistance. Finally, estimation of the degree of dominance and predictability ratio was also worked out which indicated the prevalence of non-additive gene action for most of the traits pointing towards sufficient scope for heterosis breeding in Okra.
Most of the modern-day improved watermelon varieties succumb to various biotic and abiotic stresses mainly because of their narrow genetic base. Insights into the genetic diversity and population structure are crucial for broadening the genetic base and improving the adaptive value. The present experiment was conducted to study the genetic diversity and population structure of a germplasm panel comprising 336 Citrullus sp. accessions. Another objective was to formulate a core collection of Indian Citrullus sp. accessions. Data from 23 highly polymorphic microsatellite markers were used for genetic diversity and population structure analysis while both molecular and phenotypic data from 17 traits were used to formulate the core set. The markers yielded a total of 69 alleles with an average of three alleles per locus. Initially, the accessions clustered into two populations and an admixture group. Intra-population analysis revealed three and two statistically distinct subpopulations in Pop I and Pop II, respectively. The exotic collections were predominant in Pop I-A, Pop II-A and Pop II-B while the Indian accessions were preponderant in Pop I-B and Pop I-C. Pop I-B recorded the maximum magnitude of gene diversity and the highest number of alleles. The well-adapted Indian landraces could be deployed in future watermelon improvement programmes. The formulated core collection (n = 46; 23.71% of the entire collection studied) would ease in maintenance of the diversity present among indigenous Citrullus sp. accessions; would ease trait search while exploring Indian diversity and can be pooled with other collection(s) to form a global core of watermelon.
Jackfruit (Artocarpus heterophyllus Lam.) is a nutritious crop from the Moraceae family. The current study was undertaken to evaluate the phenotypic diversity of fruit characteristics using a set of 27 standardized fruit descriptors to describe 28 jackfruit genotypes. These data were used to identify the superior jackfruit genotype that could be used for commercial cultivation. The data revealed a wide range of differences among the genotypes for all the traits studied. Cluster analysis classified the genotypes into four major groups that confirmed the wide diversity among them. Principal component analysis (PCA) also revealed that 80.22% of the variability among the jackfruit genotypes was explained by the first five principal components (PCs). Based on the overall results, the Indian Council of Agricultural Research, Research Complex for Eastern Region (ICAR-RCER) JS 6/3 and 10/3 genotypes were found to be the most promising for table purposes (medium fruit size, pulp percentage >50 and total soluble solid (TSS) >20°Brix), whereas the ICAR-RCER JS 7/7 genotype with large fruit size, pulp percentage >50 and TSS >20°Brix was found to be suitable for processing. The coefficient of variation was the least for traits such as TSS (12.56%) and average seed length (13.56%). Hence, priority may also be given to the TSS and seed size when exploring promising genotypes and operating a selection procedure for crop improvement in jackfruit. The information generated under the study forms a potential baseline for fruit breeders to use in selecting genotypes with superior fruit qualities for jackfruit crop improvement programmes in the future.
The common kestrel is evaluated as Least Concern at global level. However, at the European level, the species is considered of conservation concern due to a continuous moderate decline since the 1980s due to agriculture intensification, landscape simplification, pesticide use and loss of nesting sites. Moreover, the conservation status of some subspecies of common kestrel appears problematic. This chapter discusses the conservation status of kestrel species and subspecies, and the main top-down and bottom-up factors that affect the viability and stability of their populations. It also points out the strong limitations of our knowledge about the density-dependent and independent processes that regulate the demography and dynamics of kestrel populations. Important conservation-related topics, such as urbanisation, pesticides, or use of artificial nest boxes, have been discussed in detail in prior chapters.
Cystic echinococcosis (CE) is one of the most common zoonotic diseases worldwide, particularly in rural areas. This study aimed at the identification of the genotype/species belonging to Echinococcus granulosus sensu lato (s.l.) specimens in retrieved percutaneously from the human host and to investigate their relationship with cyst characteristics. The genetic identification of cyst material was performed by mt-CO1 gene polymerase chain reaction, and confirmed via sequencing. A total of 110 CE cysts were identified as E. granulosus s.l. In detail, 104 belonged to E. granulosus sensu stricto (G1 and G3) and six isolates were in the E. canadensis cluster (G6/7). All clusters were tested for the relationship between demographics, cyst features and genetic diversity. The relationship between genetic variation and certain clinical characteristics such as cyst volume and location were statistically significant for G6/7 cluster. Further studies are required with a larger sample set to investigate the relationship between the genetic variability of E. granulosus s.l. and cyst features.
Understanding existing levels of genetic variability of camel populations is capital for conservation activities. This study aims to provide information on the genetic diversity of four dromedary populations, including Guerzni, Harcha, Khouari and Marmouri. Blood samples from 227 individuals belonging to the aforementioned populations were obtained and genotyped by 16 microsatellite markers. A total of 215 alleles were observed, with the mean number of alleles per locus being 13.4 ± 6.26. All loci were polymorphic in the studied populations. The average expected heterozygosity varied from a maximum of 0.748 ± 0.122 in Guerzni population to a minimum of 0.702 ± 0.128 in Harcha population; Guerzni population showed the highest value of observed heterozygosity (0.699 ± 0.088), whereas Harcha population the lowest (0.646 ± 0.130). Mean estimates of F-statistics obtained over loci were FIS = 0.0726, FIT = 0.0876 and FST = 0.0162. The lowest genetic distance was obtained between Guerzni and Khouari (0.023), and the highest genetic distance between Harcha and Marmouri (0.251). The neighbour-joining phylogenetic tree showed two groups of populations indicating a cluster of Guerzni, Khouari and Marmouri, and a clear isolation of Harcha. The genetic distances, the factorial correspondence analysis, the analysis of genetic structure and the phylogenetic tree between populations revealed significant differences between Harcha and other populations, and a high similarity between Guerzni, Khouari and Marmouri. It is concluded from this study that the camel genetic resources studied are well diversified. However, the herd management, especially the random selection of breeding animals, can increase the level of genetic mixing between different populations, mainly among Guerzni, Khouari and Marmouri, that live in the same habitat and grazing area.
Starch content is an important trait in barley. To evaluate the genetic diversity and identify molecular markers of starch content in barley, 40 cultivated barley genotypes collected from different regions, including genotypes whose starch content is at either the high or low end of the spectrum (15), were used in this study. All the genotypes were re-sequenced by the double-digest-restriction associated DNA sequencing method, and a total of 299,103 single-nucleotide polymorphism (SNP) markers were obtained. The genotypes were divided into four sub-populations based on FASTSTRUCTURE, principal component analysis and neighbour-joining tree analysis. All four sub-populations had a high linkage disequilibrium, especially group 3, whose members were recently bred for malting in the Jiangsu coastal area. The starch content of the barley lines was evaluated during three growing seasons (2014–2017), and the average values of starch content across the three growing seasons at the low and high ends were 51.5 and 55.0%, respectively. The starch content was affected by population structure, the barley in group 2 had a low starch content, while the barley in group 4 had a high starch content. Twenty-six SNP markers were identified as being significantly associated with starch content (P ⩽ 0.001) based on the average values across the three growing seasons using the mixed linear model method. These SNP markers were located on chromosomes 1H and 4H, and were considered loci of qSC1-1 and qSC4-1, respectively. The major identified QTLs for starch content are helpful for further research on carbohydrates and for barley breeding.
Calotropis procera is emerging as a new, yet undomesticated, resource of fibre comparable to cotton and kapok. Screening of efficient genotypes from its wild populations would be a useful pre-domestication process. The desired genotypes can then be improved through conventional breeding programmes to develop a domesticated variety. Molecular markers play a major role in modern breeding systems. Thus, an efficient marker resource for C. procera would prove useful in germplasm selection during breeding programmes. In this study, we undertook an initial step of Simple sequence repeats (SSR) marker development for C. procera, which could be applied for germplasm selection. Furthermore, using the developed markers, we assessed the genetic diversity base within its wild populations which could be useful to identify the hotspot areas of germplasm collection. Out of 94,636 de novo assembled transcripts, 9148 sequences were found to contain 12,884 SSRs at a density of 5.5 SSRs/Mb. Twelve SSRs were found as polymorphic with a mean polymorphic information content of 0.575. We observed a moderate level of genetic diversity (Na = 3.625, Ho = 0.58) in the studied populations. Mantel's test showed significant correlation between the geographic distance and the genetic distance (r = 0.147, P = 0.010). Sirsa was found as a genetically most diverse population followed by Barnala while Gurdaspur was found with the least genetic diversity. These genetically diverse populations can serve as an important resource for effective germplasm collection for breeding programmes.