Plant breeding reduces the genetic diversity of plants and could influence the composition, structure, and diversity of the rhizosphere microbiome, selecting more homogeneous and specialized ...microbes. In this study, we used 16S rRNA sequencing to assess the bacterial community in the rhizosphere of different lines and modern cowpea cultivars, to investigate the effect of cowpea breeding on bacterial community assembly. Thus, two African lines (IT85F-2687 and IT82D-60) and two Brazilian cultivars (BRS-Guariba and BRS-Tumucumaque) of cowpea were assessed to verify if the generation advance and genetic breeding influence the bacterial community in the rhizosphere. No significant differences were found in the structure, richness, and diversity of bacterial community structure between the rhizosphere of the different cowpea genotypes, and only slight differences were found at the OTU level. The complexity of the co-occurrence network decreased from African lines to Brazilian cultivars. Regarding functional prediction, the core functions were significantly altered according to the genotypes. In general, African lines presented a more abundance of groups related to chemoheterotrophy, while the rhizosphere of the modern cultivars decreased functions related to cellulolysis. This study showed that the genetic breeding process affects the dynamics of the rhizosphere community, decreasing the complexity of interaction in one cultivar. As these cowpea genotypes are genetically related, it could suggest a new hypothesis of how genetic breeding of similar genotypes could influence the rhizosphere microbiome.
Phytotoxicity and cytogenotoxicity of composted tannery sludge de Moraes Cunha Gonçalves, Matheus; de Almeida Lopes, Angela Celis; Gomes, Regina Lucia Ferreira ...
Environmental science and pollution research international,
09/2020, Letnik:
27, Številka:
27
Journal Article
Recenzirano
Tannery sludge (TS) contains high levels of organic matter and chemical elements, mainly chromium (Cr). This can increase its toxicity, rendering it unsuitable for application to soil. However, ...composting has been proposed as an alternative method for detoxifying TS before its addition to soil. Thus, the aim of this study was to evaluate the phytotoxic and cytogenotoxic potential of untreated (TS) and composted (CTS) tannery sludge in solid and solubilized samples. Seed germination and root growth bioassays were performed with
Lactuca sativa
, while chromosomal aberrations were assessed using the
Allium cepa
bioassay. In solid samples, the
L. sativa
bioassay showed that TS adversely affected germination and root growth, while CTS had a negative affect only on root growth. In solubilized samples, only TS showed significant adverse effects on seed germination and root growth. In both solid and solubilized samples, TS and CTS showed cytotoxic, genotoxic, and mutagenic effects on
A. cepa
. Thus, results demonstrated that the composting of TS does not result in its complete detoxification. For this reason, TS and CTS cannot be recommended for agricultural use, since they may increase the risk of environmental contamination and crop damage.
ABSTRACT Some germplasm collections have a high number of accessions, which makes it difficult to explore the genetic variability present in the germplasm bank due to the redundancy and the ...difficulty of detailed analysis of all conserved accessions. Therefore, our study aimed to analyze the genetic diversity of 153 lima bean (Phaseolus lunatus) accessions for the purpose of constructing a core collection. Eleven SSRs were used for this purpose. The 153 lima bean accessions can be represented by low redundancy using a minimum of 34 accessions, thus representing 22 % of the size of the entire germplasm bank. The core collection had a higher Shannon diversity index and expected heterozygosity (1.906 and 0.811, respectively) than those presented by the entire germplasm bank (1.605 and 0.713, respectively), indicating a higher polymorphism of the representative cultivars in relation to the entire collection. The accessions selected for the core collection may be used in future studies of genome association as well as in genetic crosses in breeding programs aimed at developing improved cultivars with high genetic diversity which can meet current and future market needs.
Biodiversity underlies ecosystem functioning. While aboveground biodiversity is often well studied, the belowground microbiome, in particular protists, remains largely unknown. Indeed, holistic ...insights into soil microbiome structures in natural soils, especially in hyperdiverse biomes such as the Brazilian Cerrado, remain unexplored. Here, we study the soil microbiome across four major vegetation zones of the Cerrado, ranging from grass-dominated to tree-dominated vegetation with a focus on protists. We show that protist taxon richness increases towards the tree-dominated climax vegetation. Early successional habitats consisting of primary grass vegetation host most potential plant pathogens and least animal parasites. Using network analyses combining protist with prokaryotic and fungal sequences, we show that microbiome complexity increases towards climax vegetation. Together, this suggests that protists are key microbiome components and that vegetation succession towards climax vegetation is stimulated by higher loads of animal and plant pathogens. At the same time, an increase in microbiome complexity towards climax vegetation might enhance system stability.
Cajui (Anacardium spp.) is a native fruit tree (small cashew) of the Brazilian Cerrado and possesses the potential for commercialization. However, cajui exploitation occurs exclusively through ...extractivism in the absence of conservation strategies. The lack of conservation strategies may lead to a decrease in genetic diversity of Anacardium. In this work, the genetic diversity and population structure of three natural populations in Sete Cidades National Park (PNSC; PI, Brazil) were assessed using ISSR analysis of 56 cajui accessions and two A. occidentale accessions (outgroup) from Pacajus (CE, Brazil). A total of 112 markers were obtained, 93 (83.04%) of which were polymorphic. The diversity indices of these populations indicated moderate levels of genetic diversity. According to AMOVA, 96.17% of the genetic variability lay within populations, with low genetic differentiation among populations (ΦST = 0.03828). Furthermore, STRUCTURE analysis indicated the existence of four connected genetic groups. The findings show that the individuals from the three collection sites did not represent different subpopulations, likely due to the high gene flow (Nm = 6.7) favored by the floral biology of Anacardium, pollinators and small-animal seed dispersers. This research identifies genetically divergent individuals (C-03, C-05, C-22, C-26, C-34 and C-39), which should be considered priority individuals for conservation and can inform conservation programs for Anacardium spp.
The red spider mite,
(Acari: Tetranychidae) can be an important pest on lima bean (
L.). Thus, the objective of this work was to assess the antibiosis and antixenosis effects of lima bean genotypes ...on
, through the evaluation of performance parameters as well as the host preference for food and oviposition. Nine lima bean genotypes from the Active Bank of Germplasm of the Federal University of Piauí - BGP / UFPI were screened. To assess antibiosis parameters, eggs of
were individually placed on leaf disks of each genotype. The period and survival of the different stages of development (larvae, protonymph, deutonymph and adult), pre-oviposition, oviposition and post-oviposition period, longevity and fecundity of females were evaluated, and fertility life table parameters were calculated. In choice tests, adult females of
were used. The numbers of mites and eggs were counted for each genotype. The protonymph, egg-adult, longevity and oviposition period, fertility life table parameters, as well as the food and oviposition preference were affected by lima bean genotypes. We found that some genotypes reduced adult female longevity, increased the larval and egg-adult period, decreased oviposition period, negatively affected the fertility life table parameters, reducing the net reproductive rate (R
), the intrinsic rate of increase (r
) and the finite rate of increase (
), while increasing the population doubling time (DT), exhibiting a reliable antibiosis effect upon
. Nevertheless, these same genotypes were the most preferred for food and oviposition. By contrast, some other genotypes reduced the adult female longevity and oviposition period, elongated the larval period and affected fertility life table parameters, demonstrating an antibiosis effect upon
Moreover, these other genotypes were among the less preferred for food and oviposition, exhibiting an additional antixenosis effect. Thus, our results demonstrate that the genotypes of lima bean may present distinct levels of resistance to
, and this resistance may be an important tool for Integrated Pest Management. This is one of the first studies aiming to describe mite resistance sources in lima bean.
Phaseolus lunatus
(Lima bean) is an important legume for the poor population of the Brazilian northeast region. The legume is able to take advantage of the nitrogen fixation process, but the ...diversity of indigenous microsymbionts is poorly known. In this study, 29 bacteria isolated from root nodules of
P. lunatus
inoculated under greenhouse conditions with soils from Piauí State, in the northeast semi-arid region of Brazil, were obtained and characterized. Classical morphological and biochemical essays revealed high phenotypic diversity, splitting the bacteria into four clusters. Genetic fingerprinting by BOX-PCR indicated outstanding diversity, with the 29 strains positioned in 19 different clusters with 30% of final similarity. Nine genera were confirmed in the analysis of the 16S rRNA gene, with two typical nodulating N
2
-fixing clades,
Bradyrhizobium
and
Agrobacterium/Rhizobium,
accounting for 38% and 21% of the isolates, respectively; the results were confirmed with the housekeeping
gyrB
gene, that also indicated putative new species.
Bradyrhizobium
was confirmed as the main symbiont, being present in nodules of all plants. All rhizobia except for those with higher resemblance to agrobacteria carry
nifH
genes. Six other genera were isolated as nodules endophytes,
Bacillus, Burkholderia, Enterobacter, Franconibacter, Pseudomonas
and
Williamsia
. Several of these endophytes exhibited one or more important biochemical properties, such as the synthesis of catalase, gelatinase and the ability to solubilize phosphate, that might confer ecological advantages to the rhizobia associated with them in the harsh environment of the Brazilian semi-arid, explaining the high rate of co-infection detected in the nodules.
The rhizosphere, i.e. the interface between plant roots and soil, harbors complex bacterial communities that can influence plant growth. Different plant species can have a distinct influence on the ...bacterial assembly. However, genetic traits found in the same plant species, i.e. different plant genotypes, can also drive bacterial communities in rhizosphere. In this study, bacterial communities in a sandy soil (Fluvisol) and rhizosphere of four lima bean (Phaseolus lunatus) genotypes were assessed by 16S rRNA gene sequencing. In general, Proteobacteria (23.3%), Actinobacteria (20.6%) and Firmicutes (12%) were the most dominant phyla in all samples. We found a distinct microbial structure between genotypes and bulk soil, with an increase of Proteobacteria and Actinobacteria, and a decrease of Firmicutes in the rhizosphere compared to the bulk soil. Also, the results showed that different biological and chemical drivers of each lima bean genotype influenced bacterial structure. Interestingly, each genotype enriched specific microbial taxa in rhizosphere. Our data revealed that plants influenced bacterial assembly in rhizosphere even at a genotype level. The findings gathered in this study can contribute to identify some specific bacterial groups associated with distinct genotypes of lima bean and can drive further studies about the contribution of these bacterial groups on lima bean growth.
•Lima bean genotypes enriched specific microbial taxa in the rhizosphere.•Plants influenced bacterial assembly in rhizosphere even at a genotype level.•High taxonomical level showed a microbial core among lima bean cultivars.
Geraniums (
Pelargonium
spp.) are ornamental plants that are widely popular because of their abundant flowering, color variability, different flower patterns, and ease of cultivation. Genetic ...breeding of this species aims to reduce the plant size and flower color. The objective of this study was to carry out morphoagronomic characterization of parents and F
1
hybrids and to estimate the combined capacity and hybrid performance in the circulating diallel in F
2
geranium (
Pelargonium
sp.). We obtained 18 and 275 plants from the F
1
and F
2
generations, respectively. Characterization of the parental genotypes and F
1
and F
2
hybrids was performed based on the descriptors for
Pelargonium
. Parents and F
1
hybrids were grouped using the Tocher and UPGMA methods and diallel analyses in the F
2
generation. The F
1
hybrids G8, G11, and G17 exhibited color combinations suitable for commercialization and are promising for inclusion in breeding programs. The effects of general combining ability (GCA) and specific combining ability (SCA) were significant for these traits were also significant. The results showed the presence of both additive and non-additive genes. However, non-additive and dominant genes were predominant in most characteristics studied. Diallel analysis of the F
2
hybrids revealed that the best hybrid combinations for reducing plant height were 14 × 11, 14 × 13, and 15 × 12. Therefore, the implementation and use of diallel analysis were efficient in selecting superior parental genotypes and producing hybrids with high yields.
Lima bean (Phaseolus lunatus L.) is an important source of protein for people as it contributes all of the essential amino acids necessary for humans. In Brazil, lima bean has a great relevance, ...mainly in the Northeast, where it is an alternative income in addition to a food source. It has a high degree of phenotypic variation for seed traits, which are important for understanding the genetic diversity and origin of this crop. We aimed to characterize 166 accessions of cultivated lima bean from Brazil using qualitative and quantitative descriptors through the Ward-MLM (Modified Location Model) in order to analize the organization of the genetic diversity and the origin of this germplasm. High genetic variability was detected and seed length and width characteristics were the main contributors to genetic divergence among the accessions. Results showed the presence of accessions with characteristics typical of the Mesoamerican and Andean gene pools, and another group with intermediate characteristics of these two gene pools. Our results will be useful to breeding programs, since currently there is little information on the genetic diversity and the origin of the lima bean landraces cultivated in Brazil.
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