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The growth of high-quality in vitro potato plants ( Solanum stenotomum subsp. stenotomum , Solanum stenotomum subsp. goniocalyx , and Solanum tuberosum subsp. andigena ) is affected by multiple biological, operational, and environmental factors. Research on in vitro culture is frequently focused on the species, explant, composition of the culture medium, and incubation conditions, but only limited information is available on the effect of the gas exchange rate and volume of in vitro culture vessels under variable planting densities. In the present study, these factors were evaluated with a set of seven diverse potato landraces. The results were compared to the plants' responses in routinely used in vitro culture vessels, i.e., 13 × 100 mm and 25 × 150 mm test tubes, and GA7 ® magenta vessels. In vitro potato plants grown in plastic vessels equipped with a HEPA filter delivering a high gas exchange rate developed thicker stems (0.95 mm), a higher total average leaf area (2.51 cm 2 ), increased chlorophyll content in leaves (32.2 ppm), and lower moisture content in their tissues (90.1%) compared to filter systems with lower gas exchange rates. A high planting density of 10 × 10 plants per vessel (360 and 870 mL) negatively affected the average stem width and root length but increased the plant height (3.4 cm). High fluctuations of ion-uptake of NO 3 - , Ca ++ , K + , and Na + were observed between genotypes, with some accessions having a 4.6-times higher Ca ++ -ion concentration in their tissues (190-234 ppm). The in vitro plants developed more robust stems, longer roots, and larger leaves within in vitro culture vessels equipped with a HEPA filter (high gas exchange rate) compared to the control vessels, in contrast to the chlorophyll content in leaves, which was higher in plants grown in narrow test tubes. Depending on the purpose of the subculture of in vitro plants, their growth and development can be molded using different gas exchange rates, planting densities, and vessel volumes.

Pigeonpea, a climate-resilient legume, is nutritionally rich and of great value in Asia, Africa, and Caribbean regions to alleviate malnutrition. Assessing the grain nutrient variability in genebank collections can identify potential sources for biofortification. This study aimed to assess the genetic variability for grain nutrients in a set of 600 pigeonpea germplasms conserved at the RS Paroda Genebank, ICRISAT, India. The field trials conducted during the 2019 and 2020 rainy seasons in augmented design with four checks revealed significant differences among genotypes for all the agronomic traits and grain nutrients studied. The germplasm had a wider variation for agronomic traits like days to 50% flowering (67-166 days), days to maturity (112-213 days), 100-seed weight (1.69-22.17 g), and grain yield per plant (16.54-57.93 g). A good variability was observed for grain nutrients, namely, protein (23.35-29.50%), P (0.36-0.50%), K (1.43-1.63%), Ca (1,042.36-2,099.76 mg/kg), Mg (1,311.01-1,865.65 mg/kg), Fe (29.23-40.98 mg/kg), Zn (24.14-35.68 mg/kg), Mn (8.56-14.01 mg/kg), and Cu (7.72-14.20 mg/kg). The germplasm from the Asian region varied widely for grain nutrients, and the ones from African region had high nutrient density. The significant genotype × environment interaction for most of the grain nutrients (except for P, K, and Ca) indicated the sensitivity of nutrient accumulation to the environment. Days to 50% flowering and days to maturity had significant negative correlation with most of the grain nutrients, while grain yield per plant had significant positive correlation with protein and magnesium, which can benefit simultaneous improvement of agronomic traits with grain nutrients. Clustering of germplasms based on Ward.D2 clustering algorithm revealed the co-clustering of germplasm from different regions. The identified top 10 nutrient-specific and 15 multi-nutrient dense landraces can serve as promising sources for the development of biofortified lines in a superior agronomic background with a broad genetic base to fit the drylands. Furthermore, the large phenotypic data generated in this study can serve as a raw material for conducting SNP/haplotype-based GWAS to identify genetic variants that can accelerate genetic gains in grain nutrient improvement., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Susmitha, Kalaimagal, Senthil, Vetriventhan, Manonmani, Jeyakumar, Anita, Reddymalla, Choudhari, Nimje, Peerzada, Arveti, Azevedo and Singh.)

Finger millet [ Eleusine coracana (L.) Gaertn.] is an important climate-resilient nutrient-dense crop grown as a staple food grain in Asia and Africa. Utilizing the full potential of the crop mainly depends on an in-depth exploration of the vast diversity in its germplasm. In this study, the global finger millet germplasm diversity panel of 314 accessions was genotyped, using the DArTseq approach to assess genetic diversity and population structure. We obtained 33,884 high-quality single nucleotide polymorphism (SNP) markers on 306 accessions after filtering. Finger millet germplasm showed considerable genetic diversity, and the mean polymorphic information content, gene diversity, and Shannon Index were 0.110, 0.114, and 0.194, respectively. The average genetic distance of the entire set was 0.301 (range 0.040 - 0.450). The accessions of the race elongata (0.326) showed the highest average genetic distance, and the least was in the race plana (0.275); and higher genetic divergence was observed between elongata and vulgaris (0.320), while the least was between compacta and plana (0.281). An average, landrace accessions had higher gene diversity (0.144) and genetic distance (0.299) than the breeding lines (0.117 and 0.267, respectively). A similar average gene diversity was observed in the accessions of Asia (0.132) and Africa (0.129), but Asia had slightly higher genetic distance (0.286) than African accessions (0.276), and the distance between these two regions was 0.327. This was also confirmed by a model-based STRUCTURE analysis, genetic distance-based clustering, and principal coordinate analysis, which revealed two major populations representing Asia and Africa. Analysis of molecular variance suggests that the significant population differentiation was mainly due to within individuals between regions or between populations while races had a negligible impact on population structure. Finger millet diversity is structured based on a geographical region of origin, while the racial structure made negligible contribution to population structure. The information generated from this study can provide greater insights into the population structure and genetic diversity within and among regions and races, and an understanding of genomic-assisted finger millet improvement., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Backiyalakshmi, Vetriventhan, Deshpande, Babu, Allan, Naresh, Gupta and Azevedo.)

Information on photoperiod and temperature sensitivity of sorghum germplasm is important to identify appropriate sources for developing cultivars with a broad adaptation. The sorghum mini core collection consisting of 242 accessions along with three control cultivars were evaluated for days to 50% flowering (DFL) and plant height in two long-day rainy and two short-day post-rainy seasons, and for grain yield and 100-seed weight in the two post-rainy seasons. Differences in DFL and cumulative growing degree days (CGDD) in the rainy and post-rainy seasons were used to classify the accessions for photoperiod and temperature sensitivity. Results revealed 18 mini core landraces as photoperiod and temperature insensitive (PTINS), 205 as photoperiod sensitive and temperature insensitive (PSTINS), and 19 as photoperiod and temperature-sensitive (PTS) sources. The 19 PTS sources and 80 PSTINS sources took less DFL in the long-day rainy seasons than in the short-day post-rainy season indicating their adaptation to the rainy season and a possible different mechanism than that trigger flowering in the short-day sorghums. In all three groups, several accessions with desirable combinations of agronomic traits were identified for use in the breeding programs to develop climate-resilient cultivars and for genomic studies to identify genes responsible for the photoperiod and temperature responses., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Upadhyaya, Vetriventhan and Azevedo.)

Germplasm should be conserved in such a way that the genetic integrity of a given accession is maintained. In most genebanks, landraces constitute a major portion of collections, wherein the extent of genetic diversity within and among landraces of crops vary depending on the extent of outcrossing and selection intensity infused by farmers. In this study, we assessed the level of diversity within and among 108 diverse landraces and wild accessions using both phenotypic and genotypic characterization. This included 36 accessions in each of sorghum, pearl millet, and pigeonpea, conserved at ICRISAT genebank. We genotyped about 15 to 25 individuals within each accession, totaling 1,980 individuals using the DArTSeq approach. This resulted in 45,249, 19,052, and 8,211 high-quality single nucleotide polymorphisms (SNPs) in pearl millet, sorghum, and pigeonpea, respectively. Sorghum had the lowest average phenotypic (0.090) and genotypic (0.135) within accession distances, while pearl millet had the highest average phenotypic (0.227) and genotypic (0.245) distances. Pigeonpea had an average of 0.203 phenotypic and 0.168 genotypic within accession distances. Analysis of molecular variance also confirms the lowest variability within accessions of sorghum (26.3%) and the highest of 80.2% in pearl millet, while an intermediate in pigeonpea (57.0%). The effective sample size required to capture maximum variability and to retain rare alleles while regeneration ranged from 47 to 101 for sorghum, 155 to 203 for pearl millet, and 77 to 89 for pigeonpea accessions. This study will support genebank curators, in understanding the dynamics of population within and among accessions, in devising appropriate germplasm conservation strategies, and aid in their utilization for crop improvement., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2020 Allan, Vetriventhan, Senthil, Geetha, Deshpande, Rathore, Kumar, Singh, Reddymalla and Azevedo.)

Pseudocercospora musae , causal agent of Sigatoka leaf spot, or yellow Sigatoka disease, is considered a major pathogen of banana ( Musa spp.). Widely disseminated in Brazil, this study explored the genetic diversity in field populations of the pathogen from production areas in the Distrito Federal and the States of Bahia, Minas Gerais, and Rio Grande do Norte. Resistance to demethylation inhibitor (DMI) fungicides was also examined. For 162 isolates from 10 banana growing regions, analysis of mating type idiomorph frequency was conducted, together with estimation of genetic diversity at 15 microsatellite loci. A total of 149 haplotypes were identified across the examined populations, with an average genetic diversity of 4.06. In general, populations displayed 1:1 proportions of idiomorphs MAT1-1 and MAT1-2, providing evidence for sexual recombination. Multilocus linkage disequilibrium also indicated asexual reproduction contributing to the genetic structure of certain populations. AMOVA revealed that 86.3% of the genetic differentiation of the pathogen occurred among isolates within populations. Discriminant Analysis of Principal Components (DAPC) identified six most probable genetic groups, with no population structure associated with geographic origin or collection site. Although genetic similarity was observed among certain populations from different states, data revealed increasing genetic differentiation with increasing geographic distance, as validated by Mantel's test ( r = 0.19, P < 0.001). On the basis of DMI fungicide sensitivity testing and CYP51 gene sequence polymorphism, isolates from the Distrito Federal separated into two main groups, one with generally higher EC 50 values against eight DMI fungicides. A clear phenotype-to-genotype relationship was observed for isolates carrying the CYP51 alteration Y461N. Conventionally adopted fungicides for control of Sigatoka leaf spot are likely to be overcome by combined sexual and asexual reproduction mechanisms in P. musae driving genetic variability. Continued analysis of pathogen genetic diversity and monitoring of DMI sensitivity profiles of Brazilian field populations is essential for the development of integrated control strategies based on host resistance breeding and rational design of fungicide regimes., (Copyright © 2020 Brito, Santos, Azevedo, Peixouto, de Oliveira, Ferreira, Haddad, Amorim, Fraaije and Miller.)

Plants of the genus Phyllanthus, principally Phyllanthus amarus, Phyllanthus urinaria, Phyllanthus niruri , and Phyllanthus tenellus, are used in Brazilian folk medicine to treat kidney stones as well as other ailments, where the latter two species are listed in the Brazilian Pharmacopeia as quebra-pedra ( stone-breaker ). However, only P. niruri has been shown to be effective in a clinical setting. Nuclear ribosomal internal transcribed spacer (ITS1 - 5.8S rRNA-ITS2), internal transcribed spacer 2, and chloroplasts rbc L, mat K, psb A- trn H, trn L, and trn L- trn F were screened for their potential as DNA barcodes for the identification of 48 Phyllanthus taxa in Brazilian medicinal plant germplasm banks and in "living pharmacies". The markers were also tested for their ability to validate four commercial herbal teas labelled as quebra-pedra . Using the criterion of high clade posterior probability in Bayesian phylogenetic analysis, the internal transcribed spacer, internal transcribed spacer 2, and chloroplast mat K, psb A- trn H, trn L, and trn L- trn F markers all reliably differentiated the four Phyllanthus species, with the internal transcribed spacer and mat K possessing the additional advantage that the genus is well represented for these markers in the Genbank database. However, in the case of rbc L, posterior probability for some clades was low and while P. amarus and P. tenellus formed monophyletic groups, P. niruri and P. urinaria accessions could not be reliably distinguished with this marker. Packaged dried quebra-pedra herb from three Brazilian commercial suppliers comprised P. tenellus , but one sample was also found to be mixed with alfalfa ( Medicago sativa ). An herb marketed as quebra-pedra from a fourth supplier was found to be composed of a mixture of Desmodium barbatum and P. niruri ., Competing Interests: The authors declare no conflict of interest., (Georg Thieme Verlag KG Stuttgart · New York.)

Brazil is one of the most biodiverse countries on Earth, holding ∼10% of the world's vascular plant species. Despite that, Brazilian agriculture is highly dependent on genetic resources originating from other countries. Embrapa (Brazilian Agricultural Research Corporation) is the governmental institution that, since 1973, has been responsible for the introduction and conservation of genetic resources in Brazil. In this article, we report on the experiences that Embrapa has faced over the past 45 years to build and improve a national network for the preservation of plant genetic resources under the coordination of Embrapa Genetic Resources & Biotechnology (CENARGEN), one of the 42 Embrapa decentralized units. The first network-based model, RENARGEN, initiated in 2003, was followed by the National Platform for Genetic Resources (Platform RG) in 2009; and from 2014 until today Embrapa manages the conservation of genetic resources through Portfolio REGEN, in which the plant component is called Plant Genetic Resources Network (RGV). This network covers activities of enrichment, conservation, characterization, and documentation of genebanks. Embrapa's plant genetic resources are conserved in active genebanks (AGs), in long-term seed bank (Colbase), and in vitro and DNA banks. In situ and on-farm conservation are also handled at Embrapa to complement and reinforce ex situ conservation. The latest survey reveals that Embrapa has 134 AGs with ∼150,000 accessions of 1130 plant species, 123,000 accessions of 735 species within Colbase, 1250 in vitro accessions, and 12,000 DNA samples. At least 65% of this collection is documented and available to the public in the Embrapa Alelo system, which also handles quarantine, germplasm exchange, and herbarium data. By the end of 2018, the public Alelo data will be automatically migrated to the Genesys system. In the last 40 years, ∼650,000 accessions have been exchanged by Embrapa, with 70% of them imported from other countries.

Due to the nutritional content and commercial value of its seeds, Bertholletia excelsa is one of the most important species exploited in the Amazon region. The species is hermaphroditic, insect pollinated, and its seeds are dispersed by barochory and animals. Because the fruit set is dependent on natural pollinator activity, gene flow plays a key role in fruit production. However, to date, there have been no studies on pollen and seed flow in natural populations of B. excelsa. Herein, we used microsatellite loci and parentage analysis to investigate the spatial genetic structure (SGS), realized pollen and seed dispersal, and effective pollen dispersal for two B. excelsa populations in the Brazilian Amazon forest. Two plots were established in natural forests from which adults, juveniles, and seeds were sampled. Realized and effective pollen flow was greater than realized seed flow. The distance of realized pollen dispersal ranged from 36 to 2060 m, and the distance of realized seed dispersal ranged from 30 to 1742 m. Both pollen and seeds showed a dispersal pattern of isolation by distance, indicating a high frequency of mating among near-neighbor trees and seed dispersal near to mother trees. Both populations present SGS up to 175 m, which can be explained by isolation by distance pollen and seed dispersal patterns. Our results suggested that fragmentation of these forest populations may result in a significant decrease in gene flow, due to the isolation by distance pollen and seed dispersal patterns.

The present study was carried out in a native Brazil nut tree population (Bertholletia excelsa Bonpl., Lecythidaceae) to assess its genetic diversity and structure. Ten microsatellite markers were used to genotype 198 adult trees (B. excelsa). The population presented high genetic diversity and inbreeding absence rates. The empirical Bayesian method showed three distinct groups in the structure of this population. Molecular analysis of variance showed 98% variability within groups, and 2% between groups. The genetic divergence (F ST ) indicated little difference between groups; thus, suggesting efficient gene flow between the analyzed B. excelsa adult trees.