Mechanistic understanding of iron toxicity tolerance in contrasting rice varieties from Africa: 1. Morpho-physiological and biochemical responses

Iron (Fe) is a fundamental element involved in various plant metabolic processes. However, when Fe uptake is excessive, it becomes toxic to the plant and disrupts cellular homeostasis. The aim of this study was to determine the physiological and biochemical mechanisms underlying tolerance to Fe toxicity in contrasting rice varieties adapted to African environments. Four varieties (CK801 and Suakoko 8 (tolerant), Supa and IR64 (sensitive)) selected from our previous work were analysed in more detail, and the first part of this study reports morphological, physiological and biochemical responses induced by Fe toxicity in these four varieties. Morphological (shoot length, root length, number of lateral roots), physiological (photosynthesis rate, stomatal conductance, transpiration rate, fluorescence, relative water content and cell membrane stability) and biochemical (tissue Fe, chlorophyll pigments, soluble sugars, protein and starch) traits were measured, as appropriate, on both shoot and root tissues and at different time points during the stress period. Fe toxicity significantly (P ≤ 0.05) reduced growth and metabolism of all the four varieties. Tolerant varieties showed more lateral roots than the sensitive ones, under Fe toxic conditions as well as higher photosynthesis rate, chlorophyll content and cell membrane stability. Strong dilution of Fe concentration in cells was identified, as one of the additional tolerance mechanisms used by CK801, whereas Suakoko 8 mainly used strong mobilisation of carbohydrates at the early stage of the stress period to anticipate metabolite shortage. Traits associated with Fe toxicity tolerance in this study could be specifically targeted in trait-based breeding programs of superior lowland rice varieties tolerant of Fe toxicity

The Influence of Storage Media, Storage Room, and Time of Storage on Propagules Viability of Rhizophora stylosa Griff

Indonesia as an archipelagic country has a coastline and partly overgrown with mangrove forest which is the dominant type of coastal areas. However, at present the mangrove forests have been degraded which causes a decrease in forest potency. The effort that can be done to improve the return potential of these mangrove forests is by rehabilitation of mangrove forest.  Rhizophora sp., including the type of  Rhizophora stylosa Griff., is a pioneer tree species in the mangrove forest which has an important meaning in the mangrove forest etablishment. The main problem of this type of R. Stylosa that is the seed classified into the recalcitrant ones. Therefore, the technique of seed storage is a very important activity to be developed for supporting the success of mangrove rehabilitation activities that have been degraded. The purpose of this study is to discover the influence of storage media, storage room, and time of storage on the propagule viability of R. stylosa, and to compare the R. stylosa propagule germination potential between cutting test and directly propagule germination test results. The research was conducted at the greenhouse and Silviculture Laboratory, Faculty of Forestry IPB and Seed Technology Research Institute Laboratory (BPTP), Bogor

GENETIC DIVERSITY AND ECO-GEOGRAPHICAL DISTRIBUTION OF ELEUSINE SPECIES COLLECTED FROM ETHIOPIA

Eleusine is a small grass genus with three basic chromosome numbers (x=8, 9 and 10) and comprises of eight species including E. coracana subsp. coracana, (finger millet), which is an important subsistence crop in Africa and India. Research on these species could assist the development of high yielding and multiple stress tolerant variety(s) of the cultivable species, and also guide development of strategic genetic resource management and utilisation of the genus. A total of 72 accessions, sampled from five major species, E. coracana (including both E. coracana subsp. coracana and E. coracana subsp. africana), E. intermedia, E. indica, E. multiflora and E. floccifolia were analysed for genetic variation and inter-relationships using 20 microsatellite markers. All the SSR markers displayed high genetic polymorphism, with polymorphic information content ranging from 0.46 (UGEP110) to 0.91 (UGEP66). A total of 286 alleles were observed with an average of 14.3 alleles per locus. Classic F-statistics revealed the highest intra-specific polymorphism recorded for E. africana (32.45%), followed by E. coracana (16.83%); implying that genetic polymorphism is higher in the cultivable subspecies and its wild relatives, than the other species. Allelic frequency based inter-species genetic distance analysis, showed wider genetic distance between E. indica and E. multiflora (0.719); a narrow genetic distance between E. coracana sub-species africana and E. coracana subspecies coracana (0.3297). The weighted neighbor joining-based clustering revealed that the majority of the accessions in a species share strong similarity and are grouped together than do accessions of inter species.Eleusine est une herbe avec trois nombres de chromosomes de base (x=8, 9 et 10) et comprend huit esp\ue8ces dont E. coracana subsp. coracana, (finger millet), qui est une culture de subsistence importante en Afrique et en Inde. La recherche sur ces esp\ue8ces pourrait aider dans le d\ue9veloppement des vari\ue9t\ue9s d\u2019esp\ue8ces cultivables \ue0 rendement \ue9lev\ue9 et de tol\ue9rance aux stress multiples, et guider le d\ue9veloppement de la gestion des ressources g\ue9n\ue9tiques strat\ue9giques et l\u2019utilisation du genus. Un total de 72 accessions \ue9chantillonn\ue9es de cinq esp\ue8ces majeurs \ue0 savoir E. coracana (incluant E. coracana subsp. coracana et E. coracana subsp. africana), E. intermedia, E. indica, E. multiflora et E. floccifolia \ue9taient analys\ue9es pour variation g\ue9n\ue9tique et relations mutuelles utilisant 20 marqueurs microsatellites. Tous les marquers SSR ont manifest\ue9 un polymorphisme g\ue9n\ue9tique \ue9lev\ue9, avec un contenu d\u2019information polymorphique allant de 0.46 (UGEP110) \ue0 0.91 (UGEP66). Un total de 286 all\ue8les \ue9tait observ\ue9 avec une moyenne de 14.3 all\ue8les par locus. Les statistiqies classiques F ont r\ue9v\ue9l\ue9 le polymorphisme intrasp\ue9cifique le plus \ue9lev\ue9 enregistr\ue9 pour le E. africana (32.45%), suivi de E. coracana (16.83%), ce qui implique que le polymorphisme g\ue9n\ue9tique est le plus \ue9lev\ue9 dans les sous esp\ue8ces cultivables et ses homologues sauvages que les autres esp\ue8ces. L\u2019analyse de la fr\ue9quence all\ue9lique de la distance g\ue9n\ue9tique entre esp\ue8ces a montr\ue9 une plus large distance g\ue9n\ue9tique entre E. indica et E. multiflora (0.719); une \ue9troite distance g\ue9n\ue9tique entre les sous esp\ue8ces Africana de E. coracana et les sous esp\ue8ces coracana de E. coracana (0.3297). La pond\ue9ration des groupements a r\ue9v\ue9l\ue9 que la majorit\ue9 des accessions au sein d\u2019une esp\ue8ce partage une forte similarit\ue9 et sont group\ue9es ensemble en comparaison aux accessions des intra-esp\ue8ces

COVID-19, A Global Health Concern Requiring Science-Based Solutions

Scientifically-based concrete action points to reduce the spread, lessen the impact, reduce the concerns of the wider population, and avoid further outbreaks for governments, organizations, and individuals are neededFinal Published versio

Novel sources of resistance to blast disease in finger millet

Finger millet (Eleusine coracana(L.) Gaertn. subsp.coracana) is the most importantmillet in eastern Africa and perhaps the oldest domesticated cereal grain in Africa.One of the major factors limiting finger millet production is blast disease caused bythe fungusMagnaporthe grisea. Crop wild relatives and landraces present a poten-tial source of novel genes. This study investigated the response of cultivated and wildrelatives of finger millet to an isolate of blast disease from western Kenya. Previousgermplasm collections were purified through two generations of single-seed descentbefore screening alongside improved and farmer-preferred varieties (FPVs) under ascreen house across three seasons. Farmer-preferred varieties were identified throughparticipatory varietal selection (PVS). The plants were inoculated twice during eachgrowth period using hand-spraying method and data on disease incidence recorded atgrain-filling stage. Genotypic data was generated using diversity arrays technology(DArT) sequencing and data analysis done using Genstat 18.2 and TASSEL 5.2.58.We observed high heritability (81%), indicating that the variation observed was pre-dominantly genetic. Wild accessions were generally more resistant to the disease incomparison to the cultivated accessions. Preliminary genome-wide association study(GWAS) using general linear model with principal component analysis led to theidentification of 19 markers associated with blast disease that will be be developedinto assays for genotype quality control and trait introgression. Wild accessions andlandraces of finger millet present a good reservoir for novel genes that can be incor-porated into crop improvement programs

Predators of Anopheles gambiae sensu lato (Diptera: Culicidae) larvae in Wetlands, Western Kenya: Confirmation by polymerase chain reaction method

Polymerase chain reaction analysis was performed to determine whether mosquito predators in wetland habitats feed on Anopheles gambiae sensu lato (s.l.) larvae. Aquatic mosquito predators were collected from six wetlands near Lake Victoria in Mbita, Western Kenya. This study revealed that the whole positive rate of An. gambiae s.l. from 330 predators was 54.2%. The order of positive rate was the highest in Odonata (70.2%), followed by Hemiptera (62.8%), Amphibia (41.7%), and Coleoptera (18%). This study demonstrates that the polymerase chain reaction method can determine whether aquatic mosquito predators feed on An. gambiae s.l. larvae if the predators have undigested An. gambiae s.l. in their midgut or stomach

Identification of SNP and SSR Markers in Finger Millet Using Next Generation Sequencing Technologies

Finger millet is an important cereal crop in eastern Africa and southern India with excellent grain storage quality and unique ability to thrive in extreme environmental conditions. Since negligible attention has been paid to improving this crop to date, the current study used Next Generation Sequencing (NGS) technologies to develop both Simple Sequence Repeat (SSR) and Single Nucleotide Polymorphism (SNP) markers. Genomic DNA from cultivated finger millet genotypes KNE755 and KNE796 was sequenced using both Roche 454 and Illumina technologies. Non-organelle sequencing reads were assembled into 207 Mbp representing approximately 13% of the finger millet genome. We identified 10,327 SSRs and 23,285 non-homeologous SNPs and tested 101 of each for polymorphism across a diverse set of wild and cultivated finger millet germplasm. For the 49 polymorphic SSRs, the mean polymorphism information content (PIC) was 0.42, ranging from 0.16 to 0.77. We also validated 92 SNP markers, 80 of which were polymorphic with a mean PIC of 0.29 across 30 wild and 59 cultivated accessions. Seventy-six of the 80 SNPs were polymorphic across 30 wild germplasm with a mean PIC of 0.30 while only 22 of the SNP markers showed polymorphism among the 59 cultivated accessions with an average PIC value of 0.15. Genetic diversity analysis using the polymorphic SNP markers revealed two major clusters; one of wild and another of cultivated accessions. Detailed STRUCTURE analysis confirmed this grouping pattern and further revealed 2 sub-populations within wild E. coracana subsp. africana. Both STRUCTURE and genetic diversity analysis assisted with the correct identification of the new germplasm collections. These polymorphic SSR and SNP markers are a significant addition to the existing 82 published SSRs, especially with regard to the previously reported low polymorphism levels in finger millet. Our results also reveal an unexploited finger millet genetic resource that can be included in the regional breeding programs in order to efficiently optimize productivity

Revised age and stratigraphy of the classic Homo erectus-bearing succession at Trinil (Java, Indonesia)

Obtaining accurate age control for fossils found on Java (Indonesia) has been and remains challenging due to geochronologic and stratigraphic uncertainties. In the 1890s, Dubois excavated numerous faunal fossils—including the first remains of Homo erectus—in sediments exposed along the Solo River at Trinil. Since then, various, and often contradictory age estimates have been proposed for the Trinil site and its fossils. However, the age of the fossil-bearing layers and the fossil assemblage remains inconclusive. This study constructs a chronostratigraphic framework for the Trinil site by documenting new stratigraphic sections and test pits, and by applying 40Ar/39Ar, paleomagnetic, and luminescence (pIRIR290) dating methods. Our study identifies two distinct, highly fossiliferous channel fills at the Trinil site. The stratigraphically lower Bone-Bearing Channel 1 (BBC-1) dates to 830–773 ka, while Bone-Bearing Channel 2 (BBC-2) is substantially younger with a maximum age of 450 ± 110 ka and an inferred minimum age of 430 ± 50 ka. Furthermore, significantly younger T2 terrace deposits are present at similar low elevations as BBC-1 and BBC-2. Our results demonstrate the presence of Early and Middle Pleistocene, and potentially even late Middle to Late Pleistocene fossiliferous sediments within the historical excavation area, suggesting that Dubois excavated fossils from at least three highly fossiliferous units with different ages. Moreover, evidence for reworking suggests that material found in the fossil-rich strata may originate from older deposits, introducing an additional source of temporal heterogeneity in the Trinil fossil assemblage. This challenges the current assumption that the Trinil H.K. fauna –which includes Homo erectus-is a homogeneous biostratigraphic unit. Furthermore, this scenario might explain why the Trinil skullcap collected by Dubois is tentatively grouped with Homo erectus fossils from Early Pleistocene sediments at Sangiran, while Trinil Femur I shares affinities with hominin fossils of Late Pleistocene age

Multimodal pyrethroid resistance in malaria vectors, Anopheles gambiae s.s., Anopheles arabiensis, and Anopheles funestus s.s. in western Kenya.

Anopheles gambiae s.s., Anopheles arabiensis, and Anopheles funestus s.s. are the most important species for malaria transmission. Pyrethroid resistance of these vector mosquitoes is one of the main obstacles against effective vector control. The objective of the present study was to monitor the pyrethroid susceptibility in the 3 major malaria vectors in a highly malaria endemic area in western Kenya and to elucidate the mechanisms of pyrethroid resistance in these species. Gembe East and West, Mbita Division, and 4 main western islands in the Suba district of the Nyanza province in western Kenya were used as the study area. Larval and adult collection and bioassay were conducted, as well as the detection of point mutation in the voltage-gated sodium channel (1014L) by using direct DNA sequencing. A high level of pyrethroid resistance caused by the high frequency of point mutations (L1014S) was detected in An. gambiae s.s. In contrast, P450-related pyrethroid resistance seemed to be widespread in both An. arabiensis and An. funestus s.s. Not a single L1014S mutation was detected in these 2 species. A lack of cross-resistance between DDT and permethrin was also found in An. arabiensis and An. funestus s.s., while An. gambiae s.s. was resistant to both insecticides. It is noteworthy that the above species in the same area are found to be resistant to pyrethroids by their unique resistance mechanisms. Furthermore, it is interesting that 2 different resistance mechanisms have developed in the 2 sibling species in the same area individually. The cross resistance between permethrin and DDT in An. gambiae s.s. may be attributed to the high frequency of kdr mutation, which might be selected by the frequent exposure to ITNs. Similarly, the metabolic pyrethroid resistance in An. arabiensis and An. funestus s.s. is thought to develop without strong selection by DDT