International Crops Research Institute for the Semi-Arid Tropics
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Soybean F-Box-Like Protein GmFBL144 Interacts With Small Heat Shock Protein and Negatively Regulates Plant Drought Stress Tolerance
Get PDFThe F-box gene family is one of the largest gene families in plants. These genes regulate plant growth and development, as well as biotic and abiotic stress responses, and they have been extensively researched. Drought stress is one of the major factors limiting the yield and quality of soybean. In this study, bioinformatics analysis of the soybean F-box gene family was performed, and the role of soybean F-box-like gene GmFBL144 in drought stress adaptation was characterized. We identified 507 F-box genes in the soybean genome database, which were classified into 11 subfamilies. The expression profiles showed that GmFBL144 was highly expressed in plant roots. Overexpression of GmFBL144 increased the sensitivity of transgenic Arabidopsis to drought stress. Under drought stress, the hydrogen peroxide (H2O2) and malonaldehyde (MDA) contents of transgenic Arabidopsis were higher than those of the wild type (WT) and empty vector control, and the chlorophyll content was lower than that of the control. Y2H and bimolecular fluorescence complementation (BiFC) assays showed that GmFBL144 can interact with GmsHSP. Furthermore, our results showed that GmFBL144 can form SCFFBL144 (E3 ubiquitin ligase) with GmSkp1 and GmCullin1. Altogether, these results indicate that the soybean F-box-like protein GmFBL144 may negatively regulate plant drought stress tolerance by interacting with sHSP. These findings provide a basis for molecular genetics and breeding of soybean
BSA-seq Identifies a Major Locus on Chromosome 6 for Root-Knot Nematode (Meloidogyne graminicola) Resistance From Oryza glaberrima
Get PDFRoot-knot nematode (Meloidogyne graminicola) is one of the emerging threats to rice production worldwide that causes substantial yield reductions. There is a progressive shift of the cropping system from traditional transplanting to direct-seeded water-saving rice production that favored the development of M. graminicola. Scouting and deploying new resistance genes is an economical approach to managing the root-knot nematodes. Here, we report that the inheritance of root-knot nematode resistance in Oryza glaberrima acc. IRGC102206 is governed by a single dominant gene. Traditional mapping coupled with BSA-seq is used to map nematode resistance gene(s) using the BC1F1 population derived from a cross of O. sativa cv. PR121 (S) and O. glaberrima acc. IRGC102206 (R). One major novel genomic region spanning a 3.0-Mb interval on chromosome 6 and two minor QTLs on chromosomes 2 and 4 are the potential genomic regions associated with rice root-knot nematode resistance. Within the QTL regions, 19 putative candidate genes contain 81 non-synonymous variants. The detected major candidate region could be fine mapped to accelerate marker-assisted breeding for root-knot nematode resistance in rice
Improving the productivity of millet based cropping systems in the West African Sahel: Experiences from a long-term experiment in Niger
Get PDFResource-poor farmers who are living in the harsh environments of the West African Sahel (WAS) depend on
subsistence orientated, low-input farming systems for meeting their livelihood needs. These largely extractive
farming systems have resulted in nutrient depletion, soil fertility decline, low productivity and land degradation.
A study conducted over 25 years in Niger, aimed to evaluate the long-term effects of organic and mineral fertilizers,
cropping systems (CS) of millet and cowpea on crop productivity. The traditional millet/cowpea intercrop
system without P fertilizer (TrM/C) was compared with four improved CS receiving P fertilizer: sole millet
(MM), millet/cowpea intercrop (M/C), millet-cowpea rotation (M-C), and M/C and rotation with cowpea (M/CC).
Nitrogen fertilizer (N) and the residues of millet (CR) were applied alone or in combination in all five
cropping systems. CR were always applied as mulch. The traditional system (TrM/C) produced the lowest millet
grain yields (GY) (0.02–0.43 t/ha). All the four improved CS (MM, M/C, M-C and M/C-C) increased GY compared
with the traditional system (TrM/C). The M/C and MM systems increased millet GY 3 and 3.3 times compared
with the TrM/C, respectively. The M/C-C and M-C systems produced 4 and 4.2 times more GY than that of the
TrM/C system, respectively. The lowest revenue was obtained with the TrM/C system. Except for the TrM/C, the
revenue of the MM system was lower compared with combined cultivation of millet and cowpea. Compared with
the TrM/C system, M/C and M/C-C provided 2 times more revenue. By providing 2.4 times more revenue than
the TrM/C system, the M-C system was the most productive system. Cowpea provided from 54% and 56% of the
revenue in M/C-C and M-C system, respectively. Soil organic carbon decreased in all the CS from 46% to 63%
compared with the soil kept under natural vegetation fallow. The improved CS increased soil P from 3.4 to 4
times. Over the 25 years of cropping, the highest millet yields were obtained with the lower levels of rainfall
indicating the role of nutrients in the system. The four improved systems maintained millet yields over the 25
years of cropping. By improving water and nutrient use efficiency, integrated management of mineral fertilizers,
CR and cowpea affected more crop productivity than the rainfall. We concluded that cereal-legume based
cropping systems treated with small doses of mineral fertilizers and CR could be used for sustainable management
of soil fertility in low-input farming systems
Redox imbalance disrupts spikelet fertility in rice: A study under stage-specific and multi-stage drought in eastern Indo-Gangetic plain
No full textTo support the increasing food demand of the drought-prone eastern Indo-Gangetic plain (EIGP), we assessed the effects of natural drought stress on the individual (seedling stage drought; SSD, vegetative stage drought; VSD, reproductive stage drought; RSD) as well as the multiple growth stages (multi-stage drought; MSD) of twenty-four rice genotypes (n = 24) under field conditions for two consecutive rice growing seasons (2019–2020). High temperature and low rainfall during both the trial years exerted moderate to severe drought stress to the rice genotypes leading to average grain yield reduction of 43.5%, 28.9%, 59.3%, and 69.9% under SSD, VSD, RSD, and MSD conditions, respectively. The present study also revealed that drought stress caused enhanced accumulation of reactive oxygen species (ROS) in the spikelets of rice genotypes thereby, impeding the spikelet fertility. The promising rice genotypes showed an average decrease of 3.18%, 4.83%, 13.9%, and 13.06% in spikelet fertility under SSD, VSD, RSD, and MSD conditions, respectively. Identified promising rice genotypes, IR83929-B-B-291–2–1–1–2, IR93827–29–1–1–2 and IR84899-B-183–20–1–1–1 showed extreme drought tolerance and better maintained photosynthetic rate, stomatal conductance, relative water content, membrane stability index, and total chlorophyll content under drought conditions irrespective of growth stages. Following the study, drought tolerance in the tolerant rice genotypes was associated with increased antioxidant enzyme mediated efficacious ROS detoxification, which contributed in maintaining pollen viability and spikelet fertility. Overall, the study identified drought tolerant rice genotypes for EIGP and established a comprehensive understanding of the complexity and plasticity of the rice genotypes under stage-specific and cumulative drought stress
Apoptotic‑like PCD inducing HRC gene when silenced enhances multiple disease resistance in plants
Get PDFProgrammed cell death (PCD) plays an important role in plant environmental stress and has the potential to be manipulated to enhance disease resistance. Plants have innate immunity and, following pathogen perception, the host induces a Hypersensitive Response PCD (HR-PCD), leading to pattern (PTI) or effector triggered immunity (ETI). Here we report a non-HR type or Apoptotic-Like PCD (AL-PCD) in pathogen infected wheat and potato based on apoptotic-like DNA fragmentation. A deletion mutation in the gene encoding histidine rich calcium binding protein (TaHRC) in FHB-resistant wheat (R-NIL) failed to induce AL-PCD. Similarly, the CRISPR-Cas9 based silencing of StHRC gene in Russet Burbank potato failed to induce apoptotic-like DNA fragmentation, proved based on DNA laddering and TUNEL assays. The absence of AL-PCD in wheat R-NIL reduced pathogen biomass and mycotoxins, increasing the accumulation of resistance metabolites and FHB-resistance, and in potato
it enhanced resistance to multiple pathogens. In addition, the reduced expressions of metacaspase (StMC7) and Ca2+
dependent endonuclease 2 (StCaN2) genes in potato with Sthrc indicated an involvement of a hierarchy of genes in the induction of AL-PCD. The HRC in commercial varieties of
different crops, if functional, can be silenced by genome editing possibly to enhance resistance to multiple pathogens
Comprehensive evaluation of Chinese peanut mini‑mini core collection and QTL mapping for aflatoxin resistance
Get PDFBackground: Aflatoxin contamination caused by Aspergillus fungi has been a serious factor affecting food safety of
peanut (Arachis hypogaea L.) because aflatoxins are highly harmful for human and animal health. As three mechanisms
of resistance to aflatoxin in peanut including shell infection resistance, seed infection resistance and aflatoxin production resistance exist among naturally evolved germplasm stocks, it is highly crucial to pyramid these three resistances for promoting peanut industry development and protecting consumers’ health. However, less research effort has been made yet to investigate the differentiation and genetic relationship among the three resistances in diversified peanut germplasm collections.
Results: In this study, the Chinese peanut mini-mini core collection selected from a large basic collection was systematically evaluated for the three resistances against A. flavus for the first time. The research revealed a wide variation among the diversified peanut accessions for all the three resistances. Totally, 14 resistant accessions were identified, including three with shell infection resistance, seven with seed infection resistance and five with aflatoxin production resistance. A special accession, Zh.h1312, was identified with both seed infection and aflatoxin production resistance. Among the five botanic types of A. hypogaea, the var. vulgaris (Spanish type) belonging to subspecies fastigiata is the only one which possessed all the three resistances. There was no close correlation between shell infection resistance and other two resistances, while there was a significant positive correlation between seed infection and toxin production resistance. All the three resistances had a significant negative correlation with pod or seed size. A total of 16 SNPs/InDels associated with the three resistances were identified through genome-wide association study (GWAS). Through comparative analysis, Zh.h1312 with seed infection resistance and aflatoxin production resistance was also revealed to possess all the resistance alleles of associated loci for seed infection index and aflatoxin content. Conclusions: This study provided the first comprehensive understanding of differentiation of aflatoxin resistance in diversified peanut germplasm collection, and would further contribute to the genetic enhancement for resistance to aflatoxin contaminatio
Revamping sorghum seed production and supply systems in Tanzania: policy options forward
Get PDFSeed being an important input in agricultural production, it represents a valuable asset to farmers and the entire society because it serves as the means to attain food, nutrition and income security for both rural and urban populations (Kiambu and Mugo, 2016). To achieve a sustainable agriculture in the drylands, an effective sorghum seed system that involves quality seed production, processing, marketing, and timely delivery is important
Effects of Plastic Film Mulching on Soil Enzyme Activities and Stoichiometry in Dryland Agroecosystems
Get PDFSoil extracellular enzymes are pivotal for microbial nutrient cycling in the ecosystem. In order to study the effects of different nitrogen application rates under plastic film mulching on soil extracellular enzyme activities and stoichiometry, five nitrogen application levels (i.e., 0, 90, 150, 225 and 300 kg·hm−2) were set based on two treatments: plastic film mulching (PM) and no film mulching (LD). We measured the soil extracellular enzyme activities (EEAs) and stoichiometry (EES) of four en-zymes (i.e., β-1,4-glucosidase (βG), leucine aminopeptidase (LAP), β-1,4-N-acetylaminoglucosidase (NAG) and alkaline phosphatase (AP)) involved in the C, N and P cycles of soil microorganisms in surface soil at five maize growth stages (seedling stage, jointing stage, trumpet stage, grout stage and harvest stage). The results showed that there were significant differences in soil EEA at different maize growth stages. The soil nutrient content and soil EEA were significantly improved under PM, and the stoichiometric ratio of extracellular enzymes (EC:N:P) was closer to 1:1:1, which indicated that PM was beneficial to the balance of soil nutrients and the activity of microorganisms. At each stage, with the increase in nitrogen application levels, the soil EEA showed a trend of increasing first and then decreasing (or remained unchanged), and both LD and PM treatments reached their highest activity at the 225 kg·hm−2 nitrogen application rate. When the nitrogen application level was less than 225 kg·hm−2, the soil enzyme activity was mainly limited by the N nutrient, and when the nitrogen application level reached 300 kg·hm−2, it was mainly limited by the P nutrient. RDA and correlation analysis showed that the soil C:P, C:N, N:P and pH had significant effects on soil βG, NAG + LAP and AP activities as well as EC:N, EC:P and EN:P
Response of the Fate of In-Season Fertilizer Nitrogen to Plastic Mulching in Rainfed Maize Croplands of the Loess Plateau
Get PDFAs plastic mulching is widely used for maize production on Loess Plateau, study of the fate of fertilizer nitrogen (N) in rain-fed croplands is of great significance. Field experiments were conducted during 2015–2016 at a typical dry-land farm on the Loess Plateau, China. The stable isotope tracer technique was applied to analyze the effects of plastic mulching on the maize crop yield, N content in the grain, and mechanism of N uptake and utilization in maize plants with plastic mulch (PM) and without plastic mulch (CK) on the Loess Plateau. Maize yield, aboveground dry matter, grain N concentration, and N uptake in aboveground biomass for PM significantly increased, in addition to fertilizer nitrogen recovery and nitrogen production efficiency. Compared to CK, PM improved the total N uptake from the soil in the aboveground biomass by 16.39 and 27.75 kg ha−1 and fertilizer nitrogen recovery by 10.89 and 22.02 kg ha−1, respectively. Furthermore, PM increased in-season fertilizer N retention in the soil by 11.9–24.8 kg ha−1, and the uncountable fertilizer N decreased by approximately 33.8 kg ha−1 on average. In conclusion, PM simultaneously improved the maize yield and N utilization, which provides a scientific basis for nitrogen management in maize croplands
Soil erosion assessment in Ethiopia: A review
No full textSoil erosion is a critical problem affecting rural livelihoods in Ethiopia. Large
numbers of studies have been undertaken to identify critical areas of soil loss and prioritize
conservation options. With the advancement of geospatial analysis techniques, the use of spatially
distributed soil erosion assessment options has become increasingly common. The lack
of database and documentation related to soil erosion assessment undermines coordination
leading to duplication of efforts and in some instances generating contradictory results. The
purpose of this study is to (1) review existing knowledge related to the extent and spatial
distribution of soil erosion, (2) document the associated methods employed to assess soil erosion,
and (3) assess the spatio-temporal dynamics of soil erosion and the determinant factors
in Ethiopia. The review shows that there are about 170 peer-reviewed papers published in
scientific journals related to soil erosion in Ethiopia. In those scientific articles, 15 different
approaches were used to assess soil loss and sediment yield at different scales. Considering
the data set, soil loss rate in Ethiopia varies between 0 and 220 t ha–1 y–1, and sediment yield
ranges between 2 and 70 t ha–1 y–1. Based on the database, the national average gross soil erosion
rate is estimated to be 38 t ha–1 y–1, while the net sediment yield is about 26 t ha–1 y–1.
Generally, the observed gross soil loss is slightly lower than the mean value from cultivated
lands reported in previous estimates (42 t ha–1 y–1) by Hurni (1993). The estimate made using
the Revised Universal Soil Loss Equation gives the highest soil loss (51 t ha–1 y–1), while that
based on field-survey approaches gives the lowest (20 t ha–1 y–1). The highest average net soil
loss rate (40 t ha–1 y–1) is obtained using plot-level measurements, while the lowest (18 t ha–1
y–1) is obtained using the AGricultural Non-Point Source pollution model. The highest average
soil erosion rate is observed in the moist agro-ecological zone (57 ± 7.8 t ha–1 y–1), while
the lowest is obtained in the submoist (23.6 ± 2.7 t ha–1 y–1) following the arid zone (28.8
± 6.5 t ha–1 y–1). The wide range of soil erosion estimates imply spatio-temporal dynamics of
soil erosion in the country, which is mainly a reflection of heterogeneity of the various sites,
mainly associated with different values of cover and management factors. Such knowledge
can enable making informed conservation decisions by focusing on critical hotspots