41 research outputs found
Evaluation of rice cultivars for resistance to rice yellow mottle virus
Rice yellow mottle virus (RYMV), which is only found in Africa,
threatens rice farming on the continent. A local Oryza sativa
cultivar collected from Burkina Faso (named BM24), was evaluated with
that of well known highly resistant and tolerant cultivars. Firstly,
three RYMV isolates were used to characterise the differential
interaction within the cultivars. Secondly, disease kinetics of symptom
expression and virus titer on leaves at 21 days after inoculation were
assessed using the BF1 isolate. Thirdly, the allelic profile of O.
sativa varieties using SSR marker RM101 located on chromosome 12 was
also assessed. IR64 showed susceptibility to all isolates; while
Tog5681 was resistant to all isolates. Ng122 overcame the resistance of
Gigante, with mild leaf symptoms at 42\ua0dpi. Azucena and BM24 had,
therefore, different resistance level regarding the three isolates
(Ng117b, Ng122 and Ng144). When infected with the isolate, BF1, BM24
and Azucena exhibited same resistance patterns in early growth stages
with delayed of symptoms appearance, but BM24 outperformed Azucena at
later stages. The virus content in the two accessions, at 14 days post
inoculation, was statistically different with BM24, showing less virus
compared to Azucena. However, the two accessions depicted an identical
allelic profile at RM101 locus.Le virus de la panachure jaune du riz (RYMV) est end\ue9mique
seulement en Afrique, et fait des ravages dans les rizi\ue8res du
continent. Une vari\ue9t\ue9 de riz local (appel\ue9e BM24),
r\ue9sistante au RYMV et collect\ue9e au Burkina Faso a
\ue9t\ue9 compar\ue9e avec des cultivars bien connus qui sont
r\ue9sistants ou tol\ue9rants au RYMV. Tout d\u2019abord, trois
isolats ont \ue9t\ue9 utilis\ue9s pour caract\ue9riser les
interactions diff\ue9rentielles au sein des cultivars. Ensuite, la
cin\ue9tique de l\u2019expression des sympt\uf4mes de la maladie
et le titre en virus sur les feuilles \ue0 21 jours apr\ue8s
inoculation ont \ue9t\ue9 \ue9valu\ue9e avec l\u2019isolat
BF1. Enfin, le profile all\ue9lique des vari\ue9t\ue9s de Oryza
sativa a \ue9t\ue9 \ue9valu\ue9 au marqueur SSR RM101
situ\ue9 sur le chromosome 12. La vari\ue9t\ue9 IR64 s\u2019est
av\ue9r\ue9e sensible \ue0 tous les isolats tandis que Tog5681
s\u2019est montr\ue9 r\ue9sistant \ue0 tous les isolats.
L\u2019isolat Ng122 a surmont\ue9 la r\ue9sistance de Gigante avec
la pr\ue9sence de sympt\uf4mes mod\ue9r\ue9s \ue0 42 jours
apr\ue8s inoculation (JAI). Azucena et BM24 par contre ont eu
diff\ue9rents niveaux de r\ue9sistance en pr\ue9sence des trois
isolats (Ng117b, Ng122 and Ng144). Lorsqu\u2019ils sont infect\ue9s
avec l\u2019isolat BF1, BM24 et Azucena expriment le m\ueame niveau
de r\ue9sistance avec un retard de l\u2019apparition des
sympt\uf4mes dans les premiers moments suivant l\u2019inoculation
mais au-del\ue0 de 14 JAI, les sympt\uf4mes apparaissent plus
rapidement chez Azucena compar\ue9 \ue0 BM24. A 14 JAI, le titre de
virus contenu dans e cultivar Azucena est bien sup\ue9rieur
statistiquement \ue0 celui de BM24. Cependant, les deux cultivars ont
eu un profile all\ue9lique identique au locus RM101
Germplasm Acquisition and Distribution by CGIAR Genebanks
The international collections of plant genetic resources for food and agriculture (PGRFA)
hosted by 11 CGIAR Centers are important components of the United Nations Food and Agriculture
Organization’s global system of conservation and use of PGRFA. They also play an important
supportive role in realizing Target 2.5 of the Sustainable Development Goals. This paper analyzes
CGIAR genebanks’ trends in acquiring and distributing PGRFA over the last 35 years, with a
particular focus on the last decade. The paper highlights a number of factors influencing the Centers’
acquisition of new PGRFA to include in the international collections, including increased capacity
to analyze gaps in those collections and precisely target new collecting missions, availability of
financial resources, and the state of international and national access and benefit-sharing laws and
phytosanitary regulations. Factors contributing to Centers’ distributions of PGRFA included the
extent of accession-level information, users’ capacity to identify the materials they want, and policies.
The genebanks’ rates of both acquisition and distribution increased over the last decade. The paper
ends on a cautionary note concerning the potential of unresolved tensions regarding access and
benefit sharing and digital genomic sequence information to undermine international cooperation to
conserve and use PGRFA
Why NERICA is a successful innovation for African farmers
This paper responds to ‘Funding international agricultural research and the need to be noticed: a case study of NERICA rice’ by Stuart Orr, James Sumberg, Olaf Erenstein and Andreas Oswald, published in this issue of Outlook on Agriculture.
In summary, the article by Orr et al, based on an internal WARDA document written in November 2003 and augmented with results from Internet searches, is outdated and does not seem to be fair, objective or useful. We invite the authors to visit WARDA or any of its partners in Sub-Saharan Africa for evidence of the impact of NERICA varieties or the other improved varieties and technologies that have been developed and disseminated by WARDA in recent years
Phytosanitary Interventions for Safe Global Germplasm Exchange and the Prevention of Transboundary Pest Spread: The Role of CGIAR Germplasm Health Units
The inherent ability of seeds (orthodox, intermediate, and recalcitrant seeds and vegetative
propagules) to serve as carriers of pests and pathogens (hereafter referred to as pests) and the risk
of transboundary spread along with the seed movement present a high-risk factor for international
germplasm distribution activities. Quarantine and phytosanitary procedures have been established
by many countries around the world to minimize seed-borne pest spread by screening export and
import consignments of germplasm. The effectiveness of these time-consuming and cost-intensive
procedures depends on the knowledge of pest distribution, availability of diagnostic tools for seed
health testing, qualified operators, procedures for inspection, and seed phytosanitation. This review
describes a unique multidisciplinary approach used by the CGIAR Germplasm Health Units (GHUs)
in ensuring phytosanitary protection for the safe conservation and global movement of germplasm
from the 11 CGIAR genebanks and breeding programs that acquire and distribute germplasm to and
from all parts of the world for agricultural research and food security. We also present the challenges,
lessons learned, and recommendations stemming from the experience of GHUs, which collaborate
with the national quarantine systems to export and distribute about 100,000 germplasm samples
annually to partners located in about 90 to 100 countries. Furthermore, we describe how GHUs adjust
their procedures to stay in alignment with evolving phytosanitary regulations and pest risk scenarios.
In conclusion, we state the benefits of globally coordinated phytosanitary networks for the prevention
of the intercontinental spread of pests that are transmissible through plant propagation materials
Mobilizing Crop Biodiversity
Over the past 70 years, the world has witnessed extraordinary growth in crop productivity, 1 enabled by a suite of technological advances, including higher yielding crop varieties, improved farm management, synthetic agrochemicals, and agricultural mechanization. While this “Green Revolution” intensified crop production, and is credited with reducing famine and malnutrition, its benefits were accompanied by several undesirable collateral effects (Pingali, 2012). These include a narrowing of agricultural biodiversity, stemming from increased monoculture and greater reliance on a smaller number of crops and
crop varieties for the majority of our calories. This reduction in diversity has created vulnerabilities to pest and disease epidemics, climate variation, and ultimately to human health (Harlan, 1972). The value of crop diversity has long been recognized (Vavilov, 1992). A global system of genebanks (e.g.www.genebanks.org/genebanks/) was established in the 1970s to preserve the abundant genetic variation found in traditional “landrace” varieties of crops and in crop wild relatives (Harlan, 1972). While preserving crop variation is a critical first step, the time has come to make use of this variation to breed more resilient crops. The DivSeek International Network (https://divseekintl.org/) is a scientific, not-for profit organization that aims to accelerate such effort
Historical Contingencies Modulate the Adaptability of Rice Yellow Mottle Virus
The rymv1-2 and rymv1-3 alleles of the RYMV1 resistance to Rice yellow mottle virus (RYMV), coded by an eIF(iso)4G1 gene, occur in a few cultivars of the Asiatic (Oryza sativa) and African (O. glaberrima) rice species, respectively. The most salient feature of the resistance breaking (RB) process is the converse genetic barrier to rymv1-2 and rymv1-3 resistance breakdown. This specificity is modulated by the amino acid (glutamic acid vs. threonine) at codon 49 of the Viral Protein genome-linked (VPg), a position which is adjacent to the virulence codons 48 and 52. Isolates with a glutamic acid (E) do not overcome rymv1-3 whereas those with a threonine (T) rarely overcome rymv1-2. We found that isolates with T49 had a strong selective advantage over isolates with E49 in O. glaberrima susceptible cultivars. This explains the fixation of the mutation T49 during RYMV evolution and accounts for the diversifying selection estimated at codon 49. Better adapted to O. glaberrima, isolates with T49 are also more prone than isolates with E49 to fix rymv1-3 RB mutations at codon 52 in resistant O. glaberrima cultivars. However, subsequent genetic constraints impaired the ability of isolates with T49 to fix rymv1-2 RB mutations at codons 48 and 52 in resistant O. sativa cultivars. The origin and role of the amino acid at codon 49 of the VPg exemplifies the importance of historical contingencies in the ability of RYMV to overcome RYMV1 resistance
CGIAR Operations under the Plant Treaty Framework
The history of CGIAR and the development and implementation of the International Treaty on Plant Genetic Resources for Food and Agriculture (“Plant Treaty”) are closely intertwined. In accordance with the agreements that 11 CGIAR centers signed with the Plant Treaty’s Governing Body under Article 15 of the treaty, >730,000 accessions of crop, tree, and forage germplasm conserved in CGIAR genebanks are made available under the terms and conditions of the multilateral system of access and benefit sharing, and the CGIAR centers have transferred almost 4 million samples of plant genetic resources under the system. Many activities of CGIAR centers and their genebanks (e.g., crop enhancement, improved agronomic methods, seed system strengthening, and capacity building) are influenced by, and promote, the Plant Treaty’s objectives. The continued existence and optimal functioning of the Plant Treaty’s multilateral system of access and benefit sharing is critically important to CGIAR in the pursuit of its mission. However, the multilateral system has encountered some challenges since the Plant Treaty came into force. The successful conclusion of the ongoing process for enhancing the functioning of the multilateral system could increase monetary benefit sharing and incentives for exchanging more germplasm. In the meantime, increased efforts are necessary to promote nonmonetary benefit sharing through partnerships, technology transfer, information exchange, and capacity building. These efforts should be integrated into countries’ and organizations’ work to implement the Plant Treaty’s provisions on conservation and sustainable use of plant genetic resources, and farmers’ rights
Domestication history and geographical adaptation inferred from a SNP map of African rice
African rice (Oryza glaberrima Steud.) is a cereal crop species closely related to Asian rice (Oryza sativa L.) but was independently domesticated in West Africa-3,000 years ago. African rice is rarely grown outside sub-Saharan Africa but is of global interest because of its tolerance to abiotic stresses. Here we describe a map of 2.32 million SNPs of African rice from whole-genome resequencing of 93 landraces. Population genomic analysis shows a population bottleneck in this species that began-13,000-15,000 years ago with effective population size reaching its minimum value-3,500 years ago, suggesting a protracted period of population size reduction likely commencing with predomestication management and/or cultivation. Genome-wide association studies (GWAS) for six salt tolerance traits identify 11 significant loci, 4 of which are within-300 kb of genomic regions that possess signatures of positive selection, suggesting adaptive geographical divergence for salt tolerance in this species