Cassava molecular genetics and genomics for enhanced resistance to diseases and pests

Needs and opportunities to future-proof crops and the use of crop systems to mitigate atmospheric change

Predicted changes in atmospheric composition and climate affecting crop productivity are reviewed. These include changes in both average conditions and extreme events, with respect to temperature, drought, flooding and surface ozone, coupled with rising atmospheric [CO2]. Impacts on, and means to adapt, crops to these changes are reviewed and outlined. Particular emphasis is given to (i) the results from open air field manipulations of surface atmosphere, temperature and soil water to understand impacts and adaptation and (ii) demonstrated genetic manipulations of photosynthesis and water use that could support future food supply under current and future conditions. Finally, attention is given to means by which crop systems could serve as CO2 collectors and carbon storage systems. Here, apparent opportunities are outlined for (i) manipulations of crops to enhance carbon storage and (ii) use of high-productivity sustainable perennial C4 grasses coupled with carbon capture and storage.This article is part of the theme issue 'Crops under stress: can we mitigate the impacts of climate change on agriculture and launch the 'Resilience Revolution'?'.

Integration of temperature-driven population model and pest monitoring data to estimate initial conditions and timing of first field invasion: application to the cassava whitefly, Bemisia tabaci

Empirical field data and simulation models are often used separately to monitor and analyse the dynamics of insect pest populations over time. Greater insight may be achieved when field data are used directly to parametrize population dynamic models. In this paper, we use a differential evolution algorithm to integrate mechanistic physiological-based population models and monitoring data to estimate the population density and the physiological age of the first cohort at the start of the field monitoring. We introduce an ad hoc temperature-driven life-cycle model of Bemisia tabaci in conjunction with field monitoring data. The likely date of local whitefly invasion is estimated, with a subsequent improvement of the model's predictive accuracy. The method allows computation of the likely date of the first field incursion by the pest and demonstrates that the initial physiological age somewhat neglected in prior studies can improve the accuracy of model simulations. Given the increasing availability of monitoring data and models describing terrestrial arthropods, the integration of monitoring data and simulation models to improve model prediction and pioneer invasion date estimate will lead to better decision-making in pest management.

Metagenomics and plant-microbe symbioses: Microbial community dynamics, functional roles in carbon sequestration, nitrogen transformation, sulfur and phosphorus mobilization for sustainable soil health

Biogeochemical cycles are fundamental processes that regulate the flow of essential elements such as carbon, nitrogen, and phosphorus, sustaining ecosystem productivity and global biogeochemical equilibrium. These cycles are intricately influenced by plant-microbe symbioses, which facilitate nutrient acquisition, organic matter decomposition, and the transformation of soil nutrients. Through mutualistic interactions, plants and microbes co-regulate nutrient availability and promote ecosystem resilience, especially under environmental stress. Metagenomics has emerged as a transformative tool for deciphering the complex microbial communities and functional genes driving these cycles. By enabling the high-throughput sequencing and annotation of microbial genomes, metagenomics provides unparalleled insights into the taxonomic diversity, metabolic potential, and functional pathways underlying microbial contributions to biogeochemical processes. Unlike previous reviews, this work integrates recent advancements in metagenomics with complementary omics approaches to provide a comprehensive perspective on how plant-microbe interactions modulate biogeochemical cycles at molecular, genetic, and ecosystem levels. By highlighting novel microbial processes and potential biotechnological applications, this review aims to guide future research in leveraging plant-microbe symbioses for sustainable agriculture, ecosystem restoration, and climate change mitigation.

Unlocking the potential of 'Egusi' melon (Colocynthis citrullus L.) as a crop for biotechnological improvement

'Egusi' melon (Colocynthis citrullus L.) plays a critical role in food security and potential biofuel production in West Africa. Its seeds are valued for both their nutritional and potential industrial applications, especially in biodiesel production. However, the crop faces significant challenges, including the impacts of climate change, water scarcity, declining arable land, and increased pressure from pests and diseases. These challenges threaten the stability of 'Egusi' production and may hinder its ability to meet future demand. To address these issues, there is a growing need to complement conventional breeding methods with biotechnological approaches. Molecular approaches; including genomics, transcriptomics, proteomics, and metabolomics; have been utilized for the improvement of several cucurbit species. However, information on molecular breeding of 'Egusi' is very limited. The current review focuses on 'Egusi' melon, its biology, uses, and factors affecting its improvement, and highlights critical knowledge gaps in the molecular breeding of 'Egusi'. The review also examines the potential of omics technologies and outlines the importance of genetic transformation and genome editing methods such as CRISPR that could drive the development of more resilient and high-yielding 'Egusi'varieties that will contribute to sustainability and profitability of 'Egusi' farming.

Genome editing in Sub-Saharan Africa: a game-changing strategy for climate change mitigation and sustainable agriculture

Sub-Saharan Africa's agricultural sector faces a multifaceted challenge due to climate change consisting of high temperatures, changing precipitation trends, alongside intensified pest and disease outbreaks. Conventional plant breeding methods have historically contributed to yield gains in Africa, and the intensifying demand for food security outpaces these improvements due to a confluence of factors, including rising urbanization, improved living standards, and population growth. To address escalating food demands amidst urbanization, rising living standards, and population growth, a paradigm shift toward more sustainable and innovative crop improvement strategies is imperative. Genome editing technologies offer a promising avenue for achieving sustained yield increases while bolstering resilience against escalating biotic and abiotic stresses associated with climate change. Clustered Regularly Interspaced Short Palindromic Repeats/CRISPR-associated protein (CRISPR/Cas) is unique due to its ubiquity, efficacy, alongside precision, making it a pivotal tool for Sub-Saharan African crop improvement. This review highlights the challenges and explores the prospect of gene editing to secure the region's future foods.

Identifying genetically redundant accessions in the world's largest cassava collection

Crop diversity conserved in genebanks facilitates the development of superior varieties, improving yields, nutrition, adaptation to climate change and resilience against pests and diseases. Cassava (Manihot esculenta) plays a vital role in providing carbohydrates to approximately 500 million people in Africa and other continents. The International Center for Tropical Agriculture (CIAT) conserves the largest global cassava collection, housing 5,963 accessions of cultivated cassava and wild relatives within its genebank. Efficient genebank management requires identifying and eliminating genetic redundancy within collections. In this study, we optimized the identification of genetic redundancy in CIAT's cassava genebank, applying empirical distance thresholds, and using two types of molecular markers (single-nucleotide polymorphism (SNP) and SilicoDArT) on 5,302 Manihot esculenta accessions. A series of quality filters were applied to select the most informative and high-quality markers and to exclude low-quality DNA samples. The analysis identified a total of 2,518 and 2,526 (47 percent) distinct genotypes represented by 1 to 87 accessions each, using SNP or SilicoDArT markers, respectively. A total of 2,776 (SNP) and 2,785 (SilicoDArT) accessions were part of accession clusters with up to 87 accessions. Comparing passport and historical characterization data, such as pulp color and leaf characteristic, we reviewed clusters of genetically redundant accessions. This study provides valuable guidance to genebank curators in defining minimum genetic-distance thresholds to assess redundancy within collections. It aids in identifying a subset of genetically distinct accessions, prioritizing collection management activities such as cryopreservation and provides insights for follow-up studies in the field, potentially leading to removal of duplicate accessions.