Speed Breeding Research Articles

Accelerating soybean breeding: A comprehensive review of speed breeding

Accelerating soybean breeding: A comprehensive review of speed breeding

Temperature‐smart plants: A new horizon with omics‐driven plant breeding

AbstractThe adverse effects of mounting environmental challenges, including extreme temperatures, threaten the global food supply due to their impact on plant growth and productivity. Temperature extremes disrupt plant genetics, leading to significant growth issues and eventually damaging phenotypes. Plants have developed complex signaling networks to respond and tolerate temperature stimuli, including genetic, physiological, biochemical, and molecular adaptations. In recent decades, omics tools and other molecular strategies have rapidly advanced, offering crucial insights and a wealth of information about how plants respond and adapt to stress. This review explores the potential of an integrated omics‐driven approach to understanding how plants adapt and tolerate extreme temperatures. By leveraging cutting‐edge omics methods, including genomics, transcriptomics, proteomics, metabolomics, miRNAomics, epigenomics, phenomics, and ionomics, alongside the power of machine learning and speed breeding data, we can revolutionize plant breeding practices. These advanced techniques offer a promising pathway to developing climate‐proof plant varieties that can withstand temperature fluctuations, addressing the increasing global demand for high‐quality food in the face of a changing climate.

Early harvesting: an efficient technique for speed breeding in soybean

Early harvesting: an efficient technique for speed breeding in soybean

SpeedFlower: a comprehensive speed breeding protocol for indica and japonica rice.

To increase rice yields and feed billions of people, it is essential to enhance genetic gains. However, the development of new varieties is hindered by longer generation times and seasonal constraints. To address these limitations, a speed breeding facility has been established and a robust speed breeding protocol, SpeedFlower is developed that allows growing 4-5 generations of indica and/or japonica rice in a year. Our findings reveal that a high red-to-blue (2R > 1B) spectrum ratio, followed by green, yellow and far-red (FR) light, along with a 24-h long day (LD) photoperiod for the initial 15 days of the vegetative phase, facilitated early flowering. This is further enhanced by 10-h short day (SD) photoperiod in the later stage and day and night temperatures of 32/30 °C, along with 65% humidity facilitated early flowering ranging from 52 to 60 days at high light intensity (800 μmol m-2 s-1). Additionally, the use of prematurely harvested seeds and gibberellic acid treatment reduced the maturity duration by 50%. Further, SpeedFlower was validated on a diverse subset of 198 rice accessions from 3K RGP panel encompassing all 12 distinct groups of Oryza sativa L. classes. Our results confirmed that using SpeedFlower one generation can be achieved within 58-71 days resulting in 5.1-6.3 generations per year across the 12 sub-groups. This breakthrough enables us to enhance genetic gain, which could feed half of the world's population dependent on rice.

Speed Breeding- An Emerging Trend in Crop Improvement

During the past century, traditional breeding programs resulted in several significantly better types in a variety of unique breeding programs around the world. The plant develops slowly because of the lengthy breeding cycle, which can take ten to fifteen years from the cross to cultivar release. That stated it is quite difficult to combine multiple polygenic traits using traditional breeding methods. Speed breeding is a technique that reduces the length of the breeding cycle by lengthening the photoperiod and adjusting other glasshouse growth factors like temperature, soil type, spacing, etc. Rapid generational advancement is made possible by this strategy. Speed breeding yields 3 to 9 generations annually as opposed to 1 to 2 generations annually using standard selection processes. Instead of 2-3 generations per year under typical glasshouse conditions, speed breeding can produce up to 6 generations per year for spring wheat, durum wheat, barley, chickpea, and pea, and 4 generations for canola. Speed breeding, thus, permits the rapid generation of stable and homozygous genotypes.

A platform for whole-genome speed introgression from Aegilops tauschii to wheat for breeding future crops.

Breeding new and sustainable crop cultivars of high yields and desirable traits has been a major challenge for ensuring food security for the growing global human population. For polyploid crops such as wheat, introducing genetic variation from wild relatives of its subgenomes is a key strategy to improve the quality of their breeding pools. Over the past decades, considerable progress has been made in speed breeding, genome sequencing, high-throughput phenotyping and genomics-assisted breeding, which now allows us to realize whole-genome introgression from wild relatives to modern crops. Here, we present a standardized protocol to rapidly introgress the entire genome of Aegilops tauschii, the progenitor of the D subgenome of bread wheat, into elite wheat backgrounds. This protocol integrates multiple modern high-throughput technologies and includes three major phases: development of synthetic octaploid wheat, generation of hexaploid A. tauschii-wheat introgression lines (A-WIs) and homozygosis of the generated A-WIs. Our approach readily generates stable introgression lines in 2 y, thus greatly accelerating the generation of A-WIs and the introduction of desirable genes from A. tauschii to wheat cultivars. These A-WIs are valuable for wheat-breeding programs and functional gene discovery. The current protocol can be easily modified and used for introgressing the genomes of wild relatives to other polyploid crops.

Using CRISPR/Cas9 Technology to Improve Crops and Address the Global Food Crisis: A Review

By developing a revolutionary method for modifying the genomes of living things, genome editing (GE) has completely changed the biological sciences. Recent years have seen the development of several technologies that make altering complex genomes possible. For agricultural crop production to be sustained and contribute to global food security, a fast and dependable method of raising yield and resilience to different environmental pressures is therefore required. The GE instruments for crop enhancement are explained in detail in this analytical research. Zinc-finger nucleases (ZFNs), transcriptional activator-like effector nucleases (TALENs), and clustered regularly interspaced short palindromic repeats (CRISPR) are a few examples of these tools. This category also includes mega-nucleases (MNs). In particular, the most recent advancements in the use of CRISPR/Cas9 for genome editing for major agricultural improvements - like the creation of crops that are more yielding and of higher quality - are covered this paper. When this approach is put into practice, non-transgene crops with desired traits will be produced, which might lead to increased yield capacity under different environmental challenges. To increase agricultural production and guarantee food security, the CRISPR/Cas9 methodology may be used in conjunction with existing and future breeding techniques (such as omics-assisted breeding and speed breeding). The difficulties and restrictions associated with CRISPR/Cas9 have also been covered. Plant breeders and scientists doing a detailed analysis of the use of CRISPR/Cas9 to enhance crops by focusing on the desired gene will find this material to be helpful.

Acceleration of wheat breeding: enhancing efficiency and practical application of the speed breeding system

BackgroundCrop breeding should be accelerated to address global warming and climate change. Wheat (Triticum aestivum L.) is a major food crop. Speed breeding (SB) and speed vernalization (SV) techniques for spring and winter wheat have recently been established. However, there are few practical examples of these strategies being used economically and efficiently in breeding programs. We aimed to establish and evaluate the performance of a breeder-friendly and energy-saving generation acceleration system by modifying the SV + SB system.ResultsIn this study, a four-generation advancement system for wheat (regardless of its growth habits) was established and evaluated using an energy-efficient extended photoperiod treatment. A glasshouse with a 22-hour photoperiod that used 10 h of natural sunlight and 12 h of LED lights, and minimized temperature control during the winter season, was successful in accelerating generation. Even with one or two field tests, modified speed breeding (mSB) combined with a speed vernalization system (SV + mSB) reduced breeding time by more than half compared to traditional field-based methods. When compared to the existing SV + SB system, the SV + mSB system reduced energy use by 80% to maintain a 22-hour photoperiod. Significant correlations were found between the SV + mSB and field conditions in the number of days to heading (DTH) and culm length (CL). Genetic resources, recombinant inbred lines, and breeding materials that exhibited shorter DTH and CL values under SV + mSB conditions showed the same pattern in the field.ConclusionsThe results of our SV + mSB model, as well as its practical application in wheat breeding programs, are expected to help breeders worldwide incorporate generation acceleration systems into their conventional breeding programs.

Speed Breeding for Crop Improvement and Food Security

Amid a rapidly growing global population and increasing threats to crop yields, this review focuses on Speed Breeding (SB) in crop genetics. It traces SB’s development from carbon arc lamp experiments 150 years ago to its modern use with LED technology which significantly accelerates breeding cycles. SB has applications in genetic mapping, genetic modification, and trait stacking, enhancing crop resilience by leveraging allelic diversity. It aligns well with breeding methods like single plant selection and single seed descent. The integration of SB with gene editing, genotyping, and genomic selection holds great promise. However, SB faces challenges related to infrastructure, genotypic variations, and potential stress responses. In summary, SB is a powerful and promising approach to address food security concerns and advancing crop genetics.

Challenges for crop improvement.

The genetic improvement of crops faces the significant challenge of feeding an ever-increasing population amidst a changing climate, and when governments are adopting a 'more with less' approach to reduce input use. Plant breeding has the potential to contribute to the United Nations Agenda 2030 by addressing various sustainable development goals (SDGs), with its most profound impact expected on SDG2 Zero Hunger. To expedite the time-consuming crossbreeding process, a genomic-led approach for predicting breeding values, targeted mutagenesis through gene editing, high-throughput phenomics for trait evaluation, enviromics for including characterization of the testing environments, machine learning for effective management of large datasets, and speed breeding techniques promoting early flowering and seed production are being incorporated into the plant breeding toolbox. These advancements are poised to enhance genetic gains through selection in the cultigen pools of various crops. Consequently, these knowledge-based breeding methods are pursued for trait introgression, population improvement, and cultivar development. This article uses the potato crop as an example to showcase the progress being made in both genomic-led approaches and gene editing for accelerating the delivery of genetic gains through the utilization of genetically enhanced elite germplasm. It also further underscores that access to technological advances in plant breeding may be influenced by regulations and intellectual property rights.

Root Causes of Flowering: Two Sides of Bolting in Sugar Beet

Sugar beet is an important root crop with a biennial life cycle. In the first year of its life cycle, it produces huge amounts of leaf and root mass used for the production of sugar and bioethanol, livestock feed, confectionery and pharmaceuticals, fertilizers, and soil restoration. Normally, after exposure to cold temperatures during winter storage, in the second year of its life cycle, it enters its reproductive phase. However, during the first year of growth, sugar beet plants may be susceptible to producing flowering shoots, or “bolting”, due to vernalization and long-day conditions. Bolting reduces both the yield and the sugar content of roots. Here, we review the published research works that study the environmental factors influencing bolting, the genetic (including epigenetic) and physiological mechanisms that regulate the transition to the reproductive phase, and the agrotechnical and breeding practices used to prevent bolting. Models of gene networks that regulate the transition to flowering are presented. Methods for selecting non-bolting plants using conventional, marker-assisted, and genomic breeding are demonstrated. Attention is also paid to the speed breeding technology that stimulates bolting and flowering sugar beet plants in an artificial climate. Growing sugar beet plants “from seed to seed” can potentially accelerate the breeding and seed production of sugar beet. This review compares different conditions for inducing bolting in sugar beet in climatic chambers and greenhouses. It examines parameters such as temperature, duration of light exposure, and light intensity during the pre-vernalization, post-vernalization, and vernalization periods. The present review may be useful for specialists in sugar beet cultivation, breeders working on developing cultivars and hybrids that are resistant to bolting, and molecular biologists studying the genetic and physiological mechanisms underlying the transition of plants into the flowering stage.

Robotized indoor phenotyping allows genomic prediction of adaptive traits in the field

Breeding for resilience to climate change requires considering adaptive traits such as plant architecture, stomatal conductance and growth, beyond the current selection for yield. Robotized indoor phenotyping allows measuring such traits at high throughput for speed breeding, but is often considered as non-relevant for field conditions. Here, we show that maize adaptive traits can be inferred in different fields, based on genotypic values obtained indoor and on environmental conditions in each considered field. The modelling of environmental effects allows translation from indoor to fields, but also from one field to another field. Furthermore, genotypic values of considered traits match between indoor and field conditions. Genomic prediction results in adequate ranking of genotypes for the tested traits, although with lesser precision for elite varieties presenting reduced phenotypic variability. Hence, it distinguishes genotypes with high or low values for adaptive traits, conferring either spender or conservative strategies for water use under future climates.

Virus-induced overexpression of heterologous FLOWERING LOCUS T for efficient speed breeding in tomato.

Potato virus X (PVX) vectors expressing the Arabidopsis thaliana FLOWERING LOCUS T (FT) or tomato FT ortholog SINGLE-FLOWER TRUSS (SFT) shortened the generation time in tomato due to accelerated tomato flowering and ripening by 14-21 d, and caused a 2-3-fold increase in the number of flowers and fruits, compared with non-infected or empty vector-infected plants. The Arabidopsis FT was more effective than the tomato orthologue SFT and there was no alteration of the flower or fruit morphology. The virus was not transmitted to the next generation; therefore viral vectors with expression of a heterologous FT will be a useful approach to speed breeding in tomato and other species.

Development of a speed breeding protocol with flowering gene investigation in pepper (Capsicum annuum).

Pepper (Capsicum spp.) is a vegetable and spice crop in the Solanaceae family with many nutritional benefits for human health. During several decades, horticultural traits, including disease resistance, yield, and fruit quality, have been improved through conventional breeding methods. Nevertheless, cultivar development is a time-consuming process because of the long generation time of pepper. Recently, speed breeding has been introduced as a solution for shorting the breeding cycle in long-day or day-neutral field crops, but there have been only a few studies on speed breeding in vegetable crops. In this study, a speed breeding protocol for pepper was developed by controlling the photoperiod and light quality. Under the condition of a low red (R) to far-red (FR) ratio of 0.3 with an extended photoperiod (Epp) of 20h (95 ± 0 DAT), the time to first harvest was shortened by 75 days after transplant (DAT) compared to that of the control treatment (170 ± 2 DAT), suggesting that Epp with FR light is an essential factor for flowering in pepper. In addition, we established the speed breeding system in a greenhouse with a 20h photoperiod and a 3.8 R:FR ratio and promoted the breeding cycle of C. annuum for 110 days from seed to seed. To explain the accelerated flowering response to the Epp and supplemented FR light, genome-wide association study (GWAS) and gene expression analysis were performed. As a result of the GWAS, we identified a new flowering gene locus for pepper and suggested four candidate genes for flowering (APETALA2 (AP2), WUSCHEL-RELATED HOMEOBOX4 (WOX4), FLOWERING LOCUS T (FT), and GIGANTEA (GI)). Through expression analysis with the candidate genes, it appeared that Epp and FR induced flowering by up-regulating the flowering-promoting gene GI and down-regulating FT. The results demonstrate the effect of a combination of Epp and FR light by genetic analysis of flowering gene expression. This is the first study that verifies gene expression patterns associated with the flowering responses of pepper in a speed breeding system. Overall, this study demonstrates that speed breeding can shorten the breeding cycle and accelerate genetic research in pepper through reduced generation time.

New protocol for rapid cassava multiplication in field conditions: a perspective on speed breeding.

Despite the economic and social importance, high-yielding cassava cultivars are only released after extensive research, mainly due to the low multiplication rate. This study aimed to assess the impact of using smaller-sized seed cuttings treated with agrochemicals (8MP) compared to the conventional planting size (16 cm) on genetic parameters, agronomic performance, and the ranking of cassava clones based on yield and growth attributes. The evaluation was carried out in clonal evaluation trial (CET), preliminary yield trial (PYT), and uniform yield trials (UYT). Additionally, a new selection scheme for cassava breeding programs was proposed. A total of 169 clones were evaluated, including 154 improved clones at different stages of selection and 15 local varieties used as checks. Field trials were conducted using both sizes of propagative material (8MP and 16 cm) in each phase of the breeding program. The data were analyzed using mixed models, considering the random effects of genotype and genotype-environment interaction (G×E) to determine variances and heritabilities. Bland-Altman concordance and correlation analysis of selection indices were employed to examine the consistency in the ranking of cassava clones using different seed cutting sizes. The distribution of variance components, heritabilities, means, and range of the 8MP and 16 cm trials in different phases of the cassava breeding program exhibited remarkable similarity, thereby enabling a comparative assessment of similar genetic effects. With a selection intensity of 30%, the concordance in clone ranking was 0.41, 0.57, and 0.85 in CET, PYT, and UYT trials, respectively, when comparing the selection based on 8MP and 16 cm trials. It is worth noting that the ranking of the top 15% remained largely unchanged. Based on the findings, proposed changes in the cassava selection scheme involve increasing the number of trials starting from the CET phase, early incorporation of G×E interaction, elimination of the PYT trial, reduction of the breeding cycle from 5 to 3 years, and a decrease in the time required for variety development from 11 to 9 years. These modifications are expected to lead to cost reduction and enhance the effectiveness of cassava breeding programs.

Data-driven approaches to improve water-use efficiency and drought resistance in crop plants

With the increasing population, there lies a pressing demand for food, feed and fibre, while the changing climatic conditions pose severe challenges for agricultural production worldwide. Water is the lifeline for crop production; thus, enhancing crop water-use efficiency (WUE) and improving drought resistance in crop varieties are crucial for overcoming these challenges. Genetically-driven improvements in yield, WUE and drought tolerance traits can buffer the worst effects of climate change on crop production in dry areas. While traditional crop breeding approaches have delivered impressive results in increasing yield, the methods remain time-consuming and are often limited by the existing allelic variation present in the germplasm. Significant advances in breeding and high-throughput omics technologies in parallel with smart agriculture practices have created avenues to dramatically speed up the process of trait improvement by leveraging the vast volumes of genomic and phenotypic data. For example, individual genome and pan-genome assemblies, along with transcriptomic, metabolomic and proteomic data from germplasm collections, characterised at phenotypic levels, could be utilised to identify marker-trait associations and superior haplotypes for crop genetic improvement. In addition, these omics approaches enable the identification of genes involved in pathways leading to the expression of a trait, thereby providing an understanding of the genetic, physiological and biochemical basis of trait variation. These data-driven gene discoveries and validation approaches are essential for crop improvement pipelines, including genomic breeding, speed breeding and gene editing. Herein, we provide an overview of prospects presented using big data-driven approaches (including artificial intelligence and machine learning) to harness new genetic gains for breeding programs and develop drought-tolerant crop varieties with favourable WUE and high-yield potential traits.

Agricultural-based challenges, genetic enhancement, and obstacles to an industrially important medicinal plant, ashwagandha (Withania somnifera (L.) Dunal): A review

In the pharmaceutical enterprise, traditional/herbal remedies and commercial drug sources Withania somnifera and Withania coagulans received excellent scores. Numerous studies have been conducted on the phytochemistry and pharmacology of Withania somnifera (L.) Dunal. However, the toxicity of plant components extracted using different solvent systems is yet to be ascertained. It is important to find out and isolate active ingredients. Advanced analytical and separation chemistry studies will reveal data on the toxicity, isolation of novel compounds, chemotypic diversity, and ethnobotany of the Withania somnifera (L.) Dunal. Modern tools of speed breeding can be applied, and micropropagation technology can be developed and used to ensure the supply of superior germplasm/improved varieties with genetic fidelity for farming. Genomics-assisted breeding, transgenic technologies, and gene-, genome-, and epigenome editing approaches may be considered new potential tools for metabolic engineering beneficial compounds from Withania somnifera (L.) Dunal.

‘Single-Seed-SpeedBulks:’ a protocol that combines ‘speed breeding’ with a cost-efficient modified single-seed descent method for rapid-generation-advancement in oat (Avena sativa L.)

BackgroundIn plant breeding, one of the most cost-effective and efficient ways to increase genetic gain is to reduce the breeding cycle time. In general, modern breeding methods for self-pollinated crops should strive to develop fixed lines at the lowest possible cost and in the minimum possible amount of time. Previous studies on spring oat (Avena sativa L.) showed that combining high plant density with limited soil fertility and moisture levels in a growth media like sand effectively decreases the time and cost of generating fixed single-seed descent lines. More recently, ‘speed breeding,’ or the exposure to prolonged photoperiod regimes of 22 h, has been shown to decrease flowering time in oat significantly. The goal of this study was to combine ‘speed breeding’ with high-density planting in a limited soil fertility media to reduce further the costs and time required to develop oat single-seed-descent lines.ResultsWe grew oat plants at low density in potting-mix (control), high density in potting-mix (HD-soil), and high density in sand (HD-sand) under 16 and 22 h of day length. We observed that oat plants grown in HD-sand and exposed to 22 h day length reduced their flowering time by around 20 and 5 days on average compared to those grown in control conditions at 16 and 22 h, respectively. We also observed that 85% of plants grown at high density in sand produced a single seed when grown in bulk conditions. In contrast, only 40% of plants grown at high density in potting-mix produced a single seed.ConclusionsOur novel protocol showed that oat plants grown in high-density bulks, using sand media and 22-hour day length, reduced their flowering time by 20 days compared to control conditions and produced plants with single seeds, following closely single-seed descent assumptions while significantly reducing labor costs and greenhouse space. This methodology can be deployed in oat breeding programs to help them accelerate their rate of genetic grain for multiple traits.

Heat Stress in Vegetables: Impacts and Management Strategies – A Review

Global climate change has not only caused a significant rise in the average temperature around the world but has also threatened crop productivity and food security. Heat stress disrupts various plant physiological and biochemical processes, such as inhibition of growth and development, reduction of photosynthesis rate and nutrient uptake, consequently causing yield losses. The destructive effects of heat stress are expected to worsen in the coming years. Thus, it has become imperative to understand how vegetables respond and adapt to heat stress in order to improve their heat tolerance ability. Various approaches have been adopted to enhance heat stress tolerance in vegetables, including modifying cultural practices and crop improvements through several breeding methods. This review gives comprehensive and up-to-date information on the effects of heat stress on vegetables; and existing as well as emerging methods adopted to enhance heat tolerance in vegetables. It also provides a brief overview of a new method called speed breeding, which can be leveraged to fast-track the breeding process for developing heat stress-tolerant vegetables.

Integrated Genomic Selection for Accelerating Breeding Programs of Climate-Smart Cereals.

Rapidly rising population and climate changes are two critical issues that require immediate action to achieve sustainable development goals. The rising population is posing increased demand for food, thereby pushing for an acceleration in agricultural production. Furthermore, increased anthropogenic activities have resulted in environmental pollution such as water pollution and soil degradation as well as alterations in the composition and concentration of environmental gases. These changes are affecting not only biodiversity loss but also affecting the physio-biochemical processes of crop plants, resulting in a stress-induced decline in crop yield. To overcome such problems and ensure the supply of food material, consistent efforts are being made to develop strategies and techniques to increase crop yield and to enhance tolerance toward climate-induced stress. Plant breeding evolved after domestication and initially remained dependent on phenotype-based selection for crop improvement. But it has grown through cytological and biochemical methods, and the newer contemporary methods are based on DNA-marker-based strategies that help in the selection of agronomically useful traits. These are now supported by high-end molecular biology tools like PCR, high-throughput genotyping and phenotyping, data from crop morpho-physiology, statistical tools, bioinformatics, and machine learning. After establishing its worth in animal breeding, genomic selection (GS), an improved variant of marker-assisted selection (MAS), has made its way into crop-breeding programs as a powerful selection tool. To develop novel breeding programs as well as innovative marker-based models for genetic evaluation, GS makes use of molecular genetic markers. GS can amend complex traits like yield as well as shorten the breeding period, making it advantageous over pedigree breeding and marker-assisted selection (MAS). It reduces the time and resources that are required for plant breeding while allowing for an increased genetic gain of complex attributes. It has been taken to new heights by integrating innovative and advanced technologies such as speed breeding, machine learning, and environmental/weather data to further harness the GS potential, an approach known as integrated genomic selection (IGS). This review highlights the IGS strategies, procedures, integrated approaches, and associated emerging issues, with a special emphasis on cereal crops. In this domain, efforts have been taken to highlight the potential of this cutting-edge innovation to develop climate-smart crops that can endure abiotic stresses with the motive of keeping production and quality at par with the global food demand.