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1.
Navigating complexity to breed disease-resistant crops.
Nelson, R, Wiesner-Hanks, T, Wisser, R, Balint-Kurti, P
Nature reviews. Genetics. 2018;(1):21-33
Abstract
Plant diseases are responsible for substantial crop losses each year and pose a threat to global food security and agricultural sustainability. Improving crop resistance to pathogens through breeding is an environmentally sound method for managing disease and minimizing these losses. However, it is challenging to breed varieties with resistance that is effective, stable and broad-spectrum. Recent advances in genetic and genomic technologies have contributed to a better understanding of the complexity of host-pathogen interactions and have identified some of the genes and mechanisms that underlie resistance. This new knowledge is benefiting crop improvement through better-informed breeding strategies that utilize diverse forms of resistance at different scales, from the genome of a single plant to the plant varieties deployed across a region.
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2.
Translating High-Throughput Phenotyping into Genetic Gain.
Araus, JL, Kefauver, SC, Zaman-Allah, M, Olsen, MS, Cairns, JE
Trends in plant science. 2018;(5):451-466
Abstract
Inability to efficiently implement high-throughput field phenotyping is increasingly perceived as a key component that limits genetic gain in breeding programs. Field phenotyping must be integrated into a wider context than just choosing the correct selection traits, deployment tools, evaluation platforms, or basic data-management methods. Phenotyping means more than conducting such activities in a resource-efficient manner; it also requires appropriate trial management and spatial variability handling, definition of key constraining conditions prevalent in the target population of environments, and the development of more comprehensive data management, including crop modeling. This review will provide a wide perspective on how field phenotyping is best implemented. It will also outline how to bridge the gap between breeders and 'phenotypers' in an effective manner.
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3.
Molecular Genetics and Breeding for Nutrient Use Efficiency in Rice.
Ali, J, Jewel, ZA, Mahender, A, Anandan, A, Hernandez, J, Li, Z
International journal of molecular sciences. 2018;(6)
Abstract
In the coming decades, rice production needs to be carried out sustainably to keep the balance between profitability margins and essential resource input costs. Many fertilizers, such as N, depend primarily on fossil fuels, whereas P comes from rock phosphates. How long these reserves will last and sustain agriculture remains to be seen. Therefore, current agricultural food production under such conditions remains an enormous and colossal challenge. Researchers have been trying to identify nutrient use-efficient varieties over the past few decades with limited success. The concept of nutrient use efficiency is being revisited to understand the molecular genetic basis, while much of it is not entirely understood yet. However, significant achievements have recently been observed at the molecular level in nitrogen and phosphorus use efficiency. Breeding teams are trying to incorporate these valuable QTLs and genes into their rice breeding programs. In this review, we seek to identify the achievements and the progress made so far in the fields of genetics, molecular breeding and biotechnology, especially for nutrient use efficiency in rice.
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4.
Translational Research: Exploring and Creating Genetic Diversity.
Jacob, P, Avni, A, Bendahmane, A
Trends in plant science. 2018;(1):42-52
Abstract
The crop selection process has created a genetic bottleneck ultimately restricting breeding output. Wild relatives of major crops as well as the so-called 'neglected plant' species represent a reservoir of genetic diversity that remains underutilized. These species could be used as a tool to discover new alleles of agronomic interest or could be the target of breeding programs. Targeted induced local lesions in the genome (TILLING) can be used to translate in neglected crops what has been discovered in major crops and reciprocally. However, random mutagenesis, used in TILLING approaches, provides only a limited density of mutational events at a defined target locus. Alternatively, clustered regularly interspaced short palindromic repeats (CRISPR) associated 9 (Cas9) fused to a cytidine deaminase could serve as a localized mutagenic agent to produce high-density mutant populations. Artificial evolution is at hand.
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5.
Agronomic performance of new open pollinated experimental lines of broccoli (Brassica oleracea L. var. italica) evaluated under organic farming.
Sahamishirazi, S, Moehring, J, Zikeli, S, Fleck, M, Claupein, W, Graeff-Hoenninger, S
PloS one. 2018;(5):e0196775
Abstract
In order to develop new open pollinating cultivars of broccoli for organic farming, two experiments were conducted during fall 2015 and spring 2016. This study was aimed at comparing the agronomic performance of eleven new open pollinating breeding lines of broccoli to introduce new lines and to test their seasonal suitability for organic farming. Field experiments were carried out at the organic research station Kleinhohenheim of the University of Hohenheim (Stuttgart-Germany). Different agronomic traits total biomass fresh weight, head fresh weight, head diameter, hollow-stem, fresh weight harvest index and marketable yield were assessed together with commercial control cultivars. The data from both experiments were analyzed using a two-stage mixed model approach. In our study, genotype, growing season and their interaction had significant effects on most traits. Plants belonging to the fall growing season had bigger sizes in comparison to spring with significantly (p< 0.0001) higher biomass fresh weight. Some experimental lines had significant lower head fresh weight in spring in comparison to the fall season. The high temperature during the harvest period for the spring season affected the yield negatively through decreasing the firmness of broccoli heads. The low average minimum temperatures during the spring growing season lead to low biomass fresh weight but high fresh weight harvest index. Testing the seasonal suitability of all open pollinating lines showed that the considered fall season was better for broccoli production. However, the change in yield between the fall and the spring growing season was not significant for "Line 701" and "CHE-MIC". Considering the expression of different agronomic traits, "CHE-GRE-G", "Calinaro" and "CAN-SPB" performed the best in the fall growing season, and "CHE-GRE-G", "CHE-GRE-A", "CHE-BAL-A" and "CHE-MIC" and "Line 701" were best in the spring growing season, specifically due to the highest marketable yield and proportion of marketable heads.
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Cell size, photosynthesis and the package effect: an artificial selection approach.
Malerba, ME, Palacios, MM, Palacios Delgado, YM, Beardall, J, Marshall, DJ
The New phytologist. 2018;(1):449-461
Abstract
Cell size correlates with most traits among phytoplankton species. Theory predicts that larger cells should show poorer photosynthetic performance, perhaps due to reduced intracellular self-shading (i.e. package effect). Yet current theory relies heavily on interspecific correlational approaches and causal relationships between size and photosynthetic machinery have remained untested. As a more direct test, we applied 250 generations of artificial selection (c. 20 months) to evolve the green microalga Dunaliella teriolecta (Chlorophyta) toward different mean cell sizes, while monitoring all major photosynthetic parameters. Evolving larger sizes (> 1500% difference in volume) resulted in reduced oxygen production per chlorophyll molecule - as predicted by the package effect. However, large-evolved cells showed substantially higher rates of oxygen production - a finding unanticipated by current theory. In addition, volume-specific photosynthetic pigments increased with size (Chla+b), while photo-protectant pigments decreased (β-carotene). Finally, larger cells displayed higher growth performances and Fv /Fm , steeper slopes of rapid light curves (α) and smaller light-harvesting antennae (σPSII ) with higher connectivity (ρ). Overall, evolving a common ancestor into different sizes showed that the photosynthetic characteristics of a species coevolves with cell volume. Moreover, our experiment revealed a trade-off between chlorophyll-specific (decreasing with size) and volume-specific (increasing with size) oxygen production in a cell.
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7.
Molecular improvement of alfalfa for enhanced productivity and adaptability in a changing environment.
Singer, SD, Hannoufa, A, Acharya, S
Plant, cell & environment. 2018;(9):1955-1971
Abstract
Due to an expanding world population and increased buying power, the demand for ruminant products such as meat and milk is expected to grow substantially in coming years, and high levels of forage crop production will therefore be a necessity. Unfortunately, urbanization of agricultural land, intensive agricultural practices, and climate change are all predicted to limit crop production in the future, which means that the development of forage cultivars with improved productivity and adaptability will be essential. Because alfalfa (Medicago sativa L.) is one of the most widely cultivated perennial forage crops, it has been the target of much research in this field. In this review, we discuss progress that has been made towards the improvement of productivity, abiotic stress tolerance, and nutrient-use efficiency, as well as disease and pest resistance, in alfalfa using biotechnological techniques. Furthermore, we consider possible future priorities and avenues for attaining further enhancements in this crop as a means of contributing to the realization of food security in a changing environment.
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A transnational and holistic breeding approach is needed for sustainable wheat production in the Baltic Sea region.
Chawade, A, Armoniené, R, Berg, G, Brazauskas, G, Frostgård, G, Geleta, M, Gorash, A, Henriksson, T, Himanen, K, Ingver, A, et al
Physiologia plantarum. 2018;(4):442-451
Abstract
The Baltic Sea is one of the largest brackish water bodies in the world. Eutrophication is a major concern in the Baltic Sea due to the leakage of nutrients to the sea with agriculture being the primary source. Wheat (Triticum aestivum L.) is the most widely grown crop in the countries surrounding the Baltic Sea and thus promoting sustainable agriculture practices for wheat cultivation will have a major impact on reducing pollution in the Baltic Sea. This approach requires identifying and addressing key challenges for sustainable wheat production in the region. Implementing new technologies for climate-friendly breeding and digital farming across all surrounding countries should promote sustainable intensification of agriculture in the region. In this review, we highlight major challenges for wheat cultivation in the Baltic Sea region and discuss various solutions integrating transnational collaboration for pre-breeding and technology sharing to accelerate development of low input wheat cultivars with improved host plant resistance to pathogen and enhanced adaptability to the changing climate.
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9.
The role of plant hormones during grafting.
Nanda, AK, Melnyk, CW
Journal of plant research. 2018;(1):49-58
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Abstract
For millennia, people have cut and joined different plant tissues together through a process known as grafting. By creating a chimeric organism, desirable properties from two plants combine to enhance disease resistance, abiotic stress tolerance, vigour or facilitate the asexual propagation of plants. In addition, grafting has been extremely informative in science for studying and identifying the long-distance movement of molecules. Despite its increasing use in horticulture and science, how plants undertake the process of grafting remains elusive. Here, we discuss specifically the role of eight major plant hormones during the wound healing and vascular formation process, two phenomena involved in grafting. We furthermore present the roles of these hormones during graft formation and highlight knowledge gaps and future areas of interest for the field of grafting biology.
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10.
A critical and speculative review on microRNA technology in crop improvement: Current challenges and future directions.
Zhang, B, Unver, T
Plant science : an international journal of experimental plant biology. 2018;:193-200
Abstract
MicroRNAs (miRNAs) lie at the center of gene regulation and, as such, have become novel targets for crop improvement including the enhancement of crop quality and yields as well as responses to environmental stresses. There are several major issues related to miRNA technology including the functional analysis of miRNAs and their nomenclature. In this critical and speculative review, we recommend several directions for future plant miRNA research and perspectives. Research on miRNA needs to be extended from merely descriptive studies to functional studies. More genetic tools, such as genome editing, should be developed for miRNA functional study. Obtaining transgenic plants is a bottleneck for plant miRNA functional studies and, hence, more reliable transformation methods need to be developed. We also propose a new terminology approach for miRNA nomenclature. The current miRNA nomenclature is confusing and has mislead much research. Here we suggest to name a miRNA as miR#-5p or -3p, and to name their opposite strand as miR#*-3p or -5p. The advantages of the new nomenclature is that it covers information on the history, relationship, family, and location of an individual miRNA. It recognizes both traditional and new discovery.