The arbuscular mycorrhizal (AM) symbiosis is key to plant nutrition, and hence is potentially key in sustainable agriculture. Fertilization and other agricultural practices reduce soil AM fungi and ...root colonization. Such conditions might promote the evolution of low mycorrhizal responsive crops. Therefore, we ask if and how evolution under domestication has altered AM symbioses of crops.
We measured the effect of domestication on mycorrhizal responsiveness across 27 crop species and their wild progenitors. Additionally, in a subset of 14 crops, we tested if domestication effects differed under contrasting phosphorus (P) availabilities.
The response of AM symbiosis to domestication varied with P availability. On average, wild progenitors benefited from the AM symbiosis irrespective of P availability, while domesticated crops only profited under P-limited conditions. Magnitudes and directions of response were diverse among the 27 crops, and were unrelated to phylogenetic affinities or to the coordinated evolution with fine root traits.
Our results indicate disruptions in the efficiency of the AM symbiosis linked to domestication.
Under high fertilization, domestication could have altered the regulation of resource trafficking between AM fungi and associated plant hosts. Provided that crops are commonly raised under high fertilization, this result has important implications for sustainable agriculture.
Agricultural fields are commonly characterized by high nutrient and water availabilities, which are favourable for plant growth. Such conditions might promote the evolution of resource‐acquisitive ...strategies. We asked whether crop plants show root traits typical of resource‐acquisitive strategies and whether this strategy is primarily a result of their evolution under domestication or of the early selection of successful candidates for domestication.
We studied a set of 30 crop species and their wild progenitors. We set up a greenhouse experiment to measure five root traits: root thickness, root tissue density, specific root length (SRL), root mass fraction (RMF) and root length ratio. In addition, we compiled data from other wild herbaceous species, growth in similar conditions to this experiment, to place the root traits of our crops in the context of wider botanical variation.
Wild progenitors had thicker and less dense roots, with higher RMF and lower SRL, than other wild herbs. Thicker and less dense roots are indicative of fertile soils, which suggest that wild progenitors could have been adapted for success in agricultural conditions. Additionally, we found that domestication generally increased total plant dry mass, but none of the root traits evolved consistently towards a more resource‐acquisitive strategy after domestication across all species. Root trait values differed between progenitors and crop species for most pairs surveyed, but this occurred in diverse directions depending on crop species. Such differences were independent of phylogeny, functional group or variability in the domestication processes, such as timing of the domestication event or organ under focal artificial selection.
Our comparative study revealed that the root phenotype exhibited by wild progenitors (thick roots with low density and SRL), when compared with other wild herbs, was in accordance with plants typical of fertile habitats. However, none of the root traits reacted to domestication in accordance with evolution towards faster growth strategies. Thus, the adaptation of crop root phenotypes to the fertile conditions of agricultural fields might be largely determined by early choices of wild species, rather than by further evolution under domestication.
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Plain Language Summary
Domestication took plants from natural environments to agro-ecosystems, where resources are generally plentiful and plant life is better buffered against environmental risks such as drought or ...pathogens. We hypothesized that predictions derived from the comparison of low vs high resource ecosystems (faster-growing plants promoting faster nutrient cycling in the latter) extrapolate to the process of domestication.
We conducted the first comprehensive assessment of the consequences of domestication on litter quality and key biogeochemical processes by comparing 24 domesticated crops against their closest wild ancestors. Twelve litter chemistry traits, litter decomposability and indicators of soil carbon (C) and nitrogen (N) cycling were assessed in each domesticated vs wild ancestor pair. These assessments were done in microbial-poor and microbial-rich soils to exemplify intensively and extensively managed agricultural soils, respectively.
Plant domestication has increased litter quality, encouraging litter decomposability (36% and 44% increase in the microbial-rich and microbial-poor soils, respectively), higher soil
availability and lower soil C:N ratios. These effects held true for the majority of the crops surveyed and for soils with different microbial communities.
Our results support ecological theory predictions derived from the comparison of low- and high-resource ecosystems, suggesting a parallelism between ecosystem-level impacts of natural and artificial selection.
Stomata are the major gates regulating substrate availability for photosynthesis and water loss. Although both processes are critical to yield and to resource-use efficiency, we lack a comprehensive ...picture on how domestication and further breeding have impacted on leaf stomata. To fill this gap, stomatal sizes and densities were screened in cultivated and wild ancestor representatives of a uniquely large group of 24 herbaceous crops. Anatomical data and gas-exchange models were combined to compute maximum potential conductance to water, separately for upper and lower leaf sides. The evolution of maximum conductance under domestication was diverse. Several crops increased, others decreased (noticeably high-conductance species), and others kept a similar potential conductance following domestication. It was found that the contribution of upper leaf sides to maximum conductance was statistically higher in cultivated than in wild ancestors. For crops showing this response, reduced stomatal density in the lower side of domesticated leaves was responsible for the observed ‘adaxialization’ of conductance. Increases in the size of stomata at the upper epidermis played a comparatively minor role. Nevertheless, this overall response was varied in magnitude and direction, signalling crop-wise specificities. Observed patterns reflect only potential conductances based on anatomical traits and should be used with care until actual physiological outcomes are measured. Together with advancements in the developmental genetics of stomata, our findings might hint at new breeding avenues, focused on stomata distribution. Provided urgent needs for increasing yields, the opportunities of enhancing traits of the physiological relevance of stomata should not be ignored.
Aims
Conventional agriculture promotes negative feedbacks of soil microbes on crop performance (plant soil feedbacks, PSFs) by stimulating species-specific pathogens. Crop traits, modified by ...domestication, also influence PSFs. Therefore, we asked if crop cultivars and their wild progenitors promote soil pathogens and mutualists differently, and thus trigger different PSFs.
Methods
We studied PSFs in cultivated varieties and wild progenitors of ten crops. In a first season, we grew all genotypes separately in a common soil to obtain genotype-specific soil inocula (‘trained soil’) for a second season. In season two, we examined the effects of the trained soil on plant interactions with arbuscular mycorrhizal fungi and with root-feeding nematodes, and on plant performance.
Results
Mycorrhizal colonization was lower, and nematode infection rate was higher, in plant roots growing on soils previously trained by domesticated plants. Moreover, domesticated plants showed lower mycorrhizal colonization, and higher nematode infection rates than their wild progenitors, irrespective of previous soil training. The response of plant performance to soil training was species-specific and unrelated to cultivated vs wild status.
Conclusions
Soil legacies differed between cultivated varieties and their wild progenitors, suggesting an impact of domestication on the way rhizosphere organisms are recruited, on the resistance of plants to herbivores, and on their interactions with root mutualists.
Trait-based ecology predicts that evolution in high-resource agricultural environments should select for suites of traits that enable fast resource acquisition and rapid canopy closure. However, crop ...breeding targets specific agronomic attributes rather than broad trait syndromes. Breeding for specific traits, together with evolution in high-resource environments, might lead to reduced phenotypic integration, according to predictions from the ecological literature. We provide the first comprehensive test of these hypotheses, based on a trait-screening programme of 30 herbaceous crops and their wild progenitors. During crop evolution plants became larger, which enabled them to compete more effectively for light, but they had poorly integrated phenotypes. In a subset of six herbaceous crop species investigated in greater depth, competitiveness for light increased during early plant domestication, whereas diminished phenotypic integration occurred later during crop improvement. Mass-specific leaf and root traits relevant to resource-use strategies (e.g. specific leaf area or tissue density of fine roots) changed during crop evolution, but in diverse and contrasting directions and magnitudes, depending on the crop species. Reductions in phenotypic integration and overinvestment in traits involved in competition for light may affect the chances of upgrading modern herbaceous crops to face current climatic and food security challenges.
Lipophilic antioxidants play dual key roles in edible seeds (i) as preservatives of cell integrity and seed viability by preventing the oxidation of fats, and (ii) as essential nutrients for human ...and animal life stock. It has been well documented that plant domestication and post-domestication evolution frequently resulted in increased seed size and palatability, and reduced seed dormancy. Nevertheless, and surprisingly, it is poorly understood how agricultural selection and cultivation affected the physiological fitness and the nutritional quality of seeds. Fabaceae have the greatest number of crop species of all plant families, and most of them are cultivated for their highly nutritious edible seeds. Here, we evaluate whether evolution of plants under cultivation has altered the integrated system formed by membranes (fatty acids) and lipophilic antioxidants (carotenoids and tocopherols), in the ten most economically important grain legumes and their closest wild relatives, i.e.: Arachis (peanut), Cicer (chickpea), Glycine (soybean), Lathyrus(vetch), Lens (lentil), Lupinus (lupin), Phaseolus (bean), Pisum (pea), Vicia (faba bean) and Vigna (cowpea).
Unexpectedly, we found that following domestication, the contents of carotenoids, including lutein and zeaxanthin, decreased in all ten species (total carotenoid content decreased 48% in average). Furthermore, the composition of carotenoids changed, whereby some carotenoids were lost in most of the crops. An undirected change in the contents of tocopherols and fatty acids was found, with contents increasing in some species and decreasing in others, independently of the changes in carotenoids. In some species, polyunsaturated fatty acids (linolenic acid especially), α-tocopherol and γ-tocopherol decreased following domestication.
The changes in carotenoids, tocopherols and fatty acids are likely side-effects of the selection for other desired traits such as the loss of seed dormancy and dispersal mechanisms, and selection for seed storability and taste. This work may serve as baseline to broaden our knowledge on the integrated changes on crop fitness and nutritional quality following domestication.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Laboratory decomposition experiments measuring the mineralization of C from plant residue are increasingly used to test the effects of different litter sources and soil conditions. To date, the most ...widely used methods are infra-red gas analysis (IRGA) and gas chromatography, which are time-consuming, and relatively expensive and complex to operate. The aim of this study was to devise a simple and rapid laboratory method to assess litter decomposition rates at frequent time intervals. We modified the MicroResp™ system to measure the amount of CO2 produced by two soils supporting contrasting microbial communities and containing the litter of eight crop species. The method was sensitive enough to differentiate both soil microbial communities and litter qualities. The method combines the accuracy of gas chromatography with the speed of absorbance measurements obtained via microplate readers. This technique provides an effective means for devising complex litter decomposition experiments capable of addressing the joint influence of multiple species, soil communities, environmental conditions, and their multiple interactions.
► We tested the reliability of a rapid laboratory method to assess decomposition rates. ► It combines the accuracy of gas chromatography with the speed of absorbance measurements in microplate readers. ► It was sensitive to differentiate contrasted soil microbial communities and litter qualities. ► This method represents a promising tool in complex litter decomposition experiments.
Trait-based ecology predicts that evolution in high-resource agricultural environments should select for suites of traits that enable fast resource acquisition and rapid canopy closure. However, crop ...breeding targets specific agronomic attributes rather than broad trait syndromes. Breeding for specific traits, together with evolution in high-resource environments, might lead to reduced phenotypic integration, according to predictions from the ecological literature. We provide the first comprehensive test of these hypotheses, based on a trait-screening programme of 30 herbaceous crops and their wild progenitors. During crop evolution plants became larger, which enabled them to compete more effectively for light, but they had poorly integrated phenotypes. In a subset of six herbaceous crop species investigated in greater depth, competitiveness for light increased during early plant domestication, whereas diminished phenotypic integration occurred later during crop improvement. Mass-specific leaf and root traits relevant to resource-use strategies (e.g. specific leaf area or tissue density of fine roots) changed during crop evolution, but in diverse and contrasting directions and magnitudes, depending on the crop species. Reductions in phenotypic integration and overinvestment in traits involved in competition for light may affect the chances of upgrading modern herbaceous crops to face current climatic and food security challenges.
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