Root exudates drive interspecific facilitation by enhancing nodulation and N2 fixation

Plant diversity in experimental systems often enhances ecosystem productivity, but the mechanisms causing this overyielding are only partly understood. Intercropping faba beans (Vicia faba L.) and maize (Zea mays L.) result in overyielding and also, enhanced nodulation by faba beans. By using permeable and impermeable root barriers in a 2-y field experiment, we show that root–root interactions between faba bean and maize significantly increase both nodulation and symbiotic N2 fixation in intercropped faba bean. Furthermore, root exudates from maize promote faba bean nodulation, whereas root exudates from wheat and barley do not. Thus, a decline of soil nitrate concentrations caused by intercropped cereals is not the sole mechanism for maize promoting faba bean nodulation. Intercropped maize also caused a twofold increase in exudation of flavonoids (signaling compounds for rhizobia) in the systems. Roots of faba bean treated with maize root exudates exhibited an immediate 11-fold increase in the expression of chalcone–flavanone isomerase (involved in flavonoid synthesis) gene together with a significantly increased expression of genes mediating nodulation and auxin response. After 35 d, faba beans treated with maize root exudate continued to show up-regulation of key nodulation genes, such as early nodulin 93 (ENOD93), and promoted nitrogen fixation. Our results reveal a mechanism for how intercropped maize promotes nitrogen fixation of faba bean, where maize root exudates promote flavonoid synthesis in faba bean, increase nodulation, and stimulate nitrogen fixation after enhanced gene expression. These results indicate facilitative root–root interactions and provide a mechanism for a positive relationship between species diversity and ecosystem productivity.

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Complex interactions in legume/cereal intercropping system: role of root exudates in root-to-root communication

10.1101/097584 ◽

2017 ◽

Cited By ~ 1

Author(s):

Yinshan Jiao ◽

Entao Wang ◽

Wenfeng Chen ◽

Donald L. Smith

Keyword(s):

Nitrogen Fixation ◽

Root Exudates ◽

Faba Bean ◽

The Novel ◽

Practical Application ◽

Corn Root ◽

Complex Interactions ◽

Root Interactions ◽

Ecological Principles

Dear Editor,Legume/cereal intercropping systems have been regarded as the practical application of basic ecological principles such as diversity, competition and facilitation. In a recent PNAS paper, Li et al. (1) describe the novel finding that maize exudates promote faba bean nodulation and nitrogen fixation by upregulating genes involved in (iso)flavonoids synthesis (chalcone–flavanone isomerase) within faba bean, resulting in production of more genistein, a legume-to-rhizobia signal during establishment of the faba bean N2–fixing symbiosis. Although we salute the authors’ methodological efforts, there is another mechanism that could be responsible for the effect of corn root exudates on faba been nitrogen fixation observed in this article (1). The authors may misunderstand their data and the signalling role of maize exudates, thus got a defective model for the root interactions between faba bean and maize.

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Nitrogen fixation and crop productivity enhancements codriven by intercrop root exudates and key rhizosphere bacteria

Journal of Applied Ecology ◽

10.1111/1365-2664.13964 ◽

2021 ◽

Author(s):

Heng‐Yu Hu ◽

Hong Li ◽

Min‐Min Hao ◽

Ya‐Nan Ren ◽

Meng‐Kun Zhang ◽

...

Keyword(s):

Nitrogen Fixation ◽

Root Exudates ◽

Crop Productivity ◽

Rhizosphere Bacteria

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Effect of Time and Legume Type on Germination-Induced Proteolysis of Lentils and Faba Beans

Proceedings ◽

10.3390/foods_2020-07823 ◽

2020 ◽

Vol 70 (1) ◽

pp. 4

Author(s):

Sara Bautista-Expósito ◽

Elena Peñas ◽

Albert Vanderberg ◽

Juana Frias ◽

Cristina Martínez-Villaluenga

Keyword(s):

Amino Acids ◽

Protease Activity ◽

Protein Quality ◽

Principal Component ◽

Fold Increase ◽

Protein Digestibility ◽

Essential Amino Acids ◽

Seedling Development ◽

Positive Effects ◽

Faba Beans

Legumes are alternative protein sources that have been successfully used to develop diverse meatless foods. Although these plant-based products have a lower impact on the environment than equivalent animal-based products, they have lower protein digestibility. Germination could be a useful bioprocess to enhance protein digestibility in legumes, although its effect at different times of seedling development has been little studied in lentils and faba beans. This work investigated the effect of germination time (4 and 6 days after full seed imbibition) on the proteins of three types of Canadian lentils (“gray zero tannin”, G; “caviar black”, B; and “red dehulled”, D) and faba beans (“zero vicin/convicin”, F). Germination increased total nitrogen (4–14% increase) and total levels of some amino acids: Asp in all the sprouts studied; Ser, Pro, Ala, Cys, His and Lys in G; and Met and Tyr in B. A concurrent degradation of the 7S and 11S globulin subunits, the accumulation of peptides below 20 kDa and free essential and non-essential amino acids (4- to 6-fold increase) were observed after germination in all the legumes studied. These effects were attributable to the increased protease activity observed after sprouting. Trypsin inhibitory activity was lower in legume sprouts, except for D, where a small increase was detected. Time, legume type and their interaction showed significant effects on the parameters studied. Germination effects were generally more remarkable at longer stages of seedling development. Among the legumes studied, D showed a differential behavior characterized by a faster protein degradation and release of small peptides, probably due to its higher protease activity as indicated by principal component analysis. These results evidence the positive effects of germination on the protein digestibility of different lentil types and faba beans. The protein quality of plant-based foods could be improved through the selection of legume species with higher germination-induced proteolytic rates and optimized germination times.

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Interspecific root interactions enhance photosynthesis and biomass of intercropped millet and peanut plants

Crop and Pasture Science ◽

10.1071/cp18269 ◽

2019 ◽

Vol 70 (3) ◽

pp. 234

Author(s):

Xiaojin Zou ◽

Zhanxiang Sun ◽

Ning Yang ◽

Lizhen Zhang ◽

Wentao Sun ◽

...

Keyword(s):

Crop Yields ◽

Positive Root ◽

Foxtail Millet ◽

Phosphoglycerate Kinase ◽

Plant Productivity ◽

Photosynthetic Rates ◽

Interspecific Facilitation ◽

Growing Seasons ◽

Root Interactions ◽

Root Barrier

Intercropping is commonly practiced worldwide because of its benefits to plant productivity and resource-use efficiency. Belowground interactions in these species-diverse agro-ecosystems can greatly contribute to enhancing crop yields; however, our understanding remains quite limited of how plant roots might interact to influence crop biomass, photosynthetic rates, and the regulation of different proteins involved in CO2 fixation and photosynthesis. We address this research gap by using a pot experiment that included three root-barrier treatments with full, partial and no root interactions between foxtail millet (Setaria italica (L.) P.Beauv.) and peanut (Arachis hypogaea L.) across two growing seasons. Biomass of millet and peanut plants in the treatment with full root interaction was 3.4 and 3.0 times higher, respectively, than in the treatment with no root interaction. Net photosynthetic rates also significantly increased by 112–127% and 275–306% in millet and peanut, respectively, with full root interaction compared with no root interaction. Root interactions (without barriers) contributed to the upregulation of key proteins in millet plants (i.e. ribulose 1,5-biphosphate carboxylase; chloroplast β-carbonic anhydrase; phosphoglucomutase, cytoplasmic 2; and phosphoenolpyruvate carboxylase) and in peanut plants (i.e. ribulose 1,5-biphosphate carboxylase; glyceraldehyde-3-phosphate dehydrogenase; and phosphoglycerate kinase). Our results provide experimental evidence of a molecular basis that interspecific facilitation driven by positive root interactions can contribute to enhancing plant productivity and photosynthesis.

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First Detection of Faba bean necrotic yellow virus in Spain

Plant Disease ◽

10.1094/pdis.2000.84.6.707b ◽

2000 ◽

Vol 84 (6) ◽

pp. 707-707 ◽

Cited By ~ 7

Author(s):

M. Babin ◽

V. Ortíz ◽

S. Castro ◽

J. Romero

Keyword(s):

Faba Bean ◽

Acyrthosiphon Pisum ◽

Virus Disease ◽

Epidemiological Data ◽

Aphid Transmission ◽

Enzyme Linked Immunosorbent Assay ◽

Yellow Virus ◽

Potential Threat ◽

Bean Plants ◽

Faba Beans

Faba bean necrotic yellow virus (FBNYV) was not detected during 1994 to 1996 field surveys of faba beans (Vicia faba L.) in Spain (1). In 1997, however, one sample with symptoms of necrosis, collected in Baleares, was tested using ELISA (enzyme-linked immunosorbent assay) and was positive for both Tomato spotted wilt virus (TSWV) and FBNYV. FBNYV is a single-strand DNA virus that is transmitted by aphids and is the main virus disease of broad bean in North Africa and West Asia (2). During 1997 to 1999, faba bean plants with symptoms of necrosis, yellowing, small leaves, and stunting were collected from several fields in the Murcia Region (Spain) and were analyzed using ELISA. To detect FBNYV, we used monoclonal 2E9 supplied by H. J. Vetten (Institute of Plant Virology, Microbiology and Biosafety, BBA, Braunschweig, Germany). Of 700 samples analyzed, 34 were positive for FBNYV. Of the 34 positive samples, 12 tested positive, using commercial antiserum from Loewe, Inc. (Munich) for mixed infections with TSWV. FBNYV was transmitted to healthy faba bean plants by aphids (Acyrthosiphon pisum) in greenhouse experiments and was confirmed by ELISA. Preliminary epidemiological data showed a gradual increase in the number of plants infected with time in the same field. Aphid transmission of FBNYV to faba beans has established the disease in Spain and is a potential threat to other leguminous crops. This is the first report of a nanovirus in Europe. References: (1) J. Fresno et al. Plant Dis. 81:112, 1997. (2) L. Katul et al. Ann. Appl. Biol. 123:629, 1993.

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Bacteroid oxalate oxidase and soluble oxalate in nodules of faba beans (Vicia fabaL.) submitted to water restricted conditions: possible involvement in nitrogen fixation

Journal of Experimental Botany ◽

10.1093/jxb/47.12.1865 ◽

1996 ◽

Vol 47 (12) ◽

pp. 1865-1870 ◽

Cited By ~ 5

Author(s):

Jean-Charles Trinchant ◽

Jean Rigaud

Keyword(s):

Nitrogen Fixation ◽

Oxalate Oxidase ◽

Faba Beans

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Portal vein, hepatic vein and circulating plasma amino acids in rats given diets based on lactalbumin, faba bean (Vicia faba) and chickpea (Cicer arietinum)

Animal Science ◽

10.1017/s1357729800053595 ◽

2003 ◽

Vol 77 (1) ◽

pp. 3-10 ◽

Cited By ~ 1

Author(s):

L. A. Rubiot

Keyword(s):

Amino Acids ◽

Portal Vein ◽

Faba Bean ◽

Plasma Concentrations ◽

Portal Blood Flow ◽

Hepatic Veins ◽

Plasma Amino Acids ◽

Synthetic Amino Acids ◽

Male Wistar Rats ◽

Faba Beans

AbstractThree experiments were carried out to determine plasma amino acids concentrations in circulating, portal and hepatic blood of growing male Wistar rats given diets containing lactalbumin, faba beans or chickpeas as the only protein source. Diets contained the same amount of digestible energy (15·5 kJ/g) and protein (lactalbumin in controls or legume proteins in the experimental diets; 100 g/kg). Appropriate amounts of essential synthetic amino acids were also added to legume-based diets taking into account their amino acid composition to equalize them to control (lactalbumin) diets. Portal blood flow (8·7±0·3 ml/min) was measured by using a transit-time ultrasound flow probe. Higher (P < 001) plasma concentrations of methionine than of controls were determined in hepatic veins of legume-fed rats. In contrast, lower (P < 001) concentrations of threonine, proline, valine, leucine, phenylalanine and lysine than those of controls were found in faba bean- and chickpea-fed rats. The same result as hepatic was obtained for portal and circulating plasma samples except that alanine and histidine values of legume-fed rats were also lower (P < 001) than controls. Calculated net afferent appearance rates of amino acids to the liver were lower (P < 001) than controls in rats given faba bean and chickpea diets for threonine, alanine, proline, valine, leucine, phenylalanine and lysine. This lower contribution of amino acids to the liver mainly via the portal vein in faba bean or chickpea-fed rats might explain previously reported differences in protein utilization and growth in comparison with animals given other protein sources (lactalbumin).

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