Nordic Crops as Alternatives to Soy-An Overview of Nutritional, Sensory, and Functional Properties

Soy (Glycine max) is used in a wide range of products and plays a major role in replacing animal-based products. Since the cultivation of soy is limited by cold climates, this review assessed the nutritional, sensory, and functional properties of three alternative cold-tolerant crops (faba bean (Vicia faba), yellow pea (Pisum sativum), and oat (Avena sativa)). Lower protein quality compared with soy and the presence of anti-nutrients are nutritional problems with all three crops, but different methods to adjust for these problems are available. Off-flavors in all pulses, including soy, and in cereals impair the sensory properties of the resulting food products, and few mitigation methods are successful. The functional properties of faba bean, pea, and oat are comparable to those of soy, which makes them usable for 3D printing, gelation, emulsification, and extrusion. Enzymatic treatment, fermentation, and fibrillation can be applied to improve the nutritional value, sensory attributes, and functional properties of all the three crops assessed, making them suitable for replacing soy in a broad range of products, although more research is needed on all attributes.

Tracking Ideal Varieties and Cropping Techniques for Agroecological Weed Management: A Simulation-Based Study on Pea

Pea or Pisum sativum L. is a key diversification crop, but current varieties are not very competitive against weeds. The objective was to identify, depending on the type of cropping system and weed flora, (1) the key pea parameters that drive crop production, weed control and weed contribution to biodiversity, (2) optimal combinations of pea-parameter values and crop-management techniques to maximize these goals. For this, virtual experiments were run, using FLORSYS, a mechanistic simulation model. This individual-based 3D model simulates daily crop-weed seed and plant dynamics over the years, from the cropping system and pedoclimate. Here, this model was parameterized for seven pea varieties, from experiments and literature. Moreover, ten virtual varieties were created by randomly combining variety-parameter values according to a Latin Hypercube Sampling (LHS) plan, respecting parameter ranges and correlations observed in the actual varieties. A global sensitivity analysis was run, using another LHS plan to combine pea varieties, crop rotations and management techniques in nine contrasting situations (e.g., conventional vs. organic, no-till, type of weed flora). Simulated data were analyzed with classification and regression trees (CART). We highlighted (1) Parameters that drive potential yield and competitivity against weeds (notably the ability to increase plant height and leaf area in shaded situations), depending on variety type (spring vs. winter) and cropping system. These are pointers for breeding varieties to regulate weeds by biological interactions; (2) Rules to guide farmers to choose the best pea variety, depending on the production goal and the cropping system; (3) The trade-off between increasing yield potential and minimizing yield losses due to weeds when choosing pea variety and management, especially in winter peas. The main pea-variety rules were the same for all performance goals, management strategies, and analyses scales, but further rules were useful for individual goals, strategies, and scales. Some variety features only fitted to particular systems (e.g., delayed pea emergence is only beneficial in case of herbicide-spraying and disastrous in unsprayed systems). Fewer variety rules should be compensated by more management rules. If one of the two main weed-control levers, herbicide or tillage, was eliminated, further pea-variety and/or management rules were needed.

First Report of Pea as a Natural Host of tomato mottle mosaic virus in China

Tomato mottle mosaic virus, a new species in the genus Tobamovirus and family Virgaviridae, was first reported on tomato in Mexico in 2013 (Li et al. 2013). Subsequently, tomato mottle mosaic virus (ToMMV) was found infecting pepper and eggplant in China (Li et al. 2014; Chai et al. 2018). ToMMV was thought to pose a serious risk to solanaceous crops due to its potential to break resistance and numerous transmission ways (Li et al. 2020), meanwhile, some plant species in the families of Amaranthaceae, Brassicaceae, Cucurbitaceae, and Verbenaceae, were found as the hosts of ToMMV under experimental condition (Sui et al. 2017; Li et al. 2020). To clarify the occurrence of ToMMV in Yunnan province of China, 395 plant samples, including tomato (Solanum lycopersicum L.), pepper (Capsicum annuum L.) and pea (Pisum sativum L.), exhibiting viral-like symptoms were collected in major crop plantations in Yunnan province in 2020. Total nucleic acids were extracted from the diseased samples using a CTAB method (Li et al. 2008), and tested by reverse transcription polymerase chain reaction (RT-PCR) with ToMMV specific primers, ToMMVMPF (5'-ATGGCTCTAACTGTTAGTGGT-3') and ToMMVMPR (5'-TTAATACGAATCAGATCCCGCG-3'), which were designed based on the movement protein gene sequence of ToMMV YYMLJ isolate (KR824950). ToMMV was detected in 13 symptomatic samples (11 cherry tomato and 2 green pea plants) with a total detection rate of 3.29%. An 807-bp fragment was amplified from 2 out of 86 pea samples showing foliar chlorosis, mosaic, malformation and necrosis symptoms, and the amplicons were cloned and sequenced. Sequences obtained from the two pea samples were identical. Therefore, one sequence was deposited in the GenBank (accession no. MW561348). BLAST search result showed that the nucleotide sequence had the highest identity of 99.88% with the ToMMV TiLhaLJ isolate (KR824951). The ToMMV infection on the two pea samples was also verified by dot-enzyme immunoassay (Dot-ELISA) using ToMMV monoclonal antibody (kindly provided by Dr. Jianxiang Wu, Zhejiang University, China). To determine the pathogenicity of ToMMV on pea, ToMMV infectious cDNA clone was used to inoculate into 3-week-old healthy pea plants via an Agrobacterium-mediated method (Tu et al. 2021). Mottle or slight mosaic, chlorosis and malformation symptoms were observed on the upper leaves of the 8 out of 12 inoculated plants 8 days postinoculation, and ToMMV could be detected by RT-PCR from the 8 symptomatic plants but not from the asymptomatic and healthy control pea plants with the above described ToMMV specific primer pair. ToMMV has now only been detected in Mexico, China, Spain, USA, Israel and Australia on tomato, pepper and eggplant (Webster et al. 2014; Turina et al. 2016; Ambrós et al. 2017; Lovelock et al. 2020). To the best of our knowledge, this is the first report of natural infection of ToMMV in pea as well as the natural infection of ToMMV on plants outside of the family Solanaceae. The result also implies that ToMMV has a potential risk to more crops in the field. Since pea, pepper and tomato are economically important cash crops in China, proper virus management strategies for the cultivation of these crops should be adopted.

Identification of Stipules reduced, a leaf morphology gene in pea (Pisum sativum)

Pea (Pisum sativum) is one of relatively few genetically amenable plant species with compound leaves. Pea leaves have a variety of specialized organs: leaflets, tendrils, pulvini and stipules, which enable the identification of mutations that transform or affect distinct parts of the leaf. Characterization of these mutations offers insights into the development and evolution of novel leaf traits. The previously characterized morphological gene Cochleata, conferring stipule identity, was known to interact with Stipules reduced (St), which conditions stipule size in pea, but the St gene remained unknown. Here we analysed Fast Neutron irradiated pea mutants by restriction site associated DNA sequencing. We identified St as a gene encoding a C2H2 zinc finger transcription factor that is regulated by Cochleata. St regulates both cell division and cell expansion in the stipule. Our approach shows how systematic genome-wide screens can be used successfully for the analysis of traits in species for which whole genome sequences are not available.

A Combined Comparative Transcriptomic, Metabolomic, and Anatomical Analyses of Two Key Domestication Traits: Pod Dehiscence and Seed Dormancy in Pea (Pisum sp.)

The origin of the agriculture was one of the turning points in human history, and a central part of this was the evolution of new plant forms, domesticated crops. Seed dispersal and germination are two key traits which have been selected to facilitate cultivation and harvesting of crops. The objective of this study was to analyze anatomical structure of seed coat and pod, identify metabolic compounds associated with water-impermeable seed coat and differentially expressed genes involved in pea seed dormancy and pod dehiscence. Comparative anatomical, metabolomics, and transcriptomic analyses were carried out on wild dormant, dehiscent Pisum elatius (JI64, VIR320) and cultivated, indehiscent Pisum sativum non-dormant (JI92, Cameor) and recombinant inbred lines (RILs). Considerable differences were found in texture of testa surface, length of macrosclereids, and seed coat thickness. Histochemical and biochemical analyses indicated genotype related variation in composition and heterogeneity of seed coat cell walls within macrosclereids. Liquid chromatography-electrospray ionization/mass spectrometry and Laser desorption/ionization-mass spectrometry of separated seed coats revealed significantly higher contents of proanthocyanidins (dimer and trimer of gallocatechin), quercetin, and myricetin rhamnosides and hydroxylated fatty acids in dormant compared to non-dormant genotypes. Bulk Segregant Analysis coupled to high throughput RNA sequencing resulted in identification of 770 and 148 differentially expressed genes between dormant and non-dormant seeds or dehiscent and indehiscent pods, respectively. The expression of 14 selected dormancy-related genes was studied by qRT-PCR. Of these, expression pattern of four genes: porin (MACE-S082), peroxisomal membrane PEX14-like protein (MACE-S108), 4-coumarate CoA ligase (MACE-S131), and UDP-glucosyl transferase (MACE-S139) was in agreement in all four genotypes with Massive analysis of cDNA Ends (MACE) data. In case of pod dehiscence, the analysis of two candidate genes (SHATTERING and SHATTERPROOF) and three out of 20 MACE identified genes (MACE-P004, MACE-P013, MACE-P015) showed down-expression in dorsal and ventral pod suture of indehiscent genotypes. Moreover, MACE-P015, the homolog of peptidoglycan-binding domain or proline-rich extensin-like protein mapped correctly to predicted Dpo1 locus on PsLGIII. This integrated analysis of the seed coat in wild and cultivated pea provides new insight as well as raises new questions associated with domestication and seed dormancy and pod dehiscence.

Alkali-Soluble Pectin Is the Primary Target of Aluminum Immobilization in Root Border Cells of Pea (Pisum sativum)

We investigated the hypothesis that a discrepancy of Al binding in cell wall constituents determines Al mobility in root border cells (RBCs) of pea (Pisum sativum), which provides protection for RBCs and root apices under Al toxicity. Plants of pea (P. sativum L. 'Zhongwan no. 6') were subjected to Al treatments under mist culture. The concentration of Al in RBCs was much higher than that in the root apex. The Al content in RBCs surrounding one root apex (10(4) RBCs) was approximately 24.5% of the total Al in the root apex (0-2.5 mm), indicating a shielding role of RBCs for the root apex under Al toxicity. Cell wall analysis showed that Al accumulated predominantly in alkali-soluble pectin (pectin 2) of RBCs. This could be attributed to a significant increase of uronic acids under Al toxicity, higher capacity of Al adsorption in pectin 2 [5.3-fold higher than that of chelate-soluble pectin (pectin 1)], and lower ratio of Al desorption from pectin 2 (8.5%) compared with pectin 1 (68.5%). These results indicate that pectin 2 is the primary target of Al immobilization in RBCs of pea, which impairs Al access to the intracellular space of RBCs and mobility to root apices, and therefore protects root apices and RBCs from Al toxicity.

Early plant growth: identifying the end point of the seedling phase

•  Despite the importance of seedling establishment in plant biology, there is no consensus on what constitutes a 'seedling'. Here we examined aspects of early plant development that could be used to mark the transition from the seedling to the postseedling phase. •  Using a hypogeal species (pea, Pisum sativum) and an epigeal species (sunflower, Helianthus annuus), we investigated whether the utilization of cotyledon-stored mineral nutrients coincides with any changes in relative growth rate (RGR). We also examined how the timing of cotyledon removal at different points during early development affected subsequent growth. •  For both species, the timing of RGR_max , the exhaustion of cotyledon reserves, and the attainment of independence from cotyledons all roughly coincided (though exhaustion of seed reserves was not observed in the epigeal species because the cotyledons absorbed external nutrients). •  We conclude that because the point of attainment of RGR_max is a distinctly identifiable event, it is a more reliable marker for defining the end of the seedling stage than either the exhaustion of mineral reserves, or the cessation of dependence on cotyledon reserves.