Soto-Cerda BJ, Duguid S, Booker H, Rowland G, Diederichsen A, Cloutier S (2014). Association mapping of seed quality traits using the Canadian flax (Linum usitatissimum L.) core collection. Theoretical and Applied Genetics. 127; 4; 881-896.
Linseed oil is valued for its food and non-food applications. Modifying its oil content and fatty acid (FA) profiles to meet market needs in a timely manner requires clear understanding of their quantitative trait loci (QTL) architectures, which have received little attention to date. Association mapping is an efficient approach to identify QTL in germplasm collections. In this study, we explored the quantitative nature of seed quality traits including oil content (OIL), palmitic acid, stearic acid, oleic acid, linoleic acid (LIO) linolenic acid (LIN) and iodine value in a flax core collection of 390 accessions assayed with 460 microsatellite markers. The core collection was grown in a modified augmented design at two locations over 3 years and phenotypic data for all seven traits were obtained from all six environments. Significant phenotypic diversity and moderate to high heritability for each trait (0.73–0.99) were observed. Most of the candidate QTL were stable as revealed by multivariate analyses. Nine candidate QTL were identified, varying from one for OIL to three for LIO and LIN. Candidate QTL for LIO and LIN co-localized with QTL previously identified in bi-parental populations and some mapped nearby genes known to be involved in the FA biosynthesis pathway. Fifty-eight percent of the QTL alleles were absent (private) in the Canadian cultivars suggesting that the core collection possesses QTL alleles potentially useful to improve seed quality traits. The candidate QTL identified herein will establish the foundation for future marker-assisted breeding in linseed.
Soto-Cerda BJ, Duguid S, Booker H, Rowland G, Diederichsen A, Cloutier S. (2014) Genomic Regions Underlying Agronomic Traits in Linseed (Linum usitatissimum L.) as Revealed by Association Mapping. Journal of Integrative Plant Biology. 56; 1; 75–87.
The extreme climate of the Canadian Prairies poses a major challenge to improve yield. Although it is possible to breed for yield per se, focusing on yield-related traits could be advantageous because of their simpler genetic architecture. The Canadian flax core collection of 390 accessions was genotyped with 464 simple sequence repeat markers, and phenotypic data for nine agronomic traits including yield, bolls per area, 1,000 seed weight, seeds per boll, start of flowering, end of flowering, plant height, plant branching, and lodging collected from up to eight environments was used for association mapping. Based on a mixed model (principal component analysis (PCA) + kinship matrix (K)), 12 significant marker-trait associations for six agronomic traits were identified. Most of the associations were stable across environments as revealed by multivariate analyses. Statistical simulation for five markers associated with 1000 seed weight indicated that the favorable alleles have additive effects. None of the modern cultivars carried the five favorable alleles and the maximum number of four observed in any accessions was mostly in breeding lines. Our results confirmed the complex genetic architecture of yield-related traits and the inherent difficulties associated with their identification while illustrating the potential for improvement through marker-assisted selection.
Adams, W., Cohu, C., Amiard, V., Demmig-Adams B. (2014). Associations between the acclimation of phloem-cell wall ingrowths in minor veins and maximal photosynthesis rate. Frontiers in Plant Science. 5; 24.
The companion cells (CCs) and/or phloem parenchyma cells (PCs) in foliar minor veins of some species exhibit invaginations that are amplified when plants develop in high light (HL) compared to low light (LL). Leaves of plants that develop under HL also exhibit greater maximal rates of photosynthesis compared to those that develop under LL, suggesting that the increased membrane area of CCs and PCs of HL-acclimated leaves may provide for greater levels of transport proteins facilitating enhanced sugar export. Furthermore, the degree of wall invagination in PCs (Arabidopsis thaliana) or CCs (pea) of fully expanded LL-acclimated leaves increased to the same level as that present in HL-acclimated leaves 7 days following transfer to HL, and maximal photosynthesis rates of transferred leaves of both species likewise increased to the same level as in HL-acclimated leaves. In contrast, transfer of Senecio vulgaris from LL to HL resulted in increased wall invagination in CCs, but not PCs, and such leaves furthermore exhibited only partial upregulation of photosynthetic capacity following LL to HL transfer. Moreover, a significant linear relationship existed between the level of cell wall ingrowths and maximal photosynthesis rates across all three species and growth light regimes. A positive linear relationship between these two parameters was also present for two ecotypes (Sweden, Italy) of the winter annual A. thaliana in response to growth at different temperatures, with significantly greater levels of PC wall ingrowths and higher rates of photosynthesis in leaves that developed at cooler versus warmer temperatures. Treatment of LL-acclimated plants with the stress hormone methyl jasmonate also resulted in increased levels of wall ingrowths in PCs of A. thaliana and S. vulgaris but not in CCs of pea and S. vulgaris. The possible role of PC wall ingrowths in sugar export versus as physical barriers to the movement of pathogens warrants further attention.
Ogura, Takahiro; Ogihara, Jun; Sunairi, Michio; Takeishi, Hidetaka; Aizawa, Tomoko; Olivos‐Trujillo, Marcos R; Maureira‐Butler, Iván J; Salvo‐Garrido, Haroldo E. (2014) Proteomic characterization of seeds from yellow lupin (Lupinus luteus L.). Proteomics. 14; 12; 1543-1546.
Yellow lupin (Lupinus luteus L.) is a legume crop containing a large amount of protein in its seeds. In this study, we constructed a seed-protein catalog to provide a foundation for further study of the seeds. A total of 736 proteins were identified in 341 2DE spots by nano-LC-MS/MS. Eight storage proteins were found as multiple spots in the 2DE gels. The 736 proteins correspond to 152 unique proteins as shown by UniRef50 clustering. Sixty-seven of the 152 proteins were associated with KEGG-defined pathways. Of the remaining proteins, 57 were classified according to a GO term. The functions of the remaining 28 proteins have yet to be determined. This is the first yellow lupin seed–protein catalog, and it contains considerably more data than previously reported for white lupin (L. albus L.).
Zhang, Tao; Soto-Cerda, Braulio ; Duguid, Scott D.; Cloutier, Sylvie; Rowland, Gordon; Diederichsen, Axel; Booker, Helen; Lamb, Eric G. (2014). Structural equation modeling of the Canadian flax (Linum usitatissimum L.) core collection for multiple phenotypic traits. Canadian Journal of Plant Science. 94;8;1325-1332.
Flax seed yield is a complex trait that results from the inter-relationship between many crop characteristics. Structural equation modeling (SEM) is a statistical method used to determine the relationship between measured variables such as crop characteristics. Crop phenology, canopy traits, yield, and its components were included in structural equation models to determine how these crop characteristics relate to seed yield in a phenotypically diverse collection of flax germplasm. Early season vigor (scored as greater plant stand) was positively associated with canopy light interception and higher seed yield. Plant height also had a significant positive effect on seed yield. Moreover, yield components such as 1000-seed weight, number of bolls per unit area, and boll weight were strongly and positively correlated with seed yield. Focusing on yield-related traits, canopy architecture and expansion, and seed weight may be advantageous over yield per se in breeding for yield improvement.
Soto-Cerda, Braulio J., Diederichsen, Axel, Duguid, Scott, Booker, Helen, Rowland, Gordon; Cloutier, Sylvie. (2014). The potential of pale flax as a source of useful genetic variation for cultivated flax revealed through molecular diversity and association analyses. Molecular Breeding. 34; 4; 2091-2107.
Pale flax (Linum bienne Mill.) is the wild progenitor of cultivated flax (Linum usitatissimum L.) and represents the primary gene pool to broaden its genetic base. Here, a collection of 125 pale flax accessions and the Canadian flax core collection of 407 accessions were genotyped using 112 genomewide simple sequence repeat markers and phenotyped for nine traits with the aim of conducting population structure, molecular diversity and association mapping analyses. The combined population structure analysis identified two well-supported major groups corresponding to pale and cultivated flax. The L. usitatissimum convar. crepitans accessions most closely resembled its wild progenitor, both having dehiscent capsules. The unbiased Nei’s genetic distance (0.65) confirmed the strong genetic differentiation between cultivated and pale flax. Similar levels of genetic diversity were observed in both species, albeit 430 (48 %) of pale flax alleles were unique, in agreement with their high genetic differentiation. Significant associations were identified for seven and four traits in pale and cultivated flax, respectively. Favorable alleles with potentially positive effect to improve yield through yield components were identified in pale flax. The allelic frequencies of markers associated with domestication-related traits such as capsular dehiscence indicated directional selection with the most common alleles in pale flax being absent or rare in cultivated flax and vice versa. Our results demonstrated that pale flax is a potential source of novel variation to improve multiple traits in cultivated flax and that association mapping is a suitable approach to screening pale flax germplasm to identify favorable quantitative trait locus alleles.
Ada López-Emparán, Daniela Quezada-Martínez, Matías Zúñiga-Bustos, Víctor Cifuentes, Federico Iñiguez-Luy, María Laura Federico. (2014). Functional Analysis of the Brassica napus L. Phytoene Synthase (PSY) Gene Family. PLoS ONE. 9;12.
Phytoene synthase (PSY) has been shown to catalyze the first committed and rate-limiting step of carotenogenesis in several crop species, including Brassica napus L. Due to its pivotal role, PSY has been a prime target for breeding and metabolic engineering the carotenoid content of seeds, tubers, fruits and flowers. In Arabidopsis thaliana, PSY is encoded by a single copy gene but small PSY gene families have been described in monocot and dicotyledonous species. We have recently shown that PSY genes have been retained in a triplicated state in the A- and C-Brassica genomes, with each paralogue mapping to syntenic locations in each of the three “Arabidopsis-like” subgenomes. Most importantly, we have shown that in B. napus all six members are expressed, exhibiting overlapping redundancy and signs of subfunctionalization among photosynthetic and non photosynthetic tissues. The question of whether this large PSY family actually encodes six functional enzymes remained to be answered. Therefore, the objectives of this study were to: (i) isolate, characterize and compare the complete protein coding sequences (CDS) of the six B. napus PSY genes; (ii) model their predicted tridimensional enzyme structures; (iii) test their phytoene synthase activity in a heterologous complementation system and (iv) evaluate their individual expression patterns during seed development. This study further confirmed that the six B. napus PSY genes encode proteins with high sequence identity, which have evolved under functional constraint. Structural modeling demonstrated that they share similar tridimensional protein structures with a putative PSY active site. Significantly, all six B. napus PSY enzymes were found to be functional. Taking into account the specific patterns of expression exhibited by these PSY genes during seed development and recent knowledge of PSY suborganellar localization, the selection of transgene candidates for metabolic engineering the carotenoid content of oilseeds is discussed.
Braulio J. Soto-Cerda, C. Inostroza-Blancheteau, Mónica Mathías, E. Peñaloza, Javiera Zúñiga, G. Muñoz, Z. Rengel, Haroldo Salvo-Garrido. (2014). Marker-assisted breeding for TaALMT1, a major gene conferring aluminium tolerance to wheat. Biologia Plantarum. 59;1;83-91.
Aluminium toxicity in acid soils is the main limitation to crop production worldwide. In wheat (Triticum aestivum L.), the Al-activated malate transporter (TaALMT1) gene located on chromosome 4DL is associated with malate efflux and Al-tolerance. To introgress Al-tolerance from the breeding line CAR3911 into the high yielding Al-sensitive cultivar Kumpa-INIA, phenotypic and molecular characterizations of gene/QTL underlying Al-tolerance in CAR3911 followed by marker-assisted backcrossing (MAS-BC) were undertaken. Al-tolerant backcross (BC) lines were selected using the functional marker ALMT1-4 designed immediately upstream of the TaALMT1 coding region. Foreground and background selections using ALMT1-4 and microsatellite markers were conducted. Linkage and sequence analyses suggest that the TaALMT1 gene could underly the Al-tolerance in CAR3911, possessing the same promoter type (V) as the Al-tolerant genotypes Carazinho and ET8. The MAS-BC strategy allowed the selection of Al-tolerant lines with the smallest introgressed region (6 cM) on 4D and the highest recurrent parent genome (RPG) (98 %) covering 2 194 cM of the wheat genome. The homozygous BC3F2 line named Kumpa-INIA-TaALMT1 expressed a 3-fold higher Al-tolerance than its isogenic line Kumpa-INIA at 40 μM Al in the hydroponic solution, and similar to CAR3911 and Carazinho. The MAS-BC strategy was successful for the introgression of the TaALMT1 gene into Kumpa-INIA in only three BC generations, shortening the breeding cycle to 24 months, which promises to increase wheat production and a greater yield stability in the acid soils of Southern Chile.
Shene, C., Spuler, M. J., Acevedo, F., Rubilar, M. (2014). Seed meals as source of fractions with different effects on pancreatic lipase activity. European Journal of Lipid Science and Technology. 116; 3; 291–299.
The effect of different fractions (lipids, solids soluble in aqueous ethanol (ES), soluble protein (SP), and the residue after the extractions) of yellow lupin (Lupinus luteus), linseed (Linum usitatissimum), and soybean (Glycine max) meals on in vitro porcine pancreatic lipase (PPL) activity was determined. PPL activity against emulsions prepared with the different SPs unprocessed or denaturated by heat, digested with pepsin and homogenized at high pressure was also evaluated. In general, the lipids, ES, and the residue fractions increased PPL activity (8.4–80.0%) whereas it was reduced by the SPs of lupin (25.3%) and linseed (30.8%) at a low concentration. Residual activity after incubating the enzyme with the SPs was found between 13 and 46% depending on the source and the incubating period. The rate at which PPL hydrolyzed emulsions in which lipid droplets were covered first by gum Arabic and then with the protein was influenced by the treatment of SP; less free fatty acids were released from emulsions containing the denaturated and digested SPs. PPL activity against emulsions that contained the homogenized SPs was higher (108–174%) than the activity against emulsions that contained the untreated SP.
Acevedo, Francisca; Rubilar, Mónica; Jofré, I.; Villarroel, M.; Navarrete, P.; Esparza, M.; Romero, F.; Vilches, E.; Acevedo, V.; Shene, Carolina. (2014). Oil bodies as a potential microencapsulation carrier for astaxanthin stabilization and safe delivery. Journal of Microencapsulation. 31; 5; 488-500.
Astaxanthin (AST) is a valued molecule because of its high antioxidant properties. However, AST is extremely sensitive to oxidation, causing the loss of its bioactive properties. The purposes of this study were to define conditions for microencapsulating AST in oil bodies (OB) from Brassica napus to enhance its oxidative stability, and to test the bioactivity of the microencapsulated AST (AST-M) in cells. Conditions for maximising microencapsulation efficiency (ME) were determined using the Response Surface Methodology, obtaining a high ME (>99%). OB loaded with AST showed a strong electrostatic repulsion in a wide range of pH and ionic strengths. It was found that AST-M exposed to air and light was more stable than free AST. In addition, the protective effect of AST against intracellular ROS production was positively influenced by microencapsulation in OB. These results suggest that OB offer a novel option for stabilising and delivering AST.
Acevedo, Francisca; Morales, Eduardo; Aravena, Javiera; Amiard, Véronique; Jorquera, Milko A.; Inostroza, Nitza G.; Rubilar, Mónica. (2014). Microencapsulation by spray drying of nitrogen-fixing bacteria associated with lupin nodules. World Journal of Microbiology and Biotechnology. 30; 9; 2371-2378.
Plant growth promoting bacteria and nitrogen-fixing bacteria (NFB) used for crop inoculation have important biotechnological potential as a sustainable fertilization tool. However, the main limitation of this technology is the low inoculum survival rate under field conditions. Microencapsulation of bacterial cells in polymer matrices provides a controlled release and greater protection against environmental conditions. In this context, the aim of this study was to isolate and characterize putative NFB associated with lupin nodules and to evaluate their microencapsulation by spray drying. For this purpose, 21 putative NFB were isolated from lupin nodules and characterized (16S rRNA genes). Microencapsulation of bacterial cells by spray drying was studied using a mixture of sodium alginate:maltodextrin at different ratios (0:15, 1:14, 2:13) and concentrations (15 and 30% solids) as the wall material. The microcapsules were observed under scanning electron microscopy to verify their suitable morphology. Results showed the association between lupin nodules of diverse known NFB and nodule-forming bacteria belonging to Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria and Bacteroidetes. In microencapsulation assays, the 1:14 ratio of sodium alginate:maltodextrin (15% solids) showed the highest cell survival rate (79%), with a microcapsule yield of 27% and spherical microcapsules of 5-50 µm in diameter. In conclusion, diverse putative NFB genera and nodule-forming bacteria are associated with the nodules of lupine plants grown in soils in southern Chile, and their microencapsulation by spray drying using sodium alginate:maltodextrin represents a scalable process to generate a biofertilizer as an alternative to traditional nitrogen fertilization.