Non-food Crops-to-Industry schemes in eu27




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Non-food Crops-to-Industry schemes in EU27”

WP1. Non-food crops


D2.3 Design breeding strategies for the selected

Non -food crops

Lead beneficiary: Agricultural University of Athens

Authors: Dimitra Milioni

Theoni Margaritopoulou
September 2011
The project is a Coordinated Action supported by


Grant agreement no. 227299

Table of contents

WP2
DELIVERABLE 2.3
Design breeding strategies for the selected

non-food crops
1. OIL CROPS
1.1 Oilseed rape (Brassica napus)

During the past decades, oil crop breeding was driven by advances in analytical technologies and by a vastly improved knowledge of metabolic paths and networks. The task of the oilseed breeder has been facilitated further by new techniques of advanced breeding such as the use of DNA-based molecular markers, greatly improved tissue culture methods, and the application of transgenes. Furthermore, the sequenced genome of the model plant Arabidopsis thaliana, to which Brassica species represent the closest crop relatives, facilitate the way for thorough comparative investigations into the complex structure of Brassica genomes (Schmidt et al. 2001; Lukens et al. 2003; Parkin et al. 2003).

Today, there is considerable potential to use molecular markers to develop new varieties where traditional approaches are unable to achieve breeding aims. The rapeseed breeders can (in theory) identify whether new plantlets carry the required gene when they are only weeks old by using marker-assisted selection (Quiros and Paterson, 2004). Canola (Brassica napus L. or rapeseed) is an important oilseed crop and its cultivation is expanding particularly in the western world because of its importance as both an oilseed and a bio-diesel crop. Many efforts have been made to asses the effects of both frost and high temperatures to the cultivation by studying the percentage of pollen viability, in vitro pollen germination and pollen tube length (Singh et al., 2008). In addition, thorough studies have been performed for the investigation of genes controlling the response to high temperature stress (Young et al., 2004), identification of QTLs of great importance controlling the winter survival of winter type of Brassica napus (Asghari et al., 2008) and identification of genes which result in increased freezing tolerance for the species (Savitch et al., 2005). Another constraint that challenges Brassica napus is the nutrient deficiency. Much research has been performed for the mapping of QTLs that control the soil boron deficiency (Xu et al., 2001) and the investigation of genes responsible for the nitrate and nitrogen uptake during cultivation (Beuve et al., 2004; Malagoli et al., 2005).

Brassica napus is a very susceptible crop to fungal pathogens. Among these, Sclerotinia sclerotiorum, causing stem rot, Alternaria brassicae, causing Alternaria black spot and Leptosphaeria maculans, causing the blackleg desease, have great potential to cause significant crop losses. Mapping resistance genes and eventually cloning these genes will facilitate the transfer and pyramiding in B. napus of multiple different resistance genes through molecular marker-assisted selection. Gene families implicated in defense responses for the stem rot and black spot (Yang et al., 2009), genes responsible for the colonization of the blackleg fungus (Idnurm and Howlett, 2002) and QTLs controlling seedling resistance to the blackleg fungus (Mayerhofer et al., 2005; Long et al., 2011) have been identified.

The term “canola” was defined as cultivars with the trait of low erucic acid and low glucosinolate content in rapeseed (therefore also termed as “double low” cultivars). Recentlly, high throughput genome-specific (SCAR) and gene-specific molecular markers (SNP) for erucic acid genes in Brassica napus (L.) were identified (Rahman et al., 2008). These markers can considerably facilitate the selection of the four different erucic acid content control alleles in canola/rapeseed breeding programs. Novel locus/loci controlling erucic acid/oil content in B. napus seeds were recently revealed in the region of linkage group A8, and obvious genetic drag was found hidden in a considerable portion of canola cultivars (Cao et al., 2010). Therefore, backcrossing and the marker-assisted selection based on QTL mapping could be an efficient way to break the genetic drag in the breeding process.

It is now possible to envisage, at least in principle, the engineering of transgenic oil crops with changed oil profile and content. For example, the insertion of antisense copies of a stearate desaturase gene resulted in transgenic rapeseed plants with ten times the normal levels of stearic acid in their seed oil (Knutzon et al., 1992). One of the most notable successes of low cost production of specialty oil is that of high laurate B. napus produced by Calgene. Expression of a 12:0-acyl-ACP thioesters isolated from California bay laurel (Umbellularia California) in canola seeds resulted in highly saturated canola oil, known as BTE canola, with lauric content surpassing 50% of the seed oil (Voelker et al., 1996). Genetic manipulation of B. napus for the purpose of producing the very long chain erucic acid used in plastic film manufacture and the lubricant and emollient industries, has attracted researchers’ interest for more than a decade. It has been reported that the introduction of a mutant allele of the yeast sn-2 fatty acyltransferase LPAAT , SLC1 into cultivars of B. napus Hero and Reston, resulted in transgenic plants exhibiting increases in both overall proportions and the amounts of erucic acid (Katavic et al., 2000). Studies on lipid accumulation in oilseed rape have suggested that diacylglycerol acyltransferase (DGAT), which catalyses the final step in seed oil biosynthesis, might be an effective target for enhancing seed oil content (Weselake et al., 2008).

Genetic improvement of multiple agronomic traits (e.g. drought tolerance, nutrient-use efficiency, yield performance and disease resistance) in crops that have large and complex genomes benefit from underpinning investment in model plants As a crop, B. napus is grown in many different regions of the world, and the plant is often exposed to drought conditions, resulting in reduced productivity. Drought tolerance is thus an important trait in B. napus breeding. Thus far, there are very few reports of utilizing leaf structural modifications to enhance drought tolerance in the crop. Modification of leaf epidermal structures as demonstrated in the Arabidopsis plants overexpressing BnLAS could be a promising approach to improve drought tolerance in B. napus (Yang et al., 2011). A plant’s adaptation to cold and drought is to a greater extent under transcriptional control, and some processes are regulated by abscisic acid (ABA). The use of a drought-inducible Arabidopsis rd29A promoter to drive the antisense expression of AtFTB in canola conferred similar drought protection in this species (Wang et al., 2005). Oilseed Brassicas are particularly subject to attack by various fungal pathogens. Transgenic canola (B. napus) lines expressing S. sclerotiorum-specific scFv antibody exhibited a significant level of tolerance towards S. sclerotiorum as compared to their non-transformed counterparts (Yajima et al., 2010). White blister rust caused by Albugo candida (Pers.) Kuntze is a common and often devastating disease of oilseed and vegetable brassica crops worldwide. It has been reported that WRR4, a broad-spectrum TIR-NB-LRR gene from Arabidopsis thaliana confers white rust resistance in transgenic oilseed brassica crops (Borhan et al., 2010). Other biotic stresses that rapeseed is subjected to are Plasmodiophora Brassecae that causes club root disease, Peronospora parasitica, that causes downy mildew and Verticillium dahliae that causes verticillium wilt. There is extensive literature considering the development of strategies to increase resistance to these diseases (Tewari and Mithen, 2003; Fitt et al., 2006; Rimmer et al., 2007). A good example is the introduction of clubroot resistance genes from the Chinese cabbage (Brassica rapa) to the European rapeseed cultivars (Hirai, 2006).



However, none of the transgenic lines developed have been approved for commercial production.

References

  • Asghari A, Mohammadi SA, Moghaddam M and Shokuhian AA (2008) Identification of SSR and RAPD markers associated with QTLs of winter survival and related traits in Brassica napus L. African J Biotech 7:897-903.

  • Beuve N, Rispail N, Laine P, Cliquet JB, Ourry A and Deunff EL (2004) Putative role of γ- aminobutyric acid (GABA) as a long-distance siglan in up-regulation of nitrate uptake in Brassica napus L. Plant Cell Envi 27:1035-1046.

  • Borhan MH, Holub EB, Kindrachuk C, Omidi M, Bozorgmanesh-Frad G, Rimmer SR (2010) WRR4, a broad-spectrum TIR-NB-LRR gene from Arabidopsis thaliana that confers white rust resistance in transgenic oilseed Brassica crops. Mol Plant Pathol 11:283-91.

  • Fitt BDL, Evans N, Howlett BJ and Cooke BM (2006) Sustainable Strategies for Managing Brassica napus (oilseed Rape) Resistance. Kluwer Academic Publishers Group, Dordrecht.

  • Hirai M (2006) Genetic analysis of clubroot resistance in Brassica crops. Breeding Sci 56:223-229.

  • Idnurm A and Howlett BJ (2002) Isocitrate lyase is essential for pathogenicity of the fungus Leptosphaeria maculans to canola (Brassica napus). Eukaryotic Cell 1:719-724.

  • Katavic V, Friesen W, Barton DL, Gossen KK, Giblin EM, Luciw T, An J, Zou J, MacKenzie SL, Keller WA, Males D and Taylor DC (2000) Utility of the Arabidopsis FAE1 and yeast SLC1-1 genes for improvements in erucic acid and oil content in rapeseed. Bioch Soc Trans 28:935–937.

  • Lukens L, Zou F, Lydiate D, Parkin I and Osborn T (2003) Comparison of a Brassica oleracea genetic map with the genome of Arabidopsis thaliana. Genetics 164:359-372.

  • Long Y, Wang Z, Sun Z, Fernando DW, McVetty PB and Li G (2011) Identification of two blackleg resistance genes and fine mapping of one of these two genes in a Brassica napus canola cultivar 'Surpass 400'. Theor Appl Genet 122:1223-31.

  • Malagoli P, Laine P, Rossato L and Ourry AD (2005) Dynamics of Nitrogen Uptake and Mobilization in Field-grown Winter Oilseed Rape (Brassica napus) From Stem Extension to Harvest. II. An 15N-labelling-based Simulation Model of N Partitioning Between Vegetative and Reproductive Tissues. Annals Bot 95:1187-1198.

  • Mayerhofer R, Wilde K, Mayerhofer M, Lydiate D, Bansal VK, Good AG and Parkin IAP (2005) Complexities of chromosome landing in a highly duplicated genome: toward map-based cloning of a gene controlling blackleg resistance in Brassica napus. Genetics 171:1977-1988.

  • Mun JH, Yu HJ, Park S and Park BS (2009) Genome-wide identification of NBS-encoding resistance genes in Brassica rapa. Mol Genet Genom 282:617-631.

  • Parkin IA, Gulden SM, Sharpe AG, Lukens L, Trick M, Osborn TC and Lydiate DJ (2005) Segmental structure of the Brassica napus genome based on comparative analysis with Arabidopsis thaliana. Genetics 17:765-781.

  • Quiros CF, Paterson AH (2004) Gene mapping and analysis. In: Pua EC, Douglas CJ (eds) Biotechnology in agriculture and forestry, Brassica, 54, 31-64, Springer, Berlin.

  • Rahman M, Sun Z, McVetty PB and Li G (2008) High throughput genome-specific and gene-specific molecular markers for erucic acid genes in Brassica napus (L.) for marker-assisted selection in plant breeding. Theor Appl Genet 117:895-904.

  • Rimmer SR, Shattuck VI and Buchwaldt L (2007) Compendium of Brassica Disease. American Phytopath Soci.

  • Savitch LV, Allard G, Seki M, Robert LS, Tinker NA, Huner NPA, Shinozaki K and Singh J (2005) The effect of overexpression of two Brassica CBF/DREB1-like transcription factors on photosynthetic capacity and freezing tolerance in Brassica napus. Plant Cell Physiol 46:1525-1539.

  • Scarascia Mugnozza GT, Porceddu E and Pagnotta MA (Eds) (1999) Genetics and Breeding for crop quality and resistance. Kluwer Academic Publishers, The Netherlands.

  • Singh SK, Kakani VG, Brand D, Baldwin B and Reddy KR (2008) Assessment of cold and heat tolerance of winter-grown canola (Brassica napus L.) cultivars by pollen-based parameters. J. Agronomy & Crop Sci 194:225-236.

  • Schmidt R, Acarkan A and Boivin K (2001) Comparative structural genomics in the Brassicaceae family. Plant Physiol Biochem 39:253–262.

  • Tewari JP and Mithen RF (2003) Diseases. In: Biology of Brassica Coenospecies. Gomez-(Ed. by C. Campo), 12:375-394, Elsevier Science & Technology Books, Amsterdam, The Netherlands.

  • Voelker TA, Hayes TR, Cranmer AM, Turner JC and Davies HM (1996) Genetic engineering of a quantitative trait: metabolic and genetic parameters influencing the accumulation of laurate in rapeseed. Plant J 9:229–241.

  • Wang Y, Ying J, Kuzma M, Chalifoux M, Sample A, McArthur C, Uchacz T, Sarvas C,Wan, J,DennisDT,McCourt P and Huang Y (2005) Molecular tailoring of farnesylation for plant drought tolerance and yield protection. Plant J 43:413–24.

  • Weselake RJ, Shah S, Tang M, Quant PA, Snyder CL, Furukawa-Stoffer TL, Zhu W, Taylor DC, Zou J, Kumar A, Hall L, Laroche A, Rakow G, Raney P, Moloney MM and Harwood JL (2008) Metabolic control analysis is helpful for informed genetic manipulation of oilseed rape (Brassica napus) to increase seed oil content. J Exp Bot 59:3543-3549.

  • Xu FS, Wang YH and Meng J (2001) Mapping boron efficiency gene(s) in Brassica napus using RFLP and AFLP markers. Plant Breed 120:319-324.

  • Yang M, Yang Q, Fu T and Zhou Y (2011) Overexpression of the Brassica napus BnLAS gene in Arabidopsis affects plant development and increases drought tolerance. Plant Cell Rep 30:373-88.

  • Yang B, Jiang Y, Rahman MH, Deyholos MK and Kav NNV (2009) Identification and expression analysis of WRKY transcription factor genes in canola (Brassica napus L) in response to fungal pathogens and hormone treatments. BMC Plant Biology 9:68.

  • Yajima W, Verma SS, Shah S, Rahman MH, Liang Y and Kav NN (2010) Expression of anti-sclerotinia scFv in transgenic Brassica napus enhances tolerance against stem rot. N Biotechnol 27:816-21.

  • Young LW, Wilen RW and Bonham-Smith PC (2004) High temperature stress of Brassica napus during flowering reduces micro- and megagametophyte fertility, induces fruit abortion and disrupts seed production. J Exp Bot 55:485-495.



1.2 Sunflower (Helianthus annus)

The primary objective for sunflower breeders is to increase the overall yield and agronomic performance of newly developed high oleic sunflower hybrids. To accomplish these goals, breeders need to address pathogens, pests, and environmental constraints that have the potential to drastically reduce yield where sunflowers are grown. Biotechnology has the potential to help evoke the full potential of this valuable crop.

Recent advances, particularly in molecular marker techniques, have led to the development of novel tools that offer the promise of making molecular breeding in sunflower more precise and faster. The discovery and publication of molecular markers in sunflower has facilitated the implementation of whole genome marker applications. The availability of dense genetic maps can facilitate the ability of researchers to make marker-trait associations with important disease resistance and other genes and develop high throughput markers that facilitate marker-assisted selection (MAS) for resistant individuals in segregating breeding populations. MAS technology has been used in sunflower breeding for various disease resistance traits (Brahm et al., 2000). With the development of an array of molecular markers and a dense genetic map of the sunflower genome, MAS for both single genes and QTLs is now possible (Babu et al., 2004).

Considering that sunflower production is expanding to arid regions, tolerance to abiotic stresses as drought, low temperatures and salinity arises as one of the main constrains nowadays. Evolving crop genotypes which have enhanced drought tolerance are the most successful and cheapest strategy to cope with drought.

MAS in combination with transgenic technology have the potential to greatly accelerate sunflower product development. Drought can also be managed by incorporating traits that help crops to cope with drought stress successfully. Thus, genetic modification is usually the most successful and cheapest strategy to cope with drought. Heritable changes within a crop with the aim of improving drought tolerance can be broadly considered as breeding for improved drought tolerance.

Except from the existence of abiotic stress factors, sunflower is subjected to various biotic stress factors to different stages of development which cause diseases resulting in severe crop losses. Biotechnology can provide a number of strategies for the control of white rot (Schnabl et al., 2002), including defence activation, fungus inhibition, and detoxification (Lu, 2003). Sclerotinia wilt caused by S. sclerotiorum (Lib.) de Bay is the most important fungal disease of sunflower. It has been demonstrated that oxalate oxidase (OXO) confers resistance against Sclerotinia in transgenic sunflower plants (Hu et al., 2003). It has been reported that overexpression of a human lysozyme gene in sunflower can confer Sclerotinia resistance (Sawahel and Hagran, 2006). Sunflower biotechnologists have pursued other transgenic strategies to enhance resistance to sunflower diseases. A number of resistance (R) gene homologues have been isolated from sunflower, providing a valuable resource for engineering disease resistance in sunflower (Plocik et al., 2004; Hewezi et al., 2006). Transgenic expression of the Cry1F Bt gene in sunflower confers significant control of Rachiplusia mu and Spilosoma virginica, two important insect pests that impact sunflower production (Pozzi et al., 2000).

High oleic sunflower is proper for biodiesel since it can produce oil with up to 90% oleic acid, which has high oxidative stability and uniformity. Producing high concentrations of industrially useful fatty acids in plant seeds has been initiated using biotechnology, and modifications of the fatty acid compositions of vegetables oils can make them more versatile in their uses (Burton et al., 2004). One of the challenges for oil composition modification in sunflower is increasing the level of the new fatty acids. The gene shuffling technology can facilitate improving the activity of various desaturases for producing healthier oils or more useful industrial oils (Lu and Hoeft, 2009). Much work has been performed for the identification of resistance genes involved in primary metabolic pathways and signal transduction (Alignan et al., 2006). As sunflower is one of the leading oil-providing agricultural crops, groups have tried to gain insight into the mechanism of antioxidant defense. New genes have been identified and the metabolism of ROS and RNS have been analyzed under various biotic and abiotc conditions (Chaki et al., 2011; Fernandez-Ocana et al., 2011).

Transgenic sunflower have the potential to help meet the yield enhancement, to increase the efficient use of renewable resources such as land, water, and soil nutrients and to significantly benefit human life by providing more nutritious and healthy foods and valuable industrial products.


1.3 FLAX (Linum usitatissimum)

See below in 2.1




References

  • Babu R, Nair SK, Prasanna BM and Gupta HS (2004) Integrating marker-assisted selection in crop breeding prospects and challenges. Current Sci 87:607–619.

  • Brahm L, Rocher T and Friedt W (2000) PCR-based markers facilitating marker assisted selection in sunflower for resistance to downy mildew. Crop Sci 40:676–682.

  • Burton JW,Miller JF, Vick BA, Scarth R and Holbrook CC (2004) Altering fatty acid composition in oil seed crops. Adv Agron 84:273–306.

  • Cantamutto M and Poverene M (2007), Genetically modified sunflower release: opportunities and risks. Field Crop Res 101:133–144.

  • Dezar CA, Giacomelli JI, Manavella PA, Re DA, Alves-Ferreira M, Baldwin IT, Bonaventure G and Chan RL (2011) HAHB10, a sunflower HD-Zip II transcription factor, participates in the induction of flowering and in the control of phytohormone-mediated responses to biotic stress. J Exp Bot 62:1061-1076.

  • Fernandez P, Di Rienzo J, Fernandez L, Hopp HE, Paniego N and Heinz RH (2008) Transcriptomic identification of candidate genes involved in sunflower responses to chilling and salt stresses based on cDNA microarray analysis. BMC Plant Biology 8:11.

  • Hewezi T,Mouzeyar S, Thion L, Rickauer M, AlibertG, Nicolas P and Kallerhoff J (2006) Antisense expression of a NBS-LRR sequence in sunflower (Helianthus annuus L.) and tobacco (Nicotiana tabacum L.): evidence for a dual role in plant development and fungal resistance. Trans Res 15:165–180.

  • Hu X, Bidney DL, Yalpani N, Duvick JP, Crasta O, Folkerts O and Lu G (2003) Overexpression of a Hydrogen Peroxide-Generating Oxalate Oxidase Gene Evokes Defense Responses in Sunflower. Plant Physiol 133:170-181.

  • Lu G (2003) Engineering Sclerotinia Sclerotiorum Resistance in Oilseed Crops. African J Biotech 2:509-516.

  • Lu G and Hoeft E (2009) Sunflower

  • Plocik A, Layden J and Kesseli R (2004) Comparative analysis of NBS domain sequences of NBS-LRR disease resistance genes from sunflower, lettuce, and chicory. Molecular Phyl Evol 31:153–163.

  • Pozzi G, Lopez M, Cole G, Sosa-Dominguez G, Bidney D, Scelonge C, Wang L, Lu G, Muller-Cohn J and Bradfisch G (2000) Bt-mediated insect resistance in sunflower (Helianthus annuus, L.). Proceedings of the 15th International Sunflower Conference. June 2000 Toulouse, France, Abstract No. H45-50.

  • Rauf S (2008) Breeding sunflower (Helianthus annus L) for drought tolerance. Comm Biometry and Crop Sci 3:29-44.

  • Sawahel W and Hagran A (2006) Generation of white mold disease-resistant sunflower plants expressing human lysozyme gene. Biol Planta 50:683–687.

  • Schnabl H, Binsfeld P, Cerboncini C, Dresen B. Peisker H, Wingender R and Henn A (2002) Biotechnological methods applied to produce Sclerotinia sclerotiorum resistant sunflower. HELIA 25:191–197.



2. FIBER CROPS
2.1 FLAX (Linum usitatissimum)

Flax (Linum usitatissimum L.) has been cultivated for around 9,000 years and is therefore one of the oldest cultivated species. Developing improved flax cultivars is a continuing process using the germplasm base, created by the cumulative efforts of flax workers over many years.

Today, flax breeding objectives aim at improving crop’s production, yield stability, resilience to diseases pests or environmental conditions and optimizing the characteristics of the end product or these of bulk crop’s processing.

Flax rust, Melampsora lini, is a fungal pathogen that infects cultivated flax (Linum usitatissimum), (Barrett et al., 2009; Lawrence et al., 2007). It can cause severe losses in seed yield as well as reducing fibre quality in flax plants grown for linen production. Consequently, breeders need to pay particular attention to ensuring that any new variety released to growers is genetically resistant to all races of the rust in the geographical area that it is intended to be grown (Lawrence et al., 2007). Breeding improved flax for rust resistance requires knowledge of the genetic basis of the resistance and the identification of useful sources of resistance in the germplasm. In cultivated flax, 30 genes that confer resistance to flax rust have been mapped to five loci (K, L, M, N, P), consisting of closely linked or allelic genes (Islam and Mayo, 1990). In total, nineteen R genes have been cloned from flax (Ravensdale et al., 2011). However, although the Avr genes identified from cultivated flax rust also operate in the wild system, it is not yet known whether the corresponding R genes in L. marginale are also homologues of the cultivated flax R genes. The integration of the molecular understanding of gene-for-gene interactions with population genetics in the flax–rust system provides an excellent starting point for designing conventional and transgenic strategies to enhance rust resistance. Anther culture has been used as a tool to study the inheritance of disease resistance and to produce disease-resistant varieties. Transgenic flax plants expressing new flax rust resistance specificities conferred by L2 and L10 alleles of L locus were produced using A. tumefaciens mediated transformation of hypocotyl segments or anther culture-derived calli (Chen et al., 2008). So, it is becoming increasingly certain that introducing more than a single gene involved in pest/disease tolerance into a single plant by gene pyramiding, is considered as an efficient approach for extreme disease tolerance.



Fusarium culmorum and Fusarium oxysporum are the most common fungal pathogens of flax (Linum usitatissimum L.), thus leading to the greatest losses in crop yield. Regeneration of flax plants from anther culture and somatic tissue with increased resistance to Fusarium oxysporum was achieved (Rutkowska-Krause et al., 2003). Recently, it has been demonstrated that overproduction of Solanum sogarandinum-derived glycosyltransferase in transgenic flax resulted in higher resistance to Fusarium infection than wild-type plants, and this was correlated with a significant increase in the flavonoid glycoside content in the transgenic plants (Lorenc-Kukuła et al., 2009).

Another effective method to control these diseases is to screen and to breed resistant varieties. By identifying the molecular markers for resistant genes to rust and wilt and screening resistant germplasm in flax, a breeding procedure for maker-assisted selection can be set up and to get more resistant germplasm for flax breeding programs. Recently, a high-density oligo-microarray platform for transcriptomics in flax was developed (Fenart et al., 2010). The platform is capable of high discrimination and can provide biologically-useful information on specific gene expression profiles of different flax tissues, and developmental stages. Initial studies also enabled the identification of specifically-expressed cell wall- and defence-related genes in two different flax varieties showing contrasting fibre quality and resistance towards a fungal pathogen. It is possible that these genomic resources can contribute to gene discovery and development of expanded molecular marker sets for breeding.

Due to the environmental changes that nowadays are an emerging reality, plants of increased adaptability to various environments are of great interest. The promotion of biodiesel requires the ability to use land that is currently set aside or polluted for the production of energy crops. Cadmium (Cd) has been classified as a serious pollutant due to its high toxicity, high carcinogenicity, and widespread presence in the environment (McGrath et al., 2001). A comparative analysis of proteomic changes in contrasting flax cultivars upon cadmium exposure revealed significant changes in the expression of 14 proteins (Hradilová et al., 2010). The identified proteins (and their corresponding genes) could provide candidates of useful markers to facilitate attempts to enhance the Cd tolerance of currently available flax lines by classical breeding.

The main Cd-detoxifying mechanism seems to be chelation of Cd ions by high-affinity ligands (Hall, 2002). Potential ligands for Cd include phytochelatins (PCs), glutathione (GSH) and small Cys-rich gene-encoded proteins known as metallothioneins (MTs). Obviously, there is a potential for augmenting the natural Cd tolerance of flax by engineering transgenic lines with enhanced GSH and PC biosynthesis, and increased production of heterologous Cd-binding proteins such as MTs, which could be of value in breeding programs.

Retting is a major constraint upon production of a high yielding, high quality crop. In retting, bast fibre bundles are separated from the core, the epidermis and the cuticle. Dew or wet retting are unreliable in Europe, therefore new fungal sources of enzyme retting are currently being looked into as a solution to this problem. It has been demonstrated that over- expression of the Aspergillus aculeatus polygalacturonase (PGI) and rhamnogalacturonase (RHA) genes in flax plants resulted in a significant reduction in the pectin content in tissue-cultured and field-grown plants and in increased retting efficiency. No alteration in the lignin or cellulose content was observed in the transgenic plants relative to the control. This indicated that the over-expression of the two enzymes did not affect flax fibre composition (Musialak et al., 2007).



Flavonoids are a group of secondary plant metabolites important for plant growth and development. Thus, overproduction of these compounds in flax by genetic engineering method might potentiate biotechnological application of these plant products. An appropriate construct consisting of chalcone synthase (CHS), chalcone isomerase (CHI), and dihydroflavonol reductase (DFR) cDNAs from Petunia hybrida under the control of CaMV 35S promoter and OCS terminator, was inserted into the genome of the flax plants. Overexpression of these three key genes from the flavonoids synthesis pathway resulted in accumulation of several flavonoids, phenolic acids and lignans. All these compounds have an antioxidative nature and thus suggesting the use of modified fibres in production of fabrics for medicine (e.g. wound dressing), stable oil enriched in fatty acids for human diet and seedcakes for extraction of compounds with potential biomedical application (Zuk et al., 2011).

The biotechnological production of bio-plastics, including polyhydroxybutyrate (PHB) and polyhydroxyalkanoate (PHA), has been explored in both microorganisms and plants (Suriyamonglok et al., 2007). To produce biodegradable composites, flax was transformed with bacterial genes that encoded enzymes catalyzing the formation of PHB (Wrobel-Kwiatkowska et al., 2007b). The protocol resulted in a modification of the mechanical properties of the stem wherein PHB accumulated in growing fiber cells.

Flaxseed oil has numerous industrial applications because of higher levels of α-linolenic acid (ω-3 fatty acid) compared to other oilseed species. Although the use of traditional plant breeding methods like natural or induced mutations for increasing the level of α-linolenic acid within the genus Linum remains a legitimate option, the transgenic approach may play a key role. The manipulation of the fatty acid composition of oil to produce oils with >70% α-linolenic acid by genetic engineering may be possible (Jhala et al., 2009). Furthermore, improvement of flax varieties through breeding for varioustraits can be assisted by development of molecular markers and by understanding the genetic and biochemical bases of these characteristics. Recently, a comprehensive genomics-based dataset for flax was developed in order to advance the understanding of flax embryo, endosperm and seed coat development (Venglat et al., 2011). Specifically, gene expression as related to fatty acid, flavonoid, mucilage, and storage protein synthesis and transcription factors was analyzed. The EST database developed can contribute to gene discovery and development of expanded molecular marker sets for flax breeding.

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