Industrial Crops and Products 47 (2013) 176–185 Contents lists available at SciVerse ScienceDirect Industrial Crops and Products journa l homepage: www.elsevier.com/locate/indcrop Review Brassicaceae germplasm diversity for agronomic and seed quality traits under drought stress a,∗ a,1 a b Jean-Nicolas Enjalbert , Shusong Zheng , Jerry J. Johnson , Jack L. Mullen , a b Patrick F. Byrne , John K. McKay a Department of Soil & Crop Sciences, Colorado State University, Fort Collins, CO 80523, USA b Department of Bioagricultural Sciences & Pest Management, Colorado State University, Fort Collins, CO 80523, USA a r t i c l e i n f o a b s t r a c t Article history: Brassica juncea, Brassica carinata and Camelina sativa have previously shown potential as oilseed crops Received 18 March 2012 in semi-arid climates. However, there is limited information on variation of agriculturally important Received in revised form 28 February 2013 traits under water stress. This study screened 94 accessions of B. juncea, 30 accessions of B. carinata and Accepted 28 February 2013 81 accessions of C. sativa under dryland and fully irrigated conditions in eastern Colorado to evaluate responses to drought stress within and among species. B. carinata had the greatest phenotypic variabil- Keywords: ity. It had the largest average thousand-seed-weight (TSW), though with a 10-day longer life cycle than Oilseed crops the other species, it also suffered the most from summer heat stress during seed filling. Earlier-flowering Genetic diversity accessions among the three species were more adapted to dryland conditions. B. carinata and B. juncea Drought adaptation were both twice as tall as C. sativa and produced significantly higher biomass though they yielded less Fatty acids −1 −1 −1 under dryland conditions, 711 kg ha , 933 kg ha , and 1383 kg ha , respectively. C. sativa showed bet- ter adaptation to semi-arid environments, likely due to its shorter stature, higher harvest index, and resistance to flea beetles. We measured seed-oil fatty acid profiles in response to water stress, finding a significant decrease in linolenic acid content under dryland conditions. C. sativa had the highest levels of linolenic acid, averaging 30% of seed-oil fatty acid. B. carinata had the highest levels of erucic acid with 42% on average. B. juncea accessions showed a large range of oil profiles, related to their geographical origin. Oil profile characteristics such as high linolenic acid were correlated with fitness traits such as height and biomass. Oil profile traits could play an important future role in plant breeding, especially under dryland conditions. This work highlights traits where breeding efforts can utilize existing germplasm diversity such as flowering time, yield components, oil quality, and flea beetle susceptibility to improve cultivar adaptability to semi-arid environments. © 2013 Elsevier B.V. All rights reserved. Contents 1. Introduction . 177 2. Materials and methods. 177 2.1. Plant material and environmental conditions . 177 2.2. Field experiments . 177 2.3. Data analysis. 178 3. Results . 178 3.1. Variation in growth and development among species . 178 3.2. Insect damage evaluation . 180 3.3. Seed-oil FA profiles . 180 4. Discussion . 183 5. Conclusions . 184 Acknowledgements . 184 References . 184 Abbreviations: DR, desaturation ratio; ER, elongation ratio; LDR, linoleic desaturation ratio; ODR, oleic desaturation ratio; TSW, thousand seed weight. ∗ Corresponding author. Tel.: +33 685539431. E-mail address: [email protected] (J.-N. Enjalbert). 1 Present address: Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China. 0926-6690/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.indcrop.2013.02.037 J.-N. Enjalbert et al. / Industrial Crops and Products 47 (2013) 176–185 177 1. Introduction 2. Materials and methods Brassicaceae oilseed crops offer the potential of producing 2.1. Plant material and environmental conditions sustainable biofuels in arid and semi-arid regions. Unlike some new cellulosic bioenergy grass crops, such as switchgrass (Pan- A total of 30 accessions of B. carinata, 94 accessions of B. juncea, icum virgatum L.), Brassicaceae oilseeds fit well into semi-arid and 81 accessions of C. sativa were evaluated for plant and seed rotations, such as the dryland winter wheat (Triticum aestivum quality traits. The C. sativa, B. carinata and B. juncea accessions orig- L.)-based cropping system. Ideally, new oilseed cultivars will inated from 16, three, and five countries, respectively. B. carinata combine positive growth and development characteristics (e.g., and C. sativa accessions were sourced from the Institute of Plant nutrient efficiency, pest tolerance, early maturity and heat- and Genetics and Crop Plant Research (IPK) at Gatersleben, Germany. B. water-stress tolerance) with diverse fuel, feed and food applica- juncea accessions were received from the USDA-ARS North Central tions (Gehringer et al., 2006). Genetic information and breeding Regional Plant Introduction Station germplasm collections. Acces- efforts are needed in order to optimize oilseed crops for sus- sions were a mix of wild and landraces germplasm. Accessions were tainable oil production in diversified crop rotations. This study grown at the Colorado State University Agriculture Research Devel- examined genetic diversity in traits relevant to adaptation to semi- opment and Education Center (ARDEC) in Fort Collins in the 2008 arid environments. Specifically, we evaluated three crops all in crop season. ARDEC is located at latitude 40.65 N and longitude the Brassicaceae family – Brassica juncea (L.) Czern, Brassica car- 105.00 W, at an elevation of 1557 m. The average annual precip- inata A. Braun, and Camelina sativa (L.) Crantz – that could be itation is 356 mm. The climate is considered semi-arid, and the integrated into the dryland winter wheat rotations dominant in soil type is Nunn clay loam. In 2009 and 2010, three accessions the High Plains of Colorado, Nebraska, Kansas, Oklahoma, and per species, already tested in 2008, chosen for their yield perfor- Texas. mance, seed size and oil characteristics, were planted at Iliff, CO B. juncea, which originated in India, can be more productive than (elevation 1165 m, latitude 40.768 N, longitude 103.045 W) under B. napus in semi-arid regions with unreliable rainfall while produc- both irrigated and dryland conditions in Randomized Complete ing similar yields in well-watered conditions (Wright et al., 1995; Block Design. A spring commercial hybrid Brassica napus check from Oram et al., 2005; Gan et al., 2007). These results suggest the fea- Cargill was included in the trial. sibility of developing high-yielding cultivars for both dryland and irrigated conditions. B. carinata, a native of Ethiopia appears better 2.2. Field experiments adapted and more productive than B. napus in clay and sandy soils in semi-arid temperate climates (Alemayehu and Becker, 2001; In 2008 at Fort Collins, CO, the experimental design included Fernandez-Martinez et al., 2001). C. sativa originated in Northern dryland and flood-irrigated treatments, with two replicates for Europe and Central Asia (Putnam et al., 1993). It is considered a each accession within a treatment. The study area was divided promising oilseed crop for dryland environments, with low input into two 11 m by 7.3 m blocks. Glyphosate was used to eradicate requirements (Zubr, 1997) and favorable oil properties (Bernardo alfalfa plants remaining from the previous year, and the seedbed −1 et al., 2003). C. sativa has shown higher seed yield performance was prepared by disking at 2 l ha . Seeds were sown by hand on under semi-arid conditions than B. napus (Francis and Campbell, May 12, 2008, in single-row plots of 1-m length with 0.3-m row −1 2004). spacing between plots. Density of planting was based on 6 kg ha −1 Variation in the levels of the particular fatty acids (FA) between for C. sativa and 8 kg ha for both Brassica species – rates typically and within species has been exploited for Brassica breeding, such used in the High Plains. Both blocks were flood-irrigated until full as for lines with low erucic or linolenic acid levels (Velasco et al., emergence in all accessions. The dryland block was not irrigated 1997; Alonso et al., 1991; Pleines and Friedt, 1988). We have after emergence, while the other continued to be irrigated. The irri- found that variation in the profiles of FA in seed oils can have gated treatment was flood-irrigated four times: at planting, prior large impacts on fuel quality (J.-N. Enjalbert, J.L. Mullen, A. Lak- to flowering, post-flowering and during the seed-filling period. shminarayanan, J.J. Johnson, D. Olsen, J.K. McKay, unpublished No fertilizer was applied to the field. During the growing season, data). Thus, even if biofuels derived from these crops have been weeds were controlled manually. Flea beetles (Phyllotreata cru- shown, on average, to be in line with American Society for Testing ciferae) were controlled as needed from emergence to the flowering and Materials (ASTM) certified biodiesel (Alemayehu and Becker, stage with applications of Ortho Max (Ortho Group, Marysville, 2002), genetic variation in FA profiles can lead to differences in OH), following manufacturer instructions. Flea beetle infestation engine performance of the oil extracted from diverse cultivars was scored from one to three (no infestation, 50% infested, 100% (Nettles-Anderson and Olsen, 2009). In addition, because seed-oil infested). Flowering time was recorded in each plot as the date composition is correlated with FA profile in leaves (Wang et al., when 50% of the plants had reached flowering. Plant height was 1989; Lemieux et al., 1990; Shaw et al., 1997), genetic variation in determined for five randomly selected plants per plot by measur- the FA profiles may have a role in plant acclimation under stressful ing the distance from the soil surface to the highest point on the environments (Mene-Saffrane et al., 2009).