Search

The Vernonia galamensis (Cass.) Less [synonym: Centrapalus pauciflorus] Compositae, is a source of naturally epoxidized oil. Its commercial use is limited due to presence of a lipase enzyme that produces high free fatty acid levels in vernonia oil. The genomic information and the gene expression patterns of lipase in vernonia has not been studied in detail. The objectives of our studies were to construct a complementary DNA (cDNA) library from vernonia seed to identify expressed sequence tags (ESTs) related to various plant functions. We were successful in constructing a cDNA library from seed tissues of vernonia. A total of 1325 cDNA clones were randomly sequenced and analyzed. A total of 97 high-quality ESTs with an average length of 400 bp were generated. These ESTs indicated the existence of genes involved in varied functions such as defense, protein processing, transcription, translation, signal transduction, and secondary metabolism. Out of the total EST sequences, there were 129 ESTs containing simple sequence repeats (SSRs) from which 63 SSR primer pairs were designed. It is the first transcriptome report from the vernonia that has generated ESTs as well as EST derived SSR markers capable of being used in future oil quality, transformation and germplasm characterization studies.

Sunn hemp (Crotolaria juncea L.), a legume plant, has potential in the mid-Atlantic region of the U.S. as a renewable source of fiber and pulp, due to its biological nitrogen fixation capability that can help reduce/eliminate N pollution of Chesapeake Bay. Most research in this region has focused on kenaf (Hibiscus cannabinus L.) and little is known about sunn hemp. We evaluated effects of three planting dates (late-May, mid-June, and late-June) and three row spacings (0.3, 0.6, and 0.9 m) on dry matter yields (DMY) of kenaf and sunn hemp during 1997, and 1998 by using three crop treatments (CT1: kenaf grown with 100 kg N ha−1; CT2: sunn hemp grown without inoculation and with 100 kg N ha−1; and CT3: sunn hemp inoculated with Bradyrhizobium but without N fertilization). DMY following CT1 and CT3 (7.8 and 6.4 Mg ha−1, respectively) during 1997 were similar and greater than that following CT2 (5.7 Mg ha−1). However, DMY following CT1, CT2, and CT3 were similar in 1998 and ranged from 12.6 to 13.4 Mg ha−1. Kenaf planting date did not affect DMY during 1997 but during 1998 the highest DMY was obtained from kenaf planted in late-May. The optimal planting date for sunn hemp during 1997 was mid-June, whereas in 1998 it was late-May. Row spacing effects on kenaf DMY were not significant. Row spacings of 0.3 m were optimal for DMY of N-fertilized sunn hemp during 1997 and 1998, whereas row spacing did not affect DMY of non-fertilized, but affected inoculated sunn hemp. We conclude that both kenaf and sunn hemp could produce similar dry matter yields in the mid-Atlantic region of U.S.

The glucosinolate-free meal from rapeseed can be used as livestock feed, whereas glucosinolate-rich meal can be used as a pesticide. It has also been shown that glucosinolate content in Brassica (rapeseed) seeds can be manipulated by application of chemicals. However, the stage of seed development when potential chemical treatments could be applied has not been clearly identified. Thus, an experiment was conducted to evaluate accumulation of glucosinolate, oil, and erucic acid in developing seeds of rapeseed lines. These included lines that were classified as low or high for glucosinolate content. The florets of eight rapeseed lines were tagged at the 50% flowering stage and were sequentially harvested at 26, 28, 30, 33, 35, 37, 40, 42, 44, 47, 49, and 52 days after flowering (DAF). The oil content in both the high and low-glucosinolate lines increased approximately by a factor of four from 26 to 52 DAF. The oil content accumulation was not affected by glucosinolate content. Erucic acid content in the oil was significantly higher in low glucosinolate lines compared with high glucosinolate lines on 28 and 40 DAF. Developing seeds were most amenable to change in erucic acid content at approximately 37 DAF. The glucosinolate contents in high glucosinolate lines started to increase significantly at 26 DAF and continued up to 33 DAF. However, the glucosinolate content in the low glucosinolate lines increased only from 33 to 35 DAF. This indicates that the greatest accumulation of glucosinolate in developing rapeseed seeds may occur at approximately 26 DAF.

Epoxidized oils, manufactured by chemical epoxidation of fats and vegetable oils such as soybean [ Glycine max (L.) Merr.], are useful in reformulation of oil based (alkyd-resin) paints to reduce emissions of volatile organic compounds that contribute to production of smog. Other potential markets for epoxy fatty acids include plasticizers, additives to polyvinyl chloride, polymer blends and coatings, cosmetic, and pharmaceutical applications. Currently, no oilseed crop has been commercialized as a source of natural epoxidized oils. However, Vernonia galamensis (Cass.) Less. has been identified to have potential for domestication as a new industrial oilseed source of natural epoxy fatty acids. The main objective of this research was to evaluate feasibility of vernonia production in mid-Atlantic region of the United States. Specifically, we wanted to evaluate available vernonia germplasm for seed yield, oil content, and oil quality, and to determine suitable production practices. The seed yield (kg/ha) in field experiments conducted from 1994, 1995, and 1996 at Randolph Farm of Virginia State University (37°15′N and 77°30.8′W), with a selected group of vernonia lines, ranged from 490 to 1288, 494 to 1394, and 1070 to 1934, respectively. Oil content ranged from 30.2 to 36.7% and 32.1 to 39.2%, respectively for 1995 and 1996 and the vernolic acid content ranged from 68.9 to 74.7% and 69.1 to 75.6%. A significant positive correlation ( r =0.34) between oil content and vernolic acid content indicated that both these characteristics could be improved simultaneously. The highest seed yield was obtained with 100 kg N/ha. A pre-plant-incorporated application of Trifluralin herbicide at 0.5 kg/ha a.i. did not reduce vernonia stand establishment. Seedhead shattering was observed to be a limitation in the evaluated vernonia germplasm. These results indicate that commercial vernonia production in Virginia and other areas in the mid-Atlantic region of United States may be feasible.

The US industry uses ≈18 million kg of high erucic acid oil annually, mostly from imports. Therefore, a large overall market potential exists for development of annually renewable domestic sources of erucic acid. The present research was conducted to characterize the winter hardy rapeseed germplasm for oil, erucic acid, and glucosinolate contents for use in breeding programs to develop commercial production of rapeseed. Significant variation existed among the 455 accessions of Brassica napus L. and the 44 accessions of Brassica rapa L. for oil, erucic acid, and glucosinolate contents. B. napus had significantly higher mean oil content in the seeds (37.4%) than the Brassica rapa (36.6%). The glucosinolate content was higher in napus than the rapa meal (49.2 vs. 43.8 μmol/g). The erucic acid content was higher in rapa (32.6%) than the napus accessions (26.1%). Within species, the correlation between oil and glucosinolate contents was significantly negative among the napus accessions (−0.14), but was significantly positive among rapa accessions (+0.39). The results indicate that plant material from either napus or rapa species could be used in breeding for increasing erucic acid content. Accessions with high, medium, and low contents of oil, erucic acid, and glucosinolate contents were identified.

Seeds from nine kenaf genotypes (Cubano, Everglades 41, Everglades 71, GR2563, Guatemala 48, Indian, 178-18RS-10, Tainung #1, and Tainung #2) were evaluated for oil, fatty acid, phospholipid, and sterol content. Oil content ranged from 21.4 to 26.4% with a mean of 23.7%. Total phospholipids ranged from 3.9 to 10.3% of the oil, with a mean of 6.0%. Mean sterol percent was 0.9 and ranged from 0.6% of the total oil for 178-18RS-10 accession to 1.2% for Everglades 71. Palmitic (20.1% of the total fatty acids), oleic (29.2%), and linoleic (45.9%) were the major fatty acids, and palmitoleic (1.6%), linolenic (0.7%), and stearic (3.5%) were the minor components. Medium (C12C14) and long (C22C24) chain fatty acids were less than 1%. Sphingomyelin (4.42% of the total phospholipids), phosphatidyl ethanolamine (12.8%), phosphatidyl choline (21.9%), phosphatidyl serine (2.9%), phosphatidyl inositol (2.7%), lysophosphatidyl choline (5.3%), phosphatidyl glycerol (8.9%), phosphatidic acid (4.9%), and cardiolipin (3.6%) were identified in the nine genotypes. Phosphatidyl choline, phosphatidyl ethanolamine, and phosphatidyl glycerol were the dominant phospholipids. In addition, eight unidentified phospholipids were also found, β-sitosterol (72.3% of the total sterols), campsterol (9.9%), and stigmasterol (6.07%) were prevalent among kenaf genotypes. Kenaf's relatively high oil content and its similarity to cottonseed oil suggest that the seed oil may be used as a source of edible oil. The variation among genotypes indicates potential for genetic improvement in oil yield and quality.