Gossypol In Cotton Research Articles

Genome-wide identification and expression analysis of terpene synthases in Gossypium species in response to gossypol biosynthesis.

Cottonseed is an invaluable resource, providing protein, oil, and abundant minerals that significantly contribute to the well-being and nutritional needs of both humans and livestock. However, cottonseed also contains a toxic substance called gossypol, a secondary metabolite in Gossypium species that plays an important role in cotton plant development and self-protection. Herein, genome-wide analysis and characterization of the terpene synthase (TPS) gene family identified 304 TPS genes in Gossypium. Bioinformatics analysis revealed that the gene family was grouped into six subgroups TPS-a, TPS-b, TPS-c, TPS-e, TPS-f, and TPS-g. Whole-genome, segmental, and tandem duplication contributed to the evolution of TPS genes. According to the analysis of selection pressure, it was predicted that TPS genes experience predominantly negative selection, with positive selection occurring subsequently. RT-qPCR analysis in TM-1 and CRI-12 lines revealed GhTPS48 gene as the candidate gene for silencing experiments. To summarize, comprehensive genome-wide studies, RT-qPCR, and gene silencing experiments have collectively demonstrated the involvement of the TPS gene family in the biosynthesis of gossypol in cotton.

Molecular cloning and characterization of GhERF105, a gene contributing to the regulation of gland formation in upland cotton (Gossypium hirsutum L.)

BackgroundGossypium hirsutum L. (cotton) is one of the most economically important crops in the world due to its significant source of fiber, feed, foodstuff, oil and biofuel products. However, the utilization of cottonseed was limited due to the presence of small and darkly pigmented glands that contain large amounts of gossypol, which is toxic to human beings and non-ruminant animals. To date, some progress has been made in the pigment gland formation, but the underlying molecular mechanism of its formation was still unclear.ResultsIn this study, we identified an AP2/ERF transcription factor named GhERF105 (GH_A12G2166), which was involved in the regulation of gland pigmentation by the comparative transcriptome analysis of the leaf of glanded and glandless plants. It encoded an ERF protein containing a converved AP2 domain which was localized in the nucleus with transcriptional activity, and showed the high expression in glanded cotton accessions that contained much gossypol. Virus-induced gene silencing (VIGS) against GhERF105 caused the dramatic reduction in the number of glands and significantly lowered levels of gossypol in cotton leaves. GhERF105 showed the patterns of spatiotemporal and inducible expression in the glanded plants.ConclusionsThese results suggest that GhERF105 contributes to the pigment gland formation and gossypol biosynthesis in partial organs of glanded plant. It also provides a potential molecular basis to generate ‘glandless-seed’ and ‘glanded-plant’ cotton cultivar.

Salt Stress Effects on Secondary Metabolites of Cotton in Relation to Gene Expression Responsible for Aphid Development.

Many secondary metabolites have insecticidal efficacy against pests and may be affected by abiotic stress. However, little is known of how plants may respond to such stress as pertains the growth and development of pests. The objective of this study was to determine if and how salt stress on cotton plants affects the population dynamics of aphids. The NaCl treatment (50mM, 100mM, 150mM and 200mM) increased contents of gossypol in cotton by 26.8–51.4%, flavonoids by 22.5–37.6% and tannic by 15.1–24.3% at 7–28 d after salt stress. Compared with non-stressed plants, the population of aphids on 150 and 200 mM NaCl stressed plants was reduced by 46.4 and 65.4% at 7d and by 97.3 and 100% at 14 days after infestation. Reductions in aphid population were possibly attributed to the elevated secondary metabolism under salt stress. A total of 796 clones for aphids transcriptome, 412 clones in the positive- library (TEST) and 384 clones in the reverse-library (Ck), were obtained from subtracted cDNA libraries and sequenced. Gene ontology (GO) functional classification and KEGG pathway analysis showed more genes related to fatty acid and lipid biosynthesis, and fewer genes related to carbohydrate metabolism, amino acid metabolism, energy metabolism and cell motility pathways in TEST than in Ck library, which might be the reason of aphids population reduction. A comparative analysis with qRT-PCR indicated high expression of transcripts CYP6A14, CYP6A13, CYP303A1, NADH dehydrogenase and fatty acid synthase in the TEST group. However, CYP307A1 and two ecdysone-induced protein genes were down regulated. The results indicate that genes of aphids related to growth and development can express at a higher level in reaction to the enhanced secondary metabolism in cotton under salinity stress. The expression of CYP307A1 was positively correlated with the population dynamics of aphids since it was involved in ecdysone synthesis.

Elimination of Gossypol in Cottonseed will Improve its Utilization

Gossypol, a naturally occurring terpenoid found in pigment glands located throughout the cotton plant, is an effective insect deterrent, but is also a cumulative toxin in simple-stomached animals. Plant biotechnology utilizing RNAi was used to create a plant that has no gossypol in the seed while retaining gossypol in all other plant tissues to prevent predation. Since cotton is drought and heat tolerant, it is well suited to serve as a source of both food and fiber as climate change puts other crops in jeopardy.Agrobacterium transformation was used to insert into the cotton nuclear genome a construct containing a seed specific promoter driving an RNAi hairpin that suppresses delta-cadinene synthase. This enzyme plays a critical role early in building gossypol. This biotechnology-based proof of concept provides strong evidence that it is possible to produce a plant that retains its natural defense mechanism in the non-seed tissues while producing a drought and heat tolerant source of protein in the gossypol-free cottonseed.The presence of Gossypol in cotton seed means all the protein produced by the cotton plant is relegated to ruminant feed and (in miniscule amounts) aquacultre. Recent research demonstrates 100% replacement of fishmeal with Ultra-Low Gossypol Cottonseed (ULGCS) in the feeds of several aquaculture species without a decrease in performance.Each year about 10-11 million metric tons of cottonseed protein are produced worldwide. Without gossypol, this is enough protein to satisfy the daily, basic protein needs (50 grams/person) of more than 600 million people for one year. Food scientists have also created a wide range of food products from ULGCS, including hummus, plant-based dairy substitutes, a peanut butter alternative and protein fortified beverages. Elimination of gossypol in cottonseed could greatly improve utilization of this valuable protein resource for global food and fiber security as we move into an era of uncertain climate conditions.

Metabolic engineering of gossypol in cotton

Cotton has long been known as a fiber plant. Besides the cotton fiber, the cottonseed oil and cottonseed protein are two other major products of cotton plants. However, the applications of the cottonseed oil and protein are limited because of the presence of toxic gossypol, which is unsafe for human and monogastric animal consumption. Meanwhile, gossypol in cotton increases the plant defense response to insect herbivores and pathogens. Consequently, gossypol has been extensively used in clinical trials in biomedical science. Over the last few years, major advances have occurred in both understanding and practice with regard to molecular regulation of gossypol pathway in cotton plant or hairy root culture. This review highlights a few major recent and ongoing developments in metabolic engineering of gossypol, as well as suggestions regarding further advances needed.

Responses of three successive generations of beet armyworm, Spodoptera exigua, fed exclusively on different levels of gossypol in cotton leaves.

The beet armyworm, Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae), is an important pest of numerous crops, and it causes economic damage in China. Use of secondary metabolic compounds in plants is an important method used to control this insect as a part of integrated pest management. In this study the growth, development, and food utilization of three successive generations of S. exigua fed on three cotton gossypol cultivars were examined. Significantly longer larval life-spans were observed in S. exigua fed on high gossypol cultivar M9101 compared with those fed on two low gossypol cultivars, ZMS13 and HZ401. The pupal weight of the first generation was significantly lower than that of the latter two generations fed on ZMS13 group. Significantly lower fecundity was observed in the second and third generations of S. exigua fed on M9101 compared with S. exigua fed on ZMS13 and HZ401. The efficiency of conversion was significantly higher in the first and third generations fed on HZ401 compared with those fed on ZMS13 and M9101. A significantly lower relative growth rate was observed in the three successive generations fed on M9101 compared with those fed on ZMS13 and HZ401. Cotton cultivars significantly affected the growth, development, and food utilization indices of S. exigua, except for frass and approximate digestibility. Development of S. exigua was significantly affected by relative consumption rate and efficiency of conversion of ingested food, but not by relative growth rate or approximate digestibility, suggesting that diet-utilization efficiency was different based on food quality and generation. Measuring the development and food utilization of S. exigua at the individual and population levels over more than one generation provided more meaningful predictions of long-term population dynamics.

Biosynthesis of gossypol in cotton.

Abstract Cotton plants accumulate gossypol and related sesquiterpenoids in pigment glands as their defensive machinery against pathogens and herbivores. However, the accumulation of gossypol, which is toxic and antispermatogenic, also makes it hard to use cottonseeds for human and animal consumption. Detailed understanding of gossypol biosynthesis and its regulation should provide better strategies for resolving this problem. Recent progresses have been made to dissect gossypol pathway at molecular level. Genes encoding farnesyl diphosphate synthase (geranyltranstransferase), (+)-δ-cadinene synthase (CDN1 or CAD1), (+)-δ-cadinene-8-hydroxylase (CYP706B1), and S -adenosyl-L-Met: desoxyhemigossypol-6-O-methyltransferase, have been isolated, and their expression patterns analysed. A WRKY transcription factor from Gossypium arboreum , GaWRKY1, was found to activate CDN1-A gene expression through binding to W-box palindrome on the CDN1-A promoter. A laccase, GaLAC1, which might be involved in the later steps of gossypol biosynthesis, was also identified. In addition, a necrosis- and ethylene-inducing protein from Verticillium dahliae , VdNEP, was found to be involved in the interaction between cotton plants and the fungal pathogen. The expression of these genes has been studied under different developmental stages, and under treatment of fungal elicitor preparation. Antisense inhibition of CDN1 gene expression has reported to result in reduced gossypol accumulation in cottonseed to a varied degree. (+)-δ-Cadinene-8-hydroxylase, encoded by a single copy gene in the cotton genome, might be a better alternative for genetic engineering to specifically deplete gossypol biosynthesis/accumulation from cottonseeds.

Identification and quantification of gossypol in cotton by using packed micro-tips columns in combination with HPLC.

Self-packed micro-tip columns containing a C18-bonded silica stationary phase, based on the same principles as solid-phase extraction methods, were used to obtain gossypol and related sesquiterpenoid aldehyde-enriched fractions. The enriched metabolite fractions were then analyzed by optimized high-performance liquid chromatography (HPLC) with a C18 column (4.6 mm x 25 cm) eluted with the binary mobile phase acetonitrile-0.1% aqueous TFA solution (80:20). This method has proven to be highly reproducible. The precision and accuracy, as %RSD and %RME values, were determined to be less than 15% for the method. The minimum detection limit of gossypol was determined to be 10 ng (absolute gossypol). Absolute recovery was greater than 94% with a standard deviation of +/-3.68%. This is a simple, fast, and cost-effective method for isolation, identification, and quantification of gossypol and related secondary metabolites. Comparative analysis of gossypol content was performed on different parts of the cotton plant (seeds, stems and leaves) of two different cultivars of Gossypium hirsutum L. (Acala(1517-70) and OR19). The results indicate that the OR19 cv naturally contains higher gossypol levels than the Acala cv. It was also found that treatment of leaves with a Verticillium dahliae-derived elicitor induced production of deoxyhemigossypol rather than gossypol.

Studies on the Heritability of Gossypol in Leaves and Flower Buds of Gossypium1

The inheritance of gossypol in cotton (Gossypium spp.) flower buds and leaves was studied in populations derived from three crosses of medium ✕ medium, high × low and high × high gossypol parents. Data from all three crosses indicated that a low gossypol level was dominant to a higher gossypol level. F2 frequency distributions suggested that more than one gene controls the expression of level of gossypol in flower buds. There was an indication of additive gene action although the possibility of geometric gene action was not ruled out. Estimates of broad‐sense heritability ranged from 73.0 to 86.0%.Significant positive correlation values were found between the level of gossypol in the flower buds and leaves in four populations of Upland cotton. Thus we concluded that at least some of the genes responsible for the expression of the level of gossypol in the flower buds also control the level of gossypol in the cotton leaves.Significant positive correlation values were obtained between the level of gossypol in the leaves and the number of glands on leaf, bract, and petal. Similarly, the correlation values between the level of gossypol in the flower buds and the number of glands on leaf and petal were positive and significant. Thus we concluded that the number of glands on leaves, bracts, and petals can be a useful breeding index for developing low or high gossypol lines of Upland cotton. The maximum number of glands per 5 mm disc occurred in the leaves and the minimum number in the bracts.

Determination of gossypol in leaves and flower buds of Gossypium.

AbstractA method is described for the determination of free gossypol in cotton leaves with greater accuracy. The improved accuracy results from the elimination of the interference from chlorophyll and from quickly converting the extracted gossypol to the dianilino derivative. Methods for the determination of the free and bound gossypol in cotton flower buds are described.