Occurrence of (+)- and (-)-gossypol in wild species of cotton and in Gossypium hirsutum Var. marie-galante (Watt) Hutchinson

Gossypol occurs as a mixture of enantiomers in cottonseed. These enantiomers exhibit different biological activities. The (-)-enantiomer is toxic to animals, but it has potential medicinal uses. Therefore, cottonseed with >95% (-)-gossypol could have biopharmaceutical applications. The (+)-enantiomer shows little, if any, toxicity to nonruminant animals. Thus, cottonseed with >95% (+)-gossypol could be more readily utilized as a feed for nonruminants. The (+)- to (-)-gossypol ratio in commercial Upland (Gossypium hirsutum) cottonseed is usually about 3:2, whereas that in commercial Pima cottonseed (Gossypium barbadense) is approximately 2:3. Herein are reported the (+)- to (-)-gossypol ratios in the seed from 28 wild species of cotton (194 accessions), 94 accessions of G. hirsutum var. marie-galante, and 3 domesticated species (11 accessions). It was found that some or all of the accessions of Gossypium darwinii, Gossypium sturtianum, Gossypium areysianum, Gossypium longicalyx, Gossypium harknessii, and Gossypium costulatum produce an excess of (-)-gossypol but none >65%. At least one accession of Gossypium anomalum, Gossypium mustelinum, Gossypium gossypioides, and Gossypium capitis-viridis contained >94% (+)-gossypol. One of the 94 accessions of G. hirsutum var. marie-galante (i.e., no. 2469) contained 97% (+)-gossypol.     

Toxicity of (+)- and (-)-gossypol to the plant pathogen,Rhizoctonia solani

The dimeric sesquiterpene gossypol occurs naturally in cottonseed and other parts of the cotton plant. Gossypol exists as enantiomers because of the restricted rotation around the central binaphthyl bond. The (-)-enantiomer is toxic to nonruminant animals while the (+)-enantiomer exhibits little, if any, toxicity to these animals. Developing cotton plants with low levels of the (-)-gossypol could expand the use of cottonseed as a feed source. Gossypol also may play a role in protecting the plant from pathogens. The relative toxicity of (+)- and (-)-gossypol to plant pathogens has not been reported. We measured the concentration of (+)- and (-)-gossypol in roots from cotton seedlings that were treated with the biocontrol agent Trichoderma virens that induces biosynthesis of gossypol and related terpenoids in cotton roots. (-)-Gossypol was the minor enantiomer in control and treated roots, but levels were slightly higher in roots from T. virens-treated seed. We also determined the toxicity of the gossypol enantiomers and the racemate to the seedling disease pathogen Rhizoctonia solani. The (+)- and (-)-enantiomers of gossypol and the racemate are equally effective in inhibiting growth of this pathogen. The lethal doses of the gossypols required to kill the pathogen appeared to be similar, but their toxicities are significantly less than those of related cotton and kenaf sesquiterpenes. The results indicate that altering the enantiomeric ratio in cotton roots will not adversely affect the resistance of seedlings to the seedling pathogen R. solani.     

Cottonseed with a high (+)- to (-)-gossypol enantiomer ratio favorable to broiler production

This study was designed to evaluate the relative toxicity of (+)- and (-)-gossypol enantiomers in 0-3-week-old broilers. Treatments consisted of broiler starter diets formulated with either a glandless, which did not contain gossypol, a commercial glanded [62. 2% (+)-gossypol], or a glanded moco [83.2% (+)-gossypol] crushed cottonseed (CCS) (six replicates/treatment) plus a soybean meal negative control. Glandless cottonseed was mixed with the moco cottonseed (2.4% free gossypol) so that both the commercial glanded and moco glanded cottonseeds contained equivalent concentrations of free gossypol (2.0%). The cottonseed treatments were added at 5 and 10% of the diet. Body weights and feed conversions were determined weekly. Body weights and feed-to-gain ratios of broilers fed 5 and 10% glandless CCS and 5% moco CCS were not significantly different. Broilers receiving 10% commercial glanded CCS weighed significantly less than those subjected to all other treatments. Feed-to-gain ratios were significantly higher for broilers receiving 10% commercial glanded and 10% moco CCS as compared to 5% moco and glandless CCS, 10% glandless CCS, and control. Relative liver weights of birds receiving 10% moco CCS were significantly less than those of birds receiving 10% commercial CCS. The data clearly showed that broilers fed moco CCS containing a relatively high (+)- to (-)-gossypol enantiomer ratio performed better than broilers receiving commercial CCS with a lower (+)- to (-)-gossypol enantiomer ratio.     

Gossypol and gossypolone enantiomers in tissues of rainbow trout fed low and high levels of dietary cottonseed meal

Gossypol is an antifertilizing agent in males and females. However, gossypol and its metabolite, gossypolone, have also gained interest because of their anticarcinogenic activities. This paper examines for the first time both enantiomers of tissue gossypol and gossypolone in mature rainbow trout fed two diets containing low (15%) and high (60%) levels of cottonseed meal (CM) for 9 months. The gossypol concentration was highest in liver followed by kidney, intestine, testis, blood plasma, stomach, and muscle. Gossypol was detected in muscles of fish fed low- and high-CM diets (0.31 +/- 0.03 and 1.95 +/- 0.59 microg of total gossypol/g, wet basis, respectively). The (+)-gossypol enantiomer was predominantly retained in all tissues. The ratio of (-)- to total gossypol ranged from 30 to 44% in fish fed the high-CM diet and from 23 to 30% in fish fed the low-CM diet except for muscle tissue (44%). Higher gossypolone concentrations were found in intestine than in liver. Gossypolone, however, was not detected in blood plasma, muscle, and testis of fish fed the low-CM diet. The ratio of gossypolone to gossypol was highest in muscle (1.75), followed by intestine (1.59), stomach (1.50), kidney (0.43), liver (0.34), testis (0.28), and blood plasma (0.27). This study indicated that the retention of the (-)-gossypol enantiomer is dependent on dietary concentrations and that the oxidative conversion of gossypol to gossypolone occurs more actively in the digestive tract and muscle than in other tissues in rainbow trout.     

Simulated glyphosate drift influences nitrate assimilation and nitrogen fixation in non-glyphosate-resistant soybean

Nontarget injury from glyphosate drift is a concern among growers using non-glyphosate-resistant (non-GR) cultivars. The effects of glyphosate drift on nitrate assimilation and nitrogen fixation potential, nodule mass, and yield of non-GR soybean were assessed in a field trial at Stoneville, MS. A non-GR soybean cultivar 'Delta Pine 4748S' was treated with glyphosate at 12.5% of use rate of 0.84 kg of active ingredient/ha at 3 (V2), 6 (V7), and 8 (R2, full bloom) weeks after planting (WAP) soybean to simulate glyphosate drift. Untreated soybean was used as a control. Soybeans were sampled weekly for 2 weeks after each glyphosate treatment to assess nitrate assimilation and N2 fixation potential. Nitrate assimilation was assessed using in vivo nitrate reductase assay in leaves, stems, roots, and nodules. Nitrogen fixation potential was assessed by measuring nitrogenase activity using the acetylene reduction assay (ARA). Nitrogen content of leaves, shoots, and seed and soybean yield were also determined. In the first sampling date (4 WAP), glyphosate drift caused a significant decrease in NRA in leaves (60%), stems (77%), and nodules (50%), with no decrease in roots. At later growth stages, NRA in leaves was more sensitive to glyphosate drift than stems and roots. Nitrogenase activity was reduced 36-58% by glyphosate treatment at 3 or 6 WAP. However, glyphosate treatment at 8 WAP had no effect on nitrogenase activity. Nitrogen content was affected by glyphosate application only in shoots after the first application. No yield, seed nitrogen, protein, or oil concentration differences were detected. These results suggest that nitrate assimilation and nitrogen fixation potential were significantly reduced by glyphosate drift, with the greatest sensitivity early in vegetative growth. Soybean has the ability to recover from the physiological stress caused by glyphosate drift.     

Seed oil and fatty acid content in okra (Abelmoschus esculentus) and related species

Approximately 1100 genebank accessions of okra (Abelmoschus esculentus) and 540 additional accessions that included six of its related species-A. caillei, A. crinitis, A. esculentus, A. ficulneus, A. manihot, A. moschatus and A. tuberculatus-were evaluated for seed oil content using time domain NMR (TD-NMR). Oil content in seed of A. caillei, A. esculentus, A. ficulneus, A. manihot, A. moschatus and A. tuberculatus was in the ranges 2.51-13.61%, 12.36-21.56%, 6.62-16.7%, 16.1-22.0%, 10.3-19.8% and 10.8-23.2%, respectively. Accession PI639680 (A. tuberculatus) had the highest seed oil content (～23%). Accessions of A. esculentus with high seed oil content included PI nos. PI274350 (21.5%), PI538082 (20.9%) and PI538097 (20.9%). Values for the three accessions of A. manihot with the highest seed oil content were PI nos. PI639673 (20.4%), PI639674 (20.9%) and PI639675 (21.9%), all representing var. tetraphyllus. Average percent seed oil in materials of A. esculentus from Turkey and Sudan (17.35% and 17.36%, respectively) exceeded the averages of materials from other locations. Ninety-eight accessions (total of six species) were also examined for fatty acid composition. Values of linoleic acid ranged from 23.6-50.65% in A. esculentus. However, mean linoleic acid concentrations were highest in A. tuberculatus and A. ficulneus. Concentrations of palmitic acid were significantly higher in A. esculentus (range of 10.3-36.35%) when compared to that of other species, and reached a maximum in PI489800 Concentrations of palmitic acid were also high in A. caillei (mean = ～30%). Levels of oleic acid were highest in A. manihot, A. manihot var. tetraphyllus and A. moschatus.     

Monoclonal antibodies for the analysis of gossypol in cottonseed products

Immunogens, prepared by conjugating either (+)-gossypol or (-)-gossypol to Limulus polyphemushemolymph protein, were used for immunization in the production of monoclonal antibodies. Hybridoma were evaluated for their relative affinity to racemic gossypol, (+)-gossypol, (-)-gossypol, gossypol analogues, and their lysine derivatives. The monoclonal antibody obtained showed higher affinity to gossypol and gossypol analogues as compared to their lysine derivative counterparts. An indirect competitive enzyme-linked immunosorbent assay (ELISA) with this antibody was used to measure gossypol in 15 cottonseed meal products; the results showed good correlation with results obtained using the AOCS (free gossypol) official method (R(2) = 0.89). The direct recognition of both free gossypol and bound gossypol using this antibody will be useful for rapid screening and quality control.     

Diversity in swordbean (Canavalia gladiata (Jacq.) DC.) collected from Tamil Nadu, India

Eight accessions of swordbean (Canavalia gladiata (Jacq.) DC.) were collected from eight agroclimatic regions of Tamil Nadu, India. A portion of the collected seeds of accessions will be deposited in NBPGR, New Delhi. The most pronounced differences in agrobotanical characters were observed in seed germination percentage, plant height, number of branches per plant, number of leaves (180th day) per plant, leaf area (150th day), early flowering, fertility index and 100-seed-weight. Differences in the contents of crude protein and crude lipid in the seeds of different accessions also appeared to be significant. Performance of Lowerkodiyar and Mundanthurai accessions under test conditions was superior and suggested that breeders might exploit the genome of these accessions in current pulse crop improvement programmes.     

Proteomic analysis of high protein soybean (Glycine max) accessions demonstrates the contribution of novel glycinin subunits

Limited biochemical information is available on soybean accessions that have seed protein content greater than 45% of the seed dry weight. SDS-PAGE analysis of seed proteins from nine soybean accessions revealed significantly higher amount of seed storage proteins in these accessions when compared with that of soybean cultivar Williams 82. High-resolution two-dimensional gel electrophoretic analysis of seed proteins revealed significant differences among several seed storage protein components in these accessions. A total of 51 protein spots were identified using peptide mass fingerprinting (MALDI-TOF MS). The contribution of these proteins to the overall protein content of the accessions was quantified using Delta2D image analysis software. Results showed that among the majority of the nine accessions, the largest difference in higher protein quantity was within the seed 11S storage globulins. The high protein trait from PI407788A was successfully transferred to an experimental line, LG99-469, demonstrating that this trait was transferable and robust.     

Chromatographic fingerprinting of <Emphasis Type="Italic">Lupinus luteus</Emphasis> L. (Leguminosae) main secondary metabolites: a case of domestication affecting crop variability

Secondary metabolites (SMs), such as alkaloids and raffinose oligosaccharides (RFOs), play important roles in plant physiology. Although alkaloid and RFO phenotypic variation has been reported for yellow lupin (Lupinus luteus L.), most evaluations have used a reduced number of accessions; thus, limiting the understanding of accumulation patterns and variation ranges. The main goal of this research was to assess alkaloid and RFO content in a diverse L. luteus sample to understand possible SM accumulation patterns across this legume species. Eighteen yellow lupin accessions were analyzed using high performance thin layer chromatography to provide insights on seed and leaf RFO and alkaloid phenotypic variation. Co-dominant markers (170) were used to examine genetic relationships among L. luteus accessions and possible accumulation patterns across closely related genotypes. Significant differences were observed for seed and leaf RFOs. Total seed RFO accumulation ranged from 79.738 to 131.079 mg g^?1. Raffinose, stachyose, and verbascose were observed in all genotypes’ seeds, but at different RFO concentrations. Raffinose was the only RFO detected in leaves (2.793–0.4224 mg g^?1). Total alkaloid accumulation ranged from 0.22 to 15.12 and 0.00 to 8.007 mg g^?1 for seeds and leaves, respectively. Lupinine, sparteine, and gramine were observed in seeds and leaves, and showed a wide range of variation. Neighbor-Joining (NJ) analysis showed an apparent pattern of seed alkaloid accumulation, most likely due to domestication events. However, high RFO accumulating accessions were scattered across the NJ tree. Alkaloid and RFO significant phenotypic variation will not only help to understand the roles of these SMs in L. luteus, but also to uncover the genetic basis behind their accumulation.     

Evaluation of Gossypium arboreum L. Germplasm for resistance to thrips

Summary As part of a project to assess the U.S. Asiatic Cotton Germplasm Collection as a source of genes for pest resistance, forty-three accessions of Gossypium arboreum L. were evaluated for resistance to thrips. Thrips, Thysanoptera spp., are a minor, but widespread pest on cotton, G. hirsutum L. and G. barbadense L. Accessions were planted in free-choice field tests in 1988, 1989, and 1990 at the Cotton Branch Experiment Station, Marianna, Arkansas. Damage ratings, based on a scale of 0 (no damage) to 7 (severe damage), were made approximately one month after planting. Relative score was computed by dividing the rating of each accession by the rating of the reference, G. hirsutum Stoneville 506. The relative score averaged over all G. arboreum accessions by year varied with the year, but was less than 100 (relative score for Stoneville 506) in each case. When data were combined for all three years, twenty-five accessions were significantly better than Stoneville 506. Introgression of the better accessions into G. hirsutum is now in progress.Abbreviations NPGS National Plant Germplasm System - STV 506 G. hirsutum Stoneville 506     

Potassium‐transport rate from root to shoot unrelated to potassium‐use efficiency in tomato grown under low‐potassium stress

Four tomato (Lycopersicon esculentum Mill.) strains (203, 474, 546, and 576) that are equally efficient in potassium (K) absorption, but different in efficiency of K use were studied using a continuously flowing solution culture to determine the importance of K‐transport rate from root to shoot in relation to K‐use efficiency. Strains 203 and 546 are inefficient in K use, ratios of K in shoots to roots were found to be three times higher than those of the two K‐use efficient strains 474 and 576 when grown under low‐K stress (0.1 mM). In addition, both the K concentrations and rates of K flow in xylem exudates of decapitated strains 203 and 546 were significantly higher than those of strains 474 and 576. These results suggest that high rates of K transport from roots to shoots are unrelated to K‐use efficiency in the tomato strains grown under low‐K stress. Further studies of K distributions in leaves and stems found that K concentrations in matured leaves and stems of the two efficient strains 474 and 576 were markedly lower than those of the two inefficient strains 203 and 546, while K in young and expanding leaves of the efficient strains were significantly higher than those of the inefficient strains, indicating that the ability to mobilize K from matured leaves to young and expanding leaves is an important factor that contributes to K‐use efficiency in tomato plants grown under low‐K stress.     

Genetic differentiation of watermelon landrace types in Mali revealed by microsatellite (SSR) markers

This study describes the genetic differentiation of a collection of 134 watermelon landrace accessions from Mali, representing red fleshed dessert and white fleshed seed and cooking type watermelons from five regions, plus three commercial dessert type cultivars with red flesh. The material was represented by in total 397 plants and was analysed using 24 microsatellite primer sets, which differentiated 129 alleles across all loci. Analyses of molecular variance ascribed 51 % of the variation among the landrace accessions, and 14 % of the variation could be ascribed to the regions. Partitioning the accessions into use groups (dessert, cooking, seed processing) explained 25 % of the variation. When categorising the accessions further into 10 landrace types, differentiated on the basis of use groups, local accession name, flesh colour and seed phenotype, these landrace types explained 26 % of the variation. Analysis with the software Structure revealed that the accessions with confidence could be separated into two major genetic groups, related to flesh colour (red and white) of the watermelon fruits. The same analysis further indicated that the material may be differentiated into eight genetic sub-groups. One group included again the red fleshed dessert types with local and commercial origin, while the remaining seven genetic sub-groups comprised the white fleshed landrace types used for seed processing and cooking, as well as white fleshed types of one dessert type. Some of the seed and cooking types were to a large extent different and assigned to one genetic sub-group each. A Mantel test, based on geographical and genetic distance matrices showed a positive correlation, indicating that seed exchange has not overcome local adaptation.     

Seed protein electrophoretic characterization of cowpea (Vigna unguiculata) germplasm from IITA gene bank

Summary The total seed protein, globulin and albumin fractions of 20 cowpea (V. unguiculata) accessions from IITA gene bank were investigated by SDS-polyacrylamide gel electrophoresis. Total seed protein extracts were prepared from the defatted meal by homogenisation and centrifugation in Tris-glycine buffer. The globulins and albumins were obtained from the total protein extract by exhaustive dialysis against sodium acetate buffer. Two main total seed protein electrophoretic patterns were observed with respect to the 39 and 20 kD subunits, which were present in six out of the twenty accessions analysed. While there was no correlation between seed colour and total seed protein banding pattern, the six insect-resistant cultivars were characterized by the presence of the 39 and 20 kD subunits. The globulins were the predominant class of the total seed proteins and consisted mainly of 64, 58, 56 and 14 kD subunits which make up CP1 and CP2, the major globulins. The albumins in all accessions were a heterogeneous protein fraction consisting of both high and low molecular weight subunits. It was suggested that the insect-resistant cultivars may be genetically related and that the 39 and 20 kD subunits may be involved in the insect resistance mechanism.     

Changes in seed Morphology, Dormancy and Germination from wild to Cultivated Hyacinth bean Germplasm (Lablab purpureus: Papilionoideae)

Morphological and physiological seed characteristics of the hyacinth bean (Lablab purpureus) were investigated in a set of 18 different germplasm accessions, from wild over semi-domesticated forms to landraces and current cultivars. The objective of this study was to improve the understanding of the domestication of this tropical legume crop. Wild accessions were easily distinguished by morphological characters, such as small, greyish-brown, mottled seeds. Cultivated or semi-domesticated forms showed a much wider variation in size, colour and shape. Seed mass of cultivated accessions reached up to almost 10 times that of wild accessions. Most wild accessions showed a greater spread of germination and larger proportions of hard seeds, up to about 70%, than most cultivated and so-called semi-domesticated accessions. Cluster analysis applied separately to morphological and germination data and a subsequent discriminant analysis did not help integrating the morphological variability observed. The presumed occurrence of semi-domesticated accessions within the germplasm tested as well as the crop's origin from Africa alone or both Africa and Asia are debated on the basis of seed germination and hard seed coat dormancy.     

水稻对~(14)CO_3~(2-)的吸收和积累动态

用同位素示踪技术研究水稻对14CO32-的吸收和积累动态,及其在水稻田中的行为特性。结果表明:通过水稻根系和浸于水中的茎杆下部吸收的14CO32-离子会向上部组织输送并形成积累趋势;在上部组织中,叶和茎杆上部的14C比活度随时间呈逐渐上升的趋势,而穗中的比活度于14d达最大值(271.9Bq/g)后又呈下降趋势;茎杆下部由于直接浸于水中,表现出对14CO32-离子的快速吸收、吸附,此后随时间呈下降趋势,根部表现出上升过程迟后于茎杆下部,其14C比活度也低于茎杆下部。上部组织(穗、叶和茎杆上部)中14C的百分含量随时间上升,而下部组织(茎杆下部和根)则相反,至试验后期(21~35d),其百分含量基本持平(约各占50%),14C从下部组织向上部组织输送的特征非常明显。     

Genetic Diversity of Traditional Chinese Mustard Crops Brassica juncea as Revealed by Phenotypic differences and RAPD Markers

This investigation was aimed at exploring the genetic diversity among nine typical accessions of Chinese mustard crops using random amplified polymorphic DNA (RAPD) markers and morphological comparison. Totally, 111 reproducible DNA bands were generated by 16 arbitrary primers, of which 91 bands were proved to be polymorphic. Based on pair-wise comparisons of the amplified bands, genetic similarities were obtained using Nei & Li's similarity coefficients and a dendrogram reflecting their relationships was made using the unweighted pair–group method with arithmetic averages (UPGMA). The result of cluster analysis indicated that the nine accessions were capable of being classified into two primary groups, one including accession 2 with expanded root (root mustard), accession 3 with entirely expanded whole stem (long-stem mustard), accession 6 with edible leaves (leaf mustard), accession 8 with edible seed stalk (seed stalk mustard) and another one including accession 4 with expanded basal stem (short-stem mustard), accession 5 with bulgy petiole (leafy bulgy mustard), and accession 9 with mustard-rich seed (seed mustard). Besides, accession 1 with expanded root (root mustard) and accession 7 with edible leaves and seed stalk (seed stalk mustard) were independent of other accessions in the dendrogram. Additionally, by cluster analysis based on highly reproducible RAPD markers, the accessions with similar edible parts of leaves or roots were not actually in the same phylogenetic groups. This implied that they were probably derived from different geographical origins with dissimilar genetic background and possessed higher genetic diversification. Furthermore, the results indicated that the traditional method for classifying Chinese mustard crops was not much reliable as it was largely dependent on phenotypic behaviors. Meanwhile, the phenotypic differences among individuals did not necessarily mean they must have sharp difference in genetic background as they met in the same group. Undoubtedly, these results aforementioned make this crop quite interesting to researchers for further investigating the molecular evolution of this special AABB group.     

Determination of gossypol enantiomer ratio in cotton plants by chiral higher-performance liquid chromatography

A celulose tris(3,5-dimethylphenylcarbamate) coated onto APS silica (Nucleosil, particle size, 7 microm; pore size, 500 A) was used under a reversed-phase condition to measure the enantiomeric ratios of gossypol enantiomers in cottonseeds, flowers, and roots in a number of cultivars samples of different Gossipium species. While unidimensional chromatography was used for measuring the enantiomeric ratio of all the samples of G. hirsutum, G. mustelinum, and in the seeds of G. barbadense, multidimensional chromatography was necessary for the analysis of samples of roots and flowers of G. barbadense. In the latter case, an ODS Hypersil column was used in the first dimension for sample clean up, and the enantiomers were resolved on the second dimension by the chiral column. As expected, all the seed samples of G. hirsutum and G. mustelinum showed the (P)-(+)-enantiomer in excess, whereas the seeds of G. barbadense showed the (M)-(-)-enantiomer. However, (P)-(+)-gossypol was found in enantiomeric excess in three samples examined of roots and in one of flower of G. barbadense. These results are discussed in this paper.     

Morphological and reproductive characterization of guar (<Emphasis Type="Italic">Cyamopsis tetragonoloba</Emphasis>) genetic resources regenerated in Georgia,USA

Guar, Cyamopsis tetragonoloba is used worldwide for food stabilization, fiber source, food, and industry. The United States Department of Agriculture, Agricultural Research Service, Plant Genetic Resources Conservation Unit (USDA, ARS, PGRCU) conserves 1,298 accessions originating from India, Pakistan, and breeding lines from the USA. My objectives were to determine: (1) if these guar accessions can successfully be regenerated in Georgia, USA, (2) which traits contribute the most variation, and (3) to provide estimates for genetic relatedness among these accessions. Guar accessions were directly seeded to the field in Griffin, GA between early May and mid June 2006–2008. At 50% maturity, 73 accessions were characterized for morphological, phenological, and reproductive traits during the regeneration cycles. High quality plants regenerated from most of the accessions and produced 80 to more than 9,300 seeds per accession. Guar can be successfully grown and regenerated in Griffin, GA. Coefficients of variation and principal component analysis revealed variability among accessions for these traits evaluated. Cluster analysis separated guar accessions into three groups (clusters) based on low, intermediate or high seed numbers. Guar accessions clustered in groups 2 and 3 appear to be more genetically related than those in group 1.     

Response of A-genome cotton germplasm to the seedling disease pathogens,Rhizoctonia solani and Pythium ultimum

Summary Approximately two hundred A-genome cotton (Gossypium arboreum L. and G. herbaceum L.) accessions were evaluated for resistance to the seedling disease pathogens Rhizoctonia solani Kühn [Thanatephorus cucumeris (A. B. Frank) Donk], and Pythium ultimum Trow. Susceptibility rating was based on a scale of 1 to 6 where 1 = no symptoms and 6 = dead. Variation was found among A-genome accessions in response to R. solani and P. ultimum, but none were highly resistant to these pathogens. As a group, the A-genome cottons were more susceptible to the pathogens than the G. hirsutum control.Abbreviations STV-A G. hirsutum Stoneville 506 with agar only - STV-NP G. hirsutum Stoneville 506 with non-pathogenic isolate - STV-P G. hirsutum Stoneville 506 with pathogenic isolate - A₁ G. herbaceum - A₂ G. arboreum - GRIN Genetic Resources Information Network