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PubMed2002

Evidence for regulation of resistance in Arabidopsis to Egyptian cotton worm by salicylic and jasmonic acid signaling pathways.

Signaling cross-talk between wound- and pathogen-response pathways influences resistance of plants to insects and disease. To elucidate potential interactions between salicylic acid (SA) and jasmonic acid (JA) defense pathways, we exploited the availability of characterized mutants of Arabidopsis thaliana (L.) Heynh. and monitored resistance to Egyptian cotton worm (Spodoptera littoralis Boisd.; Lepidoptera: Noctuidae). This generalist herbivore is sensitive to induced plant defense pathways and is thus a useful model for a mechanistic analysis of insect resistance. As expected, treatment of wild-type Arabidopsis with JA enhanced resistance to Egyptian cotton worm. Conversely, the coil mutant, with a deficiency in the JA response pathway, was more susceptible to Egyptian cotton worm than wild-type Arabidopsis. By contrast, the nprl mutant, with defects in systemic disease resistance, exhibited enhanced resistance to Egyptian cotton worm. Pretreatment with SA significantly reduced this enhanced resistance of nprl plants but had no influence on the resistance of wild-type plants. However, exogenous SA reduced the amount of JA that Egyptian cotton worm induced in both npr1 mutant and wild-type plants. Thus, this generalist herbivore engages two different induced defense pathways that interact to mediate resistance in Arabidopsis.

Animals↗
PubMed2004

Genetic mapping of EST-derived microsatellites from the diploid Gossypium arboreum in allotetraploid cotton.

To increase the numbers of microsatellites available for use in constructing a genetic map, and facilitate the use of functional genomics to elucidate fiber development and breeding in cotton, we sampled microsatellite sequences from expressed sequence tags (ESTs) transcribed during fiber elongation in the A-genome species Gossypium arboreum to evaluate their frequency of occurrence, level of polymorphism and distribution in the At and Dt subgenomes of tetraploid cotton. From among ESTs derived from G. arboreum fibers at 7-10 days post anthesis (dpa), 931 ESTs were found to contain simple sequence repeats (SSRs); 544 (58.4%) EST-SSR primer pairs were developed, and 468 (86%) amplified PCR products from allotetraploid cotton (G. hirsutumcv. TM-1 and G. barbadense cv. Hai7124). However, only 99 (18.2%) of these were found to be polymorphic and segregating in our interspecific BC1 mapping population [(TM-1xHai7124)xTM-1]. In these amplified and informative EST-SSRs, hexa- and tri-nucleotide repeat motifs were the most frequent, representing 40.1 and 30%, respectively, of the total. A total of 111 loci detected with these 99 EST-SSRs were integrated into our backbone map including 511 SSR loci. The distribution of the EST-SSRs appeared to be non-random, since 72 loci were anchored to the At and 37 to the Dt subgenome of allotetraploid cotton based on linkage tests. Interestingly, out of the 10 pairs of duplicate loci amplified, seven were mapped to the corresponding homologous linkage groups and/or chromosomes. BLASTX analysis revealed that 69 of the 99 ESTs showed significant similarities to known genes. Some genes important for fiber development, such as sucrose synthase, were mapped to corresponding chromosomes. These EST-SSRs provide structural and functional genomic information that will be useful for understanding cotton fiber development.

Base Sequence↗
PubMed1999

Differential regulation of six novel MYB-domain genes defines two distinct expression patterns in allotetraploid cotton (Gossypium hirsutum L.).

A PCR-based strategy was employed to identify myb-related genes potentially involved in the differentiation and development of cotton seed trichomes. cDNA clones representing six newly identified cotton myb-domain genes (GhMYB) of the R2R3-MYB family were characterized in the allotetraploid species Gossypium hirsutum L. (2n = 4x = 52; AADD). Several interesting motifs and domains in the transregulatory region (TRR) were identified as potential candidates for modulating GhMYB activity. One such structural feature is a basic 40-amino acid stretch (TRR1) located immediately downstream of the DNA-binding domain (DBD) in five of the GhMYBs. Furthermore, the conserved motif GIDxxH identified in a subset of plant MYBs is also present in the same position in the TRR1 domains of GhMYB1 and GhMYB6, exactly 12 amino acid residues downstream of the last tryptophan in the R3 repeat of the DBD. At least two of the GhMYBs (GhMYB4 and GhMYB5) contain unidentified ORFS in the 5' leader sequence (5'-uORFs) that may serve to regulate the synthesis of these particular GhMYB proteins at the translational level. Multiple alignment of DBD sequences indicated that GhMYBs show structural similarity to plant R2R3-MYB factors implicated in phenylpropanoid biosynthesis. GhMYB5 is the most distantly related cotton R2R3-MYB and is found in an isolated cluster that includes the drought-inducible AtMYB2. Sequence comparisons of DBD and TRR domains from GhMYBs, MIXTA (AmMYBMx) and G11 (AtMYBG11) did not reveal any striking similarity beyond conserved motifs. However, based on earlier phylogenetic analysis, GhMYB2, GhMYB3, and GHMYB4 are members of a cluster that contains GLABROUS1, while GhMYB1 and GhMYB6 belong to a closely related cluster. Semi-quantitative RT-PCR analysis revealed two discrete patterns of GhMYB gene expression. Type I cotton MYB (GhMYB-1, -2, and -3) transcripts were found in all tissue-types examined and were relatively more abundant than those derived from type II GhMYB genes (GhMYB-4, -5, and -6), which showed distinct, tissue-specific expression patterns. The developmental regulation of GhMYBs is consistent with a role for these DNA-binding factors in the differentiation and expansion of cotton seed trichomes.

Amino Acid Sequence↗
PubMed2005

Molecular cloning of coat protein gene of an Indian cotton leaf curl virus (CLCuV-HS2) isolate and its phylogenetic relationship with others members of Geminiviridae.

Cotton leaf curl geminivirus is a whitefly (Bemisia tabaci Genn.) transmitted Begomovirus (Family Geminiviridae) causing a serious disease of cotton in northern India. The very typical symptoms of present isolate (CLCuV-HS2) showed thickened veins, dark green discoloration of the leaves with upward curling and leaf like structure known as enation (one in number), which develops into cup-shaped on the reverse side of leaves. The polymerase chain reaction (PCR) based technique can detect the viral DNA in samples stored upto 3 days after the collection and have wide application for the field diagnosis. The complete nucleotide sequence of the Indian isolate of cotton leaf curl geminivirus (CLCuV-HS2) coat protein (CP) gene component was determined using CP specific primers through PCR amplification from field infected cotton plants growing in Haryana, India. Comparison of the amino acid sequence of the putative CP with some other mono and bipartite geminiviruses revealed a maximum of 97.3% identity with Pakistan cotton leaf curl virus (CLCuV-62). A nuclear localization signal located close to the N-terminal of CP gene was determined.

Amino Acid Sequence↗
PubMed1975

Content and localisation of 5-methylcytosine in DNA of healthy and wilt-infected cotton plants.

5-Methylcytosine has been found in all pyrimidine isopliths isolated from the DNA of cotton plants, but it localizes predominantly in tri- (about 52%) and dipyrimidine (about 22%) clusters. The 5-methylcytosine distribution by pyrimidine isopliths in DNA of cotton plants is specific and quite different from that in other plant and animal DNA studied. The total 5-methylcytosine content in DNA from wilt-infected cotton plants (2.3 mol %) is less than half that found in DNA from non-infected cotton plants (4.9 mol %). No other visible differences (G+C content, Tm, deltaT, s20,w, frequencies of pyrimidine clusters and others) in these DNA have been found. This suggests that in wilt-infected plants, no essential alteration in DNA sequence or molecular population takes place. As a result of wilt infection 5-methylcytosine completely disappears from dipyrimidine oligonucleotides of cotton plant DNA; its content decreases markedly in long pyrimidine clusters (heptaoligonucleotides and longer) and in C3, C2 T, CT2 fragments. Thus, DNA in wilt-infected plant cells is specifically undermethylated (demethylated). The induced alteration in DNA methylation may be considered one of the possible mechanisms for the specific distortion of gene activity of host cells and primary fungal pathogenic action on plants.

Base Sequence↗
PubMed2003

Short duration aerosols of JNJ 2408068 (R170591) administered prophylactically or therapeutically protect cotton rats from experimental respiratory syncytial virus infection.

Cotton rats exposed to continuous small droplet aerosols of 2[[2-[[1-(2-aminoethyl)-4-piperidinyl]amino]-4-methyl-1H-benzimidazol-1-yl]methyl]-6-methyl-3-pyridinol (JNJ 2408068) or its hydrochloric salt for only 15 min, one day prior to virus inoculation or one day after, were significantly protected from pulmonary respiratory syncytial virus (RSV) infection compared to control animals similarly infected but exposed to aerosols of placebo at these times. No evidence of toxicity was seen in any of these animals or in cotton rats administered 10 times the minimum cotton rat efficacious dose (i.e. 10x0.39 mg of active compound per kilogram of body weight) for four continuous days. The marked selective antiviral activity observed in the cotton rats mirrored that seen for these compounds in cytotoxicity and antiviral assays performed against RSV in vitro. Plasma kinetics and tissue distribution of JNJ 2408068 in cotton rats following inhalation were determined in separate experiments performed using conditions similar to those utilized in the in vivo efficacy studies. The data from these experiments indicated that significant levels of the test compound were delivered to the lungs of exposed animals, but that extrapulmonary distribution was limited.

Administration, Inhalation↗
PubMed2005

Toxicity to cotton boll weevil Anthonomus grandis of a trypsin inhibitor from chickpea seeds.

Cotton (Gossypium hirsutum L.) is an important agricultural commodity, which is attacked by several pests such as the cotton boll weevil Anthonomus grandis. Adult A. grandis feed on fruits and leaf petioles, reducing drastically the crop production. The predominance of boll weevil digestive serine proteinases has motivated inhibitor screenings in order to discover new ones with the capability to reduce the digestion process. The present study describes a novel proteinase inhibitor from chickpea seeds (Cicer arietinum L.) and its effects against A. grandis. This inhibitor, named CaTI, was purified by using affinity Red-Sepharose Cl-6B chromatography, followed by reversed-phase HPLC (Vydac C18-TP). SDS-PAGE and MALDI-TOF analyses, showed a unique monomeric protein with a mass of 12,877 Da. Purified CaTI showed significant inhibitory activity against larval cotton boll weevil serine proteinases (78%) and against bovine pancreatic trypsin (73%), when analyzed by fluorimetric assays. Although the molecular mass of CaTI corresponded to alpha-amylase/trypsin bifunctional inhibitors masses, no inhibitory activity against insect and mammalian alpha-amylases was observed. In order to observe CaTI in vivo effects, an inhibitor rich fraction was added to an artificial diet at different concentrations. At 1.5% (w/w), CaTI caused severe development delay, several deformities and a mortality rate of approximately 45%. These results suggested that CaTI could be useful in the production of transgenic cotton plants with enhanced resistance toward cotton boll weevil.

Agriculture↗
PubMed2004

Dissipation of alachlor in cotton plant, soil and water and its bioaccumulation in fish.

Dissipation of alachlor in soil and plant in field condition (cotton cropping system), and in soil, water and fish in simulated model ecosystem was investigated. The acetanilide herbicide, alachlor (50% w/w EC) was applied as pre-emergence at 2.5 and 5.0 kg a.i.ha(-1) three days after sowing the cotton seeds in the field. Soil and plant samples were collected at intervals and analyzed for alachlor residues. To study the fate of alachlor in water and fish, a simulated model ecosystem was constructed and fish was introduced one day after herbicide application. The dissipation of alachlor in water and soil and bioaccumulation in fish was observed in model ecosystem. At harvest, cotton lint and seed samples were found to contain alachlor well below the detectable level. However, trace amounts of residues were found in cotton oil. After harvest of cotton, coriander (Coriandrum sativum) and edible amaranth (Amaranthus mangostanus L.) were raised for herbicide bioassay. The green leafy vegetable samples did not show any toxic symptoms of alachlor residues.

Acetamides↗
PubMed2006

Molecular cloning and expression analysis of a RanBP2 zinc finger protein gene in upland cotton (Gossypium hirsutum L.).

Gossypol is an important resistant substance of Gossypium, and its storage organ is pigment gland. Although, the relationship between gossypol and pigment gland has been studied for a long time, the development mechanism of pigment gland has not been revealed up to now in molecular perspective. On the basis of differentially expressed cDNAs fragments at the stage of the cotton gland development using suppression subtractive hybridization (SSH), the complete cDNA sequence of a novel RanBP2 zinc finger protein (ZFP) gene was cloned by rapid amplification of cDNA ends (RACE) from upland cotton (Gossypium hirsutum L.), Xiangmian 18. The cotton RanBP2 ZFP cDNA (GenBank accession number: DQ173926) is 717 base pair (bp) long with an open reading frame encoding 139 amino acids, which encodes a 15.6 kDa protein. The cotton RanBP2 ZFP had three Ran-binding protein (RanBP) two zinc finger motifs and belonged to RanBP2 ZFP family. There is a 292-base non-coding sequence at 3' cDNA end, which includes polyA sequence. Sequence alignment analysis revealed that the cDNA nucleotide and its deduced amino acid sequence are moderately identical to the putative ZFP from other species. The mRNA expressing profiles of the novel ZFP gene was investigated by reverse transcription-polymerase chain reaction (RT-PCR). The result showed that it expressed at different development stages of gland, including the undeveloped stage, developing stage, developed stage and cotyledon stage. However, with the development of pigment gland, the mRNA levels in the gland-developed seed and cotyledon were increased to about 1.5 and 2 folds of that in gland-undeveloped seed, respectively, which suggested that the novel ZFP played a role in the development of the cotton gland.

Amino Acid Sequence↗
PubMed2004

Cotton leaf curl Gezira virus-satellite DNAs represent a divergent, geographically isolated Nile Basin lineage: predictive identification of a satDNA REP-binding motif.

Cotton leaf curl Gezira virus (CLCuGV), a species of the genus Begomovirus (family Geminiviridae), was recently cloned from cotton, okra, and Sida alba plants exhibiting leaf-curling and vein-thickening symptoms in Sudan. Here, we describe a previously unknown lineage of single-stranded DNA satellite (satDNA) molecules, which are associated with CLCuGV, and are required for development of characteristic disease symptoms. Co-inoculation of cotton and Nicotiana benthamiana plants with satDNAs cloned from cotton, okra, and S. alba, together with CLCuGV as the 'helper virus' resulted in the development of characteristic leaf-curling and vein-thickening symptoms in both hosts. An anatomical study of symptomatic, virus-infected cotton leaves revealed that spongy parenchyma cells had developed instead of collenchyma cells at the sites of vein thickening. Phylogenetically, the CLCuGV-associated satDNAs from Sudan, together with their closest relatives from Egypt, form a new satDNA lineage comprising only satDNAs from the Upper and Lower Nile Basins. Analysis of satellites and their helper virus sequences identified a predicted REP-binding site consisting of the directly repeated sequence, 'CGGTACTCA', and an inverted repeated sequence, 'TGAGTACCG', which occur in the context of a 17-nucleotide motif. The conserved REP-binding motif identified herein, together with strict geographic isolation, and apparent host-restriction, may be the collective hallmark of these new satDNA-begomovirus lineages, extant in the Nile Basin.

Binding Sites↗
PubMed2002

Bollworm responses to release of genetically modified Helicoverpa armigera nucleopolyhedroviruses in cotton.

Helicoverpa armigera single nucleocapsid nucleopolyhedrovirus (HaSNPV) has been developed as a commercial biopesticide to control the cotton bollworm, H. armigera, in China. The major limitation to a broader application of this virus has been the relative long time to incapacitate the target insect. Two HaSNPV recombinants with improved insecticidal properties were released in bollworm-infested cotton. One recombinant (HaCXW1) lacked the ecdysteroid UDP-glucosyltransferase (egt) gene and in another recombinant (HaCXW2), an insect-selective scorpion toxin (AaIT) gene replaced the egt gene. In a cotton field situation H. armigera larvae treated with either HaCXW1 or HaCXW2 were killed faster than larvae in HaSNPV-wt treated plots. Second instar H. armigera larvae, which were collected from HaCXW1 and HaCXW2 treated plots and further reared on artificial diet, showed reduced ST(50) values of 15.3 and 26.3%, respectively, as compared to larvae collected from HaSNPV-wt treated plots. The reduction in consumed leaf area of field collected larvae infected with HaCXW1 and HaCXW2 was approximated 50 and 63%, respectively, as compared to HaSNPV-wt infected larvae at 108 h after treatment. These results suggest that in a cotton field situation the recombinants will be more effective control agents of the cotton bollworm than wild-type HaSNPV.

Animals↗
PubMed2003

Reduced levels of cadinane sesquiterpenoids in cotton plants expressing antisense (+)-delta-cadinene synthase.

Cotton plants were transformed with an antisense construct of cdn1-Cl, a member of a complex gene family of delta-(+)cadinene (CDN) synthase. This synthase catalyzes the cyclization of (E,E)-farnesyl diphosphate to form CDN, and in cotton, it occupies the committed step in the biosynthesis of cadinane sesquiterpenoids and heliocides (sesterterpenoids). Southern analyses of the digestion of leaf DNA from R(o), T(o), and T(1) plants with Hind III, Pst I and Kpn I restriction enzymes show the integration of antisense cdn1-C1 cDNA driven by the CaMV 35S promoter into the cotton genome. Northern blots demonstrate the appearance of cdn synthase mRNA preceding CDN synthase activity and the formation of gossypol in developing cottonseed. T(2) cottonseed show a reduced CDN synthase activity and up to a 70% reduction in gossypol. In T(1) leaves the accumulated amounts of gossypol, hemigossypolone and heliocides are reduced 92.4, 83.3 and 68.4%, respectively. These data demonstrate that the integration of antisense cdn1-C1 cDNA into the cotton genome leads to a reduction of CDN synthase activity and negatively impacts on the biosynthesis of cadinane sesquiterpenoids and heliocides in cotton plants.

Blotting, Southern↗
PubMed2006

[Cotton-wool spots as first ocular manifestation of giant cell arteritis].

INTRODUCTION: Giant cell arteritis is the most common vasculitis in the elderly. Visual loss is established as the most dreaded and irreversible complication of the disease, which makes giant cell arteritis an ophthalmic emergency. It is important to recognize its various ocular manifestations; isolated cotton wool spots are one of them. CASE REPORT: We describe a patient with constitutional symptoms and mild visual loss who was found to have giant cell arteritis. The ophthalmic examination was significant for only isolated cotton-wool spots. A delay in arm-to-retina circulation time was demonstrated by fluorescein angiography. Prompt treatment with corticosteroids led to preservation of vision and uneventful resolution of the cotton-wool spots. DISCUSSION: Common ophthalmologic presentations include anterior ischemic optic neuropathy or choroidal ischemia when short posterior ciliary arteries are involved, and central retinal artery occlusion. Retinal ischemia has also been recognized as a possible manifestation. Because the disease concerns medium-size and larger arteries, it cannot involve terminal retinal arterioles to produce cotton-wool spots. These are probably caused by platelet microembolization from the partially thrombosed regional arteries. CONCLUSION: Isolated cotton-wool spots can be an early ophthalmoscopic finding in giant cell arteritis and precede severe irreversible visual loss. Their detection is essential because it allows the ophthalmologist to establish a prompt treatment and preserve vision.

Diagnosis, Differential↗
PubMed2003

Social and health determinants of the efficiency of cotton farmers in Northern Côte d'Ivoire.

This article assesses the role of malaria and some social determinants on the agricultural development and more precisely on efficiency in the context of cotton crop in the Korhogo region in the North of Côte d'Ivoire. Data envelopment analyses (DEA) was first applied for the purpose of calculating relative efficiencies in production. A Tobit regression model was then used to explain the variation in the DEA scores and check the hypotheses that the efficiency deviations between farmers can be explained by the disparity of malaria morbidity rate among the farmers and their family, by social cohesiveness and cultural behaviour. Field data were collected by the authors between March 1997 and February 1998 on 700 rural households living in three rice production systems differently exposed to the malaria risk. Two malaria indicators were used for the active (11-55 years old) family members of the farm: Plasmodium falciparum infection rate and high parasite density infection rate. The DEA model was applied on the sub-sample of cotton growers (about one third of the households of the full sample). Results of the different DEA and Tobit models (depending of the production process hypothesis) show that high parasite density infection has a direct and indirect negative effect on efficiency in the cotton crop. They also show that more cotton growers in the village improve efficiency, although villages where cotton is growing more widespread have weaker social cohesion.

Agriculture↗
PubMed2002

Tolerance and accumulation of shikimic acid in response to glyphosate applications in glyphosate-resistant and nonglyphosate-resistant cotton (Gossypium hirsutum L.).

Measurement of shikimic acid accumulation in response to glyphosate inhibition of 5-enolpyruvylshikimate-3-phosphate synthase is a rapid and accurate assay to quantify glyphosate-induced damage in sensitive plants. Two methods of assaying shikimic acid, a spectrophotometric and a high-performance liquid chromatography (HPLC) method, were compared for their accuracy of recovering known amounts of shikimic acid spiked into plant samples. The HPLC method recovered essentially 100% of shikimic acid as compared with only 73% using the spectrophotometric method. Relative sensitivity to glyphosate was measured in glyphosate-resistant (GR) and non-GR cotton leaves, fruiting branches, and squares (floral buds) by assaying shikimic acid. Accumulation of shikimic acid was not observed in any tissue, either GR or non-GR, at rates of 5 mM glyphosate or less applied to leaves. All tissues of non-GR plants accumulated shikimic acid in response to glyphosate treatment; however, only fruiting branches and squares of GR plants accumulated a slight amount of shikimic acid. In non-GR cotton, fruiting branches and squares accumulated 18 and 11 times, respectively, more shikimic acid per micromolar of translocated glyphosate than leaf tissue, suggesting increased sensitivity to glyphosate of reproductive tissue over vegetative tissue. GR cotton leaves treated with 80 mM of glyphosate accumulated 57 times less shikimic acid per micromolar of translocated glyphosate than non-GR cotton but only 12.4- and 4-fold less in fruiting branches and squares, respectively. The increased sensitivity of reproductive structures to glyphosate inhibition may be due to a higher demand for shikimate pathway products and may provide an explanation for reports of fruit abortion from glyphosate-treated GR cotton.

3-Phosphoshikimate 1-Carboxyvinyltransferase↗
PubMed2006

A real-time quantitative PCR detection method specific to widestrike transgenic cotton (event 281-24-236/3006-210-23).

In compliance with global regulations on transgenic crops, a real-time quantitative PCR method specific to Widestrike transgenic cotton (event 281-24-236/3006-210-23, OECD Unique Identifier DAS-24236-5/DAS-21023-5) was established on the basis of the DNA sequences in the junction between the transgene insert and cotton genome. The optimized method consists of a DNA extraction method for cotton seeds and three PCR systems corresponding to a cotton-specific endogenous reference DNA sequence SAH7 (Sinapis Arabidopsis Homolog 7) and specific detection of event 281-24-236 and event 3006-210-23. The method performance including specificity, sensitivity, accuracy, and precision was determined at a dynamic range of Widestrike DNA levels from 0.04% to 5.0%. The limits of detection (LOD) and quantification (LOQ) were < or =0.04% and < or =0.09%, respectively, at 100 ng of DNA sample per reaction. The quantification results using either the event 281-24-236 or 3006-210-23 system were consistent, and the relative deviation from the expected (true) value was in the range of +/-25%. The robustness of the method was demonstrated by a series of tests with deviations from the optimized assay parameters such as annealing temperature, extension time, PCR instrument, interlaboratory transferability, etc. All the measurements from these tests met the criteria set by EU JRC-CRL (European Commission Joint Research Centre-Community Reference Lab). This real-time quantitative PCR method is accurate and robust, and is recommended as a global benchmark method for the detection and quantification of Widestrike cotton. The method including description, protocol, and performance results is available on the JRC-CRL website (http://gmo-crl.jrc.it/statusofdoss.htm).

DNA, Plant↗
PubMed2002

Effects of water deficit stress, shade, weed competition, and kaolin particle film on selected foliar free amino acid accumulations in cotton, Gossypium hirsutum (L.).

Leaves of cotton plants, Gossypium hirsutum L., stressed by water deficit, reduced daylight, and weed competition, or treated with a kaolin wettable powder formulation were analyzed for levels of 17 free amino acids (FAAs) using reversed-phase high-performance liquid chromatography. Water deficit stress resulted in heightened free proline levels (49.9-fold, P < 0.001) that were correlated with diffusive resistance (seconds per centimeter). Five other FAAs increased, and the amounts of total free essential (for insect growth and development) amino acids and total FAAs also increased (P < or = 0.05). Cotton grown in 50% shade accumulated significantly more free arginine than control plants. In a small-plot weed competition assay, four FAAs increased and three FAAs decreased in association with weed competition, but because free proline levels were not altered and free arginine levels increased, other stresses aside from water deficit, possibly including shading by tall weeds, appear to have caused the changes. In a small-plot kaolin particle film assay, five FAAs were lower in cotton foliage sprayed weekly with kaolin. Because free proline was unaffected and free arginine was lower, it is possible that kaolin's reflectivity heightened light reception. The responses of free proline and arginine to the treatments used in these assays demonstrate that types and degrees of some stresses to cotton can be characterized by accumulations of certain FAAs. The study also demonstrates how some FAA levels can indicate degrees of cotton stress resulting from weed competition and from kaolin particle film application. Porometry and leaf water potential measurements assisted in corroborating some findings of the study.

Adaptation, Physiological↗
PubMed2004

Effects of nematicides on cotton root mycobiota.

Baseline information on the diversity and population densities of fungi collected from soil debris and cotton (Gossypium hirsutum L.) roots was determined. Samples were collected from Tifton, GA, and Starkville, MS containing cotton field soil treated with the nematicides 1,3-dichloroproprene (fumigant) and aldicarb (granules). A total of 10,550 and 13,450 fungal isolates were collected from these two study sites, respectively. Of this total, 34 genera of plant pathogenic or saprophytic species were identified. Pathogenic root fungi included Fusarium spp. (40% of all isolations), Macrophomina, Pythium, Rhizoctonia, and Sclerotium. Fusarium and Rhizoctonia were the most common fungal species identified and included F. oxysporum, F. verticillioides and F. solani, the three Fusarium species pathogenic on cotton plants. Population densities of Fusarium were not significantly different among locations or tissue types sampled. Macrophomina was isolated at greater numbers near the end of the growing seasons. Anastomosis groups of R. solani isolated from roots and soil debris included AG-3, -4, -7, 2-2, and -13 and anastomosis groups of binucleate Rhizoctonia included CAG-2, -3, and -5. Occurrences and frequency of isolations among sampling dates were not consistent. Fluctuations in the frequency of isolation of Rhizoctonia did not correspond with changes in frequency of isolation of the biological control fungus, Trichoderma. When individual or pooled frequencies of the mycobiota were compared to nematicide treatments, no specific trends occurred between treatments, application methods or rates. Results from this study show that use of 1,3-D and aldicarb in cotton fields does not significantly impact plant pathogenic fungi or saprophytic fungal populations. Thus cotton producers need not adjust seedling disease control measures when these two nematicides are used.

Aldicarb↗