Search

The use of 1,1-dimethyl-piperidinium chloride (DPC) in Xinjiang is one of the necessary measures for regulating cotton populations and optimizing canopy structure. However, mechanical spraying involves operation and energy consumption, which can alternatively be achieved via drip application. In the present study, to investigate the effect of drip application, two types of hydrophobic nano-released DPCs were used to regulate plant type at different dosages. DPC dripingation reduced plant height by more than 10 cm and plant width by more than 4 cm, and the effect improved with increasing concentration and times. The main effect of height control was at the 6th–10th nodes of the main stem, and the effect of width control was observed at the 1st and 2nd nodes of the fruit branch. The SPAD value was higher than that in the control group during the initial stages. An irregular downward trend was observed in the subsequent stages. The proline content was higher than that of the control and increased with higher concentrations of DPC. There was no significant difference in the soil DPC content at the different sites. The DPC content decreased by more than 30% at the seventh day after dripping, and the content was 2–4 μg·g−1 in each treatment. At 15 days after application, the soil DPC was lower than 1 μg·g−1 in all treatments. The number of harvested plants was more than 150,000 plants·hm−2, and the number of bolls per plant increased at least by one, compared with the control. The final yield of seed cotton increased by at least 300 kg·hm−2, with a maximum increase of 1672.01 kg·hm−2. Considering the different types of DPCs, nano-released types worked better than the conventional type in terms of plant height, plant width, degradation in soil and boll formation. Nano-released DPC can play an even better role than conventional DPC in chemical regulation with drip irrigation. [ABSTRACT FROM AUTHOR]

Potassium deficiency causes severe losses in yield and quality in crops. Mepiquat chloride, a plant growth regulator, can increase K+ uptake in cotton (Gossypium hirsutum), but the underlying physiological mechanisms remain unclear. In this study, we used a non-invasive micro-test technique to measure K+ and H+ fluxes in the root apex with or without inhibitors of K+ channels, K+ transporters, non-selective cation channels, and plasma membrane H+-ATPases. We found that soaking seeds in mepiquat chloride solution increased the K+ influx mediated by K+ channels and reduced the K+ efflux mediated by non-selective cation channels in cotton seedlings. Mepiquat chloride also increased negative membrane potential (E m) and the activity of plasma membrane H+-ATPases in roots, due to higher levels of gene expression and protein accumulation of plasma membrane H+-ATPases as well as phosphorylation of H+-ATPase 11 (GhAHA11). Thus, plasma membrane hyperpolarization mediated by H+-ATPases was able to stimulate the activity of K+ channels in roots treated with mepiquat chloride. In addition, reduced K+ efflux under mepiquat chloride treatment was associated with reduced accumulation of H2O2 in roots. Our results provide important insights into the mechanisms of mepiquat chloride-induced K+ uptake in cotton and hence have the potential to help in improving K nutrition for enhancing cotton production. [ABSTRACT FROM AUTHOR]

Drought is a key limiting factor for cotton ( Gossypium spp.) production, as more than half of the global cotton supply is grown in regions with high water shortage. However, the underlying mechanism of the response of cotton to drought stress remains elusive., By combining genome-wide transcriptome profiling and a loss-of-function screen using virus-induced gene silencing, we identified Gossypium hirsutum Gh WRKY59 as an important transcription factor that regulates the drought stress response in cotton., Biochemical and genetic analyses revealed a drought stress-activated mitogen-activated protein ( MAP) kinase cascade consisting of Gh MAP3K15-Mitogen-activated Protein Kinase Kinase 4 (GhMKK4)-Mitogen-activated Protein Kinase 6 (GhMPK6) that directly phosphorylates Gh WRKY59 at residue serine 221. Interestingly, Gh WRKY59 is required for dehydration-induced expression of Gh MAPK3K15, constituting a positive feedback loop of Gh WRKY59-regulated MAP kinase activation in response to drought stress. Moreover, Gh WRKY59 directly binds to the W-boxes of DEHYDRATION-RESPONSIVE ELEMENT-BINDING PROTEIN 2 ( Gh DREB2), which encodes a dehydration-inducible transcription factor regulating the plant hormone abscisic acid ( ABA)-independent drought response., Our study identified a complete MAP kinase cascade that phosphorylates and activates a key WRKY transcription factor, and elucidated a regulatory module, consisting of Gh MAP3K15-Gh MKK4-Gh MPK6-Gh WRKY59 -Gh DREB2, that is involved in controlling the cotton drought response. [ABSTRACT FROM AUTHOR]

The effects of nitrogen (N) forms (ammonium- or nitrate-N) on plant growth under salinity stress [150 mmol sodium chloride (NaCl)] were studied in hydroponically cultured cotton. Net fluxes of sodium (Na+), ammonium (NH4+), and nitrate (NO3−) were also determined using the Non-Invasive Micro-Test Technology. Plant growth was impaired under salinity stress, but nitrate-fed plants were less sensitive to salinity than ammonium-fed plants due mainly to superior root growth by the nitrate-fed plants. The root length, root surface area, root volume, and root viability of seedlings treated with NO3-N were greater than those treated with NH4-N with or without salinity stress. Under salinity stress, the Na+content of seedlings treated with NO3-N was lower than that in seedlings treated with NH4-N owing to higher root Na+efflux. A lower net NO3−efflux was observed in roots of nitrate-fed plants relative to the net NH4+efflux from roots of ammonium-fed plants. This resulted in much more nitrogen accumulation in different tissues, especially in leaves, thereby enhancing photosynthesis in nitrate-fed plants under salinity stress. Nitrate-N is superior to ammonium-N based on nitrogen uptake and cotton growth under salinity stress. [ABSTRACT FROM PUBLISHER]

Defoliants can increase machine harvest efficiency of cotton (Gossypium hirusutum L.), prevent lodging and reduce the time from defoliation to harvest. Coronatine (COR) is a chlorosis-inducing non-host-specific phytotoxin that induces leaf and/or fruit abscission in some crops. The present study investigates how COR might induce cotton leaf abscission by modulating genes involved in cell wall hydrolases and ACC (ethylene precursor) in various cotton tissues. The effects of COR on cotton boll ripening, seedcotton yield, and seed development were also studied. After 14 d of treatment with COR, cells within the leaf abscission zone (AZ) showed marked differentiation. Elevated transcripts of GhCEL1, GhPG and GhACS were observed in the AZs treated with COR and Thidiazuron (TDZ). The relative expression of GhCEL1 and GhACS in TDZ treated plants was approximately twice that in plants treated with COR for 12 h. However, only GhACS expression increased in leaf blade and petiole. There was a continuous increase in the activity of hydrolytic enzymes such as cellulase (CEL) and polygalacturonase (PG), and ACC accumulation in AZs following COR and TDZ treatments, but there was greater increase in ACC activity of COR treated boll crust, indicating that COR had greater ripening effect than TDZ. Coronatine significantly enhanced boll opening without affecting boll weight, lint percentage and seed quality. Therefore, COR can be a potential cotton defoliant with different physiological mechanism of action from the currently used TDZ. [ABSTRACT FROM AUTHOR]

Genotypic differences in potassium (K) uptake and utilization were compared for eight cotton cultivars in growth chamber and field experiments. Four of the cultivars ('SGK3', 'SCRC18', 'SCRC21' and 'SCRC22') typically produce lower dry mass and the other four ('Nannong8', 'Xiangza2', 'Xinluzao12' and 'Xiangza3') produce greater dry mass in K-deficient solution (0.02 mM). The mean dry weight of seedlings (five-leaf stage) of cultivars with greater biomass was 155% higher than that of cultivars with lower biomass yield under K deficiency. However, all the genotypes had similar dry matter yields in K-sufficient solution (2.5 mM). Thus, the four cultivars with superior biomass yield under low K medium may be described as K efficient cultivars while the inferior cultivars may be described as K inefficient. Although seeds of the studied cultivars originated from different research institutes or seed companies, there were little differences in seed K content among them, irrespective of their K efficiency. Consequently, there were no significant differences in K accumulation in seedlings (4 d after germination in a K-free sand medium) just before transferring to nutrient solutions. However, the K efficient genotypes, on average, accumulated twice as much K at 21 d after transferring to K-deficient solution (0.02 mM). A much larger root system as well as a slightly higher uptake rate (K uptake per unit of root dry weight) may have contributed to the higher net K uptake by the K efficient cultivars. In addition, the K efficiency ratio (dry mass produced per unit of K accumulated) and K utilization efficiency (dry mass produced per unit of K concentration) of the K efficient cultivars exceeded those of the K inefficient genotypes by 29% and 234%, respectively, under K deficiency. On average, the K efficient cultivars produced 59% more potential economic yield (dry weight of all reproductive organs) under field conditions even with available soil K at obviously deficient level (60 mg kg-1). We noted especially that the four K inefficient cultivars studied were all transgenic insect-resistant cotton, suggesting that the introduction of foreign genes (Bt and CpTI) may affect the K use efficiency of cotton. [ABSTRACT FROM AUTHOR]

Bacillus thuringensis (Bt) transgenic (insect-resistant) cotton cultivars senesce prematurely under potassium (K+) deficiency, more often than conventional cultivars, in the North China Plain. To verify if Bt-transgenic cotton was more susceptible to K+ deficit, two transgenic cultivars, 'CCRI 41' and 'DP 99B', and two conventional cultivars, 'CCRI 35' and 'CCRI 36', selected from widely used cultivars in China, were used in a seedling hydroponic study. The culture solution K+ concentration was 0.5 mM for high K+ and 0.02 mM for low K+ conditions. Seedlings of all four cultivars accumulated more dry matter and K+ when grown at high K+ than low K+ conditions. However, under low K+ condition, the dry weight and K+ content of Bt-transgenic cultivars CCRI 41 and DP 99B were lower than those of the conventional cultivars CCRI 36 and CCRI 35. The results indicated that Bt-transgenic cultivars CCRI 41 and DP 99B were more sensitive to K+ deficiency than conventional cultivars CCRI 36 and CCRI 35, which could be the reason for premature senescence symptoms observed from fields of Bt-transgenic cotton under K+ deficiency. Seedlings of all four cultivars had a higher K+ use efficiency (KUE) under low K+ than high K+ conditions, but the KUE did not account for the differential responses between Bt-transgenic and conventional cultivars at the low K+ concentration. The K+ depletion results did not reveal the mechanism for the above differential responses in Vmax and Km of the seedlings either. Further experiments with more cultivars are needed to clarify the differential mechanisms in these genotypes. [ABSTRACT FROM AUTHOR]

Coronatine, an analog of Jasmonic acid (JA), has been shown to enhance crop tolerance to abiotic stresses, including chilling stress. However, the underlying molecular mechanism remains largely unknown. In this study, we investigated the effect of Coronatine on cotton seedlings under low temperature using transcriptomic and metabolomics analysis. Twelve cDNA libraries from cotton seedlings were constructed, and pairwise comparisons revealed a total of 48,322 differentially expressed genes (DEGs). Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis identified the involvement of these unigenes in various metabolic pathways, including Starch and sucrose metabolism, Sesquiterpenoid and triterpenoid biosynthesis, Phenylpropanoid biosynthesis, alpha-Linolenic acid metabolism, ABC transporters, and Plant hormone signal transduction. Additionally, substantial accumulations of jasmonates (JAs), abscisic acid and major cell wall metabolites were observed. Transcriptome analysis revealed differential expression of regulatory genes, and qRT-PCR analysis confirmed the expression patterns of 9 selected genes. Co-expression analysis showed that the JA-responsive genes might form a network module with ABA biosynthesis genes or cell wall biosynthesis genes, suggesting the existence of a COR-JA-cellulose and COR-JA-ABA-cellulose regulatory pathway in cotton seedlings. Collectively, our findings uncover new insights into the molecular basis of coronatine--associated cold tolerance in cotton seedlings. • Coronatine can alleviate the damage caused by low temperature to cotton. • Coronatine promote JAs, abscisic acid (ABA), and cell wall metabolites accumulations. • Coronatine may affects JA-cellulose or JA-ABA-cellulose regulatory pathways. [ABSTRACT FROM AUTHOR]

Highlights: [•] The application of plant growth regulators (PGRs) increased the lint yield and potassium (K) uptake in field-grown cotton. [•] PGRs improved the partial factor productivity, agronomic efficiency and apparent recovery efficiency of K fertilizer. [•] PGRs increased the ratio of K in N:P:K in cotton lint. [ABSTRACT FROM AUTHOR]

Abstract: A hydroponic culture experiment was conducted to determine genotypic variation in photosynthetic rate and the associated physiological changes in response to potassium (K) deficiency in cotton (Gossypium hirsutum L.) seedlings with contrasting two cotton cultivars in K efficiency. The K-efficient Liaomian18 produced 66.7% more biomass than the K-inefficient NuCOTN99B under K deficiency, despite their similar biomass under K sufficiency. Compared with NuCOTN99B, Liaomian18 showed 19.4% higher net photosynthetic rate (P n, per unit leaf area) under K deficient solutions and this was associated with higher photochemical efficiency and faster export of soluble sugars from the phloem. The lower net P n of NuCOTN99B was attributed to higher capacity for nitrate assimilation and lower export of soluble sugars. Furthermore, NuCOTN99B showed 38.4% greater ETR/P n than Liaomian18 under K deficiency, indicating that more electrons were driven to other sinks. Higher superoxide dismutase (SOD) and lower catalase (CAT) and ascorbate peroxidase (APX) activities resulted in higher levels of reactive oxygen species (ROS; e.g. O2 −and H2O2) in NuCOTN99B relative to Liaomian18. Thus, the K inefficiency of NuCOTN99B, indicated by lower biomass and net P n under K deficiency, was associated with excessively high nitrogen assimilation, lower export of carbon assimilates, and greater ROS accumulation in the leaf. [Copyright &y& Elsevier]

Abstract: The objective of this study was to determine the roles of shoot and root in the regulation of premature leaf senescence induced by potassium (K) deficiency in cotton (Gossypium hirsutum L.). Two contrasting cultivars (CCRI41, more sensitive to K deficiency; and SCRC22, a less sensitive cultivar) were selected for self- and reciprocal-grafting, using standard grafting (one scion/one rootstock), Y grafting (two scions/one rootstock) and inverted Y grafting (one scion/two rootstocks) at the seedling stage. Standard grafting was studied in the field in 2007 and 2008. There were no obvious differences in senescence between CCRI41 and SCRC22 scions while supplied with sufficient K. However, SCRC22 scions showed significantly greater K content, SPAD values (chlorophyll content), soluble protein content and net photosynthetic rates than CCRI41 scions while grown in K deficient solution or soil, regardless of rootstock cultivars, grafting types, growth stage and growth conditions. Also, SCRC22 scions had greater yield and less variation in boll weight either between upper- and lower sympodials, or between proximal and distal fruit positions from the main stem in the field under K deficiency, probably owing to reduced leaf senescence. Although the effect of rootstocks on leaf senescence under K deficiency was significant in some cases, the scion cultivars explained the highest percentage of variations within grafting treatments. The shoot-to-root feedback signal(s), rather than high shoot demand for K nutrition, was involved in the shoot regulation of premature senescence in cotton plants, achieved possibly by altering root K uptake. [Copyright &y& Elsevier]