Hasil untuk "Botany"

Juncai Wang, Shengyang Xiao, Chao Ma et al.

Cadmium (Cd) contamination in agricultural soils poses a serious threat to food security and human health. Nitric oxide (NO), as redox-related signaling molecule, is known to promote plant growth and regulate soil quality in heavy metal-contamination soils. However, the regulatory mechanisms of NO in plant physiology and soil biochemistry have not been well-demonstrated. In this study, we investigated the role of exogenous application of sodium nitroprusside (SNP) as an NO donor additive on the growth performances, Cd accumulation and translocation, physiological biochemical response of plant, soil physicochemical properties, and soil microbial communities of hyperaccumulator Solanum nigrum L. in Cd-contaminated soil. Our results showed that 100 and 200 μmol·L−1 NO addition markedly increased the plant biomass by 16.22 % and 14.85 %, and enhanced the Cd accumulation by 46.91 % and 22.08 % in S. nigrum compared to the 100 mg·kg−1 Cd treatment alone, respectively. Moreover, NO supply could mitigate Cd phytotoxicity and oxidative damage by significantly increasing the activities of antioxidant enzymes and osmoregulatory substances content. In addition, NO addition significantly changes the soil physicochemical properties, including changed the SOC, CEC, the NH4+-N and NO3−-N contents, increased the content of soil microbial biomass carbon (MBC), microbial biomass nitrogen (MBN) and soil enzymatic activities, such as the 100 μmol·L−1 NO treatment increased 4.71 %, 7.45 %, 18.44 % and 29.46 % of the soil pH, EC, the content of NO3−-N and NH4+-N as compared to Cd stress alone under 50 mg·kg−1 Cd concentrations, respectively. Meanwhile, in Cd alone treatment, the soil bacterial diversity indexes were slightly increased, while the fungal diversity slightly decreased at low Cd concentrations and increased at high Cd level compared with no Cd addition groups. After NO addition, the soil bacterial and fungal diversity was enhanced compared to without NO addition. Exogenous NO treatment also significantly changed the structures of soil bacterial and fungal communities, and increased the relative abundance of soil beneficial microbial communities. Furthermore, interactions among soil environmental factors and NO addition significantly influenced dominant bacterial, and fungal taxa. These results provide proof that soil remediation with exogenous NO addition may be an effective method to improve soil microenvironment and enhance plant tolerance to metal stress.

Mei Guo, Yueming Tang, Yiwen Yang et al.

Mechanical injury to lettuce often leads to enzymatic browning caused by polyphenol oxidase (PPO), significantly impairing its sensory quality and processing suitability. In this study, the <i>LsPPOs</i> gene family was comprehensively identified and characterized using bioinformatics methods, including gene and protein structure, codon usage bias, phylogenetic relationships, and gene expression in response to wound stress. Further analysis of the relationship between <i>LsPPOs</i> expression profile and browning was performed. A total of 17 <i>LsPPO</i> family members (<i>LsPPO1-LsPPO17</i>) were identified from publicly available lettuce databases, encoding proteins ranging from 146 to 667 amino acids, with a G/C bias. Most were localized in the chloroplast. The motif structure was highly conserved among family members, and phylogenetic analysis revealed four distinct groups. All genes lacked introns, except <i>LsPPO2</i> which contained an intron. After mechanical injury, browning at the stem site deepened over time, with PPO activity increasing. The majority of <i>PPO</i> members were significantly upregulated after fresh-cut processing. Among them, <i>LsPPO3</i>, <i>LsPPO4</i>, and <i>LsPPO12</i> showed sustained upregulation, exhibiting a strong positive correlation with the browning phenotype and PPO activity. Notably, <i>LsPPO4</i> demonstrated the highest transcriptional abundance and upregulation in response to a wound, indicating its major role in lettuce stem browning. The results of this study provide a foundation for further investigation into the functional role of <i>LsPPOs</i> and support the development of lettuce varieties with enhanced resistance to browning.

Matheus Massariol Suela, Camila Ferreira Azevedo, Ana Carolina Campana Nascimento et al.

Understanding trait relationships is fundamental in soybean breeding because the goal is to maximize simultaneous gains. Standard multi-trait genome-wide association studies (MT-GWAS) identify variants linked to multiple traits but fail to capture phenotypic structures or interrelations. Structural Equation Models (SEM) account for covariances and recursion, enabling the decomposition of single nucleotide polymorphism (SNP) effects into direct or indirect components and identifying pleiotropic regions. We applied SEM to analyze morphology (pod thickness, PT) and yield traits (number of pods, NP; number of grains, NG; hundred-grain weight, HGW). The dataset comprised 96 soybean individuals genotyped with 4070 SNP markers. The phenotypic network was constructed using the hill-climbing algorithm, a class of score-based methods commonly applied to learn the structure of Bayesian networks, and structural coefficients were estimated with SEM. According to coefficient signs, we identified negative interrelationships between NG and HGW, and positive ones between NP and NG, and HGW and PT. NG, HGW, and PT showed indirect SNP effects. We also found loci jointly controlling traits. In total, 46 candidate genes were identified: 7 associated exclusively with NP and 4 associated with NG. An additional 15 genes were common to NP and NG, 3 were common to NP and HGW, 6 were common to NG and HGW, and 11 were common to NP, NG, and HGW. In summary, SEM-GWAS revealed novel relationships among soybean traits, including PT, supporting breeding programs.

Lili Cui, Yu Song, Yongchao Zhao et al.

Abstract Background Rice is the main food crop for much of the population in China. Therefore, selecting and breeding new disease resistance and drought tolerance in rice is essential to ensure national food security. The utilization of heterosis has significantly enhanced rice productivity, yet many of the molecular mechanisms underlying this phenomenon remain largely unexplored. ‘Nei 6 You 7075’ (‘N6Y7075’) is a novel hybrid rice cultivar with exceptional quality, developed through the crossbreeding of ‘Fuhui 7075’ (‘FH7075’) and ‘Neixiang 6 A’ (‘NX6A’). However, the precise mechanisms underlying the disease resistance and drought tolerance in ‘N6Y7075’ are poorly understood. In this study, we investigated the resistance of hybrid rice ‘N6Y7075’ to bacterial blight (Xanthomonas oryzae pv. oryzae), rice blast (Magnaporthe oryzae), and drought and identified differentially expressed genes between hybrid rice ‘N6Y7075’ and its parents through RNA-seq analysis. Results Our research found that the hybrid ‘N6Y7075’ and its female parent ‘NX6A’ were less susceptible to bacterial blight and rice blast than the male parent ‘FH7075’, while ‘FH7075’ showed better drought tolerance than ‘NX6A’. The hybrid ‘N6Y7075’ exhibited heterosis. Clustering results revealed that the expression profiles of the F1 hybrid closely resembled those of its parental lines rather than exhibiting an intermediate profile between the two parental lines. The disease resistance of hybrid rice ‘N6Y7075’ may be attributed to the plant-pathogen interaction pathways involving Xa21, CDPK, and RPM1-mediated hypersensitive response and WRKY1-induced defense-related gene expression and programmed cell death. The MAPK signaling pathway PR1 could also be associated with plant defense responses. Hybrid rice ‘N6Y7075’ may enhance drought tolerance by regulating MAPKKK17 and WAK60 in the MAPK signaling pathway. These proteins affect ABA stress adaptation and stomatal development in plants, respectively. Conclusions Our results provide a preliminary exploration of ‘N6Y7075’ disease resistance and drought tolerance and provide a relevant theoretical basis for its further study and use. This study provides insights into the molecular mechanisms of heterosis in hybrid rice and identifies potential associated genes.

Katarzyna Sykłowska-Baranek, Małgorzata Gaweł, Łukasz Kuźma et al.

The in vitro cultures of <i>Rindera graeca</i>, a rare endemic plant, were developed as a sustainable source of phenolic acids. Various shoot and root cultures were established and scaled up in a sprinkle bioreactor. A multiplication rate of 7.2 shoots per explant was achieved. HPLC–PDA–ESI–HRMS analysis revealed the presence of rosmarinic acid (RA) and lithospermic acid B (LAB) as the main secondary metabolites in both the shoot and root cultures. The maximum RA (30.0 ± 3.2 mg/g DW) and LAB (49.3 ± 15.5 mg/g DW) yields were determined in root-regenerated shoots. The strongest free radical scavenging activity (87.4 ± 1.1%), according to 2,2-diphenyl-1-picrylhydrazyl-hydrate assay, was noted for roots cultivated in a DCR medium. The highest reducing power (2.3 µM ± 0.4 TE/g DW), determined by the ferric-reducing antioxidant power assay, was noted for shoots cultivated on an SH medium containing 0.5 mg/L 6-benzylaminopurine. A genetic analysis performed using random amplified polymorphic DNA and start codon targeted markers revealed genetic variation of 62.8% to 96.5% among the investigated shoots and roots. This variability reflects the capacity of cultivated shoots and roots to produce phenolic compounds.

Yu Wu, Yu Wu, Wen Hui Huang et al.

IntroductionTilia miqueliana is an endemic species whose population is declining. The permeability barrier and mechanical constraint of the pericarp (seed coat) are important causes of its seed dormancy. Although there has been considerable research on this subject, questions remain regarding how the permeability barrier and mechanical constraint of the seed coat are eliminated during dormancy release and how water enters the seed. Therefore, protecting the species by improving its germination/dormancy breaking in the laboratory is urgentMethodsIn this study, the changes in the cellular structure, mechanical properties, and components of the Tilia miqueliana seed coat after an H2SO4-gibberellic acid (GA3) treatment were analyzed during dormancy release. Various analyses (e.g., magnetic resonance imaging, scanning electron microscopy, and paraffin section detection) revealed the water gap and water channel.ResultsThe H2SO4 treatment eliminated the blockage at the micropyle and hilum of the seeds. Water entered the seeds through the water gap (micropyle) rather than through the hilum or seed coat, after which it dispersed along the radicle, hypocotyl, and cotyledon to the endosperm. During the cold stratification period, the cellular structure was damaged and an increasing number of holes appeared on the inner and outer surfaces of the seed coat. Vickers hardness tests showed that GA3 decreased the seed coat hardness. Additionally, the seed coat lignin and total phenol contents continuously decreased during the cold stratification period. Notably, the Liquid chromatography–mass spectrometry (LC–MS) analysis of the seed coat detected polyethylene glycol (osmoregulator), which may have destabilized the water potential balance inside and outside the seed and increased the water content to levels required for germination, ultimately accelerating seed dormancy release.DiscussionThis sophisticated and multi-level study reveals how H2SO4 and GA3 eliminate the permeability barrier and mechanical constraints of the seed coat during dormancy release of Tilia miqueliana seeds. This will be beneficial to artificially assist the natural regeneration and population expansion of Tilia miqueliana.

Hyun-Su Park, Chang-Min Lee, Man-Kee Baek et al.

Grain shape is one of the key factors deciding the yield product and the market value as appearance quality in rice (<i>Oryza sativa</i> L.). The grain shape of <i>japonica</i> cultivars in Korea is quite monotonous because the selection pressure of rice breeding programs works in consideration of consumer preference. In this study, we identified QTLs associated with grain shape to improve the variety of grain shapes in Korean cultivars. QTL analysis revealed that eight QTLs related to five tested traits were detected on chromosomes 2, 5, and 10. Among them, three QTLs—<i>qGL2</i> (33.9% of PEV for grain length), <i>qGW5</i> (64.42% for grain width), and <i>qGT10</i> (49.2% for grain thickness)—were regarded as the main effect QTLs. Using the three QTLs, an ideal QTL combination (<i>qGL2^P</i> + <i>qGW5^P</i> + <i>qGT10^B</i>) could be constructed on the basis of the accumulated QTL effect without yield loss caused by the change in grain shape in the population. In addition, three promising lines with a slender grain type were selected as a breeding resource with a <i>japonica</i> genetic background based on the QTL combination. The application of QTLs detected in this study could improve the grain shape of <i>japonica</i> cultivars without any linkage drag or yield loss.

Beatriz Lira, Rosaluz Tavera, Eberto Novelo

Background: The evolutionary pattern of dinophytes is complex and requires comprehensive taxonomic studies addressing the species' development and morphology, ecology, evolution, and genetics. Questions: How recent was the transition of D. baltica from Mexico to freshwater based on a calibrated phylogeny tree of the Kryptoperidiniaceae? Studied species and data description: Durinskia baltica, Kryptoperidiniaceae and the known fossil record of dinotoms (endosymbiont diatom-host dinophytes). Study sites and dates: Xochimilco, Mexico City.  2010 to 2019. Methods: Phylogenies were constructed with Bayesian inferences and host sequences were calibrated with a relaxed clock method. Results: We obtained genetic sequences of the 18S rDNA sector in the host and the rbcL sector in the endosymbiont. The Nitzschia-type endosymbiont is genetically distinct from endosymbionts of other dinotomes with the same diatom type. In contrast, considering the known freshwater species of Durinskia, the genetic relationship between hosts is robust and of recent origin. The antiquity of the Mexican sequence coincides with the geological origin of the Xochimilco basin, suggesting particularities in the evolutionary history of dinotomes linked to the geographic regions they inhabit. Conclusions: Our evolutionary scenario with a calibrated phylogeny indicates that the transition of Durinskia baltica to freshwater in the Xochimilco basin is geologically contextualized. The historical environmental change of Lake Xochimilco with respect to salinity corresponds with an initial colonization of D. baltica in a brackish environment and its subsequent adaptation to freshwater.

Stephen Maberly

Tian Cheng, Miroslav Kolařík, Luis Quijada et al.

Abstract The monotypic “bulbilliferous hyphomycete” genus Taxomyces was erected in 1993 for a fungal endophyte isolated from the Yew tree Taxus brevifolia and named Taxomyces andreanae. This fungus was reported to produce the plant-derived anti-cancer drug taxol. The original description of the fungus was not conclusive as to its taxonomic position because no sporulation or other salient morphological features were reported. Consequently, the taxonomic affinities of this fungus have remained obscure. However, a full genome sequence of this strain was generated by a German research group in 2013, in an unsuccessful attempt to detect the biosynthesis genes encoding for taxol. This prompted us to search for phylogenetic marker genes and compare those with the data that recently have become available from state-of-the-art polyphasic taxonomic studies. Surprisingly, the strain turned out to belong to the phlebioid clade of wood-destroying Basidiomycota as inferred from a comparison of its partial ITS, the 28S rDNA (LSU), the RNA polymerase II largest subunit (rpb1), the RNA polymerase II second largest subunit (rpb2), and the translation elongation factor 1-α (tef1) sequences. A multi gene genealogy based on these loci revealed that the closest relative is Ceriporiopsis (syn. Mycoacia) gilvescens. Even though such wood-destroying Basidiomycota are regularly encountered among the endophytic isolates after surface-disinfection of plant organs, the vast majority of the reported endophytic fungi belong to the Ascomycota. Nevertheless, the data available now allow for synonymizing Taxomyces with Ceriporiopsis, and the necessary new combination is made.

Tsutomu Ishimaru, Masaki Okamura, Ichiro Nagaoka et al.

There is an increased demand for developing a heat-resilient cultivar with high palatability and acceptable grain yield to cope with the impacts of progressive changes in global climate conditions. This study attempted to quantify the heat resilience level and explore the heat resilient mechanism of ‘Niji-no-kirameki’, a new Japanese cultivar with heat resilience during ripening, and compare it with the leading Japanese cultivar ‘Koshihikari’. Multi-environmental testing on grain appearance under diverse high temperature field conditions across three prefectures revealed superior performance of ‘Niji-no-kirameki’ compared to ‘Koshihikari’, especially when the average of daily mean temperatures during the first 20 days after heading was over 27 °C, a general threshold temperature previously reported to decrease grain appearance in ‘Koshihikari’. Starch properties such as amylose content and amylopectin chain length distribution were similar between cultivars across seasons. Severely chalked grains by high temperature stress had lower protein content and 13 kDa prolamin content in the grains, suggesting that inter-relationships between starch and storage protein biosynthesis affect the formation of the chalky phenotype irrespective of cultivars with different heat resilience levels. As a possible heat resilience mechanism, a novel biological response of ‘Niji-no-kirameki’ for preventing an increase in panicle temperature to rising temperatures during ripening was found. It is assumed that the erect plant phenotype until maturity concealing panicles inside the canopy could create a cooler environment for panicles of ‘Niji-no-kirameki’ during ripening. We conclude that ‘Niji-no-kirameki’ is a promising cultivar for the improvement of grain appearance in the heat-vulnerable regions of Japan.

Munir Ozturk, Volkan Altay, Tuba Mert Gönenç et al.

Global climate change, especially global warming, is affecting olive production efficiency as well as its product quality. The size and water content of fruit varies depending on the olive fruit yield along with the region, climate, and geographical position as well as agricultural applications. Anthropogenic activities also affect its ecology to a great extent. The plant prefers areas with mild winters and short rainy seasons but is facing long and dry summers, sunny habitats, well drained dry, poor, loamy, clayey-loamy, slightly calcareous, pebbly and nutrient-rich soils, with a pH around 6–8. It is resistant to drought but suffers much from harsh winters and air pollutants, which affect its production. Although the olive plant tolerates temperatures between −7 °C to 40 °C, the optimum temperature demanded for growth, development, and fruit yield is 15–25 °C. The annual precipitation demand lies between 700–850 mm. An important part of the composition of its fruit consists of water and oil or the “liquid gold”. Main ingredients are additionally fat-soluble vitamins, minerals, organic sugars, and phenolics. Phenolic substances are responsible for many beneficial health effects as well as the taste and aroma of olive fruit. Oleuropein stands out due to its inhibition of oxidation of low density lipoproteins and its hypoglycemic and cholesterolemic effects. It is also a component that protects the olive tree against various parasites and diseases, one of the reasons why olive is recorded as the “immortal tree”. Olive trees are cultivated in different regions of Turkey. A series of changes occur in morphological, physiological, and biochemical features to overcome different types of stress. In this review, information about the botanical aspects, eco-physiology, and pharmaceutical features of the oil, fruit, and leaves has been evaluated.

Marguerite Cinq-Mars, Guy Samson

The decline in CO₂ assimilation in leaves exposed to decreasing frequencies of pulsed light is well characterized, in contrast to the regulation of photosynthetic electron transport under these conditions. Thus, we exposed sunflower leaves to pulsed lights of different frequencies but with the same duty ratio (25%) and averaged light intensity (575 μmoles photons m⁻² s⁻¹). The rates of net photosynthesis P<i>n</i> were constant from 125 to 10 Hz, and declined by 70% from 10 to 0.1 Hz. This decline coincided with (1) a marked increase in nonphotochemical quenching (NPQ), and (2) the completion after 25 ms of illumination of the first phase of P₇₀₀ photooxidation, the primary electron donor of PSI. Under longer light pulses (<5 Hz), there was a slower and larger P₇₀₀ photooxidation phase that could be attributed to the larger NPQ and to a resistance of electron flow on the PSI donor side indicated by 44% slower kinetics of a P₇₀₀⁺ dark reduction. In addition, at low frequencies, the decrease in quantum yield of photochemistry was 2.3-times larger for PSII than for PSI. Globally, our results indicate that the decline in CO₂ assimilation at 10 Hz and lower frequencies coincide with the formation of NPQ and a restriction of electron flows toward PSI, favoring the accumulation of harmless P₇₀₀⁺.

M. K. Ramkumar, S. Senthil Kumar, Kishor Gaikwad et al.

Three Ethyl methansulphonate (EMS)-induced stay-green mutants (SGM-1, SGM-2 and SGM-3) and their wild-type (WT), were tested for their Stay-Green (SG) and drought tolerance nature as the relation between these two attributes is not yet established in rice. In the dark induced senescence assay, SGM-3 showed delayed senescence while SGM-1 and SGM-2 showed complete lack of senescence. Mutants showed stable transcript abundance over time, for 15 candidate genes (CGs) associated with senescence, compared to the WT. SGM-3 however showed moderately increasing transcript abundance over time for <i>ATG6a</i>, <i>ATG4a</i>, <i>NYC1</i>, <i>NOL</i> and <i>NYC3</i>. Only SGM-3 performed better than the WT for yield and harvest index under well irrigated as well as drought conditions, though all the mutants showed better performance for other agronomic traits under both the conditions and ascorbate peroxidase activity under drought. Thus, SG trait showed positive correlation with drought tolerance though only SGM-3 could convert this into higher harvest index. Sequence analysis of 80 senescence-associated genes including the 15 CGs showed non-synonymous mutations in four and six genes in SGM-1 and SGM-2 respectively, while no SNPs were found in SGM-3. Analysis of the earlier reported Quantitative Trait Loci (QTL) regions in SGM-3 revealed negligible variations from WT, suggesting it to be a novel SG mutant.

Ahmad Al-Beloushi, Ayman Elbehiry, Eman Marzouk

Diabetic foot ulcer (DFU) is one of the most serious and costly complications of diabetic patients. Enterococcus faecalis (E. faecalis) represents one of the most virulent microorganisms in diabetic foot infections (DFIs). We therefore aimed to study the frequency and precise identification of E. faecalis in DFU. Six hundred thirty specimens collected from diabetic foot patients were used in the current investigation. Biochemical identification was carried out by the Vitek® 2 system. Proteomic analysis was implemented by MALDI-TOF MS and confirmed by SYBER Green real-time polymerase chain reaction (SYBER Green qPCR). According to the results, the overall frequency of E. faecalis in patients with DFU was 8.25% (52/630). Out of 52 E. faecalis strains, 40 isolates were isolated from males and 12 from females. The results of biochemical identification revealed that 92.30% (48/52) of E. faecalis isolates were properly recognized at the species level. Whereas 100% (52/52) of E. faecalis isolates were properly recognized by MALDI-TOF MS as 44.23% (23/52), 51.92% (27/52) and 3.84% (2/52) with a score value ranging from 2.300 to 3.000, 2.000-2.299 and 1.700-1.999 Da, respectively. Seven E. faecalis virulence genes, including asa1, GelE, cylA, esp, hy1, VanA, and VanB, were detected by SYBER Green RT-PCR. In conclusion, E. faecalis was the utmost predominant single organism isolated from the DFIs. MALDI-TOF mass spectrometry is considered a fast, trustworthy and economic detection method for various significant microorganisms. E. faecalis isolates were also found to carry several virulence genes. Our findings may serve as an urgent issue for supplementary investigations of contagions caused by E. faecalis.

Talita Zupo, M. Jaime Baeza, Alessandra Fidelis

ABSTRACT Seed germination in many species from fire-prone ecosystems may be triggered by heat shock and/or temperature fluctuation, and how species respond to such fire-related cues is important to understand post-fire regeneration strategies. Thus, we tested how heat shock and daily temperature fluctuations affect the germination of four species from fire-prone ecosystems; two from the Cerrado and two from the Mediterranean Basin. Seeds of all four species were subjected to four treatments: Fire (F), temperature fluctuations (TF), fire+temperature fluctuations (F+TF) and control (C). After treatments, seeds were put to germinate for 60 days at 25ºC (dark). Responses differed according to species and native ecosystem. Germination percentage for the Cerrado species did not increase with any of the treatments, while germination of one Mediterranean species increased with all treatments and the other only with treatments that included fire. Although the Cerrado species did not respond to the treatments used in this study, their seeds survived the exposure to heat shock, which suggests they possess tolerance to fire. Fire frequency in the Cerrado is higher than that in Mediterranean ecosystems, thus traits related to fire-resistance would be more advantageous than traits related to post-fire recruitment, which are widespread among Mediterranean species.

N.V. Sulyga

Water regime of leaves is analysed and drought-resistance index of Liriodendron tulipifera L. are established on the ground of different evaluation methods of drought-resistance under conditions of introduction to Right-Bank of Forest-Steppe of Ukraine. Total water content, water deficit, relative leaf turgescence, water-holding capacity and ability of leaves to restore water content are established.

Z. Jurjevic, G.C. Rains, D.M. Wilson et al.

Aflatoxigenic and non-toxigenic Aspergillus flavus strains were grown on corn and on peanut substrates. Microbial volatile organic compounds (MVOCS) were collected by trapping headspace volatiles using thermal desorption tubes (TDT) packed with Tenax® TA and Carbotrap™ B. Samples were collected at various fungal growth stages. Trapped compounds were thermally desorbed from the adsorbent tubes, separated by gas chromatography, and identified by mass spectrometry. The fungal stage did not have many differences in the MVOCs but the concentrations of some volatiles changed over time depending on the substrate. Volatiles that were associated with both the aflatoxigenic A. flavus strain and the nontoxigenic strain on both substrates included: ethanol, 1-propanol, butanal, 2-methyl-1-propanol, 3-methylfuran, ethyl acetate, 1-butanol, 3-methylbutanal, 3-methyl-1-butanol, propanoic acid-2-methyl-ethyl-ester, 2-methyl-1-butanol, 1-pentanol, 2-pentanol, 3-methyl-3-buten-1-ol, benzaldehyde, 3-octanone, 2-ethyl-1-hexanol and octane. Volatiles that were associated only with the aflatoxigenic A. flavus strain included: dimethyl disulfide and nonanal. Volatiles that were associated only with the nontoxigenic A. fl avus strain included: hexanal, 1-hexanol, 1-octene-3-ol, 1-octen-3-one and 2-pentyl furan.