Over-expression of Gastrodia anti-fungal protein enhances Verticillium wilt resistance in coloured cotton

Currently there are no adequate control measures for the cotton fungal diseases Verticillium wilt and Fusarium wilt, which are important factors limiting yield under certain conditions. In this study the gene encoding a Gastrodia anti‐fungal protein was introduced into three cultivars of coloured cotton using the method of pollen‐tube pathway transformation, with the purpose of obtaining transgenic plants with improved resistance to wilt. Of the 121 herbicide‐resistant cotton plants two, LB‐5‐8 and ZB‐1‐49, were scored as transgenic based on Southern blot, RT‐PCR analysis and in vitro anti‐fungal activity assay. Field analysis demonstrated that the transgenic lines LB‐5‐8 and ZB‐1‐49 possess an increased resistance to wilt. After 2 years of breeding, the progeny of LB‐5‐8 and ZB‐1‐49 lines still showed a stable and strong resistance to Verticillium wilt. Lines with high levels of resistance to Verticillium wilt obtained from the present study may be widely planted and help to reduce the future impact of cotton wilt on cotton production resulting in increased yields.     

Transgenic cotton, expressing Amaranthus caudatus agglutinin, confers enhanced resistance to aphids

To evaluate the possible antiaphid function of Amaranthus caudatus agglutinin (ACA) in allogenetic plants, transgenic cotton plants expressing the ACA gene under the control of a phloem‐specific promoter were generated via Agrobacterium‐mediated gene transformation. Based on the results of Southern blot analyses, six plants with single or lower copy transgene and favourable agronomic traits were selected for further studies. ACA expression levels ranged from 0.02% to 0.45% of total soluble protein as determined by Western blot analysis in the six selected transgenic plants. Insect bioassays using nymphs of cotton aphid (Aphis gossypii Glover) showed that five of the six transgenic plants significantly inhibited the population growth of cotton aphid, with the highest inhibition rate of 64.5%. These results shed some new light on the antiaphid function of the ACA gene as well as the promising application of the gene for obtaining aphid‐resistant transgenic cotton plants to reduce the yield loss and honeydew contamination of fibre by aphids.     

Field evaluation and fiber analysis of transgenic cotton

We report the field evaluation of second generation of transgenic cotton expressing Bacillus thuringiensis (Bt) genes cry1Ac and cry2A under CaMV 35S promoter. Sixty-five transgenic lines were grown under RCBD design. Transgenic plants exhibited inherent ability to resist target insect (p < 0.05 and 0.01). Morphological studies showed significant reduction in plant height making them favorable for breeding. Yield was significantly increased for the transgenic lines. Fiber analysis showed improved gin turn out 40% for transgenic lines in comparison to 32% for non-transformed lines. Fibre quality of transgenic lines was not affected when compared with non transgenic lines. Inheritance pattern for transgenic lines suggests the need of further studies to understand the complex molecular mechanisms for resistance management and biosafety studies to develop new Bt cotton varieties.     

QTL mapping for agronomic and fibre traits using two interspecific chromosome substitution lines of Upland cotton

CS‐B14Sh and CS‐B22Sh are cotton interspecific chromosome substitution (CS)‐B lines, in which a pair of short arms of chromosome 14 and chromosome 22 were introgressed from Gossypium barbadense doubled‐haploid line 3‐79 with the background of Gossypium hirsutum line TM‐1, respectively. These two CS‐B lines were crossed with TM‐1, and segregating progenies (F₂ and F_2:3, respectively) were obtained. Phenotypic data of lint yield, yield‐related traits and fibre‐quality traits were collected from two trials. In the cross CS‐B14SH X TM‐1, QTL for boll weight (BW), lint percentage (LP), fibre upper half mean length (UHML), micronaire reading (MIC), and fibre breaking tensile strength (STR) were repeatedly detected. Alleles from 3‐79 decreased BW and MIC, but increased UHML and STR. In the cross CS‐B22Sh X TM‐1, QTL for BW, LP, UHML, MIC, STR, fibre elongation (EL),seed weight(SW), node of first fruiting branch (NFB) and fibre uniformity index (UI) were repeatedly detected, and alleles from 3‐79 decreased UHML, UI and STR, but increased NFB, SW, MIC and EL. QTL clusters were found in both populations.     

Fine‐mapping a fibre strength QTL QFS‐D11‐1 on cotton chromosome 21 using introgressed lines

An initial F₂ mapping population of 223 plants of the cross between TM‐1 (Gossypium hirsutum L.) × H102 (Gossypium barbadense L.) was used to map QTLs controlling fibre strength in cotton. A genetic linkage map with 408 SSR markers was constructed with a total length of 3872.6 cM. Multiple‐QTL model of the software MapQTL version 5.0 was used to map QTLs related to fibre strength of the F_2 : 3 population. QTL QFS‐D11‐1 conferring fibre strength was mapped between NAU2950 and NAU4855 on chromosome 21 (Chr. 21) which explained 23.4% of phenotypic variation. Introgressed lines (ILs), that is, IL‐D11‐1, IL‐D11‐2 and IL‐D11‐3 were obtained through marker‐assisted backcrossing in TM‐1 background. An F₂ population of 758 plants derived from cross IL‐D11‐2 × TM‐1 was used for fine‐mapping QTL QFS‐D11‐1. QFS‐D11‐1 was mapped between markers NAU2110 and NAU2950, adjacent to its initial interval NAU2950–NAU4855 with phenotypic variation explaining 35.8%. QFS‐D11‐1 was further mapped to 0.6 cM from the flanking marker NAU2950. The results will give a basis for marker‐assisted selection of QFS‐D11‐1 in cotton breeding and to lay the foundation for cloning QFS‐D11‐1.     

A molecular approach to combat spatio-temporal variation in insecticidal gene (<Emphasis Type="Italic">Cry1Ac</Emphasis>) expression in cotton

Spatio-temporal expression of an insecticidal gene (Cry1Ac) in pre existing transgenic lines of transgenic cotton was studied. Seasonal decline in expression of Cry1Ac differed significantly among different cotton lines tested in the field conditions. The leaves of the Bt cotton plants were found to have the highest levels of toxin expression followed by squares, bolls, anthers and petals. Expression of the gene decreased consistently with the age of plants. Toxin expression in fruiting parts was not enough to confer full resistance against bollworms. The reduction in efficacy of transgenic cotton plants late in the season was attributed to reduction in promoter activity. For this purpose, ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) small subunit (rbcS) promoter was isolated from Gossypium arboreum that was further cloned upstream of an insecticidal gene (Cry1Ac) in expression vector pCAMBIA 1301. A local cotton cultivar NIAB-846 was transformed with Cry1Ac driven by rbcS promoter. The same cotton cultivar was also transformed with Cry1Ac gene driven by 35SCaMV promoter to compare the expression pattern of insecticidal gene under two different promoters. The results showed that rbcS is an efficient promoter to drive the expression of Cry1Ac gene consistent throughout the life of cotton plant as compared to 35S promoter. The use of tissue specific promoter is also useful for addressing the biosafety issues as the promoter activity is limited to green parts of plants, hence no gene expression in roots, cotton seed and other cotton products and by products.     

<Emphasis Type="Italic">Agrobacterium</Emphasis>-mediated transformation of cotton (<Emphasis Type="Italic">Gossypium hirsutum</Emphasis> L.) with a fungal phytase gene improves phosphorus acquisition

A phytase gene (phyA), isolated from Aspergillus ficuum (AF537344), was introduced into cotton (Gossypium hirsutum L.) by Agrobacterium-mediated transformation to increase the phosphorus (P) acquisition efficiency of cotton. Southern and Northern blot analyses showed that the phyA was successfully incorporated into the cotton genome and expressed in transgenic lines. After growing for 45 days with phytate (Po) as the only P source, the shoot and root dry weights of the transgenic plants all increased by nearly 2.0-fold relative to those of wild-type plants, but were similar to those of transgenic plants supplied with inorganic phosphorus. The phytase activities of root extracts prepared from transgenic plants were 2.4- to 3.6-fold higher than those from wild-type plants, and the extracellular phytase activities of transgenic plants were also 4.2- to 6.3-fold higher. Furthermore, the expressed phytase was secreted into the rhizospheres as demonstrated by enzyme activity staining. The transgenic plants accumulated much higher contents of total P (up to 2.1-fold after 30 days of growth) than the wild-type plants when supplied with Po. These findings clearly showed that cotton plant transformed with a fungal phytase gene was able to secret the enzyme from the root, which markedly improved the plant’s ability to utilize P from phytate. This may serve as a promising step toward the development of new cotton cultivars with improved phosphorus acquisition.     

Transformation of α-EXPA1 gene leads to an improved fibre quality in Gossypium hirsutum

The Expansin protein is known for its multifaceted roles in plant growth, especially cell walls. However, very few studies have been done so far to assess the effects of expansin genes on Cotton fibre development. The present study is a successful effort to fill this gap, where the α-EXPA1 gene transformed into a local cotton variety, Gossypium hirsutum, through Agrobacterium-mediated transformation under Gossypium hirsutum Seed coat and Fibre-specific promoter (GhSCFP). The transgenic cotton plants underwent molecular characterization and fibre trait evaluation. Our results indicated that α-EXPA1 showed an up-regulated expression during the transition phase of secondary cell wall synthesis and resulted in improving the fibre parameters, especially micronaire value. Transgenic cotton fibre also showed a finer twisting under the Scanning electron microscope (SEM) as compared to non-transgenic cotton fibre samples. The fibre production is influenced by more than nine thousand genes, and the fibre improvement cannot be just achieved through a single gene transformation. However, α-EXPA1 is one of the potential candidates for cotton fibre research as it significantly improved the cotton fibre.     

Genetic analysis of agronomic and fibre traits using four interspecific chromosome substitution lines in cotton

Backcrossed chromosome substitution lines (CS‐B) have been developed with a homologous pair of chromosomes or chromosome arms of Gossypium barbadense (3‐79) germplasm substituted for the homologous Gossypium hirsutum(TM‐1) chromosomes or chromosome segments. We report on agronomic and fibre trait performance of four backcrossed chromosome or chromosome arm substitution lines including chromosomes 01, 11sh (chromosome 11 short arm), 12 sh and 26 Lo (chromosome 26 long arm). Data for agronomic and fibre traits were collected from replicated field experiments at two different locations in 2 years, and analysed under an additive dominance genetic model. CS‐B 12sh had higher, while CS‐B 01 and CS‐B 26Lo had lower boll weight than TM‐1. The presence of significant negative additive effects for micronaire with CS‐B 01 and significant positive additive effects for elongation and fibre strength with CS‐B 11sh suggested the substituted chromosome arms of 3‐79 in these CS‐B lines were more likely carrying genes causing these effects. Results revealed that several CS‐B lines had significant homozygous and heterozygous dominance effects for different agronomic and fibre traits suggesting that specific CS‐B lines may be useful for improving agronomic and fibre traits in hybrid cottons. These CS‐B lines also provide novel genetic resources for improving upland cotton germplasm.     

Transgenic soybeans expressing betaine aldehyde dehydrogenase from Atriplex canescens show increased drought tolerance

Betaine aldehyde dehydrogenase (BADH) catalyses the oxidation of betaine aldehyde to glycine betaine. To test whether BADH can increase drought tolerance in soybean (Glycine max), BADH from the drought‐tolerant plant Atriplex canescens (AcBADH) was introduced into the soybean cultivar ‘Jinong 17’ by Agrobacterium‐mediated cotyledon transformation. Eight independent AcBADH transgenic lines were subjected to drought stress. As expected, AcBADH was expressed in transgenic soybean leaves and not in the control. In transgenic plants, AcBADH expression increased following drought treatment. Under osmotic stress, the germination index was 6%–17% higher in the transgenic lines than in the control. Using a randomized block design, we measured drought‐related physiological indices and yield traits. The proline content in AcBADH transgenic soybeans increased by 12.5%–16.6%, peroxidase activity increased by 1%–7%, dry weight of plant increased by 15%–20% and malondialdehyde contents decreased by 1.5%–13%, compared to the control. Under drought conditions, two of the eight transgenic soybean lines had higher yields than the control, with increases of 7.59%–8.84%. Therefore, transgenic expression of AcBADH may provide a promising strategy to engineer drought tolerance without adverse consequences.     

Improved salt tolerance and seed cotton yield in cotton (<Emphasis Type="Italic">Gossypium hirsutum</Emphasis> L.) by transformation with <Emphasis Type="Italic">betA</Emphasis> gene for glycinebetaine synthesis

Homozygous transgenic cotton (Gossypium hirsutum L.) plants that accumulated glycinebetaine (GB) in larger quantities were more tolerant to salt than wild-type (WT) plants. Four transgenic lines, namely 1, 3, 4, and 5, accumulated significantly higher levels of GB than WT plants did both before and after salt stress. At 175 and 275 mM NaCl, seeds of all the transgenic lines germinated earlier and recorded a higher final germination percentage, and the seedlings grew better, than those of the WT. Under salt stress, all the lines showed some characteristic features of salt tolerance, such as higher leaf relative water content (RWC), higher photosynthesis, better osmotic adjustment (OA), lower percentage of ion leakage, and lower peroxidation of the lipid membrane. Levels of endogenous GB in the transgenic plants were positively correlated with RWC and OA. The results indicate that GB in transgenic cotton plants not only maintains the integrity of cell membranes but also alleviates osmotic stress caused by high salinity. Lastly, the seed cotton yield of transgenic lines 4 and 5 was significantly higher than that of WT plants in saline soil. This research indicates that betA gene has the potential to improve crop’s salt tolerance in areas where salinity is limiting factors for agricultural productivity.     

Effects of the dominant glandless gene Gl2e on agronomic and fibre characters of Upland cotton

Seven pairs of near‐isogenic lines (glandless vs. glanded) and the recurrent parents were used to determine the effects of the dominant glandless gene from ‘Hai 1’(Gossypium barbadense) on agronomic, fibre, and seed characters in Upland cotton, Gossypium hirsutum, backgrounds. The results showed that there were no apparent linkage associations of the glandless gene on most agronomic, fibre and seed characters of Upland cotton, except for seed quality. The glandless line derived from ‘Liaomian 7’had significantly more protein (489.6 g/kg), and that from H237 had significantly more oil (362.4 g/kg) and had the largest oil index (2.70 g) and protein index (3.03 g). The gossypol content of seed in dominant glandless lines in Upland cotton was very low (<0.04 g/kg). Therefore, it is suggested that the glandless gene can play an important role in breeding glandless or low seed‐gossypol Upland cotton cultivars.     

High-efficiency transformation of Gossypium hirsutum embryogenic calli mediated by Agrobacterium tumefaciens and regeneration of insect-resistant plants

A simple protocol of transformation of cotton (Gossypium hirsutum L.) at a high frequency has been developed via Agrobacterium mediation, coupled with the use of embryogenic calli as explants. Embryogenic calli derived from only one to two somatic embryogenic calli lines of two Chinese cotton cultivars, the cvs. Ekang 9 and Jihe 321 which have low embryogenic potency were first inoculated with the A. tumefaciens strain LBA4404 harbouring binary vector pBin438 carrying a synthetic Bacillus thuringiensis‐active Cry1Ac and API‐B chimeric gene. Infected embryogenic calli were co‐cultivated for 48 h and were then moved on to the selection medium with kanamycin (100 mg/l) for 7‐8 weeks. Then, the kanamycin‐resistant calli (Km¹) subcultured in proliferation medium would re‐differentiate to form somatic embryos in 30 days. Cotyledon embryos were transferred to 100‐ml Erlenmeyer flasks for germination and regeneration. Putative transformants were confirmed by polymerase chain reaction and Southern blot analysis. Forty‐five regenerated plants were successfully transferred to soil, of which 12 proved to have the active Cry1Ac and API‐B chimeric gene. Insect resistance was tested by bioassay. The transgenic plants were highly resistant to cotton bollworm (Heliothis armigera) larvae, with mortality (insect resistance) ranging from 95.8 to 100%. In comparison with the methods used in Agrobacterium‐mediated transformation of cotton hypocotyls or cotyledons, about 6 months are saved by using the method presented in this paper to obtain a large number of transgenic plants.     

Linkage map construction and mapping QTL for cotton fibre quality using SRAP, SSR and RAPD

Tetraploid cotton is one of the most extensively cultivated species. Two tetraploid species, Gossypium hirsutum L. and G. barbadense L., dominate the world's cotton production. To better understand the genetic basis of cotton fibre traits for the improvement of fibre quality, a genetic linkage map of tetraploid cotton was constructed using sequence‐related amplified polymorphisms (SRAPs), simple sequence repeats (SSRs) and random amplified polymorphic DNAs (RAPDs). A total of 238 SRAP primer combinations, 368 SSR primer pairs and 600 RAPD primers were used to screen polymorphisms between G. hirsutum cv. Handan208 and G. barbadense cv. Pima90 which revealed 749 polymorphic loci in total (205 SSRs, 107 RAPDs and 437 SRAPs). Sixty‐nine F₂ progeny from the interspecific cross of ‘Handan208’בPima90’ were genotyped with the 749 polymorphic markers. A total of 566 loci were assembled into 41 linkage groups with at least three loci in each group. Twenty‐eight linkage groups were assigned to corresponding chromosomes by SSR markers with known chromosome locations. The map covered 5141.8 cM with a mean interlocus space of 9.08 cM. A × test for significance of deviations from the expected ratio (1: 2: 1 or 3: 1) identified 135 loci (18.0%) with skewed segregation, most of which had an excess of maternal parental alleles. In total, 13 QTL associated with fibre traits were detected, among which two QTL were for fibre strength, four for fibre length and seven for micronaire value. These QTL were on nine linkage groups explaining 16.18‐28.92% of the trait variation. Six QTL were located in the A subgenome, six QTL in the D subgenome and one QTL in an unassigned linkage group. There were three QTL for micronaire value clustered on LG1, which would be very useful for improving this trait by molecular marker‐assisted selection.     

Inheritance and field performance of transgenic Korean Bt rice lines resistant to rice yellow stem borer

Transgenic Korean rice plants containing the cry1Ab gene were developed for resistance against yellow stem borer (Scirpophaga incertulas, YSB). More than 100 independent transgenic lines from three Korean varieties (P-I, P-II and P-III) were generated. The amount of Cry1Ab in transgenic T₀ plants was as high as 2.88% of total soluble proteins. These levels were sufficient to cause 100% mortality of YSB larvae. The majority of T₁ transgenic lines originated from the varieties P-I and P-II followed a Mendelian fashion of segregation. Deviation from the expected segregation ratio was observed in a small number of the transgenic lines of P-I and P-II origins. However, this deviation was primarily observed in the P-III originated lines. Segregation analysis of the T₁ generation indicated that 1–3 copies of the cry1Ab gene were integrated into the genome of the majority of the transgenic lines originating from varieties P-I and P-II. Stunted and semi-fertile mutants were observed in some transgenic lines. These aberrations were either independent or closely linked to the introduced cry1Ab gene loci in different transgenic lines. Reduction in GUS expression levels and loss of toxicity against YSB larvae were found in some transgenic lines. The transgenic T₃ and T₄ lines causing 100% mortality of third instar YSB larvae in the lab were completely protected in the field. Analysis of important yield components on nine selected transgenic lines indicated that stem length, panicle length, grain number per panicle, and seed setting rates were reduced in transgenic plants compared to those in non-transgenic parental rice lines. Number of panicles per cluster, however, was significantly higher in transgenic plants. The numerical value of the average yield was in general greater in the controls than in all the transgenic lines, indicating some ‘yield drag’. Since some selected lines were highly resistant to the YSB with good yielding potential, they offer effective potential for use in insect resistance management programs.     

Breeding high-yield upland cotton (Gossypium hirsutum) lines with high-quality fibre by mutation

The yield and fibre quality of upland cotton (Gossypium hirsutum) cultivars are very difficult to improve simultaneously. Attempts to breed upland cotton cultivars with high-quality fibre that can spin more than 40 yarn count (Ne) and present yields equal to those of commercial cultivars have not been successful. The seeds of the high-yield upland cotton line Tai 8033 were mutagenized in a Chinese Practice No. 8 recoverable satellite, and the mutated line was selected to produce high-quality and high-yield lines by pedigree selection. The eight mutated lines fit the Chinese standard of high-quality cotton class I, were suitable for spinning more than 40 Ne and had yields that were 12.7%, 7.1% and 3.5% higher than the current control cultivar yield in the cotton cultivation area tested in Jiangsu Province. The fibre of one line successfully spun 80 Ne that fit the high-quality yarn standards. After seeds were mutagenized by exposure to a space environment in a satellite, the fibre quality of upland cotton cultivars was improved through pedigree selection.     

转GHABF4转录因子棉花植株的耐盐性研究

AREB/ABFs转录因子家族基因主要参与干旱、高盐、低温等胁迫应答反应。为了获得具有较高耐盐水平的棉花新种质材料,通过农杆菌介导法将耐盐转录因子基因(GHABF4)导入陆地棉中棉35中,通过对转化植株的卡那霉素初步筛选及T1、T2、T3目的基因PCR的分子检测,获得T3转基因棉花纯合系。通过盐胁迫试验对5个T3转基因棉花株系和非转基因棉花对照进行耐盐性分析。结果表明,在200 mmol/L Na Cl胁迫下,与非转基因对照相比,5个转基因棉花株系株高提高2.5~4.4 cm,地上部分的鲜质量增加3.6%~11.8%;且抗氧化物酶SOD、POD、CAT活性以及叶绿素含量提高。在盐胁迫条件下,转GHABF4基因棉花表现出优良的生长和生理优势,转GHABF4基因能够提高棉花的抗盐能力。     

Combining ability estimates for yield and fibre quality traits in 4 × 13 line × tester crosses of Gossypium hirsutum

The aim of this study was to estimate the general combining ability of the parents and specific combining ability of hybrids considered for the development of high yielding and better quality cultivars. Seventeen genotypes and 52 F₁ hybrids obtained by crossing 4 lines and 13 testers in line × tester mating system during 2003 were sown in randomized complete block design in 2004. Line × Tester analysis revealed significant GCA and SCA effects for all the traits except fibre elongation. Preponderance of non-additive gene action was obtained for seed cotton yield per␣plant and majority of its component traits including fibre traits. Among the parents: PIL-8 for days to 50% flowering, CCH-526612 for boll weight, CITH-77 for number of open bolls per plant and CNH-36 for seed cotton yield per plant were detected with higher general combining ability. Parent, CCH-526612 for 2.5% span length, fibre strength and fibre elongation and AKH-9618 for micronaire value, fibre strength and fibre elongation were good combiners for fibre quality traits. The F₁s achieved high seed cotton yield by producing more number of open bolls. The high yielding hybrids with acceptable fibre quality traits were: CISV-24 × LH-1995, H-1242 × PIL-8 and RS-2283 × SGNR-2 deducted with significant SCA effects for seed cotton yield and fibre characteristics; 2.5% span length and fibre strength. These cross combinations involved at least one parent with high or average GCA effect for a particular trait.     

Screening Saccharum Barberi and Sinense Accessions for Flood Tolerance and Biomass Production

This study evaluated the biomass production potential of Saccharum barberi (Jeswiet) and Saccharum sinense (Roxb. Amend. Jeswiet) accessions under short‐term flooded conditions. Plots were arranged in a completely randomized design with 20 S. sinense and 29 S. barberi accessions, two flood durations with non‐flooded controls and three replications of each treatment. There were no significant flood effects. However, in two individual accessions, ‘China’ and ‘Lu Cane’, sucrose production increased with additional flooding. The plant cane produced larger plants with a greater percentage of fibre and sucrose. Higher Brix values were obtained with the ratoon crop. Brix and fibre were negatively correlated with stem diameter. Stem length in S. barberi was the only physical characteristic that was correlated with sugar factors Brix and optical rotation. S. barberi accessions had high loadings for variables associated with sugar production and stem length, and fibre had moderate loadings for factor 1. Factor 1 explained 35 % of variance in the data. The second principal factor revealed high loadings for variables associated with plant size. Factor 2 explained 30 % of the proportional and together with Factor 1 explained 65 % of the cumulative variance in the data. Several accessions with low sucrose, high plot weight and low fibre were identified. These accessions make attractive selections in breeding for biomass production.     

H2S and COS Gas Exchange of Transgenic Potato Lines with Modified Expression Levels of Enzymes Involved in Sulphur Metabolism

Different transgenic potato lines were generated for improving the nutritional value of tubers by an advanced perception of their sulphur metabolism. So far no data exist about possible implications for plant health and stress resistance. Metabolite analysis revealed that modifications of enzymes involved in sulphur metabolism were necessarily not reflected in distinctly altered thiol contents. The release of H₂S by plants is putatively involved in pathogen resistance, because of its fungi‐toxic mode of action. The emission of H₂S was determined in 16 potato lines with modified expression level in ATP sulphurylase (ATPS), serine acetyltransferase (SAT), O‐acetylserine(thiol)lyase (OASTL), homoserine kinase (HSK) and threonine synthase activities. The emission significantly increased by factor 7 in one of the ATPS antisense lines and by factor 8 in one of the OASTL antisense lines. A strong increase in H₂S emissions was observed in transgenic plants based on the potato cultivar White Lady, which expressed the Escherichia coli SAT. In addition, the exchange of COS was determined in relation to genetic modifications. Generally, plants act as a sink for COS, but all transgenic lines expressing the E. coli HSK and one of the ATPS antisense lines emitted COS indicating to strong changes in the metabolism of these plants. Such alterations in the gas exchange of transgenic potato plants will most likely also affect their resistance against biotic and abiotic stress.