Chemical Hybridization Agent Research Articles

The Stimulation of Chemical Male Sterility for F1 Hybrid Lettuce (Lactuca Sativa Var. Longifolia) Production

Male sterility is a unique application in the production of F1 hybrid seeds of some important species. Today, while F1 hybrid lettuce varieties of abroad origin take their place in the Türkiye seed market, unfortunately, we do not have a native F1 hybrid variety. Besides, F1 hybrid seed production has become a prestige for multi-national companies regardless of the type of vegetable. Within this perspective, the effects of some chemical hybridizing agents (CHAs) such as E4FO, Ethrel and GA3 on male sterilizing activity in lettuce cultivars (Maylight352 F1, Presidential and Yedikule) were evaluated. Therefore, pollen presence in the early bud stage, seed formation and seed viability (germination) were examined. The applications had different effects on pollen presence, seed formation and seed germination, and thus male sterility. Ethrel was not effective at low doses, but at high doses, it caused flower bud deformation and growth retardation. E4FO is partially effective, but the application doses are low. Therefore, E4FO should be used at higher than 1500 ppm and 2000 ppm. GA3 applications produced the best results in stimulating male sterility, and full sterility (% 100) was achieved from 200, 250 and 300 ppm in all cultivars. As a result, 200 ppm GA3 was determined as the recommendable dose in the production of Fı hybrid lettuce.

First insights into the quantitative genetic composition of the female seed yield for an efficient hybrid seed production in wheat (Triticum aestivum L.)

AbstractHybrid breeding of wheat (Triticum aestivum L.) is limited by its self‐pollinating nature. Past cross‐pollination improvements mostly focused on optimizing male traits. We tested the hybrid seed yield of 100 diverse elite lines treated with a chemical hybridization agent (CHA) and pollinated by non‐sterilized male plants in multi‐environmental field trials. Plant height and phenological traits of female plants were also assessed. In parallel, control experiments without CHA sterilization were conducted to measure per se yield of the tested material. Hybrid seed yield variation is of quantitative genetic nature, and, despite the large environmental influence, this trait has a strong genotypic component and is highly heritable (h2 = .77). The lack of correlation between hybrid seed yield and per se yield suggests a non‐shared genetic control. Phenological traits and their interactions are important factors explaining together ~1/3 of hybrid seed yield variation. In contrast to plant height and flowering traits, which are influenced by major genetic factors, no significant marker–trait associations were found for the hybrid seed yield, thus suggesting a highly polygenic genetic architecture and the need of larger populations to investigate female hybrid seed yield.

Male Fertility Genes in Bread Wheat (Triticum aestivum L.) and Their Utilization for Hybrid Seed Production.

Hybrid varieties can provide the boost needed to increase stagnant wheat yields through heterosis. The lack of an efficient hybridization system, which can lower the cost of goods of hybrid seed production, has been a major impediment to commercialization of hybrid wheat varieties. In this review, we discuss the progress made in characterization of nuclear genetic male sterility (NGMS) in wheat and its advantages over two widely referenced hybridization systems, i.e., chemical hybridizing agents (CHAs) and cytoplasmic male sterility (CMS). We have characterized four wheat genes, i.e., Ms1, Ms5, TaMs26 and TaMs45, that sporophytically contribute to male fertility and yield recessive male sterility when mutated. While Ms1 and Ms5 are Triticeae specific genes, analysis of TaMs26 and TaMs45 demonstrated conservation of function across plant species. The main features of each of these genes is discussed with respect to the functional contribution of three sub-genomes and requirements for complementation of their respective mutants. Three seed production systems based on three genes, MS1, TaMS26 and TaMS45, were developed and a proof of concept was demonstrated for each system. The Tams26 and ms1 mutants were maintained through a TDNA cassette in a Seed Production Technology-like system, whereas Tams45 male sterility was maintained through creation of a telosome addition line. These genes represent different options for hybridization systems utilizing NGMS in wheat, which can potentially be utilized for commercial-scale hybrid seed production.

Comparative analysis of the efficacy of selected gametocide agents in sorghum (Sorghum bicolor [L.] Moench)

A new generation of chemical hybridization agents (CHAs) or gametocides has shown potential to induce male sterility in predominantly self-fertilizing crops, including sorghum (Sorghum bicolor [L.] Moench). There is a lack of information on the relative efficacy of the various available CHAs for large-scale application in plant breeding programs. Therefore, the objective of the present study was to compare the relative effectiveness of three selected CHAs to induce male sterility in sorghum under a controlled environment for hybridization. Foliar applications of three CHAs and a control (ethrel, trifluoromethanesulfonamide [TFMSA], ethyl 4-fluorooxanilate [E4FO] and distilled water [control]) were tested using three grain sorghum genotypes (ICS-1, ICS-2 and ICS-3) in two seasons. The 24 treatment combinations consisting of 4 levels of CHAs, 3 sorghum varieties and two seasons were laid out using a randomized complete block design with three replications. Data on pollen sterility, pollen diameter, plant height, and panicle height were collected and analyzed. Results showed that the CHAs had significant (p<0.05) differences for efficacy of inducing male sterility in sorghum. Ethrel at a dose of 1 gl-1 induced the highest pollen sterility (98% in both seasons) but was highly phytotoxic with at least 60% mortality in the test population in both seasons, making it unsuitable for practical application. TFMSA (2 mg per plant) and E4FO (1 gl-1) d induced 93% male sterility with minimal phytotoxic effects (20 to 30%). Application of either TFMSA at 2mg per plant after flag leaf emergence or 1gl-1 of E4FO at panicle initiation can be used to successfully induce male sterility in sorghum under greenhouse conditions

Characterization of tribenuron-methyl-induced male sterility in Brassica juncea L.

Significant heterosis has been documented in Brassica juncea L. that are grown as agriculturally important oilseeds, vegetables and condiments crops. Male sterility induced by chemical hybridizing agents is an important pollination control system in hybrid crop breeding. Herein, we show that tribenuron-methyl (TBM), a sulfonylurea herbicide, is an effective male gametocide in B. juncea when used at a very low dosage. In the present study, foliar application of various rates of TBM induced a significant increase in pollen sterility in B. juncea (90.57–100%). TBM-treated plants exhibited reductions in size of floral organ and yield components; however, lower dose of TBM (0.075 g a.i. ha–1) did not cause a significant reduction in seed yield per plant. Tapetum cells of TBM-treated plants were hypertrophied and degenerated earlier, and abnormal meiosis was observed at the meiotic stage. A significant decrease of acetohydroxyacid synthase (AHAS) activities was detected in buds of plants treated with 0.10 g a.i. ha–1 TBM, and RT-qPCR analysis showed that TBM exposure perturbed AHAS expression in small buds, which support that TBM induces male sterility in B. juncea by targeting AHAS expression. Our results suggest that TBM could be used as an efficient chemical hybridization agent in B. juncea, which has practical implications for the application of hybrid breeding in B. juncea.

Cyclin-Dependent Kinase Inhibitor Gene TaICK1 acts as a Potential Contributor to Wheat Male Sterility induced by a Chemical Hybridizing Agent.

Heterosis has been widely accepted as an effective strategy to increase yields in plant breeding. Notably, the chemical hybridization agent SQ-1 induces male sterility in wheat, representing a critical potential tool in hybrid seed production. However, the mechanisms underlying the male sterility induced by SQ-1 still remain poorly understood. In this study, a cyclin-dependent kinase inhibitor gene, TaICK1, which encodes a 229 amino acid protein, was identified as a potential contributor to male sterility in common wheat. The expression of TaICK1 was upregulated during the development of anthers in Xinong1376 wheat treated with SQ-1. Meanwhile, the seed setting rate was found to be significantly decreased in TaICK1 transgenic rice. Furthermore, we identified two cyclin proteins, TaCYCD2;1 and TaCYCD6;1, as interactors through yeast two-hybrid screening using TaICK1 as the bait, which were validated using bimolecular fluorescence complementation. Subcellular localization revealed that the proteins encoded by TaICK1, TaCYCD2;1, and TaCYCD6;1 were localized in the cell nucleus. The expression levels of TaCYCD2;1 and TaCYCD6;1 were lower in Xinong1376 treated with SQ-1. A further analysis demonstrated that the expression levels of OsCYCD2;1 and OsCYCD6;1 were lower in transgenic TaICK1 rice lines as well. Taken together, these results suggest that the upregulation of TaICK1, induced by SQ-1, may subsequently suppress the expression of TaCYCD2;1 and TaCYCD6;1 in anthers, resulting in male sterility. This study provides new insights into the understanding of SQ-1-induced wheat male sterility, as well as the developmental mechanisms of anthers.

Estimation of heterosis and combining abilities of U.S. winter wheat germplasm for hybrid development in Texas

AbstractHybrid wheat (Triticum aestivum L.) offers promises to break the yield stagnation in global wheat productivity as a result of heterosis. But, for this promise to be realized, the level of heterosis must be adequate. To test this, elite winter wheat lines from the breeding programs of the University of Nebraska–Lincoln (UNL) and Texas A&M University (TAMU) were crossed in a 25‐by‐25 full‐diallel design using a chemical hybridizing agent (CHA) to produce experimental hybrids. These hybrids were planted in a modified augmented design with commercial checks and parents at McGregor, TX, in 2016 (n = 612) and Greenville and Bushland, TX, in 2017 (n = 470) to evaluate for yield heterosis and combining ability. A subset of hybrids (n = 333) were repeated between years. The effect of field heterogeneity in grain yield was corrected by spatial modelling in ASReml‐R. Commercial heterosis ranged from −78.3 to 20.4% in 2016 and −32.9 to 6.2% in 2017. High‐parent heterosis (HPH) ranged from −70.4 to 54.3% in 2016 and −26.9 to 29.2% in 2017. General combining ability (GCA) variance was significantly higher than zero, whereas specific combining ability (SCA) variance was not. Significant maternal effect was identified in some crosses tested by computing reciprocal effects between crosses and estimating variances. This indicates that most of the heterosis is due to additive rather than dominance effect. These results suggest exploitation of GCA for higher yield while underscoring the need for development of heterotic pools to maximize SCA and dominance effects.

Determining the Efficacy of a Hybridizing Agent in Wheat (Triticum aestivum L.)

Hybrid wheat (Triticum spp.) has the potential to boost yields and enhance production under changing climates to feed the growing global population. Production of hybrid wheat seed relies on male sterility, the blocking of pollen production, to prevent self-pollination. One method of preventing self-pollination in the female plants is to apply a chemical hybridizing agent (CHA). However, some combinations of CHA and genotypes have lower levels of sterility, resulting in decreased hybrid purity. Differences in CHA efficacy are a challenge in producing hybrid wheat lines for commercial and experimental use. Our primary research questions were to estimate the levels of sterility for wheat genotypes treated with a CHA and determine the best way to analyze differences. We applied the CHA sintofen (1-(4-chlorphyl)-1,4-dihydro-5-(2-methoxyethoxy)-4-oxocinnoline-3-carboxylic acid; Croisor 100) to 27 genotypes in replicate. After spraying, we counted seed in bagged female heads to evaluate CHA efficacy and CHA-by-genotype interaction. Using logit and probit models with a threshold of 7 seeds, we found differences among genotypes in 2015. Sterility was higher in 2016 and fewer genotypic differences were found. When CHA-induced sterilization is less uniform as in 2015, zero-inflated and hurdle count models were superior to standard mixed models. These models calculate mean seed number and fit data with limit-bounded scales collected by agronomists and plant breeders to compare genotypic differences. These analyses can assist in selecting parents and identifying where additional optimization of CHA application needs to occur. There is little work in the literature examining the relationship between CHAs and genotypes, making this work fundamental to the future of hybrid wheat breeding.

Cytological and Proteomic Analysis of Wheat Pollen Abortion Induced by Chemical Hybridization Agent.

In plants, pollen grain transfers the haploid male genetic material from anther to stigma, both between flowers (cross-pollination) and within the same flower (self-pollination). In order to better understand chemical hybridizing agent (CHA) SQ-1-induced pollen abortion in wheat, comparative cytological and proteomic analyses were conducted. Results indicated that pollen grains underwent serious structural injury, including cell division abnormality, nutritional deficiencies, pollen wall defect and pollen grain malformations in the CHA-SQ-1-treated plants, resulting in pollen abortion and male sterility. A total of 61 proteins showed statistically significant differences in abundance, among which 18 proteins were highly abundant and 43 proteins were less abundant in CHA-SQ-1 treated plants. 60 proteins were successfully identified using MALDI-TOF/TOF mass spectrometry. These proteins were found to be involved in pollen maturation and showed a change in the abundance of a battery of proteins involved in multiple biological processes, including pollen development, carbohydrate and energy metabolism, stress response, protein metabolism. Interactions between these proteins were predicted using bioinformatics analysis. Gene ontology and pathway analyses revealed that the majority of the identified proteins were involved in carbohydrate and energy metabolism. Accordingly, a protein-protein interaction network involving in pollen abortion was proposed. These results provide information for the molecular events underlying CHA-SQ-1-induced pollen abortion and may serve as an additional guide for practical hybrid breeding.

The initial deficiency of protein processing and flavonoids biosynthesis were the main mechanisms for the male sterility induced by SX-1 in Brassica napus

BackgroundRapeseed (Brassica napus) is an important oil seed crop in the Brassicaceae family. Chemical induced male sterility (CIMS) is one of the widely used method to produce the hybrids in B. napus. Identification of the key genes and pathways that involved in CIMS were important to understand the underlying molecular mechanism. In the present report, a multi-omics integrative analysis, including of the proteomic, transcriptomic and miRNAs, combined with morphological and physiological analysis were conducted.ResultsEarlier degeneration of the tapetosomes and elaioplasts, aberrantly stacking in tapetal cells and incompletely deposition in tryphine of pollen wall were observed in chemical hybridization agent (CHA) of SX-1 treated B. napus through SEM and TEM analysis. It was revealed that the deficiencies in protein processing in endoplasmic reticulum (ER) and flavonoids biosynthesis were occurred at early stage in the SX-1 treated materials. Subsequently, plant hormone signal transduction, biosynthesis of amino acids, fatty acids and steroid in anther at later stages were identified down-regulated after SX-1 treatment. 144 transcript factors (TFs) were also indentified to down-regulated at early stage, which suggested the early regulation in anther and pollen wall development were disordered in CHA treated B. napus. In addition, 7 important miRNAs were identified and 2 of the predicted target genes of miRNAs were Rf-like genes.ConclusionsTaken together, an interaction network of candidate genes and the putative metabolism pathways were constructed based on the multi-omics integrative analysis, it provided a new insight into the male sterility induced by CHA of SX-1 in B. napus.

Indirect effects of chemical hybridization agent SQ-1 on clones of the wheat aphid Sitobion avenae

Indirect effects of chemical hybridization agent SQ-1 on clones of the wheat aphid Sitobion avenae

Kavunda ABA Uygulamalarının Bitki Büyümesi, Çiçek Cinsiyeti ve Çiçek Tozu Kalitesine Etkileri

Kavunlarda hibrit tohum üretiminde zaman, işgücü ve verim kaybının önüne geçmek için andromonoik ana materyalde erkek kısırlık ya da erkek kısırlığa sebep olacak kimyasal hibridizasyon ajanları (KHA) kullanımı önem taşımaktadır. Bu çalışmada bazı bitki türlerinde KHA olarak kullanılan ABA hormonunun Galia Fı kavun çeşidinde bitki gelişmesi, erkek çiçek oluşumu ve çiçek tozu kalitesi üzerine etkileri araştırılmıştır. Araştırmada ABA‘nın 250 ve 500 ppm‘lik iki dozu, fidelikte (F), serada ilk çiçeklenme döneminde askıya alınmış bitkilerde (İÇ) ve fidelik+ilk çiçeklenme dönemlerinde (F+İÇ) uygulanmıştır. Kontrol uygulamasındaki bitkilere ise sadece su püskürtülmüştür. Araştırma bulgularına göre, ABA‘nın 500 ppm‘lik dozunun F+İÇ ile F uygulamaları bitki gelişimini başlangıçta biraz baskılamış olmakla birlikte, sıcaklıkların yükselmesi ile bu etki ortadan kalkmıştır. ABA uygulamaları erkek çiçeklerin açmasını engellememiş olmakla beraber, erkek çiçek sayısı 500 ppm F+İÇ uygulamasında kontrole göre %62 oranında azalmıştır. Çiçek tozu canlılık ve çimlenmesi üzerine de ABA uygulamalarının kaliteyi arttırıcı bir etkisi olmamakla birlikte, canlılık ve çimlenme oranlarının %95‘in üzerinde olduğu tespit edilmiştir.

Male Sterility of an AHAS-Mutant Induced by Tribenuron-Methyl Solution Correlated With the Decrease of AHAS Activity in Brassica napus L.

Tribenuron-methyl (TBM), an acetohydroxyacid synthase (AHAS)-inhibiting herbicide, can be used as an efficient chemical hybridization agent to induce male sterility for practical utilization of heterosis in rapeseed (Brassica napus L.). Utilization of rapeseed mutants harboring herbicide-resistant AHAS alleles as the male parent can simplify the hybrid seed production protocol. Here we characterized a novel TBM-resistant mutant K5 derived from an elite rapeseed variety, Zhongshuang No. 9 (ZS9), by ethyl methyl sulfonate mutagenesis. Comparative analysis of three BnAHAS genes (BnAHAS1, BnAHAS2, and BnAHAS3) between the mutant K5 and ZS9 identified a C-to-T transition at 544 from the translation start site in BnAHAS1 in K5 (This resistant allele is referred to as BnAHAS1544T), which resulted in a substitution of proline with serine at 182 in BnAHAS1. Both ZS9 and K5 plants could be induced complete male sterility under TBM treatment (with 0.10 and 20 mg⋅L-1 of TBM, respectively). The relationship between TBM-induced male sterility (Y) and the relative AHAS activity of inflorescences (X) could be described as a modified logistic function, Y = 100-A/(1+Be(-KX)) for the both genotypes, although the obtained constants A, B, and K were different in the functions of ZS9 and K5. Transgenic Arabidopsis plants expressing BnAHAS1544T exhibited a higher TBM resistance of male reproductive organ than wild type, which confirmed that the Pro-182-Ser substitution in BnAHAS1 was responsible for higher TBM-resistance of male reproductive organs. Taken together, our findings provide a novel valuable rapeseed mutant for hybrid breeding by chemical hybridization agents and support the hypothesis that AHAS should be the target of the AHAS-inhibiting herbicide TBM when it is used as chemical hybridization agent in rapeseed.

Mitochondrial Dysfunction Causes Oxidative Stress and Tapetal Apoptosis in Chemical Hybridization Reagent-Induced Male Sterility in Wheat.

Male sterility in plants has been strongly linked to mitochondrial dysfunction. Chemical hybridization agent (CHA)-induced male sterility is an important tool in crop heterosis. Therefore, it is important to better understand the relationship between mitochondria and CHA-induced male sterility in wheat. This study reports on the impairment of mitochondrial function duo to CHA-SQ-1, which occurs by decreasing cytochrome oxidase and adenosine triphosphate synthase protein levels and theirs activities, respiratory rate, and in turn results in the inhibition of the mitochondrial electron transport chain (ETC), excessive production of reactive oxygen species (ROS) and disruption of the alternative oxidase pathway. Subsequently, excessive ROS combined with MnSOD defects results in damage to the mitochondrial membrane, followed by ROS release into the cytoplasm. The microspores underwent severe oxidative stress during pollen development. Furthermore, chronic oxidative stress, together with the overexpression of type II metacaspase, triggered premature tapetal apoptosis, which resulted in pollen abortion. Accordingly, we propose a metabolic pathway for mitochondrial-mediated male sterility in wheat, which provides information on the molecular events underlying CHA-SQ-1-induced abortion of anthers and may serve as an additional guide to the practical application of hybrid breeding.

Assessment of male sterility and antioxidant enzyme activities induced by the chemical hybridization agent SQ-1 in Foxtail Millet (Setaria italica)

Chemical hybridization agents (CHA) induced male sterility has long been researched in other plants, however, there is little information on the male sterility induced by CHA in foxtail millet. In this experiment, we investigated the optimized application stage and efficient dosage of the SQ-1 for inducing higher male sterility in Henggu 13 in 2015 and 2016. Some studies have suggested that CHA induced male sterility may suffer from oxidative stress. To study the physiological responses, the production and scavenging effects of the reactive oxygen species (ROS) were investigated.

Efficacy of chemical hybridizing agents for inducing male sterility in wheat

The present investigations were carried out to induce male sterility in wheat by using different chemical hybridizing agents (CHAs) at CCS Haryana Agricultural University, Hisar, Haryana. The genotypes exhibited differential response to CHAs in relation to induction of male sterility at similar doses and time of spray. Higher doses of all chemicals induced more male sterility than the lower doses in all the genotypes included in the study. CHC series of chemicals viz CHC 9901, CHC 9902, CHC 9903, CHC 9904 and CHC 9905 were found effective in inducing high level of male sterility(>90%). Among CH series CH 0288 at 2000 ppm induced maximum male sterility(82.42%)in genotype UP 2425. The genotype UP 2425 was found most responsive in relation to male sterility induction followed by PBW 343, WH 542 and UP 2338. But at the same time it was also found that these genotypes were affected with female sterility. Genotype PBW 343 was observed most sensitive to CHA treatments with respect to male sterility. Seed setting was also affected by female sterility.

Generation of tribenuron‐methyl herbicide‐resistant OsCYP81A6‐expressing rapeseed (Brassica napus L.) plants for hybrid seed production using chemical‐induced male sterility

AbstractChemical‐induced male sterility (CIMS) is a method for hybrid rapeseed (Brassica napus L.) production. Some sulphonylurea herbicides such as tribenuron‐methyl (TBM) are used as chemical hybridization agents (CHAs) in CIMS systems. However, the male parents must be protected from herbicide injury with a shield during spraying of the female parents with CHAs to induce male sterility. Thus, using herbicide‐resistant rapeseed lines as the male parents can significantly simplify the seed production procedure and reduce the cost in hybrid seed production. A rice cytochrome P450 hydroxylase, OsCYP81A6, has been previously characterized to confer resistance to bentazon and sulphonylurea herbicides. We demonstrate here that the introduction of OsCYP81A6 renders rapeseed plants resistant to TBM. Compared with wild‐type plants, the transgenic plants displayed normal stamen development and male fertility when treated with 0.05 mg/l of TBM, the dose used for inducing male sterility in hybrid seed production. These results indicate that the OsCYP81A6‐expressing rapeseed plants can be used as the male parents for hybrid rapeseed production using CIMS.

Programmed cell death, antioxidant response and oxidative stress in wheat flag leaves induced by chemical hybridization agent SQ-1

Male sterility induced by a chemical hybridization agent (CHA) is an important tool for utilizing crop heterosis. Leaves, especially the flag leaves, as CHA initial recipients play a decisive role in inducing male sterility. To investigate effects of different treatment times of CHA-SQ-1 used, morphological, biochemical and physiological responses of wheat flag leaves were detected in this study. CHA induced programmed cell death (PCD) as shown in terminal deoxynucleotidyl transferase-mediated dUTP nick end-labelling (TUNEL) and DNA laddering analysis. In the early phase, CHA-SQ-1 trig-gered organelle changes and PCD in wheat leaves accompanied by excess production of reactive oxygen species (O2▪ and H2O2) and down-regulation of the activities of superoxide dismutase (SOD), catalase (CAT) and guaiacol peroxidase (POD). Meanwhile, leaf cell DNAs showed ladder-like patterns on agarose gel, indicating that CHA-SQ-1 led to the activation of the responsible endonuclease. The oxidative stress assays showed that lipid peroxidation was strongly activated and photosynthesis was obviously inhibited in SQ-1-induced leaves. However, CHA contents in wheat leaves gradually reduced along with the time CHA-SQ-1 applied. Young flags returned to an oxidative/antioxidative balance and ultimately developed into mature green leaves. These results provide explanation of the relations between PCD and anther abortion and practical application of CHA for hybrid breeding.

THE RELATIONSHIP BETWEEN MALE STERILITY AND MEMBRANE LIPID PEROXIDATION AND ANTIOXIDANT ENZYMES IN WHEAT (Triticum aestivum L.)

Malondialdehyde (MDA), which is thought to be important inducible factor of cell apoptosis if excessively accumulated in cells, is often regarded as a widely used marker of oxidative lipid injury whose concentration varies in response to biotic and abiotic stress. To elucidate the metabolic mechanism of ROS production and scavenging of the male sterility, normal fertility and male sterility wheat, including genetic and physiologically male sterility, by comparing MDA content and antioxidant enzymes changes in the sterile and fertile leaves, spikes, florets, rachillaes, ovaries and anthers at different developmental anther stages, were employed for studying the relationship between the male sterility and membrane lipid peroxidation, antioxidant enzymes. The results showed that tissue of male sterility had roughly higher content of MDA than corresponding fertile plants, and ovary performance was not obvious but most obvious in anther. Simultaneously, the higher activities of antioxidant enzymes were measured in the anthers of male sterility plant, in which an increase of ROS in anthers of abortion stage had an inducible effect on the antioxidant enzymes. MDA content and scavenging-enzyme activities had difference in the sterile and fertile leaves, spikes, florets, rachillaes at different anther stages, indicating that different tissues of ROS metabolism had noticeable difference in male sterility and normal wheat. It can be considered that the disorder of scavenging-enzyme activities and accumulation of MDA in the male organ, and supplier of nutrition blades were causing a further substance metabolism disorder, energy loss, leading to the occurrence of male sterility. Key words: Wheat - male sterility – malondialdehyde - antioxidant enzymes Abbreviations: CAT---Catalase; CMS---Cytoplasmic male sterility; CHA---Chemical Hybridization Agent; GS---Cytoplasmic male sterile line (S)-1376; MDA---Malondialdehyde; NW---Wheat cultivar 1376; PMS---CHA-SQ-1 induced male sterility wheat; POD---Peroxidase; ROS---Reactive oxygen species; SOD---Superoxide dismutase; SEM---Scanning electronm icroscopy.

Comparative proteomic analysis of a membrane-enriched fraction from flag leaves reveals responses to chemical hybridization agent SQ-1 in wheat.

The induction of wheat male fertile lines by using the chemical hybridizing agent SQ-1 (CHA-SQ-1) is an effective approach in the utilization of heterosis; however, the molecular basis of male fertility remains unknown. Wheat flag leaves are the initial receptors of CHA-SQ-1 and their membrane structure plays a vital role in response to CHA-SQ-1 stress. To investigate the response of wheat flag leaves to CHA-SQ-1 stress, we compared their quantitative proteomic profiles in the absence and presence of CHA-SQ-1. Our results indicated that wheat flag leaves suffered oxidative stress during CHA-SQ-1 treatments. Leaf O2-, H2O2, and malonaldehyde levels were significantly increased within 10 h after CHA-SQ-1 treatment, while the activities of major antioxidant enzymes such as superoxide dismutase, catalase, and guaiacol peroxidase were significantly reduced. Proteome profiles of membrane-enriched fraction showed a change in the abundance of a battery of membrane proteins involved in multiple biological processes. These variable proteins mainly impaired photosynthesis, ATP synthesis protein mechanisms and were involved in the response to stress. These results provide an explanation of the relationships between membrane proteomes and anther abortion and the practical application of CHA for hybrid breeding.