Chemical Hybridizing Agent SQ-1 Research Articles

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.

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

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.

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.

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.

De Novo Assembly and Transcriptome Analysis of Wheat with Male Sterility Induced by the Chemical Hybridizing Agent SQ-1.

Wheat (Triticum aestivum L.), one of the world’s most important food crops, is a strictly autogamous (self-pollinating) species with exclusively perfect flowers. Male sterility induced by chemical hybridizing agents has increasingly attracted attention as a tool for hybrid seed production in wheat; however, the molecular mechanisms of male sterility induced by the agent SQ-1 remain poorly understood due to limited whole transcriptome data. Therefore, a comparative analysis of wheat anther transcriptomes for male fertile wheat and SQ-1–induced male sterile wheat was carried out using next-generation sequencing technology. In all, 42,634,123 sequence reads were generated and were assembled into 82,356 high-quality unigenes with an average length of 724 bp. Of these, 1,088 unigenes were significantly differentially expressed in the fertile and sterile wheat anthers, including 643 up-regulated unigenes and 445 down-regulated unigenes. The differentially expressed unigenes with functional annotations were mapped onto 60 pathways using the Kyoto Encyclopedia of Genes and Genomes database. They were mainly involved in coding for the components of ribosomes, photosynthesis, respiration, purine and pyrimidine metabolism, amino acid metabolism, glutathione metabolism, RNA transport and signal transduction, reactive oxygen species metabolism, mRNA surveillance pathways, protein processing in the endoplasmic reticulum, protein export, and ubiquitin-mediated proteolysis. This study is the first to provide a systematic overview comparing wheat anther transcriptomes of male fertile wheat with those of SQ-1–induced male sterile wheat and is a valuable source of data for future research in SQ-1–induced wheat male sterility.

Gene expression and DNA methylation alterations in chemically induced male sterility anthers in wheat (Triticum aestivum L.)

DNA methylation plays an important role in gene expression regulation during biological development in plants. To explore the mechanism of chemically induced male sterility (CIMS) in wheat, using cDNA-amplified fragment length polymorphism (cDNA-AFLP) and methylation-sensitive amplification polymorphism (MSAP) approaches, 6.66 and 3.42 % of the sequences showed changes in gene expression and DNA methylation in 1376-CIMS as compared to its fertility line 1376. We sequenced 54 fragments that differed in cDNA-AFLP and 26 DNA fragments which differentially displayed in MSAP comparisons of CIMS and 1376. Our results provided evidences for genome-wide changes in gene expression and DNA methylation occurring in the development of the 1376-CIMS system induced by chemical hybridizing agent SQ-1, and its counterpart fertility line 1376. Moreover, this study contributed to the elucidation of CIMS effects on responses of transcriptome and methylome in the development of the anther.

Male Sterility Induced by Chemical Hybridizing Agent SQ-1 in <I>Setaria italica</I> Beauv.

Male Sterility Induced by Chemical Hybridizing Agent SQ-1 in <I>Setaria italica</I> Beauv.

Comparison of Chloroplast Proteomes Extracted from Florets of Physiological and Genic Male Sterile Lines and Their Maintainer Line in Wheat

The objective of this study was to explain the male sterile mechanism of wheat (Triticum aestivum L.) based on chloroplast proteome. A method for isolating intact chloroplast proteome from wheat floret was established. Using this method, the chloroplast proteomes were extracted from florets of the genic and physiological male sterile lines and their maintainer line, and separated in 2-dimensional electrophoresis (2-DE) gels. The cytoplasmic-nuclear sterile line, ms(S)-1376, had identical nuclear background with the maintainer line, (A)-1376, and the physiological male sterile line, ms(A)-1376, was derived from (A)-1376 after induction of chemical hybridizing agent SQ-1. The extraction method was effective to obtain high purity of intact chloroplast using discontinuous sucrose density gradient centrifugation with 3-step gradient densities of 30, 45, and 60%. The 2-DE result showed that the floret chloroplast protein profiles were different among the 3 lines at uninucleate anther stage, and 239 protein spots were visible on each gel (pH 4-7, molecular weight 14.4-66.2 kD). Six differentially expressed proteins were analyzed by matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF-MS) and indexed in bioinformation database. They were identified as acyl-CoA dehydrogenase domain protein, calmodulin-binding protein phosphatase, multiple catalytic peptidase, heat-shock protein 60, light receptor protein 2, and a protein of unknown function. These proteins are involved in series of physiological reactions such as metabolism of energy substances, chloroplast defendance, chloroplasts signal transduction, and plant growth. The differential expressions of these proteins among the 3 lines are likely related to the male sterility in wheat.

Male Sterility Induced by Chemical Hybridizing Agent SQ-1 in Common Millet

Effect of chemical hybridizing agent SQ-1 on common millet was studied with the split plot design. The different treatment stages and dosages of SQ-1 were designed as main plot and sub-plot respectively. Male sterility induced by SQ-1 was evaluated according to the three indexes: male sterile rate, crossing rate, and seed-setting rate of natural pollination. The results showed that treatment stages, dosages of SQ-1 and the interaction between them affected male sterile rate and crossing rate sig- nificantly or highly significantly. The induced male sterile rate and crossing rate were both over 95% with treatments of different dosages (4.0 and 5.0 kg ha?1) in the differentiation stage of the anlage of gynoecium and stamen, and also under the dosage of 5.0 kg ha?1 at the primary stage of forming pollen. The seed-setting rate of natural pollination was not affected significantly by the treatment stages, but affected significantly by the dosages and interaction between the treatment stages and dosages, and decreased with the dosage. Considering all the three indexes and the cost of production of hybrid seed, the optimum treatment stage is the differentiation stage of the anlage of gynoecium and stamen and the optimal dosage is 4.0 kg ha?1.