Somatic embryogenesis (SE) plays a vital role in genetic transformation and massive propagation of important agronomicaland economical crops. In this study, we conducted a systematic assessment of the morphological, cytochemical, and cytogenetical characteristics of six culture strains with various embryogenic/regenerative potential during SE process in cotton. Results indicated that the six cell culture strains had stable ploidy levels, and did not reveal any relationship between the cytogenetic state and their morphogenetic potential. Moreover, the six culture strains were compared via double staining with Evans blue and Acetocarmine to efficiently distinguish embryogenic and nonembryogenic cells and determine the embryogenic nature of the calli. In addition, the kind of auxins added in medium affected not only growth property, color, size of cell clumps but also ploidy level and regeneration ability. By combining analysis of morphological, cytochemical, and cytogenetical characteristics of the cell cultures, we are able to obtain and maintain homogeneous cell population with high morphogenic and regeneration ability and establish efficient somatic embryogenesis and regeneration system from short-term cell cultures in upland cotton, which highlight the application of biotechnological approaches in crop breeding, and above all, to better understand totipotency of cells in higher plants. The photo here shows high-regenerative somatic embryos under light microscope, provided by Prof. Zeng Fanchang from the State Key Laboratory of Crop Biology, Ministry of Science and Technology/College of Agronomy, Shandong Agricultural University, China. See pages 1–8 by Guo et al. in details.
It is important to identify resistance genetic sources for identification of the genes underlying resistance to the devastating pathogen, soybean cyst nematode (SCN, Heterodera glycines Ichinohe), on soybean (Glycine max (L.) Merr.), for management of this pathogen. In this study, two ethane methylsulfonate (EMS)- mutagenesis populations of soybean PI 437654 and Zhonghuang 13 were developed, from which many types of morphological phenotypes were observed. Thirteen mutants were identified to display alteration of resistance to SCN race 4 through forward genetic screening of 400 PI 437654 mutants. These identified mutants did not show any changes in the genomic sequences of the three known SCN-resistant genes and were still resistant to SCN race 3 similar to the wild-type soybean. Thus, the thirteen identified mutants carry the mutations of the new gene(s) contributing to the resistance to SCN race 4 in PI 437654 and can be potentially used as the genetic soybean sources to further identify the novel SCN-resistant gene(s). Photos showed here were the two representative morphological phenotypes (short but high yield (right on top panel) and coat color change (left on bottom panel)), SCN infection (left on top panel) and cysts on soybean roots (right on bottom panel) of EMS-mutagenized soybean mutants. The photos were provided by Liu Shiming, Zhang Liuping, Ge Fengyong and Peng Deliang, the Institute of Plant Protection, Chinese Academy of Agricultural Science. See pages 2734–2744 by Ge et al. in details.
Rusts are severe fungal diseases threatening the global wheat production. Our current knowledge on systemic acquired resistance (SAR) and pathogenesis-related (PR) protein in cereal crops of wheat and barley may provide valuable clues for improving their resistance in novel ways. These photos show the possible model of SAR-like responses in wheat and barley (1), symptom of wheat leaf rust (2), stripe rust (3), urediniospore (4) and uredium (5) of stripe rust. The presented issue summarizes specific features of the SAR-like responses and PR proteins in wheat and barley. The photos were provided by Prof. Kang Zhensheng from Northwest A&F University, China (2, 3, 4, and 5) and Associate Prof. Wang Xiaodong from Hebei Agricultural University, China (1), respectively. See pages 2467–2491 in details.
Silicon is a beneficial element for the healthy growth and development of a wide range of plant species, especially under various forms of abiotic and biotic stress. All plants take up Si, but Si content ranges from ca. 0.1 to 10% (w/w), depending largely on plant species and external Si concentration. Rice is a typical Si-accumulator. If Si2O content in rice straw at mature stage is below 10%, Si deficiency symptoms such as willow-shaped leaf blades occur. Under Si deficiency, lodging and disease susceptibility increases in rice. LSi1 (left) is a rice mutant defective in LSi1 gene (Si influx) responsible for Si uptake and transport from solution to root cells. The Si content of the mutant is only about 10% that of its wide type (WT, right). The rice mutant is extremely low in biomass, fertility and yield with severe grain discoloration and disease infection as compared to its WT. Cover photos were provided by Prof. LIANG Yong-chao from College of Environmental and Resource Sciences, Zhejiang University, China. See pages 2138–2150 by Yan et al. for more details.
Strawberry vein banding virus (SVBV) is an important virus infecting strawberry (Fragaria spp.). SVBVinfected strawberry cells contain cytoplasmic inclusions with isometric particles. In this study, SVBV open reading frame (ORF) VI was expressed ectopically in Nicotiana benthamiana. The P6 protein accumulates and forms amorphous, cytoplasmic inclusion bodies (IBs) with different sizes. P6 IBs aligns with microtubules and the endoplasmic reticulum, and trafficks along microfilaments for co-localization with the P1 protein at periphery of cells. In addition, P6 IB formation requires a nuclear localization signal (NLS) located within the C-terminal 25 amino acids of P6, and P6 protein deleted NLS region is also unable to facilitate exogenous green fluorescent protein expression. Photo showed here was the GFP accumulation in leaf discs at 3 days post infiltration after agroinfiltration with P6 and P6 mutant. See pages 2031–2041 by Pan Yuan et al. in detail.
Tree peony is a traditional ornamental plant and its seed oil is now being produced in China. The unsaturated fatty acids content in peony seed oil is more than 90%, especially α-linolenic acid (ALA), whose content is more than 40%, whereas in other edible oils, the ALA content is commonly lower than 10%. Paeonia ostii is the most widely used tree peony species for oil extraction, which is commercially called Fengdan and treated as a single cultivar. Here, 50 P. ostii individuals from the same population in northern China were randomly selected for fatty acid (FA) analysis, and the statistical analysis indicated that most of the individual FA, saturated FA, unsaturated FA, and total FA levels showed significant positive correlations to each other, whereas the seed yield per plant was independent. Therefore, we suggest that Fengdan cannot be simply treated as one uniform cultivar. Besides, our results may also help to simplify the resource selection in breeding and accelerate the development of this industry. See pages 1758–1767 by Wei et al. in details. Photo showed here was the fully mature seed pod of P. ostii provided by Prof. Zhang Xiuxin from Institute of Vegetables and Flowers, Chinese Academy of Agriculture Sciences, China.
The oriental armyworm, Mythimna separata (Walker), a typical long-distance migratory insect, is a major, polyphagous pest of grain crops in China and other Asian countries. With the recent adjustment in agricultural planting structure in China and global climate change, the regularity of occurrence within regions seems to be changing as well. JIA organized this special focus on the progress of population occurrence and migration regularity, including M. separata closely related species biology, migration energy from nectar plants, trajectory analysis of migration route, and immigrant habitat environment influence and resistance identification. Several related armyworm species often co-infest fields with M. separata, introducing complications in monitoring and forecasting owing to sparse knowledge of their basic biology. Access to nectar plants during migration is a prerequisite for adult long-distance migration and reproduction, and their distribution provides clues to the armyworm migration pathway. Population data and trajectory analysis provide technical support for fine-scale forecasting of outbreaks. Habitat environment such as host plant, weed coverage and temperature affect population abundance and occurrence, and taking them into account can benefit development of new agronomic management tactics. Monitoring insecticide resistance is of immediate importance in developing effective integrated pest management strategies for this insect. Cover photo is provided by Prof. JIANG Xing-fu, Institute of Plant Protection, Chinese Academy of Agricultural Sciences.
Bovine mastitis is one of the most common diseases in dairy farm, which may cause serious harm to dairy cows, including decreasing milk yield and milk quality. How to prevent/control mastitis is one of the largest issues in the whole dairy industry internationally. To enhance the international exchange of information relating to mastitis control and milk quality, the 2017 International Bovine Mastitis Conference & the National Mastitis Council (NMC) Regional in China was successfully held in Beijing on August 25–27, 2017. The conference provided an communication platform for international counterparts, and the content was closely related to all aspects of dairy cow health, including dairy mastitis pathogens, diagnose, therapeutics, management, residue, bacterial resistance and milk safety. Here, we provide a special focus relevant to the conference proceedings. The photo here is provided by Dr. Guo Jiangpeng, Beijing General Station of Animal Husbandry, China.
Peanut is an important oil crop in China which occupies an important position in production, consumption and trade in the world. Currently, there are about 9 000 variety resources and nearly 300 main cultivars in China. The rich variety resources have laid a solid foundation for the development of peanut processing industry. However, till now, few special peanut raw materials for processing have been found due to longterm neglect on raw material characteristics and quality evaluation technology which seriously restricts the peanut processing industry development. Thus, based on the deep study on the raw material characteristics and product qualities, the relationship between raw material and product has been established by mathematical correlation analysis method. Through this processing suitability evaluation model (Y=f(X)), we could easily obtain the best variety for peanut butter processing. See pages 1003–1010 by Gong et al. in detail. The photo here is provided by Prof. WANG Qiang, Institute of Food Science and Technology, Chinese Academy of Agricultural Science.
Duck hepatitis B virus (DHBV) shares many basic characteristics with hepatitis B virus (HBV) and is an attractive model for vaccine development. In this study, DHBV DNA vaccines were designed to express envelope and capsid fusion proteins to enhance the breadth of immune response in ducks. Attenuated Salmonella typhimurium (SL7207) was used as a carrier and adjuvant to boost the magnitude of immune response. The results of this study enriched our knowledge of the antigenicity of envelope and capsid fusion proteins in ducks and demonstrated the value of using attenuated S. typhimurium (SL7207) to deliver DHBV vaccines. In the future, it is worth further exploring DNA vaccines expressing multiple antigen genes delivered by attenuated S. typhimurium, as well as the therapeutic benefits when applied to the duck model of DHBV infection. See pages 928–939 by Liu et al. in details. The photo showed here were ducklings inoculated with DHBV DHA vaccines delivered by attenuated S. typhimurium which was provided by Liu Siyang and Prof. Jia Renyong from the Avian Disease Research Center, Sichuan Agricultural University, China.
The root-knot nematode Meloidogyne graminicola causes significant yield loss and is considered one of the most important pests affecting rice. After second-stage juveniles hatch from eggs, they invade at the rice root tips and induce giant cells as food resource throughout their life cycle. These giant cells are embedded as root galls, which always correlate with susceptibility of plants to nematode. In present research, we used the root gall index and number of nematodes inside the roots to evaluate resistance/susceptibility to M. graminicola in different subpopulations of rice. We observed that the number of M. graminicola nematodes inside the roots correlated very strongly with the nematode gall index. Among the tested varieties, three varieties showed significantly lower root gall index than others and were highly resistant to M. graminicola under both pot and field conditions. In addition, nematodes penetrated less often into these highly resistant varieties and more frequently failed to develop into females. Thereby, the resistant varieties found in the present research might be useful for the breeding of rice and for further practical nematode management measures in China. See pages 621–630 by Zhan et al. in details. Photos showed here were different developmental stages of M. graminicola in the root galls and were provided by Prof. Huang Wen-kun from the Institute of Plant Protection, Chinese Academy of Agricultural Sciences.
Dongxiang wild rice (Oryza rufipogon Griff., DWR) is an accession of common wild rice collected from Dongxiang County, Jiangxi Province, China. It is one of the second class national protected wild plants in China. Our previous results and other studies confirmed that DWR has owned many useful genes lacking in the cultivated rice, including strong cold tolerance, drought resistance, P-deficiency tolerance, etc. Among these useful agronomic characteristics, the cold tolerance is the most significant feature. DWR can successfully overwintering in Wuhan City, Hubei Province, China, where the minimum temperature reaches to –12°C in winter. In order to develop useful germplasms with unique gene from DWR and utilize these germplasms for cultivated rice improvement, we developed a set of BC1F10 backcross inbred lines (BILs) through a backcrossing and single-seed descent program. Firstly, an elite indica-cultivated rice Xieqingzao B (O. sativa L. ssp. indica, recurrent parent) and DWR (donor parent) were used to produce F1 hybrid (left picture). Afterward, the hybrid F1 was backcrossed to Xieqingzao B to create BC1F1 population. Finally, the BC1F1 population selfed consecutively to obtain BC1F10 inbred lines using single-seed descent method. The BC1F10 population was used to interesting traits assessment and QTL analysis. Some elite introgression lines (ILs, right picture) with interesting genes from DWR have been identified. And these elite ILs would be helpful for cloning and utilizing useful genes from wild rice. See pages 265–275 by Luo et al. in detail.
Herbaceous peony (Paeonia lactiflora Pall.) is a traditional famous flower in China. Flower color is an important trait, which is associated directly with the ornamental and commercial development values. However, although there are rich resources in herbaceous peony cultivars with diverse colors such as pink, red, purple, there is only one yellow cultivar. Breeding peony cultivars with novel colors has vital significance and market prospects. Chalcone isomerase (CHI), a key enzyme converting yellow chalcone to colorless naringenin, plays an important regulatory role in flowers color formation. In this study, we not only revealed the expression pattern of CHI gene in inner and outer petals of herbaceous peony, but also obtained the upstream promoter region of CHI. Additional, the key regulatory regions and candidate transcription factor binding sites of CHI promoter were clarified. Thereby, this study would provide theoretical basis for a further study of CHI gene function, meanwhile provide a certain strategy for the study on other flower color. See pages 122–129 by WU et al. in details. Photos showed here were different herbaceous peony cultivars provided by Prof. Tao Jun from the College of Horticulture and Plant Protection, Yangzhou University, China.
The year 2017 marks the 15th anniversary of Journal of Integrative Agriculture (JIA), an official journal of the Chinese Academy of Agricultural Sciences (CAAS). JIA has experienced a successful journey during the past 15 years. To celebrate the 15th anniversary, a special issue was organized including 25 themes addressed in crop science, plant protection, animal science and veterinary medicine, agro-ecosystem & environment, food science, agricultural economics and management. The significant scientific advances and the important methods within the specialists’ areas are highlighted in this anniversary issue.
The improvement of grain number per spike (GNPS) is widely emphasized in wheat yield breeding and depends on the development of genetic resources with high GNPS. A new wheat germplasm Pubing 3504 showed superior features in spike traits, although the genetic base of spike and yield related traits in Pubing 3504 remains unclear. A total of 282 F2:3 families were developed from the cross Pubing 3504×Jing 4839, and seven yield traits including GNPS, spike length (SL), kernel number per spikelet (KPS), spikelet number per spike (SNS), thousand grain weight (TGW), spike number per plant (SNP), and plant height (PH) were investigated in four environments including 2009 Beijing, 2010 Beijing, 2010 Shaanxi, and 2010 Sichuan. A genetic map was constructed using 190 polymorphic simple sequence repeat (SSR), expressed sequence tag (EST)-SSR, and sequencetagged-site (STS) markers. A total of 37 QTLs in a single environment analysis and 25 QTLs in joint environment analysis were detected. Additive effects of 70.3% (in a single environment) and 57.6% (in joint environment) QTLs were positive contributed by Pubing 3504 alleles. Five important genomic regions on chromosomes 1A, 4A, 4B, 2D, and 4D could be detected. Among them, the marker interval Xmag834– Xbarc83 on the short arm of chromosome 1A was a novel important genomic region, which included the QTLs that controlled GNPS, KPS, SNS, TGW, and SNP with stable environmental repeatability. The genomic region above could improve the spike trait evidently, thereby playing a very key role in improving wheat yield in future. See pages 2386–2401 by CHEN et al. in details.
Powdery mildew (PM) is a serious wheat disease. Dasypyrum villosum is an ideal genetic resource for the improvement of PM resistance of wheat. Both translocation chromosomes T6V#4S·6DL and T6V#2S·6AL developed from the cross of wheat and different Dasypyrum villosum accessions harbor good PM resistance gene(s) on the alien chromosome arms. Although molecular evidence has suggested that the two alien chromosomes are homologous to group-6 chromosomes in Triticeae, their pairing and pyramiding behavior remains unclear. Results in this study found that the two different alien chromosome arms were failed to pair in most pollen mother cells (PMCs) of their hybrid F1 at meiosis period revealed by genomic in situ hybridization (GISH), which might be caused partly by their structural differentiation; the heterochromatin knobs with different size near telomeres were observed in three types at pachytene by GISH, including well paired, partly paired, and separated chromosome arms between 6V#2S and T6V#4S; the pairing of the two alien chromosome arms might facilitate the transmission of T6V#4S·6DL from F1 to F2 generation; quadrivalent was appeared in some PMCs of the homozygote plants containing the two pairs of translocated chromosomes. Thereby, it will be possible to obtain recombinants of the two alien chromosome arms and clarify if the PM resistance determinant on one alien chromosome arm is different from that on the other one.
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