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.
A plant chimera containing cells of different genetic origins in the shoot apical meristem (SAM) will be morphologically and chemically different compared with the parents, and thus may result in differential resistance to herbivores. Two periclinal chimeras (labeled as TTC and TCC) were produced by shoot apex grafting in vitro between tuber mustard (TTT) and red cabbage (CCC). Both chimeras possessed leaf trichomes as tuber mustard, however, TTC had significantly more trichomes than TCC. Leaf wax content of both chimeras was intermediate between the two parents. Five aliphatic and two indole glucosinolates were detected in both chimeras, whereas three and one aliphatic glucosinolates were not detected in tuber mustard and red cabbage, respectively. The olfactory preference assays indicated that Bemisia tabaci preferred to CCC, followed by two chimeras and TTT, and the number of eggs laid showed the same pattern. Interestingly, more whiteflies landed on TTT plants than the other three types in a free choice experiment and the developmental duration from egg to adult was the shortest on TTT and increased on two chimeras and CCC. The results indicate that the plant traits of leaf waxes, trichomes and glucosinolates are influenced by interactions amongst cell layers of SAM. The overall findings suggest that periclinal chimera systems can be a valuable approach for the study of plantinsect interactions and may also be useful for future resistance breeding. See pages 2009–2018 by Li et al. in details.
Oryza ridleyi is an allotetraploid wild species with an HHJJ genome and one of the most divergent species of Oryza based on the phylogenetic relationship, but Oryza sativa is a diploid cultivated rice worldwide that has the AA genome. The distant phylogenetic relationship caused serious reproductive barrier to cross between them, interspecific hybrids were nevertheless obtained by means of young embryo rescue techniques. An obvious heterosis was primarily found for the plant height, tillering ability, vegetative vigor, etc. Genomic in situ hybridization (GISH) analysis demonstrated that the hybrid is an allotriploid with 36 chromosomes and its genomic constitution is AHJ. Chemical analyses conducted on the culm of O. sativa, O. ridleyi, and their interspecific hybrids showed that major changes occurred in the xylose, glucose, and arabinose contents, which are correlated with the specific hemicellulose polymer and cellulose components that are important in the primary cell walls of green plants. The anatomical analyses of culm indicated that additional large vascular bundles and an extra sclerenchyma cell layer were found in O. ridleyi, and further thickening of the secondary cell walls of the cortical fiber sclerenchyma cells and the phloem companion cells were discovered in O. ridleyi and in the interspecific hybrids. These results implied that the favorable traits from O. ridleyi could be transferred and utilized in the future rice breeding programme. See pages 1676–1681 by YI et al. in details.
Cereal cyst nematodes, one of the most important plant parasitic nematodes (PPNs), have caused severe damage to cereal crops worldwide. In China, two cyst nematodes (Heterodera avenae, Heterodera filipjevi) are important and serious pathogens of wheat and barley, which occur and distribute in 16 provinces of wheat production area and are severely threatened to wheat yield in China. Compatible interaction mechanism between host plant and cereal cyst nematodes is important for developing new management strategies. As wheat has complex genetics and a lower efficacy for transformation, an alternative host - barley cultivar Golden Promise was found as a suitable candidate model host for investigation interaction with cereal cyst nematodes. See pages 1537–1546 by LUO et al. in details. The picture showed a subcrystal attached the surface of the young female of H. avenae on barley during compatible interaction, which was provided by Prof. PENG De-liang from the Institute of Plant Protection, Chinese Academy of Agricultural Sciences.
Unlike other natural resources for renewable energy, such as the sun, wind, and water, biomass is very likely to be the only viable alternative to fossil fuels for the production of liquid biofuels, biochemicals, and biomaterials.It is a crucial issue to sustainably produce plant biomass feedstock at large scales.Northwest China has vast marginal land resources suitable for large-scale development of energy crops.JIA organized a special focus on bioenergy addressing this issue, which contains five sections: (1) Modeling of cellulosic bioenergy development; (2) Switchgrass in the Loess Plateau; (3) Improvement of energy crops for arid and semi-arid areas; (4) Analysis of cellulosic biomass; and (5) Bioconversion and bioprocess.More research capacity is required to develop new crops and cultivars that are more adaptive to multiple stresses in arid and semi-arid areas.In addition to feedstock development, more fundamental, applied and strategic research should be carried out to develop sustainable cropping systems, to well understand plant biomass production and its responses to environmental stresses, and to develop technologies for the production of bioenergy and bio-based products.The ultimate objective is to combine food security and the supply of feedstock for the development of bio-based economy in a sustainable and cost effective way.Potential energy crops, such as switchgrass (left) and sweet sorghum (right, together with the smaller grain sorghum), have been shown potential for cultivation on marginal land in Northwest China. Images were provided by Prof. Christopher Grof, University of Newcastle, Australia (right) and Prof. XU Bing-cheng, Northwest A&F University, China (left).
China’s super rice research has made great achievements in the past 20 years.In recent years, the annual planting area of super rice cultivars is maintained at about 9 million ha, which continues making significant contribution to rapid increase in national average rice yield.China is in the leading position in basic research of rice yield potential, generation of elite germplasm, and breeding theory of “generating an ideotype with strong heterosis through inter-subspecies hybridization” for both indica super hybrid rice cultivars in southern China and conventional japonica super rice cultivars in northern China.The large-erect-panicle type is one of the most famous ideotype for super rice.The main goal of this approach is to breed new super high yield rice varieties, through a combination of ideotype and hybrid vigor by crossing indica and japonica rice.To achieve the target yield of 10–13.5 t ha–1, the ideotype design patterns included: erect or semi-erect panicle, strong root activity, high and broad-spectrum disease resistance, normal tillering, 95–105 cm plant height, about 150 grains per panicle, 25–30 g per 1000-grain weight and a harvest index of 0.55–0.60.The success of super rice breeding in China provides scientific bases and technical strategies for further improvement of rice yield potential, and it also help China maintain its leading position in the field of rice crop science in the world.The figures were provided by Associate Prof. TANG Liang from Rice Research Institute, Shenyang Agricultural University, China.
Chitin is an important content in the exoskeletons of arthropods, and its hydrolyzation is catalyzed by chitinases during the process of molting.This study identified two important chitinase genes of Tetranychus cinnabarinus (TcCHIT1 and TcCHIT10) based on their expression patterns.The mRNA levels of these two genes showed high abundance during the molting process and their expression changes during the developmental stages were consistent with the enzyme concentration.Thus, TcCHIT1 and TcCHIT10 are potential targets to interfere the growth of the pest mites.This figure shows the protein structural models of TcCHIT1 (up) and TcCHIT10 (down), with amino acid sequence of predicted α-helices (green) and β-strands (blue), stereo views of the active site showing amino acid of GH18_chitolectin_chitotriosidase, and surface of the protein structure with locations of active sites.See pages 892–899 by XU et al. in details.
Plum pox virus (PPV) is one of the most ubiquitous viral pathogen of stone fruit tree and serious concern for
fruit growers worldwide (left), fruit deformation cause by PPV infection in plum (photo provided by Polák J,
Crop Research Institute, Czech Republic). Wheat streak mosaic virus (WSMV) cause a re-emerging disease
in cereal crops (mainly in wheat) with growing importance for cereal production in Central Europe (upper
right), leaf mottling (mosaic pattern of green and chlorotic zones) and leaf streaking in wheat infected by
WSMV (photo provided by Kundu J K, Crop Research Institute, Czech Republic). Heterodera avenae is one
of the most prevalent and damaging cyst-forming nematode for wheat and barley in different parts of the word
including Central Europe (bottom right), anterior region of second stage juvenile of H. avenae (photo provided
by Kumari S, Crop Research Institute, Czech Republic).
Rice area has been expanding rapidly during the past 30 years under the in?uence of global changes in northeastern China, which is the northernmost region of rice cultivation in China.However, the spatio-temporal dynamic changes in rice area are still unclear, although they may have important policy implications for environmental protection and adaptation to climate change.In this study, we aimed to identify the dynamic changes of the rice area in HeilongjiangProvince of northeastern China by extracting data from multiple Landsat images.The rice distribution in the northern part of Heilongjiang during the past 30 years is shown that the rice area increased substantially (spatio-temporal distribution of the rice area in Heilongjiang in 1984 (A), 1989 (B), 2000 (C) and 2013 (D)).The cultivated area in the survey region increased by 2.4×106 ha over the past 30 years, with an annual increase of 8.0×104 ha.Considering the rice production in three periods, i.e., 1984–1989 (1980s), 1990–1999 (1990s), and 2000–2013 (2000s), the increment in the rice area increased gradually.The increment for each period was 0.21×106, 0.65×106 and 1.55×106 ha, respectively.The annual increment of 3.50×104, 6.48×104 and 11.90×104 ha yr–1 for the three periods, respectively, also represented a progressive increase.See pages 360–367 by Li et al. in details.
Sweetpotato (Ipomoea batatas (L.) Lam.) is an important root crop and planted widely in more than 100 countries, most of which locate in the tropics and subtropics. Its wild relatives contain many useful and desirable genes lacking in the cultivated sweetpotato. However, gene transfer from these wild species to sweetpotato through sexual hybridization is usually difficult due to the cross-incompatibility between sweetpotato and its wild relatives. It is shown that somatic hybridization can be used to overcome the cross-incompatibility and transfer desired characteristics from wild relatives to cultivated plants. In this study, we analyzed morphological characteristics, drought tolerance, genetic variations, DNA methylation variations and cytoplasm genome contents of an interspecific somatic hybrid, KT1, between sweetpotato cv. Kokei No. 14 and its wild relative I. triloba. This figure indicated morphological characteristics of KT1 and its parents. KT1 has stems with no twining characteristic, similar to those of Kokei No. 14. Its vine diameter and internode length were medium between Kokei No. 14 and I. triloba. The mature leaf color was dark green, with purple veins, and petiole pigmentation was purple, which were obviously different from those of its both parents. KT1 produced the storage roots with white skin, different from Kokei No. 14, while its root fresh color was white, similar to that of Kokei No. 14. See pages 36–46 by JIA et al. in details.
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