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.
In the study, a new mitogen-activated protein kinase (MAPK) gene designated as STK1 was cloned from Setosphaeria turcica and the function of the gene was characterized by virtue of gene knockout technology. The results elucidated that STK1 shared the similar role with Saccharomyces cerevisiae and some filamentous fungi in regulating high osmotic stress reaction. We also found that STK1 was involved in pathogenicity by regulating appressorium development and Helminthosporium turcicum (HT)-toxin biosynthesis in the pathogen, which enlightened us the understanding about the functions of high osmolality glycerol (HOG)-MAPK homologues in eukaryotes. This figure indicated the differences of mycelium morphology and inhibition rates between STK1 knockout mutant (ΔSTK1, under) and wild-type strain (01-23, upper) under high osmotic stress treatments, 1 mol L–1 KCl, 1 mol L–1 LiCl, and, under 2 mol L–1 sorbitol, respectively. See pages 2786–2794 by LI et al. in detail.
Some fruit crops in warm and cold regions, such as sweet cherry (Prunus avium L.), have specific winter chilling requirements to break endodormancy. Sufficient winter chilling hours along with favorable spring temperature guarantee full and uniform development of foliage and flowering in deciduous fruit trees. One of the major limit factors for sweet cherry production in these warm regions is the winter chilling requirements, which are generally from 600 to 1400 h by a 7.2°C model. Some symptoms, such as delayed foliation, deformed or abortion of flowers, and subsequent poor fruit set have been widely observed in these warm regions. A study on morphological anatomy have shown that sweet cherry trees with insufficient chilling accumulation exhibited little difference in the progression of microspore development compared to trees with adequate chilling, but showed substantial delays in ovule and embryo sac development. Nucelli did not grow beyond the macrospore mother cell and macrospore stages. These results suggest that winter chilling hours regulates the development of female floral organs in winter dormancy. In addition, hydrogen cyanamide could eliminate the abnormalities of ovule and embryo sac, and it may be a potential strategy for sweet cherry production in these regions. As for the details, please see pages 2529–2538 by WANG et al.
Subspecific hybridization combined with utilization of ideal plant type has led to the development of high-yielding japonica rice in Northeast China for half a century. The nuclear genome plays a predominant role in the inheritance of most traits, however, cytoplasmic and cytoplasmic-nuclear interactions also influence specific physiological activities. To assess cytoplasm types, we sampled 36 varieties utilized in large-scale cultivation in Northeast China. Simultaneously, we collected samples representing five typical categories of Oryza sativa as controls, including 10 indica, 9 aus, 8 tropical japonica, 5 Japanese temperate japonica, and 2 aromatic varieties. Finally, 5 high-yielding japonica cultivars in large-scale cultivation in Northeast China were determined to possess O. sativa L. ssp. indica-type cytoplasm using cytoplasmic subspecies-specific molecular markers. This was confirmed by phylogenetic and haplotype network analysis based on cytoplasmic genome-wide single nucleotide polymorphisms (SNPs) and functional gene sequencing in the chloroplast and mitochondrial genomes. We constructed nuclear substitution lines to further demonstrate whether and how this indica type cytoplasm contributed to yield improvement by comparing yield components. Compared to recurrent parents, the nuclear substitution lines with indica type cytoplasm had a significant decrease in tillers in exchange for increased grain number per panicle. Our results implied that botanical basis of this cytoplasmic effect was to reduce the plant’s branching differentiation to produce more floral organs under the constant nutrition. See pages 2183–2191 by LIU et al. in details.
Leaf plays a key role in photosynthesis in rice, so premature senescence of this organ will directly reduce the yield and negatively affect grain quality. A novel premature senescence mutant, mps1 (mid-late stage premature senescence 1), was identified from the ethyl methane sulfonate (EMS) induced descendants of Jinhui 10 (WT), an elite indica restorer line of rice. The candidate gene, MPS1, mainly drove the leaves to turn yellow when mutant grew to tillering stage, and accelerates leaf senescence from grain filling stage to final maturation. We characterized the agronomic traits, content of photosynthetic pigments and photosynthetic efficiency of mps1 and WT, and fine-mapped MPS1. The results showed that the MPS1-drove premature phenotype appeared initially on the leaf tips at the late tillering stage and extended to the middle of leaves during the maturing stage. Compared to the WT, significant differences were observed among traits of the number of grains per panicle (–31.7%) and effective number of grains per panicle (–38.5%) of mps1. Chlorophyll contents among the 1st leaf from the top (Top 1st), the 2nd leaf from the top (Top 2nd) and the 3rd leaf from the top (Top 3rd) of mps1 were significantly lower than those of WT (P<0.05), and the levels of photosynthetic efficiency from Top 1st to Top 4th (the 4th leaf from the top) of mps1 were significantly lower than those of WT (P<0.01). Results from the genetic analysis and molecular mapping indicated that MPS1 is a recessive nuclear gene and located in a 37.4-kb physical interval between the markers Indel145 and Indel149 on chromosome 6. Genomic annotation suggested eight open reading frames (ORFs) within this physical region, none of which was formerly reported associating with premature senescence in rice. These results suggest a novel molecular mechanism associated with premature senescence in rice. See pages 1944–1954 by LIU et al. in detail.
In South China, soil and water loss results in the decrease of farmland and affects crop yield. A large amount of sediment is deposited in the farmland resulting in land desertification. When compared to the normal cultivated farmland, the sandy farmland exhibited an increase in bulk density but a decrease in soil porosity, water holding capacity and fine particulate matter. Soil physical properties showed regular changes, with a downward trend in soil quality from fan edge to fanhead in the alluvial fan of collapsing gully (a special kind of soil erosion that severely deteriorates the qualities of soil in granite regions). Additionally, the soil in alluvial fan exhibited a significant decrease in the chemical properties such as soil pH, the organic matter, cation exchange capacity, total potassium, total nitrogen, total phosphorus, available nitrogen, available phosphorus, and available potassium. The soil nutrients from fanhead to fan edge showed a gradual increase. Furthermore, collapsing gully erosion caused an increase in soil erodibility of alluvial fan, with the maximum erodibility K value observed in fanhead. We find that different land use patterns are effective to improve the quality of the soil in alluvial fan of collapsing gully, including the improvements of the soil structure, nutrients and anti-erosion ability and therefore provide important implications for the soil improvement in the farmland of alluvial fan of collapsing gully. See pages 1863–1873 by DENG et al. in details.
The trade of live poultry is suspected to be a major pathway of the spread of highly pathogenic avian influenza, but market chains of poultry trade have been studied through indirect means. Forty live domestic ducks were deployed with miniaturized GPS-GSM transmitters hidden under back feathers, and this experimental field telemetry documented movements of live ducks and provided a clue of market chains from source farms to live bird markets. See pages 1584–1594 by Choi et al. in details.