Reproduction and immune defense are costly functions, and they are expected to tradeoff with each other to drive evolution.  The brown planthopper (BPH), Nilaparvata lugens Stål (Hemiptera, Delphacidae), is a global superpest that mostly damages rice crops.  Yeast-like symbionts (YLS) exist in the abdominal fat body tissue and are tightly associated with the development, growth, and reproduction of BPH.  Our previous research demonstrated that mating behavior promotes the release of YLS from the fat body into the hemolymph in the BPH, thereby triggering an immune response.  Additionally, the fitness costs related to life-history traits of BPH (such as survival rate) have a strong dependence on the relative abundance of YLS.  However, the possible relationship between reproduction and the immune response in BPH has not been identified.  In this study, an omics-based approach was used to analyze the transcriptome of fat body tissues in mated and unmated BPH at 72 h post-eclosion, from which two antimicrobial peptide genes, NlDefensin A (NlDfA) and NlDefensin B (NlDfB), were selected since they were highly expressed in mated BPH.  Subsequently, the full-length cDNA sequences of the NlDfA and NlDfB genes were cloned and analyzed.  qPCR results showed up-regulation of the NlDfA and NlDfB genes in mated BPH when compared to unmated BPH.  Spatial-temporal expression analysis indicated that the NlDfA and NlDfB genes were expressed in all tissues and developmental stages, and they were most highly expressed in the fat body at 24 h post-eclosion.  Moreover, the symbionts in BPH were significantly inhibited by the in vitro expression of the NlDfA and NlDfB proteins.  Furthermore, RNA interference (RNAi)-mediated suppression of NlDfA and NlDfB dramatically increased the relative abundance of YLS in the fat body, while YLS in the hemolymph decreased significantly.  These BPHs also displayed some fitness disadvantages in survival, fecundity, hatchability, and possibly the vertical transmission of YLS from hemolymph to egg.  Our results indicated that mating could heighten the immunity of BPH by up-regulating the expression of the NlDfA and NlDfB genes, which protect the host from pathogen challenges during reproduction.  However, the reduced content of YLS may act as a fitness disadvantage in dictating the life-history traits of BPH.  This work has significant theoretical and practical implications for the precise green control technology that involves crucial gene targeting, as well as for the “endosymbionts for pest control” strategy in insects.

Inversion tillage with straw amendment is widely applied in northeastern China, and it can substantially increase the storage of carbon and improve multiple subsoil functions. Soil microorganisms are believed to be the key to this process, but research into their role in subsoil amelioration is limited. Therefore, a field experiment was conducted in 2018 in a region in northeastern China with Hapli-Udic Cambisol using four treatments: conventional tillage (CT, tillage to a depth of 15 cm with no straw incorporation), straw incorporation with conventional tillage (SCT, tillage to a depth of 15 cm), inversion tillage (IT, tillage to a depth of 35 cm) and straw incorporation with inversion tillage (SIT, tillage to a depth of 35 cm). The soils were managed by inversion to a depth of 15 or 35 cm every year after harvest. The results indicated that SIT improved soil multi-nutrient cycling variables and increased the availability of key nutrients such as soil organic carbon, total nitrogen, available nitrogen, available phosphorus and available potassium in both the topsoil and subsoil. In contrast to CT and SCT, SIT created a looser microbial network structure but with highly centralized clusters by reducing the topological properties of average connectivity and node number, and by increasing the average path length and the modularity. A Random Forest analysis found that the average path length and the clustering coefficient were the main determinants of soil multi-nutrient cycling. These findings suggested that SIT can be an effective option for improving soil multi-nutrient cycling and the structure of microbial networks, and they provide crucial information about the microbial strategies that drive the decomposition of straw in Hapli-Udic Cambisol.

Cell death is an important physiological phenomenon in life.  It can be programmed or unprogrammed.  Unprogrammed cell death is usually induced by abiotic or biotic stress.  Recent studies have shown that many proteins regulate both cell death and immunity in plants.  Here, we provide a review on the advances in plant immunity with cell death, especially the molecular regulation and underlying mechanisms of those proteins involved in both cell death and plant immunity.  In addition, we discuss potential approaches toward improving plant immunity without compromising plant growth.

 

Insects have developed a good adaptive mechanism in response to environmental stresses in the long-term evolution.
They have developed a helpful metabolism system to resist plant allelochemicals. Insects also harbor different kinds of
symbiotic bacteria, which provide them a competitive advantage. Here, using cotton aphid as an example, we investigated
the effects of four plant allelochemicals on the differential expression of symbiotic bacteria based on transcriptome data.
We also studied the composition of symbiotic bacteria and function on pathway level in three kinds of aphids. We found that
the bacteria have a significant role in resisting the plant allelochemicals stress and host plant selection by aphids. These
results should be useful to investigate the environmental adaption mechanism of aphids in the view of symbiotic bacteria.
These results would offer a new insight for improving strategy of aphids and developing new pest control systems.

The NAM-B1 gene is a member of the NAC (NAM, ATAF, and CUC) transcription factor family and plays an important role in regulating wheat grain protein content (GPC).  The ancestral NAM-B1 allele has been discovered in many tetraploid wild emmer (Triticum turgidum ssp. dicoccoides) accessions and few domesticated emmer accessions (T. turgidum ssp. dicoccum), however, it is rarely found in hexaploid bread wheat (Triticum aestivum L.).  There are no systematic reports on the distribution of NAM-B1 alleles in Chinese wheat cultivars.  In this study, the NAM-B1 alleles in 218 Chinese cultivars were investigated.  The cultivars were collected from five major wheat regions (12 provinces), covering most of the winter wheat growing regions in China.  The results showed that the NAM-B1 gene is present in 53 (24.3%) cultivars and absent in the remaining 165 (75.7%) cultivars.  Further analysis revealed that in contrast to the wild-type allele, the NAM-B1 gene in Chinese wheat cultivars contained a 1-bp insertion in the coding region.  This caused a frame-shift mutation and introduced a stop codon in the middle of the gene, rendering it non-functional.  Polymorphisms were detected in DNA sequences of 21 cultivars among these 53 cultivars.  However, cDNA sequence analysis suggested that these variations in the exon region were not able to restore NAM-B1 gene (1-bp insertion) function.  Thus, exploring the distribution of NAM-B1 gene variations (1-bp insertion and deletion) can provide some information for improving the quality of winter wheat in China and other countries.

Sucrose non-fermenting-1 related protein kinase 2 (SnRK2) is a unique family of protein kinases associated with abiotic stress signal transduction in plants. In this study, a maize SnRK2 gene ZmSnRK2.11 was cloned and characterized. The results showed that ZmSnRK2.11 is up-regulated by high-salinity and dehydration treatment, and it is expressed mainly in maize mature leaf. A transient expression assay using onion epidermal cells revealed that ZmSnRK2.11-GFP fusion proteins are localized to both the nucleus and cytoplasm. Overexpressing-ZmSnRK2.11 in Arabidopsis resulted in salt and drought sensitivity phenotypes that exhibited an increased rate of water loss, reduced relative water content, delayed stoma closure, accumulated less free proline content and increased malondialdehyde (MDA) content relative to the phenotypes observed in wild-type (WT) control. Furthermore, overexpression of ZmSnRK2.11 up-regulated the expression of the genes ABI1 and ABI2 and decreased the expression of DREB2A and P5CS1. Taken together, our results suggest that ZmSnRK2.11 is a possible negative regulator involved in the salt and drought stress signal transduction pathways in plants.

The bsd-pg (bundle sheath defective pale green) mutant is a novel maize mutation, controlled by a single recessive gene, which was isolated from offspring of maize plantlets regenerated from tissue callus of the maize inbred line 501. The characterization was that the biogenesis and development of the chloroplasts was mainly interfered in bundle sheath cells rather than in mesophyll cells. For mapping the bsd-pg, an F2 population was derived from a cross between the mutant bsd-pg and an inbred line Xianzao 17. Using specific locus amplified fragment sequencing (SLAF-Seq) technology, a total of 5 783 polymorphic SLAFs were analysed with 1 771 homozygous alleles between maternal and paternal parents. There were 49 SLAFs, which had a ratio of paternal to maternal alleles of 2:1 in bulked normal lines, and three trait-related candidate regions were obtained on chromosome 1 with a size of 3.945 Mb. For the fine mapping, new simple sequence repeats (SSRs) markers were designed by utilizing information of the B73 genome and the candidate regions were localized a size of 850 934 bp on chromosome 1 between umc1603 and umc1395, including 35 candidate genes. These results provide a foundation for the cloning of bsd-pg by map-based strategy, which is essential for revealing the functional differentiation and coordination of the two cell types, and helps to elucidate a comprehensive understanding of the C4 photosynthesis pathway and related processes in maize leaves.

Apple replant disease (ARD) causes the inhibition of root system development, stunts tree growth and so on. To further investigate the effects of ARD on apple fruits, a 25-year-old apple orchard was remediated to establish a replant orchard between November 2008 and March 2009. A rotational cropping orchard was established on an adjacent wheat field. The cultivar and rootstock-scion combination used in the newly established orchards was Royal Gala/M26/Malus hupehensis Rehd. Ripe fruits were collected in mid-August 2011 and mid-August 2012, meanwhile, the following indices were measured: yield per plant; fruit weight; the fruit shape index; the contents of anthocyanin, carotenoid and chlorophyll; the soluble sugar content in the flesh; titratable acid; the sugar-acid ratio; firmness; and aroma components; apple plant ground diameter, plant height increment and the total length of the current-year shoots. The results showed that compared to rotational cropping, continuous cropping yielded statistically significant reductions in fruit weight and yield per plant of 39.8 and 76.5%, respectively. However, there were no changes in the fruit shape index. The anthocyanin and carotenoid contents decreased by 81.7 and 37.7%, respectively, while the chlorophyll content increased by 251.0%. All of these differences in content were statistically significant. The soluble sugar levels and sugar-acid ratio decreased by 25.4 and 60.9%, respectively, but the titratable acid levels and fruit firmness increased by 90.9 and 42.8%, respectively. Ten of the most important esters contributing to the apple aroma were analyzed, and the following changes were observed: hexyl acetate, butyl acetate, hexyl butyrate, acetate-2-methyl butyl, 2-methyl-hexyl butyrate, amyl acetate, butyl butyrate, 2-methyl-butyl butyrate, hexyl propionate and hexyl hexanoate decreased by 25.5, 78.4, 89.1, 55.5, 79.5, 77.2, 86.8, 69.9, 61.2, and 68.1%, respectively. The contents of three other aroma components, (E)-2-hexenal, hexanal and 1-hexanol, significantly increased. Eight characteristic aroma components were found in the rotational cropping fruits: hexyl acetate, butyl acetate, acetate-2-methyl butyl, 2-methyl-hexyl butyrate, amyl acetate, 2-methyl- butyl butyrate, hexyl acetate and hexyl propionate. There were four characteristic ester components (hexyl acetate, butyl acetate, acetate-2-methyl butyl, 2-methyl-hexyl butyrate) and two characteristic aldehyde aroma components ((E)-2-hexenal and hexanal) in the continuous cropping fruits. Compared with the rotational cropping fruits, four characteristic ester components were declined and two characteristic aldehyde aroma components were increased. Compared with the control, replanted apple plant ground diameter, plant height increment and the total length of the current-year shoots were reduced by 27.6, 40.6 and 72.2%, respectively.

Aptamers are specific nucleic acid sequences that can bind to a wide range of nucleic acid and non-nucleic acid targets with high affinity and specificity. Nucleic acid aptamers are selected in vitro from single stranded DNA or RNA ligands containing random sequences of up to a few hundred nucleotides. Systematic evolution of ligands by exponential enrichment (SELEX) was used to select and PCR amplify DNA sequences (aptamers) capable of binding to and detecting Listeria monocytogenes, one of the major food-borne pathogens. A simplified affinity separation approach was employed, in which L. monocytogenes in exponential (log) phase of growth was used as the separation target. A fluorescently-labeled aptamer assay scheme was devised for detecting L. monocytogenes. This report described a novel approach to the detection of L. monocytogenes using DNA aptamers. Aptamers were developed by nine rounds of SELEX. A high affinity aptamer was successfully selected from the initial random DNA pool, and its secondary structure was also investigated. One of aptamers named e01 with the highest affinity was further tested in aptamer-peroxidase and aptamer-fluorescence staining protocols. This study has proved the principle that the whole-cell SELEX could be a promising technique to design aptamer-based molecular probes for dectection of pathogenic microorganisms without tedious isolation and purification of complex markers or targets.

Ethylene receptors play important roles not only in regulation of growth and development but also in response to environmental stimuli of plants. However, there are few reports on ethylene receptors in soybean. In this article, putative ethylene receptors of soybean were searched from soybean genomic database (http://www.phytozome.net/search.php) and analyzed. The ethylene receptor gene family in soybean comprising eight members, designated as GmERS1-1, GmERS1-2, GmETR1-1, GmETR1-2, GmETR2-1, GmETR2-2, GmEIN4-1, and GmEIN4-2 corresponding with their homologous genes in Arabidopsis, were isolated and analyzed. Phylogenetic analysis indicated that the eight soybean ethylene receptors (SERs) were in two subfamilies and further divided into four groups, viz., groups I (GmERS1-1 and GmERS1-2), II (GmETR1-1 and GmETR1-2), VI (GmETR2-1 and GmETR2-2), and VII (GmEIN4-1 and GmEIN4-2). Protein structure of the members in groups I and II from subfamily I were more conserved than the members in other two groups from subfamily II. Expression patterns of the SERs were compared with the homologous genes in Arabidopsis. The results demonstrated that expression patterns of the SERs differed from Arabidopsis members in the same group, suggesting that SERs are involved in different signal pathways compared to ethylene receptors in Arabidopsis. Promoter analysis showed that the sequences of the members in each group were different from each other, and some specific binding elements of transcription factors detected in promoter sequences might explain the differences between the members in the same group. A novel soybean TPR protein (tetratricopeptide repeat protein), GmTPR, was identified to interact with GmETR1-1, apparently an important ethylene receptor in ethylene signaling pathway in soybean. This suggested that GmTPR might be a novel downstream component of the ethylene signaling pathway.

Transgenic insect-resistant cotton is being increasingly planted in Xinjiang cotton-planting regions, where geographical climate conditions and species composition of pests and natural enemies are greatly unique in China. Limited studies have been conducted on the ecological impacts of transgenic insect-resistant cotton, especially for transgenic double genes (Bt+CpTI) cotton, in this region. In this study, the potential effects of transgenic Bt+CpTI cotton on the seasonal abundance of non-target pests and predators were assessed from 2009 to 2011 in Korla, Xinjiang. The results showed that species composition and seasonal abundance of 5 groups of pests and 5 groups of predators were not significantly different between transgenic Bt+CpTI cotton and non-transgenic cotton every year. It suggests that transgenic Bt+CpTI cotton per se does not affect the population dynamics of non-target pests and predators on this crop in Xinjiang.