Soybean is one of the most important food crops worldwide.  Like other legumes, soybean can form symbiotic relationships with Rhizobium species.  Nitrogen fixation of soybean via its symbiosis with Rhizobium is pivotal for sustainable agriculture.  Type III effectors (T3Es) are essential regulators of the establishment of the symbiosis, and nodule number is a feature of nitrogen-affected nodulation.  However, genes encoding T3Es at quantitative trait loci (QTLs) related to nodulation have rarely been identified. Chromosome segment substitution lines (CSSLs) have a common genetic background but only a few loci with heterogeneous genetic information; thus, they are suitable materials for identifying candidate genes at a target locus.  In this study, a CSSL population was used to identify the QTLs related to nodule number in soybean.  Single nucleotide polymorphism (SNP) markers and candidate genes within the QTLs interval were detected, and it was determined which genes showed differential expression between isolines.  Four candidate genes (GmCDPK28, GmNAC1, GmbHLH, and GmERF5) linked to the SNPs were identified as being related to nodule traits and pivotal processes and pathways involved in symbiosis establishment.  A candidate gene (GmERF5) encoding a transcription factor that may interact directly with the T3E NopAA was identified.  The confirmed CSSLs with important segments and candidate genes identified in this study are valuable resources for further studies on the genetic network and T3Es involved in the signaling pathway that is essential for symbiosis establishment. 

With the increased cultivation of Bt crops in China, Apolygus lucorum and other mirid bugs have emerged as important agricultural pests because they are insensitive to the Bt proteins.  In addition, the reduction of pesticide applications after planting Bt crops also increases the severity of mirid bug outbreaks.  Peristenus spretus is a parasitoid of mirid nymphs, but its sensitivity to Bt proteins is not known.  In the current study, we developed a dietary exposure assay to assess the effects of Bt proteins (Cry1Ab, Cry1Ac, Cry1F, Cry2Aa, and Cry2Ab) on P. spretus adults using a diet consisting of a 10% honey solution with or without Bt proteins at 400 µg g^–1 diet.  The results showed that the survival and reproduction of P. spretus adults were reduced by the cysteine protease inhibitor E-64 (a positive control) but were not affected by any of the five Bt proteins.  The activities of digestive, detoxifying, and antioxidant enzymes in P. spretus were also unaffected by diets containing the Cry proteins, but they were significantly affected by the diet containing E-64.  We then developed a tri-trophic bioassay to determine the effects of the five Bt proteins on P. spretus larvae and pupae.  In this assay, A. lucorum nymphs fed an artificial diet containing Cry proteins were used as the hosts for P. spretus.  The results of the tri-trophic assay indicated that neither the pupation rate nor the eclosion rate of the P. spretus parasitoids were significantly affected by the presence of high concentrations of Bt proteins in the parasitized A. lucorum nymphs.  The overall results indicate that these two assays can be used to evaluate the toxicity of insecticidal compounds to P. spretus and that the tested Cry proteins are not toxic to P. spretus.  

Wheat crown rot caused by Fusarium spp. is a common disease worldwide.  Both Fusarium pseudograminearum and Fusarium graminearum infect wheat crown and produce mycotoxin leading to grain loss due to white head.  F. pseudograminearum (Fp) was reported in wheat from Henan Province of China a couple of years ago.  The wheat crown rot (CR) caused by this new pathogen is as an emerging severe disease of wheat, which has recently expanded to several provinces in China and is, therefore, under rapid investigation.  Colonization of wheat tissue by Fp is accomplished though the formation of a septated foot-shaped appressoria and generation of a penetration peg to break through the internal cells of leaf sheath.  The molecular mechanism by which Fp regulates the pathogenesis on wheat host is unclear.  Here, we report FpPDE1, a P-type ATPase-encoding predicted PDE1 orthologue gene of Magnaporthe oryzae, belonging to the DRS2 subfamily of aminophospholipid translocases.  The gene deletion of FpPDE1 with the split-marker approach did not obviously affect hyphae growth and conidiation, but led to an attenuated virulence on wheat base stem and root.  Our finding indicates that the putative aminophospholipid translocases is not essential for the infectious hyphae development in Fp.  

Nitric oxide (NO) is a gaseous signaling molecule in plants that plays a key role in mediating a wide range of physiological processes and responses to biotic and abiotic stresses. The present study was conducted to investigate the effects of the exogenous application of sodium nitroprusside (SNP), an NO donor, on cadmium (Cd)-induced oxidative stress and Cd uptake in rice plants. Rice plants were exposed to Cd stress (0.2 mmol L-1 CdCl2) and different concentrations of SNP (0.05, 0.1, 0.2, and 0.4 mmol L-1). A SNP concentration of 0.1 mmol L-1 (SNP10) significantly reduced the Cd-induced decrease in shoot and root dry weights and leaf chlorophyll concentrations. The addition of NO also reduced the malondialdehyde (MDA), hydrogen peroxide (H2O2) and ascorbic acid (ASA) concentrations. However, the reduction in glutathione (GSH) concentration was inhibited by NO treatment. Moreover, NO prevented the Cd-induced increase in antioxidative enzyme activity. The amount of Cd accumulation in rice plants was also influenced by the addition of NO. The NO supplied by the SNP enhanced the Cd tolerance of the rice by increasing the Cd uptake by the roots and decreasing the Cd accumulation by the shoots. However, the application of potassium ferrocyanide (Cd+Fe) or sodium nitrate and nitrite (Cd+N) (without NO release), did not exhibit the effects of the SNP. Furthermore, the effects of the SNP were reversed by the addition of hemoglobin (an NO scavenger). Our results suggested that exogenous NO was involved in the resistance of rice to Cdtoxicity.