Processing Properties and Potency of Bacillus thuringiensis Cry Toxins in the Rice Leaffolder Cnaphalocrocis medinalis (Guenée).

Different Cry toxins derived from Bacillus thuringiensis (Bt) possess different insecticidal spectra, whereas insects show variations in their susceptibilities to different Cry toxins. Degradation of Cry toxins by insect midgut extracts was involved in the action of toxins. In this study, we explored the processing patterns of different Cry toxins in Cnaphalocrocis medinalis (Lepidoptera: Crambidae) midgut extracts and evaluated the impact of Cry toxins degradation on their potency against C. medinalis to better understand the function of midgut extracts in the action of different Cry toxins. The results indicated that Cry1Ac, Cry1Aa, and Cry1C toxins could be degraded by C. medinalis midgut extracts, and degradation of Cry toxins by midgut extracts differed among time or concentration effects. Bioassays demonstrated that the toxicity of Cry1Ac, Cry1Aa, and Cry1C toxins decreased after digestion by midgut extracts of C. medinalis. Our findings in this study suggested that midgut extracts play an important role in the action of Cry toxins against C. medinalis, and the degradation of Cry toxins by C. medinalis midgut extracts could reduce their toxicities to C. medinalis. They will provide insights into the action of Cry toxins and the application of Cry toxins in C. medinalis management in paddy fields.

SmJAZ4 interacts with SmMYB111 or SmMYC2 to inhibit the synthesis of phenolic acids in Salvia miltiorrhiza.

Jasmonic acid (JA), as an important plant hormone, can induce the synthesis of phenolic acids in Salvia miltiorrhiza Bunge, a model medicinal plant, but the specific mechanism remains to be further elucidated. JA-responsive SmMYB111 positively regulates the biosynthesis of salvianolic acid B (SalB), but the molecular mechanism is unclear. Here, we found that SmMYB111 directly binds to the promoters of SmTAT1 and SmCYP98A14 and activates their transcription. Yeast two hybrid and bimolecular fluorescent complementation assay indicated that SmMYB111 interacts with SmJAZ4. Furthermore, we systematically characterized the function of SmJAZ4, which was highly expressed in flowers and roots and located in the nucleus and cell membrane. The contents of phenolic acids in the SmJAZ4-overexpressed transgenic plantlets and SmJAZ4-overexpressed transgenic hairy roots decreased significantly. SmJAZ4 interacts with SmMYC2 or SmMYB111 to repress their transcriptional activation activity on target enzyme genes of the biosynthesis pathway of phenolic acids. Overall, the molecular mechanism of SmJAZ4-SmMYC2/SmMYB111 module participating in JA signaling regulation of SalB biosynthesis was elucidated, which give a clue for the molecular regulation of phenolic acids biosynthesis in S. miltiorrhiza.

R2R3-MYB Transcription Factor SmMYB52 Positively Regulates Biosynthesis of Salvianolic Acid B and Inhibits Root Growth in Salvia miltiorrhiza.

The dried root of Salvia miltiorrhiza is a renowned traditional Chinese medicine that was used for over 1000 years in China. Salvianolic acid B (SalB) is the main natural bioactive product of S. miltiorrhiza. Although many publications described the regulation mechanism of SalB biosynthesis, few reports simultaneously focused on S. miltiorrhiza root development. For this study, an R2R3-MYB transcription factor gene (SmMYB52) was overexpressed and silenced, respectively, in S. miltiorrhiza sterile seedlings. We found that SmMYB52 significantly inhibited root growth and indole-3-acetic acid (IAA) accumulation, whereas it activated phenolic acid biosynthesis and the jasmonate acid (JA) signaling pathway. Quantitative real-time polymerase chain reaction (qRT-PCR) analyses revealed that SmMYB52 suppressed the transcription levels of key enzyme-encoding genes involved in the IAA biosynthetic pathway and activated key enzyme-encoding genes involved in the JA and phenolic acid biosynthesis pathways. In addition, yeast one-hybrid (Y1H) and dual-luciferase assay showed that SmMYB52 directly binds to and activates the promoters of several key enzyme genes for SalB biosynthesis, including SmTAT1, Sm4CL9, SmC4H1, and SmHPPR1, to promote the accumulation of SalB. This is the first report of a regulator that simultaneously affects root growth and the production of phenolic acids in S. miltiorrhiza.

Cloning of a putative extracellular Cu/Zn superoxide dismutase and functional differences of superoxide dismutases in invasive and indigenous whiteflies.

Superoxide dismutases (SODs) are a group of important antioxidant defense enzymes. In this study, a putative extracellular Cu/Zn superoxide dismutase (ecCuZnSOD) complementary DNA was cloned and characterized from the whitefly, Bemisia tabaci. Quantitative polymerase chain reaction analysis showed that the expression level of BtecCuZnSOD was more than 10-fold higher in the invasive Middle East Asia Minor 1 (MEAM1) than in the native Asia II 3 species of the B. tabaci species complex. After exposure to low temperature (4 °C), the expression of Bt-ecCuZnSOD gene was significantly up-regulated in MEAM1 but not in Asia II 3. Furthermore, the expression level of B. tabaci intracellular CuZnSOD (Bt-icCuZnSOD), Bt-ecCuZnSOD and mitochondrial MnSOD (Bt-mMnSOD) was compared after transferring MEAM1 and Asia II 3 whiteflies from favorable (cotton) to unfavorable host plants (tobacco). On cotton, both CuZnSOD genes were expressed at a higher level in MEAM1 compared with Asia II 3. Interestingly, after transferring onto tobacco, the expression of Bt-ecCuZnSOD was significantly induced in Asia II 3 but not in MEAM1. On the other hand, while Bt-mMnSOD was expressed equally in both species on cotton, Bt-mMnSOD messenger RNA was up-regulated in MEAM1 on tobacco. Consistently, enzymatic activity assays of CuZnSOD and MnSOD demonstrated that CuZnSOD might play an important protective role against oxidative stress in Asia II 3, whereas MnSOD activation was critical for MEAM1 whiteflies during host adaptation. Taken together, our results suggest that the successful invasion of MEAM1 is correlated with its constitutive high activity of CuZnSOD and inducible expression of MnSOD under stress conditions.

Mapping QTLs for yield and nitrogen-related traits in wheat: influence of nitrogen and phosphorus fertilization on QTL expression.

KEY MESSAGE: The present study identified some new important genomic regions and demonstrated the availability of conditional analysis in dissecting QTLs induced by environmental factors. The high input and low use efficiency of nutrient fertilizers require knowledge of the genetic control of crop reaction to nutrient supplements. In this study, 14 morphological and 8 physiological traits of a set of 182 wheat (Triticum aestivum L.) recombinant inbred lines (Xiaoyan 54 × Jing 411) were investigated in six environments to map quantitative trait loci (QTLs). The influence of nitrogen (N) and phosphorus (P) fertilization on QTL expression was studied by unconditional and conditional analysis. A total of 117 and 30 QTLs were detected by unconditional and conditional analysis, respectively, among which 21 were common for both methods. Thirty-four QTL clusters were identified. Eighteen conserved QTLs (15.4 % of the 117 QTLs) between years, but within nutritional treatment were found. The three major QTLs on chromosomes 2D, 4B and 6A were coincident with Rht8, Rht-B1b and TaGW2, respectively. The other two important intervals on chromosomes 4B and 7A for yield component traits were newly detected QTLs that warrant further study. By conditional analysis, spikelet number per spike was found to be induced by P fertilization mostly, whereas N fertilization had more effects on the expression of the QTLs for nitrogen concentration and utilization efficiency traits. QTLs that respond to N and P interactions were also detected. The results are helpful for understanding the genetic basis of N utilization efficiency in wheat under different N and P supplement environments and provide evidence for the availability of conditional analysis in dissecting QTLs induced by environmental factors.

Xiaochaihu Decoction attenuates the vicious circle between the oxidative stress and the ALP inactivation through LPS-catecholamines interactions in gut, liver and brain during CCI4+ethanol-induced mouse HCC.

BACKGROUND: Xiaochaihu Decoction (XCHD) prevents hepatocarcinogenesis in association with inhibition of oxidative stress. However, alkaline phosphatase (ALP) activity, lipopolysaccharides (LPS)-catecholamines (CA) interactions in gut, liver and brain may play an important role in the status of oxidative stress. This study was to assess whether XCHD attenuates the vicious circle between oxidative stress and ALP inactivation through LPS-CA interactions. METHODS: Hepatocellular carcinoma group (HCC) were induced by CCI4 + ethanol; HCC with Liver Depression and Spleen Deficiency (HCC + LDSD) were induced by squeezing tails (30 min/day), solitary breeding and intermittent fasting on the basis of HCC; XCHD was administered after 4 weeks of the HCC + LDSD. The degree of tissue injury were studied using a scoring system, and brain weights were measured. Peroxynitrite (ONOO(-)), malondialdehyde (MDA), 4-hydroxy-3-methoxymandelic acid (VMA, CA metabolites), lipopolysaccharide-phosphate (LPS-P), ALP activity (ALP-A) and Concanavalin A (ConA)-binding rate of ALP (ALP-C) were determined by colorimetric method and lectin (ConA) affinity precipitation method. RESULTS: More injuries and ONOO(-), MDA, VMA, LPS-P, ALP-C were increased, ALP-A were decreased in the gut, liver and brain of HCC group, the most in HCC + LDSD group, after treatment with XCHD, all of which were improved. A positive association found between gut-liver-brain injury and ONOO(-), MDA, VMA, LPS-P, ALP-C, between ONOO(-), MDA, VMA, LPS-P and ALP-C in the gut, liver and brain, and a negative association found between gut-liver-brain injury and ALP-A, between ALP-A and ONOO(-), MDA, VMA, LPS-P, ALP-C in the gut, liver and brain. CONCLUSIONS: XCHD can attenuates the vicious circle between the oxidative stress, nitrosative stress, N-glycan deficiency and inactivation of ALP through LPS-CA interactions in gut, liver and brain.