StHAB1, a negative regulatory factor in abscisic acid signaling, plays crucial roles in potato drought tolerance and shoot branching.

Abscisic acid (ABA) is critical in drought tolerance and plant growth. Group A protein type 2C phosphatases (PP2Cs) are negative regulators of ABA signaling and plant adaptation to stress. Knowledge about the functions of potato group A PP2Cs is limited. Here, we report that the potato group A PP2C StHAB1 is broadly expressed in potato plants and strongly induced by ABA and drought. Suppression of StHAB1 enhanced potato ABA sensitivity and drought tolerance, whereas overexpression of the dominant mutant StHAB1G276D compromised ABA sensitivity and drought tolerance. StHAB1 interacts with almost all ABA receptors and the Snf1-Related Kinase OST1. Suppressing StHAB1 and overexpressing StHAB1G276D alter potato growth morphology; notably, overexpression of StHAB1G276D causes excessive shoot branching. RNA-sequencing analyses identified that the auxin efflux carrier genes StPIN3, StPIN5, and StPIN8 were up-regulated in StHAB1G276D-overexpressing axillary buds. Correspondingly, the auxin concentration was reduced in StHAB1G276D-overexpressing axillary buds, consistent with the role of auxin in repressing lateral branch outgrowth. The expression of BRANCHED1s (StBRC1a and StBRC1b) was unchanged in StHAB1G276D-overexpressing axillary buds, suggesting that StHAB1G276D overexpression does not cause axillary bud outgrowth via regulation of BRC1 expression. Our findings demonstrate that StHAB1 is vital in potato drought tolerance and shoot branching.

Chinese Preservice Teachers' Perspectives of Mentoring Relationships in an International Learning Partnership.

Mentoring is an essential fixture of teacher education. With growing opportunities for international learning exchanges, there is a need to better understand how cross-cultural mentoring can be characterized by reciprocal learning. This study investigated mentee perceptions of the mentoring relationship in an international, cross-cultural teacher education exchange. We conducted research among 19 Chinese preservice teachers who participated in an international teacher education exchange program, exploring their perspectives on the cross-cultural mentoring relationship and mutual learning. Our findings suggest that learning outcomes are improved in a mentoring relationship when there are strong relational ties, opportunities for reciprocal learning, and a greater awareness of cultural complexity. We contend that there is value in supporting the mentoring relationship directly, which has implications for both international exchanges and teacher education programs.

Resistance to RNA interference by plant-derived double-stranded RNAs but not plant-derived short interfering RNAs in Helicoverpa armigera.

Plant-mediated RNA interference (RNAi) has emerged as a promising technology for pest control through expression of double-stranded RNAs (dsRNAs) targeted against essential insect genes. However, little is known about the underlying molecular mechanisms and whether long dsRNA or short interfering RNAs (siRNAs) are the effective triggers of the RNAi response. Here we generated transplastomic and nuclear transgenic tobacco plants expressing dsRNA against the Helicoverpa armigera ATPaseH gene. We showed that expression of long dsRNA of HaATPaseH was at least three orders of magnitude higher in transplastomic plants than in transgenic plants. HaATPaseH-derived siRNAs are absent from transplastomic plants, while they are abundant in transgenic plants. Feeding transgenic plants to H. armigera larvae reduced gene expression of HaATPaseH and delayed growth. Surprisingly, no effect of transplastomic plants on insect growth was observed, despite efficient dsRNA expression in plastids. Furthermore, we found that dsRNA ingested by H. armigera feeding on transplastomic plants was rapidly degraded in the intestinal fluid. In contrast, siRNAs are relatively stable in the digestive system. These results suggest that plant-derived siRNAs may be more effective triggers of RNAi in Lepidoptera than dsRNAs, which will aid the optimization of the strategies for plant-mediated RNAi to pest control.

Synergistic action of the gut microbiota in environmental RNA interference in a leaf beetle.

BACKGROUND: RNA interference (RNAi) has emerged as an efficient tool to control insect pests. When insects ingest double-stranded RNAs (dsRNAs) targeted against essential genes, strong gene silencing and mortality can be induced. To exert their function, dsRNA molecules must pass through the insect's gut and enter epithelial cells and/or the hemolymph. Gut bacteria are known to play multifarious roles in food digestion and nutrition, and confer protection against pathogens and parasites. Whether there is a cross talk between gut bacteria and ingested dsRNAs and whether the microbiome affects RNAi efficiency are unknown. RESULTS: Here, using a leaf beetle gut microbiota system, we investigated whether gut bacteria interact with dsRNA molecules and how the gut microbiota affects RNAi responses in insects. We first showed that the leaf beetle Plagiodera versicolora (Coleoptera) is highly susceptible to RNAi. We then demonstrated that ingestion of dsRNAs by non-axenic P. versicolora larvae results in (i) significantly accelerated mortality compared with axenic larvae, and (ii) overgrowth and dysbiosis of the gut microbiota. The latter may be caused by bacterial utilization of dsRNA degradation products. Furthermore, we found that Pseudomonas putida, a gut bacterium of P. versicolora, acts as major accelerator of the death of P. versicolora larvae by transitioning from commensal to pathogenic lifestyle. CONCLUSIONS: The present study illuminates the complex interplay between lethal dsRNA, the insect host, and its gut microbiota. The ingestion of dsRNA by the leaf beetle caused a dysbiosis of gut bacterial community, and the dsRNA degradation products by host insect preferentially promoted the growth of an entomopathogenic bacterium, which accelerated dsRNA lethality to the insect. Our findings reveal a synergistic role of the gut microbiota in dsRNA-induced mortality of pest insects, and provide new insights in the mechanisms of RNAi-based pest control. Video abstract.

Plastid-expressed Bacillus thuringiensis (Bt) cry3Bb confers high mortality to a leaf eating beetle in poplar.

KEY MESSAGE: The Bacillus thuringiensis (Bt) cry3Bb gene was successfully introduced into poplar plastid genome, leading to transplastomic poplar with high mortality to Plagiodera versicolora. Poplar (Populus L.) is one of the main resource of woody industry, but being damaged by insect pests. The feasibility and efficiency of plastid transformation technology for controlling two lepidopteran caterpillars have been demonstrated previously. Here, we introduced B. thuringiensis (Bt) cry3Bb into poplar plastid genome by biolistic bombardment for controlling P. versicolora, a widely distributed forest pest. Chimeric cry3Bb gene is controlled by the tobacco plastid rRNA operon promoter combined with the 5'UTR from gene10 of bacteriophage T7 (NtPrrn:T7g10) and the 3'UTR from the E. coli ribosomal RNA operon rrnB (TrrnB). The integration of transgene and homoplasmy of transplastomic poplar plants was confirmed by Southern blot analysis. Northern blot analysis indicated that cry3Bb was transcribed to both read through and shorter length transcripts in plastid. The transplastomic poplar expressing Cry3Bb insecticidal protein showed the highest accumulation level in young leaves, which reach up to 16.8 µg/g fresh weight, and comparatively low levels in mature and old leaves. Feeding the young leaves from Bt-Cry3Bb plastid lines to P. versicolora caused 100% mortality in the first-instar larvae after only 1 day, in the second-instar larvae after 2 days, and in the third-instar larvae for 3 days. Thus, we report a successful extension of plastid engineering poplar against the chrysomelid beetle.

Profiling and simultaneous quantitative determination of oligostilbenes in Paeonia ostii seed shell from different geographical areas in China and their comparative evaluation.

INTRODUCTION: The Paeonia ostii T. Hong & J. X. Zhang seed shell, characterised by a high content of oligostilbenes, is one of the two most important by-products in the preparation of seed oil. Oligostilbenes are considered characteristic constituents of the genus Paeonia, and can be used in fingerprinting to determine the geographical origin and the quality of raw materials. OBJECTIVE: To develop and optimise a simple and reproducible high-performance liquid chromatography diode array detection (HPLC-DAD) method for the simultaneous determination of seven oligostilbenes in P. ostii seed shell from different geographical areas, and to associate the cultivation area. METHODOLOGY: A validated HPLC method coupled with a DAD detector was performed for the detection and determination of target compounds in the samples. Optimal chromatographic conditions were achieved using an Agilent Zorbax Eclipse SB-AQ-C18 column and a gradient elution with acetonitrile and potassium dihydrogen phosphate solution. RESULTS: The proposed quantitative method showed appropriate accuracy and precision, and was successfully applied to the routine analysis of seven oligostilbenes and the quality evaluation of 50 P. ostii seed shell samples. There were significant differences between the contents of the seven oligostilbenes in different samples (P < 0.01). CONCLUSION: The results demonstrated that the oligostilbenes were main secondary metabolites in the P. ostii seed shells, and the content of seven components in P. ostii seed shells sourced from different cultivation areas in China was different.

Oil Contact Angles in a Water-Decane-Silicon Dioxide System: Effects of Surface Charge.

Oil wettability in the water-oil-rock systems is very sensitive to the evolution of surface charges on the rock surfaces induced by the adsorption of ions and other chemical agents in water flooding. Through a set of large-scale molecular dynamics simulations, we reveal the effects of surface charge on the oil contact angles in an ideal water-decane-silicon dioxide system. The results show that the contact angles of oil nano-droplets have a great dependence on the surface charges. As the surface charge density exceeds a critical value of 0.992 e/nm2, the contact angle reaches up to 78.8° and the water-wet state is very apparent. The variation of contact angles can be confirmed from the number density distributions of oil molecules. With increasing the surface charge density, the adsorption of oil molecules weakens and the contact areas between nano-droplets and silicon dioxide surface are reduced. In addition, the number density distributions, RDF distributions, and molecular orientations indicate that the oil molecules are adsorbed on the silicon dioxide surface layer-by-layer with an orientation parallel to the surface. However, the layered structure of oil molecules near the silicon dioxide surface becomes more and more obscure at higher surface charge densities.

Amylases StAmy23, StBAM1 and StBAM9 regulate cold-induced sweetening of potato tubers in distinct ways.

Cold-induced sweetening (CIS) in potato is detrimental to the quality of processed products. Conversion of starch to reducing sugars (RS) by amylases is considered one of the main pathways in CIS but is not well studied. The amylase genes StAmy23, StBAM1, and StBAM9 were studied for their functions in potato CIS. StAmy23 is localized in the cytoplasm, whereas StBAM1 and StBAM9 are targeted to the plastid stroma and starch granules, respectively. Genetic transformation of these amylases in potatoes by RNA interference showed that ß-amylase activity could be decreased in cold-stored tubers by silencing of StBAM1 and collective silencing of StBAM1 and StBAM9. However, StBAM9 silencing did not decrease ß-amylase activity. Silencing StBAM1 and StBAM9 caused starch accumulation and lower RS, which was more evident in simultaneously silenced lines, suggesting functional redundancy. Soluble starch content increased in RNAi-StBAM1 lines but decreased in RNAi-StBAM9 lines, suggesting that StBAM1 may regulate CIS by hydrolysing soluble starch and StBAM9 by directly acting on starch granules. Moreover, StBAM9 interacted with StBAM1 on the starch granules. StAmy23 silencing resulted in higher phytoglycogen and lower RS accumulation in cold-stored tubers, implying that StAmy23 regulates CIS by degrading cytosolic phytoglycogen. Our findings suggest that StAmy23, StBAM1, and StBAM9 function in potato CIS with varying levels of impact.

[Mechanisms of epigenetic reprogramming in Mammalian resonstructed embryos produced by nuclear transfer.].

Circumstantial studies indicated that incomplete or inappropriate epigenetic reprogramming of donor nuclei was likely to be the primary reason for failures in nuclear transfer. In this view, we discussed the roles of several epigenetic mechanisms, including DNA methylation, chromatin remodeling, imprinting and X chromosome inactivation, telomere maintenance, and epigenetic inheritance in the observed abnormalities in clones from different species. Understanding the mechanisms underlying epigenetic reprogramming control will help us resolve the inherent problems in nuclear transfer technology and make its applications promising.