Active changes of lignification-related enzymes in pepper response to Glomus intraradices and/or Phytophthora capsici

The activities of enzymes responsible for lignification in pepper, pre-inoculation with arbuscular mycorrhizal (AM) fungus of Glomus intraradices and/or infection with pathogenic strain of Phytophthora capsici, and the biological control effect of G. intraradices on Phytophthora blight in pepper were investigated. The experiment was carried out with four treatments: (1) plants pre-inoculated with G. intraradices (Gi), (2) plants pre-inoculated with G. intraradices and then infected with P. capsici (Gi+Pc), (3) plants infected with P. capsici (Pc), and (4) plants without any of the two microorganisms (C). Mycorrhizal coloni-zation rate was reduced by about 10% in pathogen challenged plants. Root mortality caused by infection of P. capsici was com-pletely eliminated by pre-inoculation with antagonistic G. intraradices. On the ninth day after pathogen infection, Peroxidase (POD) activity increased by 116.9% in Pc-treated roots but by only 21.2% in Gi+Pc-treated roots, compared with the control, respectively. Polyphenol oxidase (PPO) and Phenylalanine ammonia-lyase (PAL) activities gradually increased during the first 3 d and dramatically decreased in Pc-treated roots but slightly decreased in Gi+Pc-treated roots, respectively. On the ninth day after pathogen infection, PPO and PAL decreased by 62.8% and 73.9% in Pc-treated roots but by only 19.8% and 19.5% in Gi+Pc-treated roots, compared with the control, respectively. Three major POD isozymes (45 000, 53 000 and 114 000) were present in Pc-treated roots, while two major bands (53 000 and 114 000) and one minor band (45 000) were present in spectra of Gi+Pc-treated roots, the 45 000 POD isozyme was significantly suppressed by G. intraradices, suggesting that the 45 000 POD isozyme was induced by the pathogen infection but not induced by the antagonistic G. intraradices. A 60 000 PPO isozyme was induced in Pc-treated roots but not induced in Gi+Pc-treated roots. All these results showed the inoculation of antagonistic G. intraradices alleviates root mortality, activates changes of lignification-related enzymes and induces some of the isozymes in pepper plants infected by P. capsici. The results suggested that G. intraradices is a potentially effective protection agent against P. capsici.

Direct Modulation of the Guard Cell Outward- Rectifying Potassium Channel （CORK） by Abscisic Acid

Dear Editor,Abscisic acid （ABA） induces turgot loss and hence stomatal closure by promoting rapid net K^＋ efflux from guard cells （GCs） through outward-rectifying K^＋ （K^＋out） channels （Schroeder et al., 1987; Blatt, 1990）. The mechanisms of ABA signaling in GCs are detailed elsewhere （see Munemasa et al., 2015; Weiner et al., 2010; Pandey et al., 2007）. Briefly, ABA binds to the PYR/ PYL/RCARs, a family of soluble steroidogenic acute regulatory- related lipid transfer （START） proteins, and, in turn, inactivates the downstream PP2C （type 2C protein phosphatase）, leading to the activation of SnRK2.6 （SNF1 [sucrose non-fermenting-1- related protein kinase]/OST1 [open stomata 1]） protein kinases.

An insert in the Hpy region of hscp in Hefiothis virescens （Lepidoptera： Noctuidae） reveals a possible CORE-SINE of insects

A new putative transposon was identified in the tobacco budworm, Helio- this virescens. This transposon was characterized as a full length CORE-SINE （65 bp of ＂CORE＂ core specific nucleotide short interspersed elements） that resembled sequences from three other lepidopterans and humans. In particular, the A-box and B-box regions of this sequence most closely conformed to the signature of CORE-SINEs from widely divergent species. This CORE-SINE was present as a polymorphism in a hypervariable region of the gene hscp, which is the target of pyrethroid insecticides and other xenobiotics in the nerve axon. We described this new putative transposon as Noct-1 due to its presence in a noctuid moth. This is the first description of a full-length CORE-SINE with the A-box, B-box, target site duplication, and candidate core domain from an insect.

The Use of High-Throughput Phenotyping for Assessment of Heat Stress-Induced Changes in Arabidopsis

The worldwide rise in heatwave frequency poses a threat to plant survival and productivity.Determining the new marker phenotypes that show reproducible response to heat stress and contribute to heat stress tolerance is becoming a priority.In this study,we describe a protocol focusing on the daily changes in plant morphology and photosynthetic performance after exposure to heat stress using an automated noninvasive phenotyping system.Heat stress exposure resulted in an acute reduction of the quantum yield of photosystem II and increased leaf angle.In longer term,the exposure to heat also affected plant growth and morphology.By tracking the recovery period of the WT and mutants impaired in thermotolerance(hsp101),we observed that the difference in maximum quantum yield,quenching,rosette size,and morphology.By examining the correlation across the traits throughout time,we observed that early changes in photochemical quenching corresponded with the rosette size at later stages,which suggests the contribution of quenching to overall heat tolerance.We also determined that 6 h of heat stress provides the most informative insight in plant’s responses to heat,as it shows a clear separation between treated and nontreated plants as well as the WT and hsp101.Our work streamlines future discoveries by providing an experimental protocol,data analysis pipeline,and new phenotypes that could be used as targets in thermotolerance screenings.

Nitric Oxide： A Multitasked Signaling Gas in Plants

Nitric oxide （NO） is a gaseous reactive oxygen species （ROS） that has evolved as a signaling hormone in many physiological processes in animals. In plants it has been demonstrated to be a crucial regulator of development, acting as a signaling molecule present at each step of the plant life cycle. NO has also been implicated as a signal in biotic and abiotic responses of plants to the environment. Remarkably, despite this plethora of effects and functional relationships, the fundamental knowledge of NO production, sensing, and transduction in plants remains largely unknown or inadequately characterized. In this review we cover the current understanding of NO production, perception, and action in different physiological sce- narios. We especially address the issues of enzymatic and chemical generation of NO in plants, NO sensing and downstream signaling, namely the putative cGMP and Ca^2＋ pathways, ion-channel activity modulation, gene expression regulation, and the interface with other ROS, which can have a profound effect on both NO accumulation and function. We also focus on the importance of NO in cell-cell communication during developmental processes and sexual reproduction, namely in pollen tube guidance and embryo sac fertilization, pathogen defense, and responses to abiotic stress.

Arabidopsis SUMO protease ASP1 positively regulates flowering time partially through regulating FLC stability

The initiation of flowering is tightly regulated by the endogenous and environment signals, which is crucial for the reproductive success of flowering plants. It is well known that autonomous and vernalization pathways repress transcription of FLOWERING LOCUS C（FLC）, a focal floral repressor, but how its protein stability is regulated remains largely unknown. Here, we found that mutations in a novel Arabidopsis SUMO protease 1（ASP1） resulted in a strong late-flowering phenotype under long-days, but to a lesser extent under short-days. ASP1 localizes in the nucleus and exhibited a SUMO protease activity in vitro and in vivo. The conserved Cys-577 in ASP1 is critical for its enzymatic activity, as well as its physiological function in the regulation of flowering time. Genetic and gene expression analyses demonstrated that ASP1 promotes transcription of positive regulators of flowering, such as FT,SOC1 and FD, and may function in both CO-dependent photoperiod pathway and FLC-dependent pathways.Although the transcription level of FLC was not affected in the loss-of-function asp1 mutant, the protein stability of FLC was increased in the asp1 mutant. Taken together, this study identified a novel bona fide SUMO protease, ASP1,which positively regulates transition to flowering at least partly by repressing FLC protein stability.

A fully inkjet-printed disposable glucose sensor on paper

Inexpensive and easy-to-use diagnostic tools for fast health screening are imperative,especially in the developing world,where portability and affordability are a necessity.Accurate monitoring of metabolite levels can provide useful information regarding key metabolic activities of the body and detect the concomitant irregularities such as in the case of diabetes,a worldwide chronic disease.Today,the majority of daily glucose monitoring tools rely on piercing the skin to draw blood.The pain and discomfort associated with finger pricking have created a global need to develop non-invasive,portable glucose assays.In this work,we develop a disposable analytical device which can measure physiologically relevant glucose concentrations in human saliva based on enzymatic electrochemical detection.We use inkjet-printing technology for the rapid and low-cost deposition of all the components of this glucose sensor,from the electronics to the biorecognition elements,on commercially available paper substrates.The only electronic component of the sensor is the conducting polymer poly(3,4 ethylenedioxythiophene)doped with polystyrene sulfonate(PEDOT:PSS),while the biorecognition element comprises of the enzyme glucose oxidase coupled with an electron mediator.We demonstrate that one month after its fabrication and storage in air-free environment,the sensor maintains its function with only minor performance loss.This fully printed,all-polymer biosensor with its ease of fabrication,accuracy,sensitivity and compatibility with easy-to-obtain biofluids such as saliva aids in the development of next generation low-cost,noninvasive,eco-friendly,and disposable diagnostic tools.

Efficient Mimics for Elucidating Zaxinone Biology and Promoting Agricultural Applications

Zaxinone is an apocarotenoid regulatory metabolite required for normal rice growth and development.In addition,zaxinone has a large application potential in agriculture,due to its growth-promoting activity and capability to alleviate infestation by the root parasitic plant Striga through decreasing strigolactone(SL)production.However,zaxinone is poorly accessible to the scientific community because of its laborious organic synthesis that impedes its further investigation and utilization.In this study,we developed easy-to-synthesize and highly efficient mimics of zaxinone(MiZax).We performed a structure-activity relationship study using a series of apocarotenoids distinguished from zaxinone by different structural features.Using the obtained results,we designed several phenyl-based compounds synthesized with a high-yield through a simple method.Activity tests showed that MiZax3 and MiZax5 exert zaxinone activity in rescuing root growth of a zaxinone-deficient rice mutant,promoting growth,and reducing SL content in roots and root exudates of wild-type plants.Moreover,these compounds were at least as efficient as zaxinone in suppressing transcript level of SL biosynthesis genes and in alleviating Striga infestation under greenhouse conditions,and did not negatively impact mycorrhization.Taken together,MiZax are a promising tool for elucidating zaxinone biology and investigating rice development,and suitable candidates for combating Striga and increasing crop growth.