Altered methionine metabolism impacts phenylpropanoid production and plant development in Arabidopsis thaliana.

Phenylpropanoids are specialized metabolites derived from phenylalanine. Glucosinolates are defense compounds derived mainly from methionine and tryptophan in Arabidopsis. It was previously shown that the phenylpropanoid pathway and glucosinolate production are metabolically linked. The accumulation of indole-3-acetaldoxime (IAOx), the precursor of tryptophan-derived glucosinolates, represses phenylpropanoid biosynthesis through accelerated degradation of phenylalanine-ammonia lyase (PAL). As PAL functions at the entry point of the phenylpropanoid pathway which produces indispensable specialized metabolites such as lignin, aldoxime-mediated phenylpropanoid repression is detrimental to plant survival. Although methionine-derived glucosinolates in Arabidopsis are abundant, any impact of aliphatic aldoximes (AAOx) derived from aliphatic amino acids such as methionine on phenylpropanoid production remains unclear. Here, we investigate the impact of AAOx accumulation on phenylpropanoid production using Arabidopsis aldoxime mutants, ref2 and ref5 . REF2 and REF5 metabolize aldoximes to respective nitrile oxides redundantly, but with different substrate specificities. ref2 and ref5 mutants have decreased phenylpropanoid contents due to the accumulation of aldoximes. As REF2 and REF5 have high substrate specificity toward AAOx and IAOx respectively, it was assumed that ref2 accumulates AAOx, not IAOx. Our study indicates that ref2 accumulates both AAOx and IAOx. Removing IAOx partially restored phenylpropanoid production in ref2 , but not to the wild-type level. However, when AAOx biosynthesis was silenced, phenylpropanoid production and PAL activity in ref2 were completely restored, suggesting an inhibitory effect of AAOx on phenylpropanoid production. Further feeding studies revealed that the abnormal growth phenotype commonly observed in Arabidopsis mutants lacking AAOx production is a consequence of methionine accumulation. Significance Statement: Aliphatic aldoximes are precursors of various specialized metabolites including defense compounds. This study reveals that aliphatic aldoximes repress phenylpropanoid production and that altered methionine metabolism affects plant growth and development. As phenylpropanoids include vital metabolites such as lignin, a major sink of fixed carbon, this metabolic link may contribute to available resource allocation during defense.

Precise chirp control with model-based reinforcement learning for broadband frequency-swept laser of LiDAR.

Artificial intelligence (AI) has been widely used in various fields of physics and engineering in recent decades. In this work, we introduce model-based reinforcement learning (MBRL), which is an important branch of machine learning in the AI domain, to the broadband frequency-swept laser control for frequency modulated continuous wave (FMCW) light detection and ranging (LiDAR). With the concern of the direct interaction between the optical system and the MBRL agent, we establish the frequency measurement system model on the basis of the experimental data and the nonlinearity property of the system. In light of the difficulty of this challenging high-dimensional control task, we propose a twin critic network on the basis of the Actor-Critic structure to better learn the complex dynamic characteristics of the frequency-swept process. Furthermore, the proposed MBRL structure would stabilize the optimization process greatly. In the training process of the neural network, we apply a delaying strategy to the policy update and introduce a smoothing regularization strategy to the target policy to further enhance the network stability. With the well-trained control policy, the agent generates the excellent and regularly updated modulation signals to control the laser chirp precisely and an excellent detection resolution is obtained eventually. Our proposed work demonstrates that the integration of data-driven reinforcement learning (RL) and optical system control gives an opportunity to reduce the system complexity and accelerate the investigation and optimization of control systems.

Altered methionine metabolism impacts phenylpropanoid production and plant development in Arabidopsis thaliana.

Phenylpropanoids are specialized metabolites derived from phenylalanine. Glucosinolates are defense compounds derived mainly from methionine and tryptophan in Arabidopsis. It was previously shown that the phenylpropanoid pathway and glucosinolate production are metabolically linked. The accumulation of indole-3-acetaldoxime (IAOx), the precursor of tryptophan-derived glucosinolates, represses phenylpropanoid biosynthesis through accelerated degradation of phenylalanine ammonia lyase (PAL). As PAL functions at the entry point of the phenylpropanoid pathway, which produces indispensable specialized metabolites such as lignin, aldoxime-mediated phenylpropanoid repression is detrimental to plant survival. Although methionine-derived glucosinolates in Arabidopsis are abundant, any impact of aliphatic aldoximes (AAOx) derived from aliphatic amino acids such as methionine on phenylpropanoid production remains unclear. Here, we investigate the impact of AAOx accumulation on phenylpropanoid production using Arabidopsis aldoxime mutants, ref2 and ref5. REF2 and REF5 metabolize aldoximes to respective nitrile oxides redundantly, but with different substrate specificities. ref2 and ref5 mutants have decreased phenylpropanoid contents due to the accumulation of aldoximes. As REF2 and REF5 have high substrate specificity toward AAOx and IAOx, respectively, it was assumed that ref2 accumulates AAOx, not IAOx. Our study indicates that ref2 accumulates both AAOx and IAOx. Removing IAOx partially restored phenylpropanoid content in ref2, but not to the wild-type level. However, when AAOx biosynthesis was silenced, phenylpropanoid production and PAL activity in ref2 were completely restored, suggesting an inhibitory effect of AAOx on phenylpropanoid production. Further feeding studies revealed that the abnormal growth phenotype commonly observed in Arabidopsis mutants lacking AAOx production is a consequence of methionine accumulation.

Occurrence, Function, and Biosynthesis of the Natural Auxin Phenylacetic Acid (PAA) in Plants.

Auxins are a class of plant hormones playing crucial roles in a plant's growth, development, and stress responses. Phenylacetic acid (PAA) is a phenylalanine-derived natural auxin found widely in plants. Although the auxin activity of PAA in plants was identified several decades ago, PAA homeostasis and its function remain poorly understood, whereas indole-3-acetic acid (IAA), the most potent auxin, has been used for most auxin studies. Recent studies have revealed unique features of PAA distinctive from IAA, and the enzymes and intermediates of the PAA biosynthesis pathway have been identified. Here, we summarize the occurrence and function of PAA in plants and highlight the recent progress made in PAA homeostasis, emphasizing PAA biosynthesis and crosstalk between IAA and PAA homeostasis.

The RhLOL1-RhILR3 module mediates cytokinin-induced petal abscission in rose.

In many plant species, petal abscission can be considered the final step of petal senescence. Cytokinins (CKs) are powerful suppressors of petal senescence; however, their role in petal abscission is ambiguous. Here, we observed that, in rose (Rosa hybrida), biologically active CK is accumulated during petal abscission and acts as an accelerator of the abscission process. Using a combination of reverse genetics, and molecular and biochemical techniques, we explored the roles of a LESION SIMULATING DISEASE1 (LSD1) family member RhLOL1 interacting with a bHLH transcription factor RhILR3 in CK-induced petal abscission. Silencing RhLOL1 delays rose petal abscission, while the overexpression of its ortholog SlLOL1 in tomato (Solanum lycopersicum) promotes pedicel abscission, indicating the conserved function of LOL1 in activating plant floral organ abscission. In addition, we identify a bHLH transcription factor, RhILR3, that interacts with RhLOL1. We show that RhILR3 binds to the promoters of the auxin signaling repressor auxin/indole-3-acetic acid (Aux/IAA) genes to inhibit their expression; however, the interaction of RhLOL1 with RhILR3 activates the expression of the Aux/IAA genes including RhIAA4-1. Silencing RhIAA4-1 delays rose petal abscission. Our results thus reveal a RhLOL1-RhILR3 regulatory module involved in CK-induced petal abscission via the regulation of the expression of the Aux/IAA genes.

Linearization of nonlinear frequency modulated continuous wave generation using model-based reinforcement learning.

The prevalence of machine learning (ML) opens up new directions for plenty of scientific fields. The development of optics technologies also benefits from it. However, due to the complex properties of nonlinear and dynamic optical systems, optical system control with ML is still in its infancy. In this manuscript, to demonstrate the feasibility of optical system control using reinforcement learning (RL), i.e., a branch of ML, we solve the linearization problem in the frequency modulated continuous wave (FMCW) generation with the model-based RL method. The experiment results indicate an excellent improvement in the linearity of the generated FMCW, showing a sharp peak in the frequency spectrum. We confirm that the RL method learns the implicit physical characteristics very well and accomplishes the goal of the linear FMCW generation effectively, indicating that the marriage of ML and optics systems could have the potential to open a new era for the development of optical system control.

Genome- and Transcriptome-Wide Identification of C3Hs in Common Bean (Phaseolus vulgaris L.) and Structural and Expression-Based Analyses of Their Functions During the Sprout Stage Under Salt-Stress Conditions.

CCCH (C3H) zinc-finger proteins are involved in plant biotic and abiotic stress responses, growth and development, and disease resistance. However, studies on C3H genes in Phaseolus vulgaris L. (common bean) are limited. Here, 29 protein-encoding C3H genes, located on 11 different chromosomes, were identified in P. vulgaris. A phylogenetic analysis categorized the PvC3Hs into seven subfamilies on the basis of distinct features, such as exon-intron structure, cis-regulatory elements, and MEME motifs. A collinearity analysis revealed connections among the PvC3Hs in the same and different species. The PvC3H genes showed tissue-specific expression patterns during the sprout stage, as assessed by real-time quantitative PCR (RT-qPCR). Using RNA-sequencing and RT-qPCR data, PvC3Hs were identified as being enriched through Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses in binding, channel activity, and the spliceosome pathway. These results provide useful information and a rich resource that can be exploited to functionally characterize and understand PvC3Hs. These PvC3Hs, especially those enriched in binding, channel activity, and the spliceosome pathway will further facilitate the molecular breeding of common bean and provide insights into the correlations between PvC3Hs and salt-stress responses during the sprout stage.

[A caregiver survey in Beijing, Xi'an, Shanghai and Chengdu: health services status for the elderly with dementia].

OBJECTIVE: In order to rationally allocate resources and to improve the quality of life of people with dementia, it is necessary to assess their current health services status. METHODS: A population-based door-to-door caregiver survey was conducted in Beijing, Xi'an, Shanghai and Chengdu in 1998. Totally 1 141 individuals with dementia were found among 34 807 residents aged 55 years and over on the basis of national prevalence study of dementia. Then 428 families with demented patients were randomly selected for questionare interview. Interviews were completed in 405 but refused by 23 families. Measurements included demographic characteristics of patients and their caregivers, perspective of the victim of the disease, current awareness of the disease and medical and welfare services provided. RESULTS: Among 405 cases of dementia (including 298 cases of AD and 81 cases of VaD), mean MMSE scores were 16.3 +/- 5.3 for 157 mild cases, 12.7 +/- 5.4 for 135 moderate cases, and 6.2 +/- 5.8 for 110 severe cases. Most patients (96%) were cared for at home by family members. Among caregivers, 189 (48.8%) considered the impairment of cognition, behavior and daily living activity in demented persons as a result of normal aging. Half of the caregivers spend over 8 hours each day looking after the patient. Whether the caregivers brought their relatives with dementia to a doctor was determined by disease severity, i.e. 8.3% for mild, 13.5% for moderate, and 19.4% for severe in 1996 to approximately 1997 and 14.4%, 25.6% and 33.6%, respectively in 1998-1999. Of those, only 26.9% reported receiving a dementia diagnosis, and only 21.3% received a recommedation to take medication. However, there was no established standard treatment and only 2% patient's used Ache-I. CONCLUSIONS: General education is needed to increase the public awareness of dementia. For patients with dementia, early diagnosis, early treatment and optimal care are important to improve their quality of life.