Development of a new 17-item Asthenopia Survey Questionnaire using Rasch analysis

AIM

To develop the 17-item Asthenopia Survey Questionnaire (ASQ)-17 by Rasch analysis, and to generate a predictiveness score.

METHODS

Totally 739 participants were recruited and 680 were involved in the result analysis in this prospective, cross-sectional study. Three rounds of Rasch analysis were used to analyze the psychometric characteristics of items and options.

RESULTS

Phase 1 assessed the original ASQ-19, adjusted the item scoring mode to a four-point Likert response rating scale and combined the 18th and 19th items into a new item. Phase 2 deleted the 11th item. Phases 3 and 4 assessed the new ASQ-17. All the evaluation indexes of ASQ-17 were acceptable. The Infit and Outfit MnSq values of items were 0.67-1.48, the variance explained by the principal component and the unexplained variance explained by the first contrast were 53.90%-59.40% and 1.50-1.80 in three dimensions. The curve peaks of scores in each dimension were separated and in the same order. The PSR and PSI values were 2.80 and 0.89, respectively. The mean scores of dimensions A (9.5±4.1 vs 3.5±3.2), B (7.3±3.3 vs 2.5±2.7), C (4.3±2.2 vs 1.4±2.0) and total (21.1±8.1 vs 7.4±7.0) in asthenopia participants were significantly higher than those without asthenopia (all P<0.001). The area under the curve in two groups was 0.899 (P<0.001). Youden's index was up to the maximum value of 0.784 when the cut-off value was 12.5.

CONCLUSION

ASQ-17 has stronger option sorting and suitability than ASQ-19. It is an effective assessment tool for asthenopia with an optimal cut-off threshold value of 12.5, which is suitable for diagnosis and curative effect evaluation.

Integration of Jasmonic Acid and Ethylene Into Auxin Signaling in Root Development

As sessile organisms, plants must be highly adaptable to the changing environment by modifying their growth and development. Plants rely on their underground part, the root system, to absorb water and nutrients and to anchor to the ground. The root is a highly dynamic organ of indeterminate growth with new tissues produced by root stem cells. Plants have evolved unique molecular mechanisms to fine-tune root developmental processes, during which phytohormones play vital roles. These hormones often relay environmental signals to auxin signaling that ultimately directs root development programs. Therefore, the crosstalk among hormones is critical in the root development. In this review, we will focus on the recent progresses that jasmonic acid (JA) and ethylene signaling are integrated into auxin in regulating root development of Arabidopsis thaliana and discuss the key roles of transcription factors (TFs) ethylene response factors (ERFs) and homeobox proteins in the crosstalk.

HOMEOBOX PROTEIN52 Mediates the Crosstalk between Ethylene and Auxin Signaling during Primary Root Elongation by Modulating Auxin Transport-Related Gene Expression

The gaseous hormone ethylene participates in many physiological processes in plants. Ethylene-inhibited root elongation involves PIN-FORMED2 (PIN2)-mediated basipetal auxin transport, but the molecular mechanisms underlying the regulation of PIN2 function by ethylene (and therefore auxin distribution) are poorly understood. Here, we report that the plant-specific and ethylene-responsive HD-Zip gene HB52 is involved in ethylene-mediated inhibition of primary root elongation in Arabidopsis thaliana Biochemical and genetic analyses demonstrated that HB52 is ethylene responsive and acts downstream of ETHYLENE-INSENSITIVE3 (EIN3). HB52 knockdown mutants displayed an ethylene-insensitive phenotype during primary root elongation, while its overexpression resulted in short roots, as observed in ethylene-treated plants. In addition, root auxin distribution and gravitropism were impaired in HB52 knockdown and overexpression lines. Consistent with these findings, in vitro and in vivo binding experiments showed that HB52 regulates the expression of auxin transport-related genes, including PIN2, WAVY ROOT GROWTH1 (WAG1), and WAG2 by physically binding to their promoter regions. These findings suggest that HB52 functions in the ethylene-mediated inhibition of root elongation by modulating the expression of auxin transport components downstream of EIN3, revealing a mechanism in which HB52 acts as an important node in the crosstalk between ethylene and auxin signaling during plant growth and development.

Correction: Arabidopsis ERF1 Mediates Cross-Talk between Ethylene and Auxin Biosynthesis during Primary Root Elongation by Regulating ASA1 Expression

[This corrects the article DOI: 10.1371/journal.pgen.1005760.].

L-Cysteine inhibits root elongation through auxin/PLETHORA and SCR/SHR pathway in Arabidopsis thaliana

L-Cysteine plays a prominent role in sulfur metabolism of plants. However, its role in root development is largely unknown. Here, we report that L-cysteine reduces primary root growth in a dosage-dependent manner. Elevating cellular L-cysteine level by exposing Arabidopsis thaliana seedlings to high L-cysteine, buthionine sulphoximine, or O-acetylserine leads to altered auxin maximum in root tips, the expression of quiescent center cell marker as well as the decrease of the auxin carriers PIN1, PIN2, PIN3, and PIN7 of primary roots. We also show that high L-cysteine significantly reduces the protein level of two sets of stem cell specific transcription factors PLETHORA1/2 and SCR/SHR. However, L-cysteine does not downregulate the transcript level of PINs, PLTs, or SCR/SHR, suggesting that an uncharacterized post-transcriptional mechanism may regulate the accumulation of PIN, PLT, and SCR/SHR proteins and auxin transport in the root tips. These results suggest that endogenous L-cysteine level acts to maintain root stem cell niche by regulating basal- and auxin-induced expression of PLT1/2 and SCR/SHR. L-Cysteine may serve as a link between sulfate assimilation and auxin in regulating root growth.

MADS-box transcription factor AGL21 regulates lateral root development and responds to multiple external and physiological signals

Plant root system morphology is dramatically influenced by various environmental cues. The adaptation of root system architecture to environmental constraints, which mostly depends on the formation and growth of lateral roots, is an important agronomic trait. Lateral root development is regulated by the external signals coordinating closely with intrinsic signaling pathways. MADS-box transcription factors are known key regulators of the transition to flowering and flower development. However, their functions in root development are still poorly understood. Here we report that AGL21, an AGL17-clade MADS-box gene, plays a crucial role in lateral root development. AGL21 was highly expressed in root, particularly in the root central cylinder and lateral root primordia. AGL21 overexpression plants produced more and longer lateral roots while agl21 mutants showed impaired lateral root development, especially under nitrogen-deficient conditions. AGL21 was induced by many plant hormones and environmental stresses, suggesting a function of this gene in root system plasticity in response to various signals. Furthermore, AGL21 was found positively regulating auxin accumulation in lateral root primordia and lateral roots by enhancing local auxin biosynthesis, thus stimulating lateral root initiation and growth. We propose that AGL21 may be involved in various environmental and physiological signals-mediated lateral root development and growth.

Sulfate availability affects ABA levels and germination response to ABA and salt stress in Arabidopsis thaliana

Sulfur-containing compounds play a critical role in the response of plants to abiotic stress factors including drought. The phytohormone abscisic acid (ABA) is the key regulator of responses to drought and high-salt stress. However, our knowledge about interaction of S-metabolism and ABA biosynthesis is scarce. Here we report that sulfate supply affects synthesis and steady-state levels of ABA in Arabidopsis wild-type seedlings. By using different mutants of the sulfate uptake and reduction pathway, we confirmed the impact of sulfate supply on steady-state ABA content in Arabidopsis and demonstrated that this impact was due to cysteine availability. Loss of the chloroplast sulfate transporter3;1 function (sultr3;1) resulted in significantly decreased aldehyde oxidase (AO) activity and ABA levels in seedlings and seeds. These mutant phenotypes could be reverted by exogenous application of cysteine or ectopic expression of SULTR3;1. In addition the sultr3;1 mutant showed a decrease of xanthine dehydrogenase activity, but not of nitrate reductase, strongly indicating that in seedlings cysteine availability limits activity of the molybdenum co-factor sulfurase, ABA3, which requires cysteine as the S-donor for sulfuration. Transcription of ABA3 and NCED3, encoding another key enzyme of the ABA biosynthesis pathway, was regulated by S-supply in wild-type seedlings. In contrast, ABA up-regulated the transcript level of SULTR3;1 and other S-metabolism-related genes. Our results provide evidence for a significant co-regulation of S-metabolism and ABA biosynthesis that operates to ensure sufficient cysteine for AO maturation and highlights the importance of sulfur for stress tolerance of plants.

[Estimation of allergenic potency of "Dermatophagoides pteronyssinus" by radioimmunoassay of antigenic extracts (author's transl)]

The allergenic potency of different extracts of Dermatophagoides pteronyssinus was evaoluated by in vitro methods based on the RAST-procedure (radioallergosorbent-test). Both the direct titration and the inhibition methods were performed and gave comparable results. The inhibition method was studied particularly because it presented various technical advantages, such as the use of a standard immunoadsorbent. The allergenic activity of different extracts of D. pteronyssinus were compared and the results demonstrated the value of this method for the routine estimations of biological activity in allergenic extracts and for control uses in allergen standardization.