Guanine nucleotide exchange factor RopGEF2, which is directly activated by phytochrome phyB, suppresses red light-induced stomatal opening by activating ROP7 an

Background: Given the serious consequences of depression and the lack of information about it during the crucially developmental period from the National College Entrance Exam (CEE, i.e., Chinesegaokao) to college, this study aimed to estimate the cumulative incidence, prevalence, age of onset, correlates, and service use of depressive disorders (DDs) among youth who passed the CEE and were enrolled at Hunan Normal University in China.Methods: A two-stage cross-sectional epidemiological survey of DDs was conducted from October to December, 2017 among 6,922 incoming college students (98.5% effective response, N = 6,818, 71.4% female, age range: 16–25 years, mean age = 18.6). Using a stratified sampling method based on the risk of depression, 926 participants (mean age = 18.5, 75.2% female) were selected and subsequently interviewed with the Kiddie–Schedule for Affective Disorders and Schizophrenia–Present and lifetime version (K-SADS-PL).Results: The sex-adjusted 9-month (i.e., 3 months pre-CEE, 3 months after CEE, and 3 months post-matriculation) incidence of new-onset DDs was 2.3% (standard error [S.E.] 0.3%), and the sex-adjusted 1-month, 6-month and lifetime prevalence were 0.7 (S.E. 0.3%), 1.7 (S.E. 0.2%) and 7.5% (S.E. 1.3%), respectively. The median age of onset was 17 (interquartile range: 16–18) years. Critically, over one-third (36.5%, S.E. 0.6) of depressed youth had their new onset during the 9-month period. The risk factors for depression included having mothers with higher education, experiencing major life events, being female, and experiencing parental divorce or death. The adjusted lifetime treatment rate was 8.7%.Conclusion: The 9-month incidence of new-onset depression fromgaokaoto college among the youth sample in China is similar to the global annual incidence (3.0%), but the 1-month and lifetime prevalence are significantly lower than the global point (7.2%) and lifetime prevalence (19%). These findings suggest a high proportion of new-onset depression during the CEE to college among the sample youth in China. The risk of depression is associated with familial and stress correlates. Low treatment is a serious concern. Emphasis on early prevention and available treatment for adolescent and young adult depression is a critical need in China.

Light is an important environmental factor for plant growth and development. Phytochrome B (phyB), a classical red/far-red light receptor, plays vital role in controlling plant photomorphogenesis and light-induced stomatal opening. Phytohormone abscisic acid (ABA) accumulates rapidly and triggers a series of physiological and molecular events during the responses to multiple abiotic stresses. Recent studies showed that phyB mutant synthesizes more ABA and exhibits improved tolerance to salt and cold stress, suggesting that a crosstalk exists between light and ABA signaling pathway. However, whether ABA signaling components mediate responses to light remains unclear. Here, we showed that SnRK2.6 (Sucrose Nonfermenting 1-Related Protein Kinase 2.6), a key regulator in ABA signaling, interacts with phyB and participates in light-induced stomatal opening. First, we checked the interaction between phyB and SnRK2s, and found that SnRK2.2/2.3/2.6 kinases physically interacted with phyB in yeast and in vitro. We also performed co-IP assay to support that SnRK2.6 interacts with phyB in plant. To investigate the role of SnRK2.6 in red light-induced stomatal opening, we obtained the snrk2.6 mutant and overexpression lines, and found that snrk2.6 mutant exhibited a significantly larger stomatal aperture under red light treatment, while the two independent overexpression lines showed significantly smaller stomatal aperture, indicative of a negative role for SnRK2.6 in red light-induced stomatal opening. The interaction of SnRK2.6 with red light receptor and the negative role of SnRK2.6 in red light-induced stomatal opening provide new evidence for the crosstalk between ABA and red light in guard cell signaling.

Guard cells undergo quick volume changes during stomatal movements. However, the contribution of aquaporins to stomatal movements has not been well understood. The plasma membrane aquaporin PIP2;1in Arabidopsis has been found to mediate abscisic acid–induced or flag22-induced stomatal closure. In this research, we investigated the role of PIP2;1 in light-induced stomatal opening by measuring the stomatal apertures of the pip2;1 mutant and PIP2;1 overexpression lines after light treatment. pip2;1 mutant exhibited a larger stomatal aperture, and the overexpression lines displayed a smaller stomatal aperture. It has been reported that the phosphorylation at Ser-280 and Ser-283 of PIP2;1 in rosette tissue increased in response to darkness, whereas osmotic water permeability (P_f) in mesophyll protoplasts in darkness was lower than that under light, suggesting that phosphorylation at Ser-280 and Ser-283 of PIP2;1 affected P_f in mesophyll protoplasts. Therefore, we obtained the pip2;1 mutant expressing phosphorylation-deficient (PIP2;1 AA) or phosphomimetic (PIP2;1 DD) forms of PIP2;1. The PIP2;1 AA lines exhibited a larger stomatal aperture as pip2;1 mutant, whereas PIP2;1 DD lines exhibited a smaller stomatal aperture as PIP2;1 overexpression lines under light. These results suggest that PIP2;1 plays a negative role in light-induced stomatal opening, and phosphorylation of PIP2;1 at Ser-280 and Ser-283 causes reduced water absorption in guard cells and decreased stomatal opening.

When plants encounter environmental stresses, phytohormone abscisic acid (ABA) accumulates quickly and efficiently reduces water loss by inducing stomatal closure. Reactive oxygen species (ROS) is an important regulator in ABA-induced stomatal closure, and ROS generation is modulated by multiple components in guard-cell ABA signaling. ROP interactive CRIB-containing protein 7 (RIC7) has been found to negatively regulate ABA-induced stomatal closure. However, the molecular details of the RIC7 function in this process are unclear. Here, by using two RIC7 overexpressing mutants, we confirmed the negative role of RIC7 in ABA-induced stomatal closure and found that guard cells of RIC7 overexpressing mutants generated less H₂O₂ than the wild type with ABA treatment, which were consistent with the reduced expression levels of ROS generation related NADPH oxidase genes AtRBOHD and AtRBOHF, and cytosolic polyamine oxidase genes PAO1 and PAO5 in the RIC7 overexpressing mutants. Furthermore, external applied H₂O₂ failed to rescue the defects of stomatal closure in RIC7 overexpressing mutants. These results suggest that RIC7 affects H₂O₂ generation in guard cells, and the function of H₂O₂ is dependent on RIC7 in ABA-induced stomatal closure, indicative of interdependency between RIC7 and H₂O₂ in ABA guard-cell signaling.