Analysis on the Employment of Landless Farmers during the Reconstruction of Urban Village: A Case Study of S Village in Shaanxi Province

The re-employment of landless farmers in reconstruction of urban village is an important way to solve the problems concerning farmers. In S Village of Shaanxi Province,the landless farmers are facing the employment problems such as low re-employment rate and quality,lack of employment competitiveness,and weak employment willingness. This paper analyzes the main factors influencing the employment of landless farmers in this urban village such as local government's lack of overall design on the employment of landless farmers,landless farmers' lack of long-term employment concept,poor employment conditions,and lack of vocational education in rural areas. Finally some recommendations are set forth to enhance the employment of landless farmers in S Village: strengthening the institutional support for the employment of landless farmers; perfecting the fund guarantee for the employment of landless farmers; actively expanding the employment channels; enhancing the employability of landless farmers.

The OsAMT1.1 gene functions in ammonium uptake and ammoniumepotassium homeostasis over low and high ammonium concentration ranges

Rice （Oryza sativa） grown in paddy fields is an ammonium （NH4^＋）-preferring crop; however, its AMT-type NH4^＋ transporters that mediate root N acquisition have not been well characterized yet. In this study, we analyzed the expression pattern and physiological function of the OsAMT1.1 gene of the AMT1 subfamily in rice. OsAMT1.1 is located in the plasma membrane and is mainly expressed in the root epidermis, stele and mesophyll cells. Disruption of the OsAMTI.1 gene decreased the uptake of NH4^＋, and the growth of roots and shoots under both low NH4^＋ and high NH4^＋ conditions. OsAMT1.1 contributed to the short-term （5 min） ^15NH4^＋ influx rate by approximately one-quarter, irrespective of the NH4^＋ concentration. Knockout of OsAMTI.I significantly decreased the total N transport from roots to shoots under low NH4^＋ conditions. Moreover, compared with the wild type, the osamt1.1 mutant showed an increase in the potassium （K） absorption rate under high NH4^＋ conditions and a decrease under low NH4^＋ conditions. The mutants contained a significantly high concentration of K in both the roots and shoots at a limited K （0.1 mmol/L） supply when NH4^＋ was replete. Taken together, the results indicated that OsAMT1.1 significantly contributes to the NH4^＋ uptake under both low and high NH4^＋ conditions and plays an important role in N-K homeostasis in rice.

Hydrogen sulfide, a signaling molecule in plant stress responses

Gaseous molecules, such as hydrogen sulfide(H_2S)and nitric oxide(NO), are crucial players in cellular and(patho)physiological processes in biological systems. The biological functions of these gaseous molecules, which were first discovered and identified as gasotransmitters in animals, have received unprecedented attention from plant scientists in recent decades. Researchers have arrived at the consensus that H_2S is synthesized endogenously and serves as a signaling molecule throughout the plant life cycle.However, the mechanisms of H_2S action in redox biology is still largely unexplored. This review highlights what we currently know about the characteristics and biosynthesis of H_2S in plants. Additionally,we summarize the role of H_2S in plant resistance to abiotic stress. Moreover, we propose and discuss possible redox-dependent mechanisms by which H_2S regulates plant physiology.

Hydrogen sulfide-linked persulfidation of ABI4 controls ABA responses through the transactivation of MAPKKK18 in Arabidopsis

Hydrogen sulfide(H2S)is a signaling molecule that regulates plant hormone and stress responses.The phytohormone abscisic acid(ABA)plays an important role in plant adaptation to unfavorable environmental conditions and induces the persulfidation of L-CYSTEINE DESULFHYDRASE1(DES1)and the production of H2S in guard cells.However,it remains largely unclear how H2S and protein persulfidation participate in the relay of ABA signals.In this study,we discovered that ABSCISIC ACID INSENSITIVE 4(ABI4)acts downstream of DES1 in the control of ABA responses in Arabidopsis.ABI4 undergoes persulfidation at Cys250 that is triggered in a time-dependent manner by ABA,and loss of DES1 function impairs this process.Cys250 and its persulfidation are essential for ABI4 function in the regulation of plant responses to ABA and the H2S donor NaHS during germination,seedling establishment,and stomatal closure,which are abolished in the ABI4Cys250Ala mutated variant.Introduction of the ABI4Cys250Ala variant into the abi4 des1 mutant did not rescue its hyposensitivity to ABA.Cys250 is critical for the binding of ABI4 to its cognate motif in the promoter of Mitogen-Activated Protein Kinase Kinase Kinase 18(MAPKKK18),which propagates the MAPK signaling cascade induced by ABA.Furthermore,the DES1-mediated persulfidation of ABI4 enhances the transactivation activity of ABI4 toward MAPKKK18,and ABI4 can bind the DES1 promoter,forming a regulatory loop.Taken together,these findings advance our understanding of a post-translational regulatory mechanism and suggest that ABI4 functions as an integrator of ABA and MAPK signals through a process in which DES1-produced H2S persulfidates ABI4 at Cys250.

Rice GLUTATHIONE PEROXIDASE1-mediated oxidation of bZIP68 positively regulates ABA-independent osmotic stress signaling

Osmotic stress caused by drought and high salinity is a significant environmental threat that limits plant growth and agricultural yield. Redox regulation plays an important role in plant stress responses, but the mechanisms by which plants perceive and transduce redox signals are still underexplored. Here, we report a critical function for the thiol peroxidase GPX1 in osmotic stress response in rice, where it serves as a redox sensor and transducer. GPX1 is quickly oxidized upon exposure to osmotic stress and forms an intramolecular disulfide bond, which is required for the activation of bZIP68, a VRE-like basic leucine zipper (bZIP) transcription factor involved in the ABA-independent osmotic stress response pathway. The disulfide exchange between GPX1 and bZIP68 induces homo-tetramerization of bZIP68 and thus positively regulates osmotic stress response by regulating osmotic-responsive gene expression. Furthermore, we discovered that the nuclear translocation of GPX1 is regulated by its acetylation under osmotic stress. Taken together, our findings not only uncover the redox regulation of the GPX1-bZIP68 module during osmotic stress but also highlight the coordination of protein acetylation and redox signaling in plant osmotic stress responses.

Heme Oxygenase-1 is Associated with Wheat Salinity Acclimation by Modulating Reactive Oxygen Species Homeostasis

Heme oxygenase-1 （HO-1） has been recently identified as an endogenous signaling system in animals. In this study, HO-1 upregulation and its role in acquired salt tolerance （salinity acclimation） were investigated in wheat plants. We discovered that pretreatment with a low concentration of NaCl （25 mmol/L） not only led to the induction of HO-1 protein and gene expression, as well as enhanced HO activity, but also to a salinity acclimatory response thereafter. The effect is specific for HO-1, since the potent HO-1 inhibitor zinc protoporphyrin IX blocks the above cytoprotective actions, and the cytotoxic responses conferred by 200 mmol/L NaCl are reversed partially when HO-1 inducer hemin is added. Heme oxygenase catalytic product, carbon monoxide （CO） aqueous solution pretreatment, mimicked the salinity acclimatory responses. Meanwhile, the CO-triggered re-establishment of reactive oxygen species （ROS） homeostasis was mainly guaranteed by the induction of total and isozymatic activities, or corresponding transcripts of superoxide dismutase, ascorbate peroxidase, and cytosolic peroxidase （POD）, as well as the downregulation of NADPH oxidase expression and cell-wall POD activity. A requirement of hydrogen peroxide homeostasis for HO-1-mediated salinity acclimation was also discovered. Taken together, the above results suggest that the upregulation of HO-1 expression was responsible for the observed salinity acclimation through the regulation of ROS homeostasis.