Abscisic acid (ABA) plays key roles in plant development and responses to abiotic stresses. A wide number of transcriptional and post-translational regulatory mechanisms on ABA signaling are known; however, less to know about the regulatory roles of alternative splicing. In this work, we found that SKIP, a splicing factor, positively regulates ABA signaling. SKIP binds to the pre-mRNA of ABA signaling related genes, such as PYL7, PYL8, ABI1, HAB1, and ABI5, to regulate their splicing. The precursor mRNA alternative splicing of several PYL receptors, PP2C phosphatases, and ABF transcriptional factors is disrupted by skip-1 mutation. The abnormal alternative splicing in skip-1 represses the expression of ABA positive regulators, including PYLs and ABFs, and activates the expression of ABA negative regulators, such as PP2Cs, which confers ABA hyposensitive phenotype of skip-1. We also found that ABA-mediated genome-wide alternative splicing and differential gene expression are changed by skip-1 mutation. The number of the differential splicing events is increased by skip-1; however, the number of differential expressed genes in response to ABA is reduced by skip-1. Our results reveal a principle on how a splicing factor regulates ABA signaling and ABA-mediated genome-wide alternative splicing.

The global rise in food demand requires urgent attention in the aspect of crop production. The microclimate of a greenhouse is a critical issue in agricultural practice, due to the variations of the external climatic conditions and their negative effect on crop production. In this work, a dynamic model of the internal air temperature of a Chinese solar greenhouse was designed in Matlab/Simulink environment. The dynamic model was designed with the use of energy balance equations. The weather data consisting of solar radiation, relative humidity, ambient temperature, and Photosynthetically Active Radiation (PAR) were acquired from meteorological stations. The results of the simulations show that the temperature of the internal air varies with weather conditions, location, number of covers, and the structure of the solar greenhouse.

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