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New Progress On ABA Signal Pathway

On September 25, Prof. Li Xia’s team paper was published onNature Communications. It introduces the latest findings on the phytohormone ABA(abscisic acid ) signal pathway. The findings indicates a new control system after the transcription of ABA signal pathway and provides a new method in understanding adversity-tolerant genetic system of plants.

The splicing of pre-mRNA is the process during which mRNA removes introns and connects exons. Sometimes pre-mRNA messages may be spliced at different splicing positions, thus producing varied mRNAs. Such alternative splicing increases proteome abundances and serves as a very important regulatory mechanism after genetic transcription, mediating various biological process. In recent years, pre-mRNA alternative splicing and its regulatory mechanism has become a hot research issue in plant science. Studies have showed the involvement of pre-mRNA alternative splicing in the response of plants to auxin and jasmonic acid, but little has been known about its regulatory function and molecular mechanism in plants’ response to ABA.

Li Xia’s team has conducted a research and proved that the PP2C gene HAB1 in arabidopsis can generate two variable transcripts, i.e. HAB1.1 and HAB1.2 through alternative splicing. HAB1.1 is a full length protein through full length transcript coding while HAB1.2 is a truncated protein without C end in that the last intron is detained which lead to earlier termination of the coding process. The HAB1.1 to HAB1.2 ratio varies slightly in different tissues but this ratio increases apparently after the plant is handled by ABA. HAB1.1 and HAB 1.2 are of the same subcellular localization and both can combine with OST1(Open Stomata1), a kind of kinase in SnRK family, in ABA signal pathway. Therefore, the two variable splice forms have an antagonistic effect on regulating ABA signal pathway. A further study proves that RBM25(RRM-binding motif 25) in arabidopsis can combine with the number 5 splicing point on the last intron in Pre-HAB1. The study first revealed the function of HAB1 variable splicing, regulated by RBM25, played in ABA signal and provide important evidence for its regulation in ABA signal pathway after mRNA transcription and the plant response to ABA.

Deputy Professors Wang Zhijuan and Ji Hongtao inProf. Li Xia’s Team are both the lead authors of this paper and Prof. Li is the corresponding author. The research is funded by The National Natural Science Foundation of China, National GM Special Fund and The Major State Basic Research Development Program of China (973 plan).

(By ZHANG Yin)