The working model of SMA1 regulatory roles  [Image by Li Shengjun]

The growth, development, and yield of plants are greatly affected by various biotic and abiotic stresses, such as bacteria, fungi, pests, drought, salt, and temperature stresses. Plants need to tightly control the developmental progress and stress responses through regulating gene express levels.

MicroRNAs (miRNAs) are a class of regulatory RNA (Ribonucleic Acid) with the small size about 21 nucleotide. They target their specific mRNAs via the complementary sequences for degradation or translational inhibition. However, the mechanisms on how miRNA abundance is controlled are largely unknown in plants.

Recently, researchers from a collaborative team of Dr. Li Shengjun’s group at Qingdao Institute of Bioenergy and Bioprocess Technology (QIBEBT), the Chinese Academy of Sciences (CAS), and Dr. Li Yunhai’s group at the Institute of Genetics and Developmental Biology, CAS, and Dr. Yu Bin’s group at the University of Nebraska-Lincoln have identified the function of SMA1 gene in plant miRNA generation.

They found that SMA1 gene encodes a DEAD-box protein and plays a multifaceted role in miRNA processing: (1) interacts with DCL1 complex to promote pri-miRNA processing; (2) directly interacts with MIR promoter regions; (3) influences DCL1 protein levels via regulating intron alternative splicing of DCL1 pre-mRNA. The findings suggested SMA1 may be important to fine-tune microRNA levels to keep plant healthy.

“Because the loss-of-function mutation of SMA1 leads embryo lethal in plants, SMA1 gene function remains unknown in plants. This work isolated a weak allele with a hypomorphic mutation and will facilitate the functional study of SMA1 gene,” said Dr. Li Shengjun. “The study on how plants control miRNA amounts is very important in improving crops.”

Their findings entitled “SMA1, a homolog of the splicing factor Prp28, has a multifaceted role in miRNA biogenesis in Arabidopsis” were recently published in Nucleic Acids Research.

 This work was financially supported by grants from the National Natural Science Foundation of China, the Ministry of Agriculture and Rural Affairs, the Strategic Priority Research Program “Molecular Mechanism of Plant Growth and Development”, CAS’ Pioneer Hundred Talents Program, the Nebraska Soybean Board, and the US National Science Foundation.

For more information, please contact:

Cheng Jing

E-mail: chengjing@qibebt.ac.cn

Source: Qingdao Institute of Bioenergy and Bioprocess Technology, CAS