Genome-wide identification and expression of monoacylglycerol lipase (MAGL) gene family in peanut (Arachis hypogaea L.) and functional analysis of AhMGATs in neutral lipid metabolism.

Monoacylglycerol lipase (MAGL) involved in regulating plant growth and development and stress responses, hydrolyzes monoacylglycerol (MAG) into free fatty acid and glycerol, which is the last step of triacylglycerol (TAG) breakdown. Here, a genome-wide characterization of MAGL gene family from cultivated peanut (Arachis hypogaea L.) was performed. In total, 24 MAGL genes were identified and unevenly distributed on 14 chromosomes, encoding 229-414 amino acids with molecular weights ranging from 25.91 to 47.01 kDa. Spatiotemporal and stress-induced expression was analyzed by qRT-PCR. Multiple sequence alignment revealed that AhMAGL1a/b and AhMAGL3a/b were the only four bifunctional enzymes with conserved regions of hydrolase and acyltransferase, which could also be named as AhMGATs. GUS histochemical assay showed that AhMAGL1a and -1b were strongly expressed in all tissues of the plants; whereas both AhMAGL3a and -3b were weakly expressed in plants. Subcellular localization analysis indicated that AhMGATs were localized in the endoplasmic reticulum and/or Golgi complex. Seed-specific overexpression of AhMGATs in Arabidopsis decreased the oil content of the seeds and altered the fatty acid compositions, indicating that AhMGATs were involved in TAG breakdown but not TAG biosynthesis in plant seeds. This study lays the foundation for better understanding AhMAGL genes biological function in planta.

Ectopic Expression of AeNAC83, a NAC Transcription Factor from Abelmoschus esculentus, Inhibits Growth and Confers Tolerance to Salt Stress in Arabidopsis.

NAC transcription factors play crucial roles in plant growth, development and stress responses. Previously, we preliminarily identified that the transcription factor AeNAC83 gene was significantly up-regulated under salt stress in okra (Abelmoschus esculentus). Herein, we cloned the nuclear-localized AeNAC83 from okra and identified its possible role in salt stress response and plant growth. The down-regulation of AeNAC83 caused by virus-induced gene silencing enhanced plant sensitivity to salt stress and increased the biomass accumulation of okra seedlings. Meanwhile, AeNAC83-overexpression Arabidopsis lines improved salt tolerance and exhibited many altered phenotypes, including small rosette, short primary roots, and promoted crown roots and root hairs. RNA-seq showed numerous genes at the transcriptional level that changed significantly in the AeNAC83-overexpression transgenic and the wild Arabidopsis with or without NaCl treatment, respectively. The expression of most phenylpropanoid and flavonoid biosynthesis-related genes was largely induced by salt stress. While genes encoding key proteins involved in photosynthesis were almost declined dramatically in AeNAC83-overexpression transgenic plants, and NaCl treatment further resulted in the down-regulation of these genes. Furthermore, DEGs encoding various plant hormone signal pathways were also identified. These results indicate that AeNAC83 is involved in resistance to salt stress and plant growth.