Isolation, characterization, and functional verification of salt stress response genes of NAC transcription factors in Ipomoea pes-caprae.

Adverse environmental stress is a major environmental factor threatening food security, which is why improving plant stress resistance is essential for agricultural productivity and environmental sustainability. The NAC (NAM, ATAF, and CUC) transcription factors (TFs) play a dominant role in plant responses to abiotic and biotic stresses, but they have been poorly studied in Ipomoea pes-caprae. In this research, 12 NAC TFs, named IpNAC1-IpNAC12, were selected from transcriptome data. The homologous evolution tree divided IpNACs into four major categories, and six IpNACs were linearly associated with Arabidopsis ANAC genes. From the gene structures, protein domains, and promoter upstream regulatory elements, IpNACs were shown to contain complete NAC-specific subdomains (A-E) and cis-acting elements corresponding to different stress stimuli. We measured the expression levels of the 12 IpNACs under abiotic stress (salt, heat, and drought) and hormone treatment (abscisic acid, methyl jasmonate, and salicylic acid), and their transcription levels differed. IpNAC5/8/10/12 were located in the nucleus through subcellular localization, and the overexpressing transgenic Arabidopsis plants showed high tolerance to salt stress. The cellular Na+ homeostasis content in the mature and elongation zones of the four IpNAC transgenic sweetpotato roots showed an obvious efflux phenomenon. These conclusions demonstrate that IpNAC5/8/10/12 actively respond to abiotic stress, have significant roles in improving plant salt tolerance, and are important salt tolerance candidate genes in I. pes-caprae and sweetpotato. This study laid the foundation for further studies on the function of IpNACs in response to abiotic stress. It provides options for improving the stress resistance of sweetpotato using gene introgression from I. pes-caprae.

Parallel analysis of global garlic gene expression and alliin content following leaf wounding.

BACKGROUND: Allium sativum (garlic) is an economically important food source and medicinal plant rich in sulfides and other protective substances such as alliin, the precursor of allicin biosynthesis. Cysteine, serine and sulfur is the precursor of alliin biosynthesis. However, little is known about the alliin content under abiotic stress or the mechanism by which it is synthesized. RESULTS: The findings revealed that the content of alliin was lowest in the garlic roots, and highest in the buds. Furthermore, alliin levels decreased in mature leaves following wounding. Transcriptome data generated over time after wounding further revealed significant up-regulation of genes integral to the biosynthetic pathways of cysteine and serine in mature garlic leaves. CONCLUSIONS: The findings suggest that differential expression of cysteine, serine and sulfide-related genes underlies the accumulation of alliin and its precursors in garlic, providing a basis for further analyses of alliin biosynthesis.