Summary: Myo‐inositol‐1‐phosphate synthase (MIPS) is a key rate limiting enzyme inmyo‐inositol biosynthesis. TheMIPSgene has been shown to improve tolerance to abiotic stresses in several plant species. However, its role in resistance to biotic stresses has not been reported. In this study, we found that expression of the sweet potatoIbMIPS1gene was induced by NaCl, polyethylene glycol (PEG), abscisic acid (ABA) and stem nematodes. Its overexpression significantly enhanced stem nematode resistance as well as salt and drought tolerance in transgenic sweet potato under field conditions. Transcriptome and real‐time quantitativePCRanalyses showed that overexpression ofIbMIPS1up‐regulated the genes involved in inositol biosynthesis, phosphatidylinositol (PI) andABAsignalling pathways, stress responses, photosynthesis andROS‐scavenging system under salt, drought and stem nematode stresses. Inositol, inositol‐1,4,5‐trisphosphate (IP₃), phosphatidic acid (PA), Ca²⁺,ABA, K⁺, proline and trehalose content was significantly increased, whereas malonaldehyde (MDA), Na⁺and H₂O₂content was significantly decreased in the transgenic plants under salt and drought stresses. After stem nematode infection, the significant increase of inositol,IP₃,PA, Ca²⁺,ABA, callose and lignin content and significant reduction ofMDAcontent were found, and a rapid increase of H₂O₂levels was observed, peaked at 1 to 2 days and thereafter declined in the transgenic plants. This study indicates that theIbMIPS1gene has the potential to be used to improve the resistance to biotic and abiotic stresses in plants.

Auxin response factors (ARFs) compose a family of transcription factors and have been found to play major roles in the process of plant growth and development. However, their roles in plant carotenoid biosynthesis and responses to abiotic stresses are rarely known to date. In the present study, we found that the IbARF5 gene from sweetpotato (Ipomoea batatas (L.) Lam.) line HVB-3 increased the contents of carotenoids and enhanced the tolerance to salt and drought in transgenic Arabidopsis. The transgenic Arabidopsis plants exhibited the increased abscisic acid (ABA) and proline contents and superoxide dismutase (SOD) activity and the decreased H₂O₂ content. Furthermore, it was found that IbARF5 positively regulated the genes associated with carotenoid and ABA biosynthesis and abiotic stress responses. These results suggest that IbARF5 is involved in carotenoid biosynthesis and salt and drought tolerance in transgenic Arabidopsis. This study provides a novel ARF gene for improving carotenoid contents and salt and drought tolerance of sweetpotato and other plants.

BBX24 regulates the jasmonic acid pathway, Fusarium wilt resistance, and storage root yield in sweet potato, providing a candidate target gene for enhancing pat