Summary: Nuclear factor Y (NF‐Y) is a ubiquitous transcription factor formed by three distinct subunits, namely NF‐YA, NF‐YB and NF‐YC. A stress‐responsive cDNA of NF‐YC (Cdt‐NF‐YC1) was isolated from triploid bermudagrass (Cynodon dactylon × Cynodon transvaalensis), and its role in abiotic stress tolerance was investigated in this study. Cdt‐NF‐YC1 transcript was detected in all vegetative tissues with higher levels being observed in roots. Transcription of Cdt‐NF‐YC1 in leaves was induced by dehydration, salinity, and treatments with abscisic acid (ABA), hydrogen peroxide (H₂O₂) or nitric oxide (NO), but not altered by cold. The dehydration‐ or salt‐induced transcription of Cdt‐NF‐YC1 was blocked by inhibitor of ABA synthesis and scavenger of H₂O₂ or NO, indicating that ABA, H₂O₂ and NO were involved in the dehydration‐ and salt‐induced transcription of Cdt‐NF‐YC1. Overexpression of Cdt‐NF‐YC1 resulted in elevated tolerance to drought and salt stress and increased sensitivity to ABA in transgenic rice. Transcript levels of stress/ABA responsive genes (OsLEA3, OsRAB16A, OsLIP9 and OsP5CS1), ABA synthesis and signalling genes (OsNCED3 and OsABI2), and ABA‐independent genes (OsDREB1A, OsDREB1B and OsDREB2A) were substantially higher in transgenic rice than in wild‐type plants. The results suggested that that Cdt‐NF‐YC1 is a good candidate gene to increase drought and salinity tolerance in transgenic rice through modulating gene regulation in both ABA‐dependent and ABA‐independent pathways.

Ethylene responsive factor (ERF) subfamily transcription factors play an important role in plant abiotic and biotic stress tolerance. A cold responsive ERF, MfERF1, was isolated from Medicago falcata, an important forage legume that has great cold tolerance. Overexpression of MfERF1 resulted in an increased tolerance to freezing and chilling in transgenic tobacco plants, whereas down-regulation of the ortholog of MfERF1 in Medicago truncatula resulted in reduced freezing tolerance in RNAi plants. Higher transcript levels of some stress responsive genes (CHN50, OSM, ERD10C, and SAMS) and those involved in spermidine (Spd) and spermine (Spm) synthesis (SAMDC1, SAMDC2, SPDS1, SPDS2, and SPMS) and catabolism (PAO) were observed in transgenic plants than in wild type. However, neither Spd nor Spm level was accumulated in transgenic plants as a result of promoted polyamine oxidase activity. Transgenic plants had higher activities of antioxidants associated with the induced encoding genes including Cu, Zn-SOD, CAT1, CAT2, CAT3, and cpAPX and accumulated more proline associated with induced P5CS and reduced PROX2 transcription as compared with wild type. The results suggest that MfERF1 confers cold tolerance through promoted polyamine turnover, antioxidant protection, and proline accumulation.

LACCASE8 from the model system Cleome hassleriana possesses the unusual property of oxidizing caffeyl alcohol but not coniferyl alcohol and plays a critical rol