Homologous regions (hrs) are repetitive DNA sequences widely distributed in baculovirus genomes, and are known to function as transcriptional enhancers. In this study, we systematically characterized the seven hrs (hr1, hr2L, hr2R, hr3, hr4L, hr4R, and hr5) from a novel isolate of Bombyx mori nucleopolyhedrovirus (strain BmNPV-YT). The seven hrs range from 390 to 880 bp in length and consist of 1–7 repeat units of approximately 72 bp, each containing a 30 bp palindrome with an EcoRI site. Structural diversity among the hrs includes variable numbers of stem–loop motifs, major late transcription factor (MLTF) sites, cAMP response elements (CRE-like), and 12-O-tetradecanoylphorbol 13-acetate (TPA)-response elements (TRE-like). Functional assays using luciferase reporter plasmids revealed that all seven hrs function as potent transcriptional enhancers for both homologous and heterologous promoters in vitro and in vivo. In BmN cells and fifth-instar silkworm larvae, the hrs enhanced the homologous ie1 promoter 11–1258-fold and 43–1545-fold, respectively, with hr2L showing the strongest activity (counts per minute: 4.82 × 10⁸ in cells; 7.08 × 10⁷ in larvae) and hr4R the weakest. Similarly, when driving the heterologous AcMNPV ie1 promoter in Sf21 cells and larvae, enhancement ranged from 19- to 1023-fold and 13- to 449-fold, respectively, again with hr2L and hr3 showing maximal effects and hr4R minimal enhancement. Notably, all the hrs, except hr4R, also stimulated the homologous late p10 promoter, with activation levels of up to 37.7-fold in vitro and 79.2-fold in vivo, significantly above baseline. However, hr4R showed negligible or no enhancement (0.84–1.05-fold). Among all the active hrs, hr5 emerged as the most potent enhancer of the p10 promoter. Spearman’s correlation analyses demonstrated that enhancer efficiency for all three promoters (homologous ie1, heterologous ie1, and homologous p10) correlated significantly with the number of palindromic sequences, the combined count of CRE and TRE motifs, and the total number of characteristic sequences (r = 0.873–0.982, p < 0.05 or p < 0.01). Collectively, our findings clarify the structural features of hrs from the newly isolated strain BmNPV-YT, systematically identify their promoter preferences and host adaptability as transcriptional enhancers, and establish their structure–function relationships. These findings provide novel insights into the transcriptional regulation of baculoviruses and offer valuable tools for optimizing baculovirus expression vector systems.

To investigate the adaptation ability of triticale to saline–alkaline stress, SN-1 triticale was used in this study to determine the roles of different saline–alkaline ratios for stress treatment from seed germination to the seedling stage. This study uniquely evaluates combined saline–alkaline mixtures that mimic field soil composition, rather than single salt treatments. In this study, we used two neutral salts (NaCl and Na₂SO₄) and two alkaline salts (Na₂CO₃ and NaHCO₃), mixed in 25 mixtures across five salt type combinations and five concentration levels (0, 50, 100, 150, 200, 300), with pH values from 7.15 to 11.47. We treated SN-1 under these 25 different saline–alkaline conditions and tested physiological indices at the seed germination and seedling stages, including germination percentage, germination energy, germination index, seedling stem length, seedling root length, the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and soluble proteins. The results showed that during the germination period, when the pH and salt concentration were low, the germination percentage and potential increased; the germination percentage increased from 91% in the control to 93% at 50 mmol·L⁻¹ in treatment B. The treatment groups exhibited similar changing trends. The lengths of the germ and radicle decreased as the salt–alkali concentration, especially the pH, increased, and the radicle was more sensitive than the germ. The activities of the protective enzymes SOD, POD, and CAT increased when the salt–alkali content was low. The soluble protein content initially increased and then decreased as the salt–alkali content increased. In the photosynthetic system, chlorophyll a increased while chlorophyll b decreased, leading to an increased Chl a/b ratio, which may reflect a stress-induced reallocation of light-harvesting complexes. The root was highly sensitive to salt–alkaline stress, and all indices showed the same trend of an initial increase followed by a subsequent decrease. The root surface area, length, and number of root tips showed the same trend and decreased rapidly. These results indicate that both pH and ionic composition should be considered when selecting sowing sites or breeding for tolerance.