Seed abortion is a common phenomenon in woody plants, especially in rare and endangered species. Serious seed abortion occurs in the dove tree and largely restricts its natural reproduction. A number of differentially expressed genes (DEGs) between normal and aborted seeds of the dove tree have been previously identified through transcriptome profiling. Among these, most DEGs encoding laccase showed significant upregulation in the aborted seeds. In this study, the laccase gene with the highest expression level in aborted seeds, DiLAC17, was cloned from the dove tree genome and further verified. Overexpression of the DiLAC17 gene in Arabidopsis resulted in retarded growth, deformed siliques, and severe seed abortion. Most Arabidopsis genes involved in seed development, such as AtLEC2, AtANT1, and AtRGE1, were suppressed in the transgenic lines. Laccase activity and lignin content were significantly improved in transgenic lines under ectopic overexpression of the DiLAC17 gene. Excessive lignin accumulation in the early developmental stage was assumed to be a key cause of restricting silique growth and seed expansion, which ultimately led to seed abortion. These results indicate a laccase-mediated pathway for seed abortion, which might be a strategy adopted by this rare and endangered species to reduce the reproductive load.

Trehalose and some members of the trehalose 6-phosphate synthase (TPS) gene family play important roles in response to abiotic stress in plants. However, no studies investigating the TPS gene in rose have been reported. In this study, the trehalose content in the stems and roots of Rosa chinensis was significantly increased under heat stress, and nine TPS family members were identified from the genome of R. chinensis. The R. chinensis TPS (RcTPS) family members could be divided into two subfamilies based on the structure and phylogenetic analysis. In this study, we found that segmental duplications contributed to the expansion of the RcTPS gene family, and the type II subfamily gene pairs RcTPS9–RcTPS10 and RcTPS7a–RcTPS7b were created by segmental duplication events. The type I subfamily RcTPS members contained 17 exons in the protein-coding region, whereas type II subfamily members only had 3 or 4 exons. Most cis-acting elements in the promoters of RcTPS members were related to plant hormones, especially ABA hormones. A phylogenetic tree of 78 TPS homologous amino acids from R. chinensis and another 7 species was constructed, which could be divided into 5 clades, and purity selection was observed to be the dominant evolutionary selection pressure. Under heat stress, except for RcTPS1b, the other eight RcTPS members were upregulated in the roots, stems, orleaves. The type II subfamily members RcTPS7a and RcTPS7b showed significantly high expression patterns in response to heat stress in all three tissues. Our findings indicate that RcTPS7a and RcTPS7b may play important roles in the heat tolerance of R. chinensis and are helpful for future functional studies of the two RcTPS members during heat stress.

Lilium × formolongi is an important cut flower species that is able to flower within a year following seed propagation, with flower induction that is very sensitive to the photoperiod. Cryptochromes are blue/UV-A light receptors that regulate many important plant growth and development processes, including photoperiodic flowering. In this study, we isolated the cryptochrome 1 (CRY1) gene from L. × formolongi and analyzed its function in transgenic Arabidopsis. The predicted LfCRY1 protein was strongly homologous to other CRY1 proteins. The transcription of LfCRY1 was induced by blue light, with LfCRY1 exhibiting its highest expression and diurnal expression patterns during the flowering-induction stage under both long-day (LD) and short-day (SD) photoperiods. Overexpression of LfCRY1 in Arabidopsis promoted flowering under LDs but not SDs and inhibited hypocotyl elongation under blue light. The LfCRY1 protein was located in both the nucleus and cytoplasm. LfCRY1 interacted with the important flowering activator LfCOL9 in both yeast and onion cells. These results provide functional evidence for the role of LfCRY1 in controlling photoperiodic flowering under LDs and indicate that LfCRY1 may be a counterpart of AtCRY1. Understanding the role of LfCRY1 in photoperiodic flowering is beneficial for the molecular breeding of lilies with shorter vegetative stages.

[目的]研究不同预处理方式下培养方法协同作用对新铁炮百合种子萌发的影响.[方法]以新铁炮百合雷山1号种子为材料,采用三因素四水平正交试验设计,研究不同水平的预处理方式、培养温度、培养方式对新铁炮百合雷山1号种子萌发的影响,以及不同温度下种子萌发过程中可溶性糖和过氧化物歧化酶(SOD)的动态变化规律.[结果]培养温度是影响新铁炮百合雷山1号种子萌发的主要因素,其次是预处理方式和培养方式.雷山1号种子的最佳预处理方式是4℃浸种7 d,最佳培养温度是21℃,最佳培养方式是土壤播种,发芽率为99.18％,播种后第9 d发芽指数为4.65.不同温度处理下,种子萌发过程中超氧化物歧化酶(SOD)活性表现出先增加后下降的趋势,可溶性糖含量则呈现出先下降再上升的趋势,其中21℃处理下种子的抗逆性和贮藏物质的转化利用要高于15、18和25℃处理下的种子,21℃为适宜温度.[结论]雷山1号种子的最佳处理方式为4℃浸种7 d于21℃下土壤播种.