Basic leucine zipper (bZIP) family in Asparagus (Asparagus officinalis): genome-wide identification, evolutionary, structure, collinearity, and expression analyses under abiotic stress at the seeding stage

Asparagus (Asparagus officinalis) is a crop with medicinal, horticultural, and nutritional uses. The basic leucine zipper (bZIP) family is a transcription factor family distributed throughout eukaryotes, including plants, and whose members participate in various biological processes, including plant growth, development, flowering, and stress responses. However, a few genome-wide studies of the bZIP family members have been reported. Here, 46 Asparagus bZIP members, named AobZIP01–AobZIP46, were identified from the reference genome via PFAM search and could be divided into 14 subgroups which were shown to be similar via motif and gene structure analysis. The molecular evolution, motif, and gene structure comparative analysis between A. officinalis and Arabidopsis indicated the accuracy of AobZIP member identification. Additionally, the cis-acting elements of the AobZIP members revealed that they might be associated with plant hormones and responses to abiotic stress. The collinear analysis predicted that the function of AobZIP members might be comparable to that of other species. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis showed that AobZIP genes were enriched in the abscisic acid (ABA) pathway. Furthermore, the tissue-specific expression at the seedling stage revealed that root tissue could be used as a target tissue because of its high expression level. The expression of AobZIP genes determined by quantitative real-time PCR under abiotic stress at the seeding stage revealed that some AobZIP members could be candidate genes for plant breeding. This study offers insights for future research in improving the abiotic stress resistance of asparagus utilizing the AobZIP genes.

芦笋（Asparagus officinalis）是一种兼具药用、园艺与营养应用价值的作物。碱性亮氨酸拉链（basic leucine zipper, bZIP）家族是一类广泛分布于包括植物在内的真核生物中的转录因子家族，其成员参与植物生长发育、开花调控及胁迫应答等多种生物学过程。然而，目前针对该家族成员的全基因组水平研究报道较少。本研究通过PFAM检索从芦笋参考基因组中鉴定得到46个bZIP家族成员，命名为AobZIP01–AobZIP46；经基序与基因结构分析，这些成员可划分为14个亚组，且各亚组间特征高度相似。通过对芦笋与拟南芥的bZIP家族进行分子进化、基序及基因结构的比较分析，验证了AobZIP成员鉴定结果的准确性。此外，对AobZIP成员的顺式作用元件分析显示，其可能与植物激素信号通路及非生物胁迫应答相关。共线性分析预测，AobZIP家族成员的功能与其他物种的同源基因功能具有一定可比性。京都基因与基因组百科全书（Kyoto Encyclopedia of Genes and Genomes, KEGG）富集分析结果表明，AobZIP基因显著富集于脱落酸（abscisic acid, ABA）通路。进一步的苗期组织特异性表达分析显示，根系组织因AobZIP基因表达量较高，可作为后续研究的靶组织。通过实时定量PCR检测苗期非生物胁迫下AobZIP基因的表达模式，发现部分AobZIP成员可作为植物抗逆育种的候选基因。本研究为未来利用AobZIP基因改良芦笋非生物胁迫抗性提供了重要的理论依据与研究思路。