Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, 210037, China.
College of Forestry, Nanjing Forestry University, Nanjing, 210037, China.
BMC Plant Biol. 2021 Aug 28;21(1):400. doi: 10.1186/s12870-021-03171-7.
Pomegranate is an excellent tree species with nutritional, medicinal, ornamental and ecological values. Studies have confirmed that SPL factors play an important role in floral transition and flower development.
Used bioinformatics methods, 15 SPL (SQUAMOSA promoter-binding protein-like) genes were identified and analyzed from the 'Taishanhong' pomegranate (P. granatum L.) genome. Phylogenetic analysis showed that PgSPLs were divided into six subfamilies (G1 ~ G6). PgSPL promoter sequences contained multiple cis-acting elements associated with abiotic stress or hormonal response. Based on the transcriptome data, expression profiles of different tissues and different developmental stages showed that PgSPL genes had distinct temporal and spatial expression characteristics. The expression analysis of miR156 in small RNA sequencing results showed that miR156 negatively regulated the expression of target genes. qRT-PCR analysis showed that the expression levels of PgSPL2, PgSPL3, PgSPL6, PgSPL11 and PgSPL14 in leaves were significantly higher than those in buds and stems (p < 0.05). The expression levels of PgSPL5, PgSPL12 and PgSPL13 in flower buds were significantly higher than that in leaves and stems (p < 0.05). The full-length of coding sequence of PgSPL5 and PgSPL13 were obtained by homologous cloning technology. The full length of PgSPL5 is 1020 bp, and PgSPL13 is 489 bp, which encodes 339 and 162 amino acids, respectively. Further investigation revealed that PgSPL5 and PgSPL13 proteins were located in the nucleus. Exogenous plant growth regulator induction experiments showed that PgSPL5 was up-regulated in leaves and stems. PgSPL13 was up-regulated in leaves and down-regulated in stems. When sprayed with 6-BA, IBA and PP333 respectively, PgSPL5 and PgSPL13 were up-regulated most significantly at P2 (bud vertical diameter was 5.1 ~ 12.0 mm) stage of bisexual and functional male flowers.
Our findings suggested that PgSPL2, PgSPL3, PgSPL6, PgSPL11 and PgSPL14 played roles in leaves development of pomegranate. PgSPL5, PgSPL12 and PgSPL13 played roles in pomegranate flower development. PgSPL5 and PgSPL13 were involved in the response process of different plant hormone signal transduction in pomegranate development. This study provided a robust basis for further functional analyses of SPL genes in pomegranate.
石榴是一种具有营养、药用、观赏和生态价值的优良树种。研究证实 SPL 因子在花发育和花发育中起着重要作用。
利用生物信息学方法，从‘泰山红’石榴（P. granatum L.）基因组中鉴定并分析了 15 个 SPL（SQUAMOSA 启动子结合蛋白样）基因。系统发育分析表明，PgSPLs 分为六个亚家族（G1G6）。PgSPL 启动子序列含有与非生物胁迫或激素反应相关的多个顺式作用元件。基于转录组数据，不同组织和不同发育阶段的表达谱显示 PgSPL 基因具有明显的时空表达特征。miR156 在小 RNA 测序结果中的表达分析表明，miR156 负调控靶基因的表达。qRT-PCR 分析表明，叶片中 PgSPL2、PgSPL3、PgSPL6、PgSPL11 和 PgSPL14 的表达水平明显高于芽和茎（p<0.05）。花蕾中 PgSPL5、PgSPL12 和 PgSPL13 的表达水平明显高于叶片和茎（p<0.05）。利用同源克隆技术获得 PgSPL5 和 PgSPL13 的全长编码序列。PgSPL5 的全长为 1020bp，PgSPL13 为 489bp，分别编码 339 和 162 个氨基酸。进一步研究表明，PgSPL5 和 PgSPL13 蛋白定位于细胞核内。外源植物生长调节剂诱导实验表明，PgSPL5 在叶片和茎中上调。PgSPL13 在叶片中上调，在茎中下调。当分别用 6-BA、IBA 和 PP333 喷洒时，PgSPL5 和 PgSPL13 在两性花和功能雄花的 P2（花蕾垂直直径为 5.112.0mm）阶段表达最为显著。
本研究表明 PgSPL2、PgSPL3、PgSPL6、PgSPL11 和 PgSPL14 参与了石榴叶片的发育。PgSPL5、PgSPL12 和 PgSPL13 参与了石榴花的发育。PgSPL5 和 PgSPL13 参与了石榴发育过程中不同植物激素信号转导的响应过程。本研究为进一步研究石榴 SPL 基因的功能提供了坚实的基础。
