College of Life Sciences , Nankai University , Tianjin 300071 , People's Republic of China.
College of Horticulture and Landscape , Tianjin Agricultural University , Tianjin , People's Republic of China.
J Agric Food Chem. 2018 Sep 19;66(37):9588-9597. doi: 10.1021/acs.jafc.8b01531. Epub 2018 Sep 6.
MiR171 plays pleiotropic roles in the growth and development of several plant species. However, the mechanism underlying the miR171-mediated regulation of organ development in broccoli remains unknown. In this study, bol-miR171b was characterized and found to be differentially expressed in various broccoli organs. The ectopic overexpression of bol-miR171b in Arabidopsis affected the leaf and silique development of transgenic lines. In particular, the chlorophyll content of leaves from overexpressed bol-miR171b transgenic Arabidopsis was higher than that of the vector controls. The fertility and seed yield of Arabidopsis with overexpressed bol-miR171b were markedly lower than those of the vector controls. Similarly, overexpressed bol-miR171b transgenic broccoli exhibited dark green leaves with high chlorophyll content, and nearly all of the flowers were sterile. These results demonstrated that overexpression of bol-miR171b could increase the chlorophyll content of transgenic plants. Degradome sequencing was conducted to identify the targets of bol-miR171b. Two members of the GRAS gene family, BolSCL6 and BolSCL27, were cleaved by bol-miR171b-3p in broccoli. In addition to the genes targeted by bol-miR171b-3p, adenylylsulfate reductase 3 ( APSR3), which played important roles in plant sulfate assimilation and reduction, was speculated to be cleaved by bol-miR171b-5p, suggesting that the star sequence of bol-miR171b may also have functions in broccoli. Comparative transcriptome analysis further revealed that the genes involved in chloroplast development and sulfate homeostasis should participate in the bol-miR171b -mediated regulatory network. Taken together, these findings provided new insights into the function and regulation of bol-miR171b in broccoli and indicated the potential of bol-miR171b as a small RNA molecule that increased leaf chlorophyll in plants by genetic engineering.
miR171 在几种植物物种的生长和发育中发挥着多种作用。然而，miR171 介导的西兰花器官发育调控的机制尚不清楚。在这项研究中，bol-miR171b 被表征并发现其在不同的西兰花器官中差异表达。bol-miR171b 在拟南芥中的异位过表达影响了转基因株系的叶片和角果发育。特别是，过表达 bol-miR171b 的拟南芥叶片的叶绿素含量高于载体对照。过表达 bol-miR171b 的拟南芥的育性和种子产量明显低于载体对照。同样，过表达 bol-miR171b 的转基因西兰花表现出叶绿素含量高的深绿色叶片，几乎所有的花都不育。这些结果表明，bol-miR171b 的过表达可以增加转基因植物的叶绿素含量。降解组测序用于鉴定 bol-miR171b 的靶标。GRAS 基因家族的两个成员，BolSCL6 和 BolSCL27，在西兰花中被 bol-miR171b-3p 切割。除了被 bol-miR171b-3p 靶向的基因外，还推测腺苷酰硫酸还原酶 3（APSR3）被 bol-miR171b-5p 切割，表明 bol-miR171b 的星序列可能在西兰花中也具有功能。比较转录组分析进一步表明，参与叶绿体发育和硫酸盐稳态的基因应该参与 bol-miR171b 介导的调控网络。综上所述，这些发现为 bol-miR171b 在西兰花中的功能和调控提供了新的见解，并表明 bol-miR171b 作为一种通过基因工程增加植物叶片叶绿素的小 RNA 分子具有潜力。
