Forestry and Pomology Research Insitute, Shanghai Academy of Agricultural Sciences, Jinqi Road No. 1000, Fengxian District, Shanghai, 201403, China.
Shanghai Key Lab of Protected Horticultural Technology, Shanghai Academy of Agricultural Sciences, Jinqi Road No. 1000, Fengxian District, Shanghai, 201403, China.
BMC Plant Biol. 2020 Apr 25;20(1):182. doi: 10.1186/s12870-020-02398-0.
Propagation of cuttings is frequently used in various plant species, including blueberry, which shows special root characteristics that may hinder adventitious root (AR) formation. AR formation is influenced by various factors, and auxin is considered to play a central role; however, little is known of the related regulatory mechanisms. In this study, a comparative transcriptome analysis of green cuttings treated with or without indole-butyric acid (IBA) was performed via RNA_seq to identify candidate genes associated with IBA-induced AR formation.
Rooting phenotypes, especially the rooting rate, were significantly promoted by exogenous auxin in the IBA application. Blueberry AR formation was an auxin-induced process, during which adventitious root primordium initiation (rpi) began at 14 days after cutting (DAC), root primordium (rp) was developed at 21 DAC, mature AR was observed at 28 DAC and finally outgrowth from the stem occurred at 35 DAC. Higher IAA levels and lower ABA and zeatin contents might facilitate AR formation and development. A time series transcriptome analysis identified 14,970 differentially expressed genes (DEGs) during AR formation, of which there were 7467 upregulated and 7503 downregulated genes. Of these, approximately 35 candidate DEGs involved in the auxin-induced pathway and AR formation were further identified, including 10 auxin respective genes (ARFs and SAURs), 13 transcription factors (LOB domain-containing protein (LBDs)), 6 auxin transporters (AUX22, LAX3/5 and PIN-like 6 (PIL6s)) and 6 rooting-associated genes (root meristem growth factor 9 (RGF9), lateral root primordium 1 (LRP1s), and dormancy-associated protein homologue 3 (DRMH3)). All these identified DEGs were highly upregulated in certain stages during AR formation, indicating their potential roles in blueberry AR formation.
The transcriptome profiling results indicated candidate genes or major regulatory factors that influence adventitious root formation in blueberry and provided a comprehensive understanding of the rooting mechanism underlying the auxin-induced AR formation from blueberry green cuttings.
在包括蓝莓在内的各种植物物种中，扦插繁殖经常被使用，蓝莓表现出特殊的根系特征，可能会阻碍不定根（AR）的形成。AR 的形成受到各种因素的影响，生长素被认为起着核心作用；然而，相关的调节机制知之甚少。在这项研究中，通过 RNA-seq 对用或不用吲哚丁酸（IBA）处理的绿色插条进行了比较转录组分析，以鉴定与 IBA 诱导的 AR 形成相关的候选基因。
生根表型，特别是生根率，在外源生长素的应用中显著促进。蓝莓 AR 的形成是一个生长素诱导的过程，不定根原基起始（rpi）在切割后 14 天（DAC）开始，根原基（rp）在 21 DAC 发育，成熟的 AR 在 28 DAC 观察到，最后从茎中长出在 35 DAC。较高的 IAA 水平和较低的 ABA 和玉米素含量可能促进 AR 的形成和发育。时间序列转录组分析确定了 AR 形成过程中 14970 个差异表达基因（DEGs），其中 7467 个上调和 7503 个下调基因。其中，约有 35 个候选 DEGs 涉及生长素诱导途径和 AR 的形成，包括 10 个生长素相关基因（ARFs 和 SAURs）、13 个转录因子（LOB 结构域蛋白（LBDs））、6 个生长素转运蛋白（AUX22、LAX3/5 和 PIN-like6（PIL6s））和 6 个生根相关基因（根分生组织生长因子 9（RGF9）、侧根原基 1（LRP1s）和休眠相关蛋白同源物 3（DRMH3））。所有这些鉴定的 DEGs 在 AR 形成的某些阶段高度上调，表明它们在蓝莓 AR 形成中可能发挥作用。
转录组分析结果表明，候选基因或主要调节因子影响蓝莓不定根的形成，为蓝莓绿色插条中生长素诱导的 AR 形成提供了对生根机制的全面理解。
