Key Laboratory for Quality Regulation of Tropical Horticultural Crops of Hainan Province, School of Breeding and Multiplication (Sanya Institute of Breeding and Multiplication), Center of Nanfan and High-Efficiency Tropical Agriculture, Hainan University, Sanya 572025, China.
Key Laboratory for Quality Regulation of Tropical Horticultural Crops of Hainan Province, School of Tropical Agriculture and Forestry, Hainan University, Haikou 570228, China.
Int J Mol Sci. 2024 Jul 9;25(14):7547. doi: 10.3390/ijms25147547.
In our research, we utilized six small-fruited pepper germplasms as materials, selected cotyledons with the petiole and hypocotyls as explants, and conducted in vitro regeneration studies. Our outcomes specify that the most suitable explant is cotyledon with the petiole, and the suitable genotype is HNUCA341. The optimal medium for inducing and elongating adventitious buds for this genotype is Murashige and Skoog medium (MS) + 9.12 μM Zeatin (ZT) + 0.57 μM 3-Indoleacetic acid (IAA), with a bud induction rate of 44.4%. The best rooting induction medium is MS + 1.14 μM IAA, with a rooting rate of 86.7%. Research on the addition of exogenous hormones has revealed that the induction speed of buds in small-fruited pepper (HNUCA341) in the combination of ZT and IAA hormones (abbreviated as ZI) is quicker, and the induction effect is better. The histological observations indicate that ZI treatment accelerates the initiation of explant division and differentiation, causing a shorter duration of vascular-bundle tissue production. The plant hormone signaling pathway was significantly enriched by Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis, including (LOC107843874, LOC107843885), (LOC107848380, LOC107862455), (LOC107870540), (LOC107839518), (LOC107846008), (LOC107852624), (LOC107841020), (LOC107839415), (LOC107843441), and (LOC107871127); these significantly enriched genes may be associated with in vitro regeneration. In addition, the carbon metabolism pathway and plant mitogen-activated protein kinase (MAPK) signaling pathway are also significantly enriched in KEGG. The results of the Gene Ontology (GO) analysis revealed that differentially expressed genes related to carbon metabolism and fixation, photosynthesis and MAPK signaling pathways were upregulated under ZI treatment. It was found that they might be associated with enhanced regeneration in vitro. Furthermore, we also screened out differentially expressed transcription factors, primarily from the MYB, bHLH, AP2/ERF, and NAC families. Overall, our work accumulated important data for the in-depth analysis of the molecular mechanism of in vitro regeneration of pepper, and provides valuable germplasm for establishing an efficient stable pepper genetic-transformation system based on tissue culture.
在我们的研究中，我们利用六个小果型辣椒种质资源作为材料，选择带叶柄和下胚轴的子叶作为外植体，进行体外再生研究。结果表明，最适宜的外植体是带叶柄的子叶，适宜的基因型是 HNUCA341。该基因型诱导和伸长不定芽的最佳培养基是 Murashige 和 Skoog 培养基（MS）+9.12μM 玉米素（ZT）+0.57μM 吲哚乙酸（IAA），芽诱导率为 44.4%。最佳生根诱导培养基是 MS+1.14μM IAA，生根率为 86.7%。对外源激素添加的研究表明，ZT 和 IAA 激素组合（简称 ZI）中，小果型辣椒（HNUCA341）的芽诱导速度更快，诱导效果更好。组织学观察表明，ZI 处理加速了外植体分裂和分化的启动，导致维管束组织产生的时间更短。京都基因与基因组百科全书（KEGG）分析表明，植物激素信号通路显著富集，包括 （LOC107843874，LOC107843885）、 （LOC107848380，LOC107862455）、 （LOC107870540）、 （LOC107839518）、 （LOC107846008）、 （LOC107852624）、 （LOC107841020）、 （LOC107839415）、 （LOC107843441）和 （LOC107871127）；这些显著富集的基因可能与体外再生有关。此外，KEGG 还显著富集了碳代谢途径和植物丝裂原活化蛋白激酶（MAPK）信号通路。GO 分析结果表明，ZI 处理下与碳代谢和固定、光合作用和 MAPK 信号通路相关的差异表达基因上调。发现它们可能与体外再生增强有关。此外，我们还筛选出差异表达的转录因子，主要来自 MYB、bHLH、AP2/ERF 和 NAC 家族。总的来说，我们的工作为深入分析辣椒体外再生的分子机制积累了重要数据，为建立基于组织培养的高效稳定辣椒遗传转化体系提供了有价值的种质资源。
