Ramakrishnan Rameshkumar, Zurgil Udi, Kanna Shamili, Tarkowská Danuše, Novák Ondřej, Strnad Miroslav, Tel-Zur Noemi, Sitrit Yaron
French Associates Institute for Agriculture and Biotechnology of Drylands, The Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Sede Boqer Campus, 84990, Beer-Sheva, Israel.
Laboratory of Growth Regulators, Faculty of Sciences, Palacký University & Institute of Experimental Botany AS CR, Šlechtitelů 27, 783 71, Olomouc, Czech Republic.
Plant Cell Rep. 2025 Aug 6;44(9):194. doi: 10.1007/s00299-025-03568-w.
A parthenocarpic fruit mutant of prickly pear was isolated, revealing the role of GAs in parthenocarpic fruit development which is controlled by the GID-GA20ox/GA2ox genetic system modulating GA biosynthesis/regulation. We explored the intricate dynamics of parthenocarpic fruit development in prickly pear Opuntia ficus-indica (Cactaceae) through the investigation of fruits of the Beer Sheva1 (BS1) a parthenocarpic mutant and its revertant non-parthenocarpic stems. BS1 fruits, characterized by parthenocarpy and enlarged unfertilized ovules, provide a unique model for investigating the regulatory mechanisms underlying fruit development in prickly pear. We hypothesized that elevated levels of gibberellins (GAs) in BS1 ovaries induce parthenocarpic fruit development. By integrating different approaches, including GA quantification and expression analysis of ovaries from BS1 and revertant flowers, we elucidated the pivotal role of biosynthetic, catabolic, and regulatory GA genes in orchestrating ovule development. Notably, our investigation revealed a complex interplay between GA biosynthesis and catabolic genes, particularly GID1, GA20ox, and GA2ox, which significantly influenced GA levels in BS1 ovaries. Quantification of endogenous GAs confirmed higher levels of bioactive GA1, GA3, and GA4 in BS1 compared to revertant ovules, indicating the central role of GAs in parthenocarpy. Furthermore, application of the GA inhibitor paclobutrazol (PBZ) to BS1 flower buds resulted in the reversion of BS1 fruits to the progenitor phenotype containing viable seeds, thereby validating the critical involvement of GAs in seed development. High-throughput RNA-sequencing analysis identified a total of 7717 differentially expressed genes (DEGs) in BS1, among them GA-related genes. Overall, our findings shed light on the complex hormonal regulatory network governing parthenocarpic fruit development in prickly pear, paving the way for future studies aiming at understanding ovule development and development of commercially desirable seedless fruits.
分离出一种仙人掌的单性结实果实突变体，揭示了赤霉素（GAs）在单性结实果实发育中的作用，该过程由调控GA生物合成的GID-GA20ox/GA2ox遗传系统控制。我们通过研究单性结实突变体比尔谢瓦1（BS1）及其回复突变的非单性结实茎的果实，探索了仙人掌科仙人掌属植物单性结实果实发育的复杂动态。BS1果实具有单性结实和未受精胚珠增大的特征，为研究仙人掌果实发育的调控机制提供了独特模型。我们假设BS1子房内赤霉素（GAs）水平升高诱导了单性结实果实的发育。通过整合不同方法，包括GA定量以及对BS1和回复突变花的子房进行表达分析，我们阐明了生物合成、分解代谢和调控GA基因在协调胚珠发育中的关键作用。值得注意的是，我们的研究揭示了GA生物合成和分解代谢基因之间的复杂相互作用，特别是GID1、GA20ox和GA2ox，它们显著影响了BS1子房内的GA水平。内源性GA的定量分析证实，与回复突变胚珠相比，BS1中生物活性GA1、GA3和GA4的水平更高，表明GA在单性结实中起核心作用。此外，将GA抑制剂多效唑（PBZ）应用于BS1花芽，导致BS1果实回复为含有可育种子的原始表型，从而验证了GA在种子发育中的关键作用。高通量RNA测序分析在BS1中总共鉴定出7717个差异表达基因（DEGs），其中包括GA相关基因。总体而言，我们的研究结果揭示了控制仙人掌单性结实果实发育的复杂激素调控网络，为未来旨在理解胚珠发育和商业上所需无籽果实发育的研究铺平了道路。
