Chavan Siddhi, Phalake Satish, Tetali Sujata, Barvkar Vitthal T, Patil Ravindra
Genetics and Plant Breeding Group, Agharkar Research Institute, G. G. Agarkar Road, Pune, 411004, India.
Savitribai Phule Pune University, Ganesh Khind, Pune, 411007, India.
BMC Plant Biol. 2025 Feb 3;25(1):138. doi: 10.1186/s12870-025-06075-y.
Seedless grapes are in high demand for fresh and dry fruit consumption. Seedlessness in grapes (Vitis vinifera L.) is triggered by two different mechanisms: stenospermocarpy and parthenocarpy. However, the key regulators of seed development and their targets in grapes are not well characterized. The present study used the seeded grape hybrid ARI 516 and its seedless mutant to understand the molecular mechanisms controlling the seedless phenotype in grapes.
Gametogenesis studies demonstrated that the seedless mutant exhibits pollen sterility due to abnormal pollen morphology, significantly low viability, and a complete lack of germination ability. The macrogametophyte in the seedless mutant was significantly smaller than in ARI 516. Transcriptomic comparisons were performed during three developmental stages, including pre-flowering stage E-L 15, anthesis stage E-L 23, and berry formation E-L 31, to study altered developmental processes in the seedless mutant and ARI 516. Genes downregulated in the seedless mutant were enriched in the male gametophyte development-related pathways, which may cause pollen sterility. The RNAseq results were validated by qRT-PCR. Genome sequence data was also used to identify induced mutations in the seedless mutant, which revealed three homozygous and 25 heterozygous InDels in the genes related to male gametophyte development. RNAseq and genome sequencing data collectively indicate parthenocarpic seedless phenotype due to aberrant developmental and physiological processes involved in pollen formation, maturation and germination in the seedless mutant of ARI 516.
The study showed the downregulation of transcription factors and their target genes involved in cell division, gibberellin biosynthesis and signalling, cell wall development, organization, and pollen germination. This study represents a comprehensive attempt to identify putative candidate genes associated with parthenocarpic pollen sterility in grapes using genomic approaches.
无核葡萄在鲜食和制干消费方面需求很高。葡萄（欧亚种葡萄）的无核性状由两种不同机制引发：单性结实和无籽结实。然而，葡萄种子发育的关键调控因子及其作用靶点尚未得到充分表征。本研究利用有籽葡萄杂交种ARI 516及其无核突变体来了解控制葡萄无核表型的分子机制。
配子发生研究表明，该无核突变体由于花粉形态异常、活力显著低下且完全缺乏萌发能力而表现出花粉不育。无核突变体中的大孢子体明显小于ARI 516中的大孢子体。在三个发育阶段进行了转录组比较，包括开花前期E-L 15、开花期E-L 23和浆果形成期E-L 31，以研究无核突变体和ARI 516中发育过程的变化。在无核突变体中下调的基因富集于与雄配子体发育相关的途径，这可能导致花粉不育。RNA测序结果通过qRT-PCR得到验证。基因组序列数据还用于鉴定无核突变体中的诱导突变，结果显示在与雄配子体发育相关的基因中有三个纯合和25个杂合插入缺失。RNA测序和基因组测序数据共同表明，ARI 516无核突变体中由于花粉形成、成熟和萌发过程中异常的发育和生理过程导致了单性结实的无核表型。
该研究表明参与细胞分裂、赤霉素生物合成和信号传导、细胞壁发育、组织和花粉萌发的转录因子及其靶基因表达下调。本研究代表了一项利用基因组方法鉴定与葡萄单性结实花粉不育相关的假定候选基因的全面尝试。
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