Understanding and Mapping Cold-Induced Seedless Fruit Development in Cucumbers

Greg Howard
26th August, 2024

Understanding and Mapping Cold-Induced Seedless Fruit Development in Cucumbers

Image Source: Natural Science News, 2024

Key Findings

  • Researchers at Nanjing Agricultural University identified a cucumber line, EC5, that can grow fruit under cold conditions
  • They discovered a gene, CsAGL11, which is less active in cold, helping cucumbers produce fruit without fertilization
  • This finding can help develop cucumber varieties that yield more fruit in cold climates, benefiting farmers
Cold stress significantly impacts fruit development, leading to substantial yield reductions in many fruit-bearing vegetables. Cucumber, a vegetable of subtropical origin, is particularly sensitive to cold. Cold-inducible parthenocarpy (CIP) offers promise for maintaining fruit yield under cold conditions. Researchers at Nanjing Agricultural University have identified a CIP line in cucumber, named EC5, which exhibits strong parthenocarpy and sustained fruit growth under cold conditions (16°C day/10°C night)[1]. However, the candidate gene and genetic mechanism underlying CIP in cucumber were previously unknown. In this study, both Bulked Segregant Analysis sequencing (BSA-seq) and conventional Quantitative Trait Loci (QTL) mapping strategies were employed on F2 populations to investigate the genetic control of CIP. A single QTL, CIP5.1, was consistently mapped across two winter seasons in 2021 and 2022. Fine mapping delimited the CIP locus to a 38.3kb region on chromosome 5, which harbors eight candidate genes. Among these candidates, CsAGL11 (CsaV3_5G040370) was identified, exhibiting multiple deletions and insertions in the promoter and 5' untranslated region (UTR). The CsAGL11 gene encodes a MADS-box transcription factor protein, which is homologous to genes previously recognized as negative regulators in ovule and fruit development in Arabidopsis and tomato[2]. In tomato, the MADS-box gene TM29 was shown to function in floral organ development, fruit development, and the maintenance of floral meristem identity[2]. Similarly, in cucumber, the CsAGL11 gene appears to play a crucial role in ovule and fruit development. Correspondingly, cold treatment resulted in decreased expression of CsAGL11 during the early developmental stage of the fruit in EC5. A promoter activity assay confirmed that promoter polymorphisms lead to weak transcriptional activation of CsAGL11 under cold conditions. This finding suggests that the reduced expression of CsAGL11 under cold stress may facilitate parthenocarpic fruit development, allowing the cucumber plants to produce fruit without fertilization. The study ties together previous findings on the role of MADS-box genes in fruit and floral development and expands on them by identifying a specific genetic mechanism that enables cucumbers to sustain fruit growth under cold conditions. This is particularly relevant given the importance of fruit set under varying environmental conditions. For instance, in tomato, the SlHB15A gene was identified as a key regulator preventing fruit set in the absence of fertilization, acting as a sentinel against adverse temperatures[3]. The identification of CsAGL11 as a critical gene for CIP in cucumber under cold stress provides a similar insight into how specific genes can be manipulated to enhance fruit yield under suboptimal growing conditions. Moreover, the discovery of CsAGL11's role in CIP has practical implications for crop breeding. By understanding the genetic basis of cold-induced parthenocarpy, breeders can develop cucumber cultivars with enhanced fruiting capabilities under cold conditions. This could lead to more stable yields and reduced economic losses for farmers in regions prone to cold stress. In conclusion, the study conducted by Nanjing Agricultural University elucidates the genetic characteristics of CIP in cucumber and highlights the potential role of the CsAGL11 gene in developing cultivars with improved fruiting under cold conditions. This research not only advances our understanding of plant responses to environmental stress but also offers practical solutions for enhancing crop resilience and productivity.

AgricultureGeneticsPlant Science

References

Main Study

1) Characterization and fine mapping of cold-inducible parthenocarpy in cucumber (Cucumis sativus L.).

Published 23rd August, 2024

https://doi.org/10.1016/j.plantsci.2024.112237

Related Studies

2) Down-regulation of TM29, a tomato SEPALLATA homolog, causes parthenocarpic fruit development and floral reversion.

Journal: Plant physiology, Issue: Vol 130, Issue 2, Oct 2002

3) The miR166-SlHB15A regulatory module controls ovule development and parthenocarpic fruit set under adverse temperatures in tomato.

https://doi.org/10.1016/j.molp.2021.05.005


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