Understanding the Cause of Abnormal Leaf Fall in Rubber Trees

Jim Crocker
23rd August, 2024

Understanding the Cause of Abnormal Leaf Fall in Rubber Trees

Image Source: Natural Science News, 2024

Key Findings

  • The study, conducted in Kerala, India, identified eight different colony morphology patterns of Phytophthora meadii from rubber tree samples affected by Abnormal Leaf Fall (ALF) disease
  • Highly virulent isolates of P. meadii showed rapid growth and petaloid morphology, and all isolates were susceptible to the fungicide metalaxyl
  • Molecular analysis confirmed the pathogen as P. meadii, providing a basis for targeted management strategies to combat ALF disease in rubber trees
Phytophthora species are notorious for causing severe plant diseases, significantly impacting agriculture and natural ecosystems. The Rubber Research Institute of India recently conducted a study on Abnormal Leaf Fall (ALF) disease affecting rubber trees, caused by Phytophthora meadii[1]. This research is crucial as it addresses a significant threat to rubber production in India. The study involved collecting 30 Phytophthora isolates from ALF-affected samples during the Southwest monsoon season in Kerala. The researchers observed eight different colony morphology patterns among the isolates, with some growing rapidly and others slowly. Highly virulent isolates exhibited a petaloid morphology and rapid growth rates, while all isolates, regardless of virulence, were susceptible to the fungicide metalaxyl. Under laboratory conditions, the most virulent isolate, labeled R17, caused severe infections in chili, brinjal, and tomato, manifesting as brown water-soaked lesions. Molecular analysis using multiple genetic markers, including Internal Transcribed Spacer (ITS), Cytochrome c oxidase 1 (COX 1), Heat Shock Protein 90 (HSP 90), and Ribosomal Protein L10 (RPL 10), confirmed the pathogen as Phytophthora meadii. This study builds on previous research efforts to understand Phytophthora species better. Earlier studies have highlighted the importance of genetic and genomic analyses in identifying and understanding the relationships among Phytophthora species. For instance, a comprehensive phylogenetic analysis of 82 Phytophthora species using seven informative loci provided a detailed evolutionary history of the genus[2]. Another study developed an open-access phylogenetic tool to centralize diverse sequence data, facilitating the identification and research of Phytophthora species[3]. These resources have been instrumental in advancing our understanding of the genus and its impact on various crops. The current study's findings are significant as they offer a detailed understanding of the morphological and molecular traits of P. meadii, essential for precise identification and future genetic variability studies. By confirming the pathogen as P. meadii, the researchers have provided a foundation for developing targeted management strategies to mitigate the impact of ALF disease on rubber trees. The study's approach involved both morphological and molecular analyses, ensuring accurate identification of the pathogen. This dual approach aligns with previous research emphasizing the importance of combining different methods for a comprehensive understanding of Phytophthora species. For instance, the development of the Tree-Based Alignment Selector Toolkit (T-BAS) allowed for real-time updates and visualization of phylogenetic trees, enhancing data sharing and collaboration among researchers[3]. Additionally, the study's finding that all isolates were susceptible to the fungicide metalaxyl is promising for disease management. This aligns with previous research that explored various preservation methods for P. infestans, another Phytophthora species, highlighting the importance of maintaining pathogen viability for biological research and fungicide screening[4]. In conclusion, the Rubber Research Institute of India's study on ALF disease caused by Phytophthora meadii provides valuable insights into the pathogen's characteristics and offers a foundation for developing effective management strategies. By building on previous research and employing a comprehensive approach, this study contributes significantly to our understanding of Phytophthora species and their impact on agriculture.

GeneticsBiochemPlant Science

References

Main Study

1) Integrating multilocus phylogeny and morphological analysis reveals the prevalence of Phytophthora meadii (McRae) associated with abnormal leaf fall disease of Hevea brasiliensis in India.

Published 22nd August, 2024

https://doi.org/10.1016/j.funbio.2024.07.012

Related Studies

2) A multi-locus phylogeny for Phytophthora utilizing markers derived from complete genome sequences.

Journal: Fungal genetics and biology : FG & B, Issue: Vol 45, Issue 3, Mar 2008

3) An open-access T-BAS phylogeny for emerging Phytophthora species.

https://doi.org/10.1371/journal.pone.0283540

4) Simple and inexpensive long-term preservation methods for Phytophthora infestans.

https://doi.org/10.1016/j.mimet.2018.07.020


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