scholarly journals Virulence of Rigidoporus microporus Isolates Causing White Root Rot Disease on Rubber Trees (Hevea brasiliensis) in Malaysia

Plants ◽  
2021 ◽  
Vol 10 (10) ◽  
pp. 2123
Author(s):  
Wen Ze Go ◽  
Kit Ling Chin ◽  
Paik San H’ng ◽  
Mui Yun Wong ◽  
Chuah Abdullah Luqman ◽  
...  

Latex production from Hevea brasiliensis rubber tree is the second most important commodity in Malaysia, but this industry is threatened by the white root rot disease (WRD) caused by Rigidoporus microporus that leads to considerable latex yield loss and tree death. This study aimed to characterize and compare the virulence of five R. microporus isolates obtained from infected rubber trees located at different states in Malaysia. These isolates were subjected to morphological and molecular characterization for species confirmation and pathogenicity test for the determination of virulence level. BLAST search showed that the ITS sequences of all the pathogen isolates were 99% identical to R. microporus isolate SEG (accession number: MG199553) from Malaysia. The pathogenicity test of R. microporus isolates conducted in a nursery with 24 seedlings per isolate showed that isolate RL21 from Sarawak has developed the most severe above- and below-ground symptoms of WRD on the rubber clone RRIM600 as host. Six months after being infected with R. microporus, RL21 was evaluated with the highest average of disease severity index of 80.52% for above- and below-ground symptoms, followed by RL22 (68.65%), RL20 (66.04%), RL26 (54.38%), and RL25 (43.13%). The in vitro growth condition tests showed that isolate RL21 of R. microporus has optimum growth at 25–30 °C, with the preference of weakly acidic to neutral environments (pH 6–7). This study revealed that different virulence levels are possessed among different R. microporus isolates even though they were isolated from the same host species under the same climate region. Taken together, field evaluation through visual observation and laboratory assays have led to screening of the most virulent isolate. Determination of the most virulent isolate in the present study is vital and shall be taken into consideration for the selection of suitable pathogen isolate in the development of more effective control measures in combating tenacious R. microporus.

2017 ◽  
Vol 08 (07) ◽  
pp. 1646-1658 ◽  
Author(s):  
Mua Genevieve Nam ◽  
Njonje Stephen Wawa ◽  
Ehabe Eugene Ejolle ◽  
Njukeng Jetro Nkengafac

2016 ◽  
Vol 56 (4) ◽  
pp. 380-388 ◽  
Author(s):  
Porntip Sangsil ◽  
Charassri Nualsri ◽  
Natthakorn Woraathasin ◽  
Korakot Nakkanong

AbstractPhenylalanine ammonia lyase (PAL) is a specific branch point enzyme of primary and secondary metabolism. It plays a key role in plant development and defense mechanisms. Phenylalanine ammonia lyase from Hevea brasiliensis (HbPAL) presented a complete open reading frame (ORF) of 2,145 bp with 721 encoded amino acids. The sequence alignment indicated that the amino acid sequence of HbPAL shared a high identity with PAL genes found in other plants. Phylogenetic tree analysis indicated that HbPAL was more closely related to PALs in Manihot esculenta and Jatropha curcas than to those from other plants. Transcription pattern analysis indicated that HbPAL was constitutively expressed in all tissues examined, most highly in young leaves. The HbPAL gene was evaluated by quantitative real-time PCR (qRT-PCR) after infection with Rigidoporus microporus at 0, 12, 24, 48, 72 and 96 hours post inoculation. The expression patterns of the PAL gene differed among the three rubber clones used in the study. The transcription level of the white root rot disease tolerant clone, PB5/51 increased sharply during the latter stages of infection, while it was relatively subdued in the white root rot disease susceptible clones, RRIM600 and BPM24. These results suggest that the HbPAL gene may play a role in the molecular defense response of H. brasiliensis to pathogen attack and could be used as a selection criterion for disease tolerance.


Rhizosphere ◽  
2020 ◽  
Vol 15 ◽  
pp. 100221
Author(s):  
Imran Shabbir ◽  
Mohd Yusoff Abd Samad ◽  
Radziah Othman ◽  
Mui-Yun Wong ◽  
Zulkefly Sulaiman ◽  
...  

2018 ◽  
Vol 85 (3) ◽  
Author(s):  
Clara Pliego ◽  
José Ignacio Crespo-Gómez ◽  
Adrián Pintado ◽  
Isabel Pérez-Martínez ◽  
Antonio de Vicente ◽  
...  

ABSTRACTThe rhizobacteriumPseudomonas pseudoalcaligenesAVO110, isolated by the enrichment of competitive avocado root tip colonizers, controls avocado white root rot disease caused byRosellinia necatrix. Here, we applied signature-tagged mutagenesis (STM) during the growth and survival of AVO110 in fungal exudate-containing medium with the goal of identifying the molecular mechanisms linked to the interaction of this bacterium withR. necatrix. A total of 26 STM mutants outcompeted by the parental strain in fungal exudate, but not in rich medium, were selected and namedgrowth-attenuatedmutants (GAMs). Twenty-one genes were identified as being required for this bacterial-fungal interaction, including membrane transporters, transcriptional regulators, and genes related to the metabolism of hydrocarbons, amino acids, fatty acids, and aromatic compounds. The bacterial traits identified here that are involved in the colonization of fungal hyphae include proteins involved in membrane maintenance (a dynamin-like protein and ColS) or cyclic-di-GMP signaling and chemotaxis. In addition, genes encoding a DNA helicase (recB) and a regulator of alginate production (algQ) were identified as being required for efficient colonization of the avocado rhizosphere.IMPORTANCEDiseases associated with fungal root invasion cause a significant loss of fruit tree production worldwide. The bacteriumPseudomonas pseudoalcaligenesAVO110 controls avocado white root rot disease caused byRosellinia necatrixby using mechanisms involving competition for nutrients and niches. Here, a functional genomics approach was conducted to identify the bacterial traits involved in the interaction with this fungal pathogen. Our results contribute to a better understanding of the multitrophic interactions established among bacterial biocontrol agents, the plant rhizosphere, and the mycelia of soilborne pathogens.


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