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Bakanae disease on rice has been recorded almost in all countries where paddy is grown commercially, especially in Asian countries, including Malaysia and Indonesia. Bakanae disease was widespread in Peninsular Malaysia and three provinces of Indonesia with the range of disease severity from scale 1 to 5 and disease incidence from 0.5 to 12.5% during 2004-2005 main growing seasons. A total of five Fusarium species belonging to section Liseola and their allied i.e. Fusarium fujikuroi, F. proliferatum, F. sacchari, F. subglutinans and F. verticillioides were isolated and identified on the basis of their morphological characteristics. Literature data showed that the bakanae disease of rice all over the world is caused by F. fujikuroi and probably some other Fusarium species from section Liseola or allied. However, from pathogenicity tests that have been carried out by using variety MR 211 of rice it was evident that F. fujikuroi was highly virulent and the only species involved in causing bakanae disease. Therefore, this species was the only one detected to be able to produce gibberellic acid - (GA3) with Rf value 0.40 and 0.62, developed in solvent systems isopropanol:ammonia:water (10: 1: 1), v/v/ v and chloroform:ethyl acetate:formic acid (5: 4: 1), v/v/v, respectively. This knowledge would be invaluable in developing our understanding on the interaction between F. fujikuroi and the host plants.
Fruit rot of tomato is a serious disease caused by Fusarium species. Sampling was conducted throughout Selangor, Malaysia and fungal species identification was conducted based on morphological and gene encoding translation elongation factor 1-α (tef1-α) sequence analysis. Five species of Fusarium were discovered namely F. oxysporum (including F. oxysporum f. sp. lycopersici), F. solani, F. equiseti, F. proliferatum and F. verticillioides. Our results provide additional information regarding the diversity of Fusarium species associated with fruit rot disease of tomato.
Relative to the established and well known rice diseases, sheath brown rot caused by Pseudomonas fuscovaginae can be considered new but getting widespread and serious all over the world. Our research was aimed to monitor and quantify the incidence and importance of the disease in Malaysia. A series of field monitoring and sampling were conducted to quantify the incidence and severity of the disease. Laboratory analysis of the collected diseased plant was done to identify the causal organism. Disease resistance screening of selected rice cultivars were also conducted to overcome the problem. The disease was found to become more important, prevalent and widely spread throughout rice growing areas in Peninsular Malaysia. Infected plants in the field became yellowish, lower leaf sheaths turned light or dark brown, while grains produced by an infected plant were discoloured, malformed and empty. The highest disease incidence was recorded in the state of Pahang (62%) and Selangor (62%), while the most severe infection was recorded in Pahang (55%) and Terengganu (61%). The evaluations of varietal resistance evaluation showed that the pathogen naturally infected all tested rice varieties at different levels of infection. Several rice varieties i.e. MR240, MR243, MR244, MR245, MR246, MR248 and MR249, classified as moderately resistant to the disease, could be recommended for planting in the next planting season.
A total of 26 isolates of Fusarium proliferatum and F. sacchari were isolated from rice in the Peninsular Malaysia and Kalimantan, Indonesia. Spontaneous chlorate-resistant sectors (CRSs) were recovered from all wild type of both Fusarium species when cultured on two chlorate media. The non-utilizing (nit) mutants were generated as crn (chlorate resistant, nitrate utilizing), nit1, nit3 and nitM based on phenotyping growth-types on diagnostic media with different sources of nitrogen. The nit mutants were paired on minimal medium (MM) for examining the vegetative compatibility. The majority of nit mutants (32.3-46.5%) recovered were nit1. Eight and seven vegetative compatibility groups (VCGs) of F. proliferatum and F. sacchari were identified, respectively. The isolates of F. proliferatum and F. sacchari were genetically diverse as shown by the number and distribution of the VCGs. No strong correlation was observed between VCGs of both species and location.
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