Abdul Gafur

Rust (Puccinia psidii) recorded in Indonesia poses a threat to forests and forestry in South-East Asia

Over the past decade, Puccinia psidii, which causes rust on species of Myrtaceae, has spread rapidly to new areas and is now widespread. Quarantine has done little to prevent its movement through the Americas, the Pacific, Africa, and in this report, South-East Asia. Puccinia psidii is reported for the first time from Indonesia on two genera of Myrtaceae, namely Eucalyptus and Melaleuca. Its identity was confirmed using morphology, a molecular barcode comparison to an epitype specimen, and with a molecular phylogenetic approach. Comparison of seven microsatellite markers indicates that the rust genotype in Indonesia and Australia is identical. The potential impacts of P. psidii in South-East Asia to the natural environment and plantation forestry are discussed in light of this first report from the region.

A single dominant Ganoderma species is responsible for root rot of Acacia mangium and Eucalyptus in Sumatra

Ganoderma root rot is the most serious disease affecting commercially planted Acacia mangium in plantations in Indonesia. Numerous Ganoderma spp. have been recorded from diseased trees of this species and to a lesser extent Eucalyptus, causing confusion regarding the primary cause of the disease. In this study, a large collection of Ganoderma isolates were obtained from the roots of A. mangium showing early signs of root rot in disease centres in South Sumatra plantations. Isolates were also collected from Eucalyptus roots at Lake Toba in North Sumatra showing similar symptoms as well as from sporocarps connected to these samples. Phylogenetic analyses showed that a single Ganoderma sp., identified as G. philippii, is the major causal agent of Ganoderma root rot on A. mangium. Results from this study also showed that the isolates obtained for Eucalyptus trees in North Sumatra belong to G. philippii. Isolates from roots and connected fruiting bodies together with the morphology of the fruiting structures confirmed this identification. Symptoms associated with this pathogen are obvious and it should not be confused with other diseases. Other Ganoderma spp. found in disease centres are considered to be of minor importance and management strategies for root rot should be focused on G. philippii.

Characterization and genetic analysis of laboratory mutants of Cochliobolus heterostrophus resistant to dicarboximide and phenylpyrrole fungicides

Abstract Laboratory mutants of Cochliobolus heterostrophus resistant to iprodione were obtained after chemical mutageneses. All the mutants were able to grow on the medium amended with iprodione 100 μg/ml. They showed positive cross-resistance to procymidone and fludioxonil and were sensitive to high osmolarity. Crosses between the mutant and a wild-type strain revealed that the fungicide resistance and osmotic sensitivity traits were inherited by their offspring in a 1 : 1 mutant/wild type ratio, indicating that the mutant phenotypes in these strains were due to alteration at a single gene locus. Results from allelism tests indicated that three genes (Dic1, Dic2, Dic3) conferred the mutant phenotypes. Among them, Dic1 mutant strains were classified into three types on the basis of their phenotypes. The first type was moderately resistant to the fungicides and less sensitive to osmotic stress than the other Dic1 mutant strains. The second type showed moderate fungicide resistance, but growth was inhibited under lower osmotic stress (50 mM KCl). The other Dic1 mutant strains grew well on medium containing iprodione and fludioxonil even at a concentration of 100 μg/ml and were highly sensitive to osmotic stress. The Dic2 and Dic3 mutant strains had moderate resistance to the fungicides with low-level osmotic sensitivity. The Dic1 gene was epistatic to Dic2 and Dic3 for fungicide resistance and hypostatic to them for osmotic sensitivity. These results suggest that the osmoregulatory system is involved in fungicide resistance in laboratory mutants of C. heterostrophus.

Genetic analysis of Cochliobolus heterostrophus polyoxinresistant mutants

Nine polyoxin-resistant mutants ofCochliobolus heterostrophus were isolated after ethyl methanesulphonate mutagenesis. All were highly resistant to polyoxin (MIC≥1,600 ppm). Crosses between the mutants and a wild-type strain revealed that the resistance trait was inherited to the offsprings in different fashions. Four of the mutant strains inherited polyoxin resistance in a 1∶1 segregation ratio, indicating that the phenotypes in these strains were due to alteration at a single locus. Allelism tests revealed four new loci,Pol1, Pol2, Pol3 andPol4, for polyoxin resistance in these mutant strains. The genes responsible for the phenotypes of the other five mutant strains were not determined, because of extremely slow growth of progenies in one cross, sterility in another cross, and inexplicable responses to polyoxin of the progenies in the other crosses. No linkage was detected between the genes for polyoxin resistance and mating type.

A PCR-based method for mating type determination in Cochliobolus heterostrophus

A rapid and accurate method based on multiplex PCR using three different primers was developed for determining mating type inCochliobolus heterostrophus. The primers of MAT113 and MAT123 were uniquely derived fromMAT1-1 andMAT1-2, respectively, and the primer MATcon5 is conserved in the flanking regions of the idiomorphs. The amplification product was estimated to be 702 bp (MAT1-1) or 547 bp (MAT1-2). Crossing experiments confirmed the accuracy of this method, which requires less time than the conventional determination of mating type.

Polyoxin Resistance of Reddish Brown Laboratory Mutants of Cochliobolus heterostrophus

Six reddish brown polyxin-resistant mutants of Cochliobolus heterostrophus were isolated after ethyl methanesul-phonate and N-nitroquinoline oxide mutageneses followed by selection on polyoxin. All the mutants were highly resistant to polyoxin (MIC > 1600 μg/ml). When mutants were crossed with the wild-type strain, all crosses had a 1 : 1 ratio of mutant (reddish brown pigmentation and polyoxin resistance) : wild type (non-reddish brown pigmentation and polyoxin sensitivity), indicating that the phenotypes in these strains were due to alteration at a single gene locus in each strain. Allelism tests revealed the existence of two loci, Pol2 and Pol5. The results of the crossing and mutation-rate studies suggest that the each gene was pleiotropic for the reddish brown color and polyoxin resistance.

Molecular Analysis of Intraspecific Variations of the Indonesian Cochliobolus heterostrophus

The primary objective of the current research was to detect genetic variations within the Indonesian isolates of Cochliobolus heterostrophus collected from ecologically different places of the country at molecular level using PCR-RFLP analyses. The primer pair of NS3 and NS6 produced amplification fragment in all of the isolates tested. A single fragment of estimated 907 bp was observed in the PCR product pattern. RFLP analysis of the PCR product employing three restriction enzymes, HaeIII, HhaI, and RsaI, respectively, did not reveal intraspecific variations within the fungus. Similarly, nucleotide sequences of portion of small subunit of the ribosomal DNA gene of two of the isolates collected showed no appreciable differences, indicating the absence of genetic diversities among the isolates tested. A phylogenetic tree was constructed and the Indonesian C. heterostrophus, represented by SM-1 isolate, was found to be phylogenetically located near C. sativus, a closely related species.

Role of site in the mortality and production of Acacia mangium plantations in Indonesia

In Indonesia, Acacia mangium plantations exceed 1.6 Mha contributing approximately 3.5% of the country’s GDP. The viability of these plantations is increasingly threatened by fungal pathogens, insect pests, squirrels, monkeys, elephants and wind damage. Studies indicate that the problem is growing and in some areas, fungal pathogens such as Ganoderma and Ceratocystis species have contributed up to 50% tree mortality by the fourth rotation. Multiple statistical procedures were employed to examine the influence of soil and topographical properties on tree survival (trees ha−1), wood production (m3 ha−1), and mortality associated with Ganoderma root rot, Ceratocystis wilt and by wind. Soil family level was found to be a good indicator of tree mortality. Plots with fine-loamy Typic Kandiudult soils had the highest tree survival and mortality associated with species of Ganoderma and Ceratocystis, but had the lowest incidence of mortality by wind. The degree of association between soil and topographic variables with tree survival, wood production and the cause of mortality were poor and inconsistent. Tree survival was slightly higher on upslope areas away from valley bottoms, and drier mid-slopes, ridges and hilltops, and very low pH (<3.3) soils. Wood production was also slightly higher in drier, elevated locations, away from valley bottoms. Mortality by wind was slightly higher in moist, poorly drained, low-lying valley bottoms and topographically flat areas. Our ability to further pinpoint the influence of topography and soil attributes on wood production and cause of mortality was greatly compromised by the lack of site-specific soil data, and potential misclassification of the cause of mortality. This study could not reliably or consistently relate tree survival, wood production or the cause of mortality to any one, or combination of, soil and topographic variables.

A new screening method for Ganoderma philippii tolerance in tropical Acacia species

Red root rot disease caused by Ganoderma philippii is one of the most economically important diseases of tropical Acacia species. Research on field control of the disease has to date focused on inoculum reduction, silviculture practices and application of biological control agents. Incorporation of tolerant genotypes, a key component of integrated disease management, has not been adequately explored because of a lack of reliable and quick screening protocols. Recently, we developed a more rapid method of screening for red root rot tolerance in Acacia mangium, A. crassicarpa and A. mangium A. auriculiformis hybrid planting stock, in which groups of five, 6-week-old plants were subjected to inoculum consisting of a rubber (Hevea brasiliensis) wood block culture of the pathogen held within a polythene bag. As symptoms start to appear 10 weeks after inoculation, experiments can be completed in a six-month period instead of the years needed by the traditional pot system. Using this technique we were able to identify variations in tolerance and/or susceptibility to G. philippii in A. mangium, A. crassicarpa and A. mangium × A. auriculiformis hybrid planting stock in a more consistent manner. Tolerant and susceptible genotypes subsequently have been selected for further experiments or crosses. While the ultimate goal of this study was to develop and deploy high-yielding Acacia genotypes that are also tolerant to red root rot disease, results of the current screening studies may also be used to investigate the basis for tolerance to G. philippii in Acacia species.

Peroxidase Activity in Poplar Inoculated with Compatible and Incompetent Isolates of Paxillus involutus

The Balinese is comprised of genealogical patrilineal clans named as soroh. However, remnants of ancient Bali Mula communities have their own local genealogy which differ from the general soroh. The Pasek Trunyan together with Pasek Kayu Selem, Pasek Celagi, and Pasek Kayuan are part of Bali Mula which believed to be descendants of one ancestor, Empu Kamareka. Here we reported genetic variation of the Terunyan society. The microsatellites Y-chromosome markers (DYS19, DYS390, DYS393, and DYS395) were used in this study. There were 12 alleles found and the result showed the low genetic diversity (D = 0.28 + 0.05) within Terunyan society. Nine haplotypes based on allelic combination were found, dominated by major haplotype with frequency of 0.50 which spread out in many genealogical lineage called dadia. The haplotype data showed that Terunyan society derived from many gene sources. Key words: patrilineal, pasek, soroh, dadia, haplotipe