Source: SEAMEO BIOTROP's Research Grant | 2020
Forest trees are a source of raw material for many of the essential needs of humans, including building material, paper products, firewood for heat and cooking, energy and many tree-crop foods. Forest trees also provide various ecological services, such as preservation of biodiversity, carbon sink, climate regulation and preservation of water quality; also represent our cultural and patrimonial heritage.
Deforestation in Indonesia, that has impacted in huge loss of natural resources to meet the community's need for forest products, has urged the Government to build industrial forest plantation. As a part of reforestation and afforestation program, industrial forest plantation commonly use fast-growing tree species, such as acacia, eucalyptus, pine, and others. Sengon (Paraserianthes falcataria) is one of the most used fast-growing tree species in plantation forestry programs. It is widely planted by farmers and communities, particularly for reforestation program. Sengon is a multipurpose tree that is easily cultivated both in monoculture and agroforestry, it also a type of legume that produce nitrogen and thus able to increase soil fertility (Budelman 2005; Iskandar and Ellen 2008).
Sengon is a commodity in the light wood industry in Indonesia and its needs are always increasing. According to Indonesian Light Wood Association (ILWA) sengon wood products coming from forest industries in Jawa worth US$ 244.46 million export to China alone in 2018 (https://katadata.co.id/berita/2019/03/13). Efforts to increase wood production have led to the expansion of monoculture Sengon plantations. However, monoculture plantation often suffers from pest and disease, so that high funding is needed to protect plants and the losses can be minimized. In addition, pests and diseases potentially emerge the endemics and widespread attacks due to the ecosystem imbalance.
The main pest and disease wich are capable of destroying sengon plantation ware Boktor stem borer (Xystrocera festiva) and gall rust disease (NFTA 1989; Rimbawanto 2006). Stem borer began attacking the 3-4 year old plants, and without adequate control of pests can ruin the entire crop. Meanwhile gall rust disease, caused by the fungus Uromycladium falcatarum, attacks plants at all ages, from seedlings in the nursery until mature plants in the field, also potentially could damage the entire crop. Observations in the field showed that both the boktor pests and gall rust disease could attack plants at the same time causing enormous economic losses. The main concern is that the effective control method both for pests and diseases is not yet available.
Although almost all Sengon are susceptible to both pest and disease mentioned above, observations in the field showed that some individual trees show signs of resistance, because they can survive among severely affected populations. The existence of individuals who are resistant among the most vulnerable tress is highly expected, because the population of sengon in Indonesia generally, and Java particularly, are known to have a fairly high genetic diversity (Siregar 2009). Currently there are no fundamental information about biological processes and mechanisms of resistances in tropical tree species. Thus, research on Sengon resistant to boktor pests 2 and gall rust disease is necessary, as the basis for the resistant Sengon tree breeding programs.
a. Evaluate sengon inheritance pattern of resistance to stem borer pest (Xystrocera festiva) and gall rust disease (Uromycladium falcatarum) in a progeny test. b. Phenotyping and genotyping sengon progenies which are resistance to pest and diseases using microsatellites from transcriptomic sequence data.
c. Obtaining sengon clone/family that is resistant to boktor pests and gall rust disease to be registered as a new variety, and as a forerunner to the establishment of a superior sengon seed plantation.
Success of plant selection through breeding is determined by genetic diversity,
heritability values, and correlation between characters. Genetic diversity, expected genetic
progress and character correlation in both populations of sengon were high and had a positive
correlation, but the heritability value was low. The results of DEG were related to defenses
of sengon trees against boktor pests. The gene that is included in plant resistance is the
EARLI1 protein. like lipid transfer protein 3, Trypsin inhibitor B, Trypsin inhibitor A, Kunitz
type trypsin inhibitor like 2 protein, Aquaporin NIP6, Heat shock cognate 70 kDA protein,
Thaumatin like protein, Leucine rich extension like protein 4, and Chalcone synthase.
Chalcone synthase is an enzyme related to flavonoid biosynthetic pathway, so that this gene
can be related to sengon tree resistance gene to boktor pests. The gene that is induced under
abiotic stress is Putative lipid transfer protein DIR1, 17.5 kDA class heat shock protein,
Peptidyl prolyl cis trans isomerase Pin1, and Glutathione S.transferase T1, genes that are
induced in biotic stress conditions are Glucan endo 1.3 beta glucosidase. This difference in
gene expression can be caused by the absence of a driving factor to be expressed more,
protein isoforms, and the presence of mutations. A total of 21 TI sequences were found and
then the nucleotide base sequence was cut so that it became 19 sequences belonging to the
Kunitz-type TI. There are two large groups that are closely related to the outgroup. Group 1
has a genetic distance value of 1.329 which is closer to the outgroup than group 2 which has
a genetic distance value of 1.322. The occurrence of this grouping is due to the location and
length of the nucleotide base sequences in different conserved domains and the possibility
of differences in the intron splicing process. The conserved domain of group 1 is located at
the front with a length of 26 bp and has a percent pairwise identity of 64.1%, while Group 2
is located in the middle with a length of 30 bp and has a percent pairwise identity of 54.1%.
A total of 29 transcript sequences were identified as AAI type on sengon plants with P.
vulgaris plants, namely AAI, AAI1, AAI2 and CLAI which belong to the Lectin class.
Kinship relationship showed that there were 4 groups of AAI sequences of sengon plants.
The length of the sequences of each group were Group I 618-728 bp, Group II 540-690 bp,
Group III 201-489 bp, and Group IV 573-576 bp. The group with close kinship with the P.
vulgaris comparators had a branching distance of 0.903 and the farthest group had a genetic
distance value of 2.058. Groups III and IV changed more quickly because the number of
branches was more than groups I, II, and had low identical sites, namely 2% and 3.4%.