Screening of chitinase-producing rhizosphere actinomycetes and their genetic diversity

Wahyudi AT, Fitriansyah NG, Amri MF, Priyanto JA, Nawangsih AA. 2021. Screening of chitinase-producing rhizosphere actinomycetes and their genetic diversity. Biodiversitas 22: 4186-4192. Soil microbial community, especially rhizosphere actinomycetes, plays an important role in protecting plants from phytopathogenic fungi by producing various agroactive compounds, including mycolytic enzymes particularly chitinase. The objective of this study was to investigate chitinase activity and analyze the diversity of family 19 chitinase genes of actinomycetes isolated from maize and soybean rhizosphere. Of fivety actinimycetes, Seventeen isolates exhibited chitinolytic activities and formed a hydrolytic zone around the colony with chitinolytic index ranging from 0.49±0.01 to 2.15±0.69, qualitatively tested in 0.3% chitin agar medium. Six selected isolates (ARJ 36, ARJ 81, ARJ 15, ARK 17, ARK 143, ARK 103) showed chitinase activities ranging from 0.157±0.04 to 0.440±0.09 U/mL, based on chitinolytic index. The production of chitinase was confirmed by the presence of family 19 chitinase encoding genes from Streptomyces sp. Some conserved regions and essential amino acid residues were also detected. This study suggests that chitinolytic actinomycetes isolated from maize and soybean rhizosphere can be studied further as biological control candidates for controlling phytopathogenic fungi.

CLONING AND EXPRESSION OF CHITINASE 19 FAMILIE FROM D.CAPENSIS

Sequence of family 19 chitinase was cloned from Drosera capensis. Implemented expression in different strains of E.coli and developed a refolding method. Describes the primary biochemical characteristics of the full-length chitinase and its shape without chitin-binding domain.

Overexpression of the mulberry latex gene MaMLX-Q1 enhances defense against Plutella xylostella in Arabidopsis thaliana

Purified mulberry latex chitinase (MLX) has a role in defense against some lepidopteran insects. In this study, a full length chitinase gene, MaMLX-Q1, of 1405 bp with a 1140 bp open reading frame, was obtained from mulberry leaves by the degenerate primers and rapid amplification of cDNA ends polymerase chain reaction (RACE-PCR) procedure. The gene encoded a mature protein with the predicted molecular mass of 39.38 kDa and an isoelectric point (pI) of 6.43; it contained two chitin-binding domains and a hydrolase family 19 chitinase domain. Sequence alignment and phylogenetic analysis grouped it in the class I chitinase protein group. Heterogeneous expression of this MaMLX-Q1 in Arabidopsis showed non-visible alterations in growth phenotype, except for the higher transcriptional expression of MaMLX-Q1 when compared to that of wild-type Arabidopsis. This ectopic MaMLX-Q1 exhibited toxicity to the growth and development of Plutella xylostella larvae, causing significantly lower weight gain and higher mortality. These results indicate an application of MaMLX-Q1 as an insecticide for plant protection.