RESUMEN
BACKGROUND: Productivity and quality of crops can be increased through polyploidy plants induced by colchicine. The use of colchicine has never been applied to Katokkon pepper, a local red pepper variety from North Toraja Indonesia. This pepper is characterized by its unique shape like the small-bell pod type of paprika and its strong spicy taste. Therefore, this study aimed to determine the effects of colchicine treatment on the ploidy level and morphological characters of Katokkon pepper. RESULTS: Flow cytometer analysis showed that all colchicine concentration treatments ranging from 0.025 to 0.1% with 24 h immersion time generated two plant groups based on their ploidy level; 50% of the total treatment plants was diploid while the rest plants were mixoploid. All colchicine treatment plants were significantly different in their width of stomata guard cells from the control plant. The effect of colchicine was also significantly on the plant height, thickness of fruit flesh, and the number of fruits per plant. CONCLUSIONS: The results of this study showed that colchicine treatment had a significant effect on the ploidy level and several morphological characters of the Katokkon pepper. The colchicine treatment increased the number of fruits per plant and thicker flesh of fruits but reduced the size and weight of Katokkon pepper. Our findings provide essential information to obtain tetraploid Katokkon plants through colchicine treatment in further research. This study benefits as a preliminary step for increasing the productivity and quality of the local red peppers in Indonesia.
RESUMEN
Cross-breeding is a method of producing progeny with better resistance to pathogens. Resistance to pathogens usually involves pathogenesis-related (PR) proteins. Class II chitinase is an example of a defensive PR protein in plants. The class II chitinase in chilli is coded by the CaChi2 gene. In this study, we crossed susceptible with resistant chilli cultivars, analysed the F1 resistance response against pathogenic F. oxysporum, and analysed the level of CaChi2 gene expression in the F1. Data were collected using disease severity index (DSI) determination and gene expression analysis by qRT-PCR (quantitative Reverse Transcriptase Polymerase Chain Reaction). Results showed that the DSI of F1 was not significantly different from the resistant ancestor. The relative CaChi2 expression level of F1 was higher than the susceptible ancestor but not significantly different from the resistant ancestor. We concluded that the F1 can be categorised as resistant to F. oxysporum, and the CaChi2 gene is involved in the molecular defense response.
RESUMEN
BACKGROUND/PURPOSE: Shiga-like toxin (Stx) is an important factor in the pathogenesis of Escherichia coli O157:H7 infection and is responsible for some severe complications. Stx2 is usually associated with hemolytic uremic syndrome in humans. Its expression is regulated by elements located upstream of the stx2 gene, including stx2-promoter sequence, ribosome binding site, and the antiterminator q gene. The present study aimed to find the correlation between regulatory elements and the expression level of Stx2 in two local isolates of E. coli O157:H7. METHODS: Two local E. coli O157:H7 strains SM-25(1) and KL-48(2), originating from human and cattle feces, respectively, and an E. coli reference strain, ATCC 43894, were investigated. The complete stx2 gene covering the sequences of promoter, ribosome binding site, and open reading frame and q gene of each strain was analyzed. The magnitude of Stx2 production was detected with a reverse passive latex agglutination method and Stx mediated cellular damage was determined with the Vero cell assay. RESULTS: A comparison of the complete stx2 gene contained stx2-promoter, ribosome binding site, and q genes of two local strains KL-48(2) and SM25(1), and the E. coli ATCC 43894 showed that the amino acid sequences were identical. Both local isolates were Stx negative in the reverse passive latex agglutination test and nontoxic in the Vero cell assay. CONCLUSION: The expression level of Shiga-like toxin of the two local isolates of E. coli O157:H7 did not only depend on the regulatory elements of the stx2 gene.
