RESUMO
Phytophthora root and stem rot (PRSR) disease results in substantial losses in soybean production worldwide. The occurrence of PRSR caused by Phytophthora sojae Kaufmann & Gerdemann has become increasingly important for soybean production in the Republic of Korea, but domestic soybean-P. sojae interaction has been less studied. The disease has been managed by developing varieties harboring resistance to the Phytophthora sojae (Rps) gene. The present study aimed to identify a major gene locus conferring resistance to new P. sojae isolate 2858 in the recombinant inbred line population derived from a cross between parental lines 'Daepung' (susceptible) and 'Saedanbaek' (resistant). Seventy-three recombination inbred lines (RILs) were evaluated for resistance to P. sojae isolate 2858. A resistance locus was identified in the approximate 3.3-4.3 megabase pair region on chromosome 3 using both single-marker and linkage analyses. The Rps of Saedanbaek (RpsSDB) was located on the well-known Rps gene/allele cluster region, which also partially overlapped with a locus previously identified in the Korean soybean variety, 'Daewon', resistant to another P. sojae isolate 2457 (RpsDW). Approximately 402 kilobase pairs of the interval region overlapped, including six nucleotide-binding site-leucine-rich repeat (NBS-LRR)-coding genes. Additional phenotypic assays revealed that Saedanbaek was susceptible to isolate 2457 and that Daewon was susceptible to isolate 2858, indicating that RpsSDB and RpsDW are different genes or alleles that confer race-specific resistance to the two P. sojae isolates. These results provide information that will be helpful for breeders developing P. sojae-resistant cultivars.
RESUMO
In cartilage tissue regeneration, it is important that an implant inserted into a defect site can maintain its mechanical integrity and endure stress loads from the body, in addition to being biocompatible and able to induce tissue growth. These factors are crucial in the design of scaffolds for cartilage tissue engineering. We developed an elastic biodegradable scaffold from poly(L-lactideco-epsilon-caprolactone) (PLCL) for application in cartilage treatment. Biodegradable PLCL co-polymer was synthesized from L-lactide and epsilon-caprolactone in the presence of stannous octoate as a catalyst. A highly elastic PLCL scaffold was fabricated by a gel-pressing method with 80% porosity and 300-500 microm pore size. The tensile mechanical and recovery tests were performed in order to examine mechanical and elastic properties of the PLCL scaffold. They could be easily twisted and bent and exhibited almost complete (over 94%) recoverable extension up to breaking point. For examining cartilaginous tissue formation, rabbit chondrocytes were seeded on scaffolds. They were then cultured in vitro for 5 weeks or implanted in nude mice subcutaneously. From in vitro and in vivo tests, the accumulation of extracellular matrix on the constructs showed that chondrogenic differentiation was sustained onto PLCL scaffolds. Histological analysis showed that cells onto PLCL scaffolds formed mature and well-developed cartilaginous tissue, as evidenced by chondrocytes within lacunae. From these results, we are confident that elastic PLCL scaffolds exhibit biocompatibility and as such would provide an environment where cartilage tissue growth is enhanced and facilitated.
