Soybean [Glycine max. (L.) Merr] is one of the most important legumes in the world. However, soybean varieties are sensitive to flooding stress and their seed yields are substantially reduced in response to the flooding stress. 192 soybean germplasm collection was screened to identify flooding tolerant germplasm at an early vegetative growth stage (V1). Soybean plants at V1 stage were waterlogged for 4 to 10 days. To evaluate flooding tolerance, survival rate were investigated as a time dependent manner. Jangbaegkong, Danbaegkong, Sowonkong, Socheong2 and Suwon269 showed flooding tolerance, while Shillog, T201, T181, NTS1116 and HP-963 showed flooding sensitivity. We also investigated effects of flooding stress on soybean morphology. The adventitious root development was greatly increased in flooding tolerant plants compared to it in flooding sensitive plants. In addition, root length and root number were analyzed. The significant reduction of root length and root number was observed in flooding sensitive plants. Thus, these results indicate that the morphological changes in roots are important for acclimation to flooding stress. Taken together, the relationship between the morphological changes in the roots and flooding tolerance may be useful in selecting a flooding tolerant soybean germplasm.

Cathepsins are members of the multigene family of lysosomal cysteine proteinases and have regulated function in several life processes. The potential role of cathepsin F cysteine gene was expected as protease in the yolk processing mechanism during early developmental stage, but expression analysis was unknown after fertilization. The alignment analysis showed that amino acid sequence of cathepsin F from olive flounder liver expressed sequence tag (EST) homologous to cathepsin F of other known cathepsin F sequences with 87－98% identity. In this study, we examined the gene expression analysis of cathepsin F in various tissues at variety age flounder. Tissue distribution of the cathepsin F mRNA has been shown to be ubiquitous and constitutive pattern regardless of age in each group, although derived from cDNA library using liver sample. The mRNA level of cathepsin F more increased as developmental proceed during embryogenesis and early developmental stage, especially increased in the blastula, hatching stage and 3 days post hatching (dph). As a result, it may suggest that the proteolysis of yolk proteins (YPs) has been implicated as a mechanism for nutrient supply during early larval stages in olive flounder.

Olive flounder (Paralichthys olivaceus) is a most important aquaculture species in Korea. Like most marine fishes, olive flounders are stomachless at first feeding and aquired gastric function during the metamorphosis, so food was mainly digested by pancreatic enzyme from first feeding to premetamorphosis. However, comprehensive analysis of pancreatic and gastric digestive enzyme of olive flounder at early developmental period is still unclear. In the expression study of pancreatic and gastric digestive enzyme by real-time PCR at early developmental stage, pancreatic enzyme such as chymotrypsinogen 2, preproelastase 2 and 4, pancreatic protein somatomedin-B domain (PPSB) mRNA expression were initiated at first feeding and strongly expressed in the pancreas developmental stage, while gastric digestive enzyme signal was not at all detected during same period. Although, trypsinogens were secreted from pancreas and have similar amino acid sequence, trypsinogen 3 expression induction was detected both pancreas and stomach developmental stage, while trypsinogen 2 expression was significantly increased only post-metamorphosis period. Pepsinogen mRNA expression was only detected at metamorphosis according to stomach differentiation. Lipid digestive enzyme, lipase and intestine fatty acid binding protein 1 (I-FABP 1), were already reached a certain level at beginning of hatching and more increased during early developmental stage and then gradually decreased before metamorphosis. These results suggested that feed ingestion of olive flounder was exclusive charged by pancreatic digestive enyme, lipid digestive enzyme and trypsinogen 3 from first feeding and then fully swiched by gastric digestive enzyme and trypsinogen 2 from metamorphosis period.