Effects of Low Temperature on Plant Growth and Their Protein Patterns in Phloem Exudates of Luffa cylindrica

Abstract

One-week-old seedling s of Luffa cylindrice were grown in phytotron at 15, 20, 25 and 30 t for four weeks. Growth curves of the plant organs were compared with their fresh weight and size during the cultured period. lsozymes of defensive enzymes and phloem proteins were measured on elctrophorogram of native gel and 2-dimcnstonal gel respectively. Low temperature not only retards plant growth, but also increases the ratio of root/shoot. Leaf blades of plants grown at 25 and 30℃have typical sigmoid growth curve but with different slope factors. Plants grown at 15℃ do not show the normal sigmoid curves in leaf growth. Isozyme patterns in plant grown at 15℃ are changed as follows: two minor bands in group II isozyme of acid phosphatase were induced in green leaf blades and cotyledons; group II isozymes of peroxidase were enhanced in hypocotyls and cotyledons; group III isozyme of acid phosphatase was induced in leaf. All isozyme patterns show the specificity in tissues and developmental stages. One of phloem proteins with molecular weight of 31.5 kDa and pi at 4.9 was induced in plants grown al 15℃.