The Effect Of Exogenous Spermidine And SAMDC Expression Analysis In Citrus Under Stress

Citrus is one of the most impotant and popular economic fruit tree in the world. As a chilling-sensitive, warm temperature acclimated and high salt content hated plant, citrus plant suffered frequently from the periodic frozen or a sudden cold wave, salt stress in seaside field or soil salinization in overfarming field, which leads to decline of fruit quality and yield severely. Surveying on stress physiology and resistance regulation mechanism do have important meaning in theory and practice.This reseach was carried out on callus inducing system which proved be uniform and comparable under controlled envionment factors. Relationship between polyamine and the growth and physiological changes of the callus from different citrus species under salinity and chilling stress was investigated. SAMDC gene was isolated and analysed. The main results were summatized as following:1. Under the salinity stress (0-200mmol/LNaCl), calli were weighted after 35 days, then found that: Low salinity promoted calli growth, especially under 25mmol/LNaCl concentration. But under 150mmol/L NaCl stress, calli became growing slowly. A lot of calli turned to be yellow and dead, under the 200mmol/LNaCl stress. Under the stress, different variety showed different appearance: Sour Orange callus had the best tolarent, Meiwa Kumquat callus was second, Newhall Navel Orange was weakest under the 0mmol/L-150mmol/L NaCl stress.2. Uuder chilling stress (4℃, 0-9d) after 35 days, calli were weighted, then found that: the growth of calli under 12h and 24h chilling stress induced greatly and magnigicantly, the growth of calli was affected slow under low temperature stress by 5 days. Under 9 days chilling stress, the growth of calli almost stopped. Similaryly, different variaty had different growth rate. The growth rate of Sour orange callus was lower than others under 5 days stress.3. The study of physiological changes in salinity stress showed that the value of relative electrical conductivity was increased as the time continued, but before 24h it increased quickly. Similaryly, the MDA content was also increased as the time continued under the salinity stress. In constrat, the value of relative electrical conductivity was steadying under chilling stress. MDA content had increased in a degree. The result...