The Response Of Endogenous Phytohormones In Gracilaria Lemaneiformis Under Environmental Stress

The marine red algae Gracilaria lemaneiformis has become the fourth cultivated seaweeds in China. It is not only a kind of high quality raw materials for agar production, but also have the function of the marine ecological environment improvement. With the development of social economy, industrial pollution become more and more serious, which increased deterioration of mariculture environment. The cultivation of Gracilaria lemaneiformis and other seaweeds can be one of the effective way for improving the Marine environment, alleviating ocean acidification, reducing the Marine pollution.In this thesis, the marine red alga Gracilaria lemaneiformis was used as materials and a set of method for isolation, purification, quantification the phytohormones in algae was established. And then the method was used to study the changes of anti-stress related phytohormones when Gracilaria lemaneiformis was stressed by adverse temperature, salinity, N/P nutrition. The objective was to reveal the relationship between endogenous phytohormones and their functions against environmental stress. The results in detail were as follows:(1) A set of methods were developed for determination of 5 kinds of phytohormones: indole-3-acetic acid (IAA), abscisic acid (ABA), jasmonic acid (JA), salicylic acid(SA), cinnamic acid(RA) in macroalgae by gas chromatography-mass spectrometry (GC-MS) and solid phase extraction (SPE). The average recoveries of 5 kinds of phytohormones at three spiked levels (100 ng, 150 ng, 250 ng) ranged from 76.7% to 104.3%, the relative standard deviations (RSD) is less than 3%, and the limit of detection(LOD) ranged from 1.0×10-2 mg.L-1 to 2.5×10-2 mg.L-1. The method was easy, fast, and sensitive, with good accuracy and repeatment.(2) The Gracilaria lemaneiformis was cultured in three temperature (15℃, 25℃, 33℃) and then the 5 kinds of phytohormones were analyzed by the above method. Under normal temperature (25℃), the IAA content in samples increased starting from 6h, the other four phytohormones: SA, RA, JA, ABA began to increase in the late cultivation stage. Under low temperature stress (15℃) and high temperature stress (33℃), the IAA content was lower than normal condition (25℃), ABA, JA ,SA,RA have similar changes under stress with the trend as increasing firstly and decreasing lately.(3) The Gracilaria lemaneiformis was cultured in three salinity (10‰, 25‰, 35‰) conditions and the five kinds of phytohormones were analyzed by the method established. Under the normal salinity (25‰), the IAA content in samples increase gradually, and SA, RA, JA, ABA content remained stable, and only began to increase in the late cultivation stage. Under low salt stress (10‰) and high salt stress (35‰) conditions, the change of SA and RA is similar. Both JA and ABA changes violently under high salt stress, while SA changes violently in low salinity conditions. From the above, it can be deduced that different phytohormones produced to resist the two kinds of salt stress, SA and RA produced in low salt condition, while JA produced in high salt stress. And the SA, RA sythesized might be inhibited by the high JA content.(4) The Gracilaria lemaneiformis was cultured in five N/P (0:1, 1:1, 2:1: 3:1, 4:1) medium and then the 5 kinds of phytohormones were analyzed by the method mentioned established. Under the conditions of N/P=0:1 medium the IAA content increased from 3h and reached to the peak in 10h. SA content was first decreased and then increased. RA reached the maximum value in 3h and then declined sharply, which was corresponded with the JA and ABA content increasing; the content of JA maintains a high level during the period of experiment. Under the conditions of N/P=2:1 medium, the five kinds of hormones showed almost the same regulation as in N/P=1:1 medium, which is the normal provasoli medium. The content of five kinds of phytohormones remained stable, ABA and SA content increased in the late cultivation stage. In the condition of N/P=3:1 and 4:1 the content of five kinds of phytohormones has similar results: IAA content remains stable in the early stage and decreased rapidly after 48h cultivation. ABA,JA content increased after 1h of cultivarion and reach the maximum after 6h and 10h and then decreased slowly. SA content showed no obvious change firstly and increased after 72h cultivation in N/P=3:1 medium. SA content decreased firstly and then increased in N/P=4:1 medium. RA content increased firstly and decreased lately both in N/P=3:1 and 4:1 medium.