Selection And Characteristic Analysis On New Strain Of High Temperature Resistance Of Gelidium Amansii

Gelidium amansii is a kind of the economic marine algae in the genus of Gelidium,Rhodophyta.Gelidium amansii is the main raw material for industrial extraction of agar,with better quality than other seaweeds.Therefore,it can be used for industrial scale cultivation and industrial development.The life history of Gelidium amansii is relatively complex,including the alternation of three generations:tetrasporophyte generation,carposporophyte generation and gametophyte generation.Different life history stages have different characteristics,which tetrasporophyte generation belongs to asexual reproduction,and the gametophyte generation has sexual reproduction.There are also some propagations such as vegetative reproduction.In the actual cultivation process,it has guiding significance to clarify the morphological and the characteristics of the main stages of the life history for its application in artificial cultivation and guidance of artificial cultivation technology.The combination of mutagenesis technology and directional screening laid a firm foundation for the selection of new varieties.The optimal growth temperature of Gelidium amansii is 20-25? When the water temperature is over 27?,the algae becomes brittle and easily broken or rot.In this study,60Co-y mutagenesis and high-temperature screening technology were applied for the first time in the breeding of Gelidium amansii,and the breeding effects of 60Co-y radiation and high temperature stress selection were discussed.Through observation and selective breeding of mutant algae,the aim is to breed new high-temperature resistant Gelidium amansii strains,and to explore a method suitable for screening new high-temperature resistant strains.In the end,lay the experimental foundation for further selection of the new strains of stress resistance.The results showed that:(1)Based on rbcL and COI gene binding morphological classification methods,the research object was identified as Gelidium amansii.The algae body was generally purple-red,pinnately branched,under the microscope,there are apical cells and peripheral cells on the top of the branches.The internal structure consisted two parts,the pith and the cortex.The life history of Gelidium amansii was composed of the tetrasporophyte generation,carposporophyte generation and gametophyte generation.Different stages of life history have different characteristics.(2)Gelidium amansii was made up of rich nutrients,the highest total sugar content was 41.7 g/100g,followed by protein 18.39 g/100g and the crude fat content was the lowest at 3.13 g/100g.Phycoerythrin content was 1.43 mg·g-1,the content of phycocyanin was 0.42 mg·g-1,the content of chlorophyll a was 1.04 mg·g-1,and the content of carotenoids was 0.08 mg·g-1.The extraction of agar was 20.92%.There are many types of hydrolyzed amino acids,the total amount of amino acids was 17.71 g/100g,essential amino acids were 5.13 g/100g and non-essential amino acids were 12.58 g/100g.(3)Using the tetrasporophyte tips as the experimental material and 1100 Gy as the mutagenic dose,treated at 39? for 30 min and 32? for 96 h,the mutant algae strain 1801 has the characteristics of high temperature resistance and rapid growth.The heat resistance of Gelidium amansii was identified by the survival rate,growth rate,and antioxidant enzyme activity under high temperature stress.The new strain 1801 had higher survival rate,lower MDA content and higher resistance to heat stress and the expression level of hsp70 gene increased significantly with the extension of heat stress time,indicating that 1801 had stronger heat resistance.(4)The average daily growth rate of the new strain 1801 was 3.97%.Compared with the control group,the fat content of basic nutrients decreased by 3.51%,protein content increased by 4.47%,and total sugar content increased by 2.21%.R-PE was 1.40%higher than the control group.The content of agar was 4.78%higher than that of the control group,the total amino acid content increased by 1.69%.The new 1801 strain has better advantages in terms of growth,nutrient content,photosynthetic pigment content,agar content and other traits.