In Vitro Conservation Of Plantlets And Analyses Of The Physiological And Ultrastructural Changes During Conservation In Loquat Germplasm From Fujian

In this experiment, 52 accessions of loquat germplasm with a total of 30cultivars were collected from Fujian Province. The young embryos or mature embryos were used as explants for establishing in vitro regeneration system of loquat. The cultivar 'Zaozhong No. 6' was used as the material for exploring the method of loquat restricting growth preservation, and the optimalized method was further used to preserve 52 accessions of loquat germplasm from Fujian Province. Further studies including the analyses of the changes of the contents of the endogenous hormones by HPLC, the activities of the protective enzymes of the cell membrane, the contents of MDA and soluble protein contents, as well as the observations of ultrastructure of ltrathin sections of the blade by the transmission electron microscopy (TEM), were conducted for discuss the mechanism of loquat restricting growth preservation. The main results were as follows:1 The establishment of loquat in vitro regeneration system.The results from the embryo culture from 30 cultivars of loquat showed that the appropriate size of the embryo, cutting of cotyledons, the flat inoculation on 1/2 MS medium supplemented with 20g/L sugar in light were beneficial to germination of the embryos. The comparisons of germination of the different types in loquat indicated that the highest germination rate occurred in Wild type loquat, and lower in the cultivars; the highest germination rate occurred in Eriobotrya deflexa (Hemsl.) Nakai forma koshunensis (Kanehira et Sasaki) Li among the germplasm of wild type prinldes; The germination rates of the red cultivars were higher than those of the white cultivars among the cultivating loquats. The best medium for the proliferation was MS medium supplemented with BA1.0mg/L and NAA0.1mg/L, and the optimal rooting medium was MS medium adding with IBA0.2mg/L and NAA0.4mg/L.2 Approach to the method of loquat restricting growth preservationThe results showed that the appropriate size of the embryo, cutting of cotyledons, the inoculation density of 3 plantlets in each bottle on 1/3 MS medium supplemented with 30g /L white sugar and 10 g/L agar in light were beneficial to in vitro conservation of plantlets. AC was unfit for the additive of restricting growth preservation of loquat plantlets, but 5mg/L PP333 was beneficial to the preservation of loquat plantlets. The proper cycle for subculture was 8 months. The survival rate of Wild type loquat was higher than that of the red cultivars and the white cultivars by the conservation of different types of loquat plantlets. 3 Restricting growth preservation in vitro of 52 accessions of loquat germplasm.The plantlets of 52 accessions of loquat germplasm with a total of 30cultivars were preserved by the optimized method with the restricting growth preservation. The preserved plantlets were subcultured every 8 months, and the plantlets kept health and were normal in terms of growth potential.4 Analyses of the changes of the contents of the endogenous hormones by HPLC during the in vitro conservation of the loquat plantlets.The results from the loquat plantlets treated with PP333 showed that the ABA content significantly increased while the contents of GA3 and ZT decreased during the early 3 months; the ABA content reduced from 3 months to 7 months but enhanced after 7 months; the ZT content enhanced after 3 months and reached highest at 8 month; the change of the IAA content was completely opposite with that of CK during the earlier 6 month and was basically consistent after the latter 6. month, the IAA content reached highest at 2 month. The rate of ABA and IAA, ABA and GA3, ABA and ZT, ABA and IAA+GA3, ABA and IAA+GA3+ZT significantly enhanced during the earlier 3 month and reached highest at 4 month, the rate of ABA content and ZT content significantly delayed of 2 months.5 The determination of some physiological indexes during the in vitro conservation of the loquat plantlets.During the whole of in vitro conservation the change of the activities of SOD, POD, CAT and soluble protein contents increased in the earlier stages and decreased in the later stages, the change of MDA increased. Compared with CK, the SOD, POD and CAT contents of plantlets reduced by the medium adding PP333, the contents of MDA and soluble protein also reduced during the 5 months of the in vitro conservation and the high-peak contents of SOD, POD, CAT and soluble protein were delayed.6 The observation of the ultrastructure of ultrathin-section of leaves by TEM during the in vitro conservation of the loquat plantlets.During the period of the restricting growth preservation of loquat, the deformation and shift and disintegration of chlorolplasts and the mosaic of the mitochondria significantly delayed at the 6 month, the structure of the chloroplasts in the mesophyll cells was complete but only some of that disintegrated, starch grain significantly became bigger and more, and the structure of the mitochondria and cell nuclear was normal. In the total, the development of the cell was efficiently inhabited and the aging of plants was delayed by restricting growth preservation.