Studies On Morphogenesis In Vitro And Relative Research Of Eriobotrya

Loquat(Eriobotrya japonica Lindl.) belongs to Rosaceae, Maloideae, is one of subtropical evergreen fruit trees. There are various loquat germplasm resources in China, including 20 species(species, varieties or formas), however, only one species, namely common loquat, is being used for cultivating.Though there are some reports on in vitro culture, morphogenesis and regeneration for the cultivating species, few researches foucused on the other 19 wild species. In this case, Studies on in vitro morphogenesis and relative researches of wild species would play significant role insaving the germplasm in vitro, biotechnology breeding and so on.This study consists of three parts. At first, diversified phytohormone combinations and carbohydrate sources were used to induce calluses of E. japonica cv. ‘Jiefangzhong' and its redifferentiation. Then, three wild species, E. bengalensis f.angustifolia Vidal, E. kwangsiensis Chun, E. deflexa Nakai, and two hybrids, ie.E. japonica cv. ‘Jiefangzhong'× E. deflexa Nakai and E. japonica cv. ‘Jiefangzhong'×E. prinoides Redh.&Wils were took for further studies. Secondly, the calluses with good quality from the first portion were selected for paraffin section, tostudy in vitro morphogenesis process of loquat by histologic observation. In the third place, the well- grown calligot in the first section of this study were chosen to measure sucrose, glucose and sorbitol content by HPLC, providing basis material of the relationship between soluble carbohydratelevel and in vitro morphogenesis. The main results obtained were as follows:(1) MS + BA0.2 mg / L + K T0.2 mg / L + 2,4-D1.0 mg / L + sucrose 30 g / L was suitable for inducing callues of E. japonica cv. ‘Jiefangzhong', E. bengalensisf.angustifolia Vidal, E. deflexa Nakai, E. japonica cv. ‘Jiefangzhong'×E. deflexa Nakai and E. japonica cv. ‘Jiefangzhong' ×E. prinoides Redh.&Wils, All explants got callus induction rates of 100%, except ‘Jiefangzhong' which showed 93.00%. what is worse, the callus induction rate of ‘Jiefangzhong' field leaves was about 11.00% while showing a high browning rate about 89.00% on the same medium.While MS + BA 0.4 mg / L + KT 0.2 mg / L + 2,4-D 1.0 mg / L + sucrose 30 g / L or MS + BA 0.2 mg / L + KT 0. 4 mg / L + 2,4-D 1.0 mg / L + sucrose 30 g / L were more compatible for E. kwangsiensis C hun leaves calli induction, and the rate could reach at 98.20% in both media.(2) As carbon source, sucrose and sorbitol were better than glucose for leaves calluses induction on ‘Jiefangzhong', E. bengalensisf.angustifolia Vidal and E. kwangsiensis Chun cultivation, with higher callus induction rate and better quality,though it is hard to achieve morphogenesis. Embryogenic calli of ‘Jiefangzhong' were able to achieve regenerated rooting on MS + KT 3.0 mg / L + NAA1.0 mg / L+ sucrose 30 g / L and MS + KT 3.0 mg / L + NAA 0.1 mg / L + 2,4-D 0.1 mg / L + sucrose 30 g / L with 2.00% and 4.00% rooting rate respectively, but both fail to regenerate buds. On the co ntrast, calluses of wild species always got high browning rate and low morphogenesis rate. Only if stems of E. bengalensis f.angustifolia Vidal, E. kwangsiensis Chun and E. deflexa Nakai were cultured on MS+BA 1.0 mg/L +NAA 0.1 mg/L + sucrose 30 g / L or MS+BA 1.0 mg/L +NAA 0.3 mg/L + sucrose 30 g / L could them keep morphogenesis and obtain higher plantlets rates. By the way, these plantlets were always in good condition.(3) In vitro anatomical slices showed that ‘Jiefangzhong' calluses could form clear meristems, vascular nodules and abnormal somatic embryos, in like manner, E. bengalensis f.angustifolia Vidal and E. kwangsiensis C hun intended to generate abnormal somatic embryos, and these abnormal somatic embryos would not develop into seedlings.(4) The contents of sucrose, glucose and sorbitol of calli varied with phytohormone types, concentration and sugar source. Medium supplemented with sorbitol would improve sorbitol content of calluses, while the more vigorously dividing calluses generally had lower sorbitol content. What's more, embryogenic calli with high sorbitol content often tend to possess higher browning rate, and were unlikely to achieve redifferentiation. In a word, sorbitol is main component of Rosaceae including loquat, but it was likely not to promote morphogenesis.