火炬松成熟合子胚培养直接体细胞胚胎发生和植株再生

以Hb、Ma和Mc3个基因型的火炬松成熟合子胚为外植体，建立了火炬松的离体培养直接体细胞胚胎发生植株再生体系实验结果表明，不同基因型火炬松之间的直接体细胞胚诱导频率有明显差异3个基因型中．Hb的成熟合子胚在附加1mg·L－12，4－D和4mg·L－1BA的DCR培养基上的直接体细胞胚诱导频率最高，达18％,扫描电镜观察表明，直接体细胞胚主要形成于成熟合子胚的子叶表而且胚轴较短，和母体组织仅保持胚根部位的联系组织细胞学切片结果表明，直接体细胞胚上胚根的发育落后于子叶，但是由直接体细胞胚发育形成的再生小苗有独立的维管组织，根部也较发达，并且整个小植株的维管系统和成熟合子胚上子叶的维管组织没有直接的联系.

DIRECT SOMATIC EMBRYOGENESIS AND PLANTLETREGENERATION FROM MATURE ZYGOTICEMBRYOS OF LOBLOLLY PINE

Direct somatic embryogenesis and plantlet regeneration system was established by culturing thethree genotypes Hb, Ma, and Mc in loblolly pine (Pinus taeda L. ). The results showed that the induction frequency of direct somatic embryos smong the three genotypes was greatly different . Genotype Hb had the highestinduction frequency of direct somatic embryos (18% ) among the three genotypes tested, when cultured on DCRmedium supplemented with 1 mg. L-1 2,4-D and 4 mg. L-1 BA. Scanning electron microscopy showed that direct somatic embryos with a short hypocoty were formed on the surface of mature zygotic embryos, and onlyconnected with mother tissue by radicle. Cytological observation showed that the development of radicle laggedbehind the cotyledons in direct somatic embryos. Mature direct somatic embryos had independent vascular tissueand their roots developed well. There are no connection between the vascular system of regenerated plantlets andthe vascular tissue in cotyledons of the mature zygotic embryos.