Intergeneric Somatic Hybrid Plants Between Citrus and Poncirus trifoliata and Evaluation of Their Root Rot Resistance

Protoplasts of Page tangelo (Citrus reticulata Blanco×C. paradisi Macf.) cell suspension culture were electrically fused with mesophyll protoplasts isolated from trifoliate orange (Poncirus trifoliata (L.) Raf.). More than 150 plantlets regenerated after 4-5 months of culture. The regenerated plants were trifoliate with well developed root systems. Root_tip chromosome counting of more than 20 randomly selected plants revealed that they were all tetraploids (2n=4x=36). RAPD analysis of 7 randomly selected plants verified their hybridity. Inoculation of citrus Phytophthora parasitica Dastar toxin on leaves of somatic hybrids and both parental genotypes showed that Page tangelo was moderately susceptible, and trifoliate orange was highly resistant while the somatic hybrids were resistant. The potential of this somatic hybrid as rootstock is also discussed.

柑桔体细胞杂种对柑桔脚腐病的抗病性研究

本文采用叶片接种法和枝条接种法对２５个柑桔种类体细胞杂种或品种进行了抗脚腐病鉴定，结果表明：体细胞杂种中枳＋酸橙、枳＋甜橙为高抗类型；酸橙＋兰普来檬、枳＋印度酸桔；蚝壳刺＋哈姆甜橙、酸橙＋澳洲指桔为抗性；酸橙＋印度酸桔为中抗。建立了叶片接种法的抗病性分级标准。初步分析了柑桔体细胞杂种的抗性规律。

一种快速鉴定柑桔体细胞杂种对脚腐病抗性的方法

通过用菌丝块接种柑桔叶片法进行柑桔体细胞杂种抗病性鉴定，并与接种柑桔枝条法、菌丝块接种嫁接苗法比较，证明柑桔不同部位对脚腐病的抗性存在着相关性，可采用这种相关性接种柑桔叶片进行体细胞杂种的抗病性鉴定。

柑橘脚腐病菌的鉴定及柑橘种质的抗性测定

从具有典型柑橘脚腐病症的组织中分离出疫霉菌和镰刀菌菌株。致病性测定结果显示,接种疫霉菌1周后,离体柑橘叶片出现变褐腐烂症状,一年生实生苗的接菌部位出现茎腐、流胶等脚腐病症状,确证了该菌株的致病性。通过对菌的形态特征,培养形状和内转录间隔区ITS及延长因子TEF-1α序列进行分析,确认该菌为烟草疫霉菌(Phytophthora nicotianae)。依据枝条接菌结果,枳和枳橙对烟草疫霉菌有高的耐性。