Ogura细胞质雄性不育(Ogura CMS)最初在野生萝卜中被鉴定，其特征为花粉完全败育。但Ogura CMS在大白菜中的分子机制尚不清楚。细胞学分析证实，细胞核降解发生在花粉发育的单核后期，在三核期几乎消失，而绒毡层细胞从四分体时期开始异常增大并出现空泡化。花粉壁存在严重的发育缺陷。在花粉发育早期，与细胞色素c和程序性细胞死亡(PCD)相关的基因在Ogura CMS系中上调表达。相反，与花粉壁有丝分裂相关的基因表达下调。在花粉发育后期，Ogura CMS系中过氧化物酶体和自噬相关基因上调表达。线粒体orf138基因突变刺激绒毡层细胞PCD过程，导致其内容物异常增大和降解，直至三核期绒毡层细胞空泡化。由于绒毡层缺陷，其不能为小孢子提供足够的孢粉素和营养物质，从而导致花粉壁发育异常和小孢子有丝分裂异常。综上所述，核弥散与自噬发生在花粉发育后期导致大白菜Ogura CMS系不能产生功能性花粉，表现出雄性不育。

A novel phytoplasma was detected in a cherry plum (Prunus cerasifera Ehrh) tree that mainly showed yellow leaf symptom. The tree was growing in an orchard located in Yangling District, Shaanxi Province, China. The leaves started as chlorotic and yellowing along leaf minor veins and leaf tips. Chlorosis rapidly developed to inter-veinal areas with the whole leaf becoming pale yellow in about 1-4 wk. Large numbers of phytoplasma-like bodies (PLBs) were seen under transmission electron microscopy. The majority of the PLBs was spherical or elliptical vesicles, with diameters in range of 0.1-0.6 μm, and distributed in the phloem cells of the infected tissues. A 1246-bp 16S ribosomal RNA (rRNA) gene fragment was amplified from DNA samples extracted from the yellow leaf tissues using two phytoplasma universal primer pairs R16mF2/R16mR1 and R16F2n/R16R2. Phylogenetic analysis using the 16S rRNA gene sequence suggested that the phytoplasma associated with the yellow leaf symptoms belongs to a novel subclade in the aster yellows (AY) group (16SrI group). Virtual and actual restriction fragment length polymorphism (RFLP) analysis of the 16S rRNA gene fragment revealed that the phytoplasma was distinguishable from all existing 19 subgroups in the AY group (16SrI) by four restriction sites, Hinf I, Mse I, Sau3A I and Taq I. The similarity coefficients of comparing the RFLP pattern of the 16S rRNA gene fragment of this phytoplasma to each of the 19 reported subgroups ranged from 0.73 to 0.87, which indicates the phytoplasma associated with the cherry plum yellow leaf (CPYL) symptoms is probably a distinct and novel subgroup lineage in the AY group (16SrI). In addition, the novel phytoplasma was experimentally transmitted to periwinkle (Catharanthus roseus) plants from the tree with CPYL symptoms and then back to a healthy 1-yr-old cherry plum tree via dodder (Cuscuta odorata) connections.