引起向日葵盘腐和瘦果花皮的根霉种类及其生物学特性

 根霉(Rhizopus spp.)引起的盘腐病是向日葵生产中的毁灭性病害。近年甘肃酒泉的食用向日葵制种田和生产田,向日葵根霉盘腐和瘦果“花皮”发生严重,重病田盘腐病的发病率达100%,给该地区食用向日葵制种和生产造成了巨大损失。2017年和2018年从酒泉食用向日葵罹病花盘和“花皮”瘦果样本上分离得到34株根霉属真菌,样本检出率达100%。依据菌株的形态学和分子生物学特征,将其鉴定为葡枝根霉(Rhizopus stolonifer)和少根根霉(R. arrhizus)。致病性测定结果表明,葡枝根霉可侵染向日葵的舌状花和花托,引起褐色盘腐;少根根霉和葡枝根霉在人工接种条件下还可侵染向日葵叶片和胚根。葡枝根霉引起向日葵盘腐病在我国系首次报道。

Identification and biological characteristics of Rhizopus spp. causing head rot and seed-case discolor of confectionery sunflower in Gansu Province,China

Head rot caused by Rhizopus spp. is a destructive disease of sunflower (Helianthus annuus) seed heads. In recent years, Rhizopus head rot and discolored seed-case of confectionery sunflower occurred seriously in commercial seed and production fields in Jiuquan region of Gansu province. The incidence of head rot reached 100% in some severely affected fields. It caused great losses to the confectionery sunflower seed industry and commercial production in this area. A total of 34 strains of Rhizopus spp. were isolated from rotten heads and discolored seed-case samples of confectionery sunflower in Jiuquan area in 2017 and 2018, while the detection rate reached up to 100% in diseased samples. These Rhizopus strains were identified as R. stolonifer and R. arrhizus, based on morphological and molecular biological characteristics. The results of pathogenicity determination showed that R. stolonifer could infect ray floret and head of sunflower, causing brown head rot; under artificial inoculation conditions, R. arrhizus and R. stolonifer could also infect leaves and embryo roots of sunflower. This is the first report of confectionery sunflower head rot caused by R. stolonifer in China.