Botryosphaeria dothidea在苹果果实上的侵染过程(英文)

对Botryosphaeria dothidea通过皮孔侵入果实的过程进行了光学显微镜和扫描电镜观察,发现接种后2d分生孢子完成萌发和附着胞形成过程。接种后10d,菌丝体在皮孔表面缓慢生长。从20￣30d菌丝体加速扩展并形成几个分枝,通常从皮孔外围侵入果实,但仅限于皮孔表面组织。从40～50d,菌丝体扩展更为繁茂,一些菌丝开始突入皮孔的第2层组织。接种皮孔中可检测到多聚半乳糖醛酸酶(PG),但活性比对照高。皮孔有3层,第1层为含果胶的死组织,易被病菌侵染降解,底部的第3层非常坚固,是阻止病菌侵染的有效屏障。随果实发育,皮孔大小、数目和裂口均有规律地增加。我们的研究结果进一步证实了苹果轮纹病的潜伏侵染特性。

Infection process of Botryosphaeria dothidea in apple fruit

The penetration process of Botryosphaeria dothidea through the lenticels of apple fruit was observed with light microscope and scanning electronic microscope. Condidiospore germination and appressorium formation were completed 2 days after inoculation,the mycelium grew slowly on the lenticel surface 10 days after inoculation. From 20 to 30 days after inoculation, mycelium development speeded up with branching, At this stage, pathogen hyphae only penetrated through the surface tissue of the lenticels, and infection usually occurred around the outer area of the lenticels. From 40 to 50 days after inoculation, the mycelium developed more lushly and some hyphae intruded into the second layer of the lenticels. Low polygalacturonase (PG) activity was detected in inoculated lenticels. The lenticels were composed of three layers. The first layer was dead tissue rich in pectins which were easily degraded during pathogen infection. The third layer at the bottom of the lenticels was very firm and considered as an effective barrier against pathogen penetration. The number, size and cracks of the lenticels increased regularly with fruit development. Our result further demonstrated the character of latent infection in apple ring rot disease.