Chen Yun-Hao, Straube Jannis, Khanal Bishnu P, Knoche Moritz, Debener Thomas
Institute of Horticultural Production Systems, Fruit Science Section, Leibniz University Hannover, Herrenhäuser Straße 2, 30419 Hannover, Germany.
Institute of Plant Genetics, Molecular Plant Breeding Section, Leibniz University Hannover, Herrenhäuser Straße 2, 30419 Hannover, Germany.
Plants (Basel). 2020 Sep 30;9(10):1293. doi: 10.3390/plants9101293.
Russeting (periderm formation) is a critical fruit-surface disorder in apple ( × Borkh.). The first symptom of insipient russeting is cuticular microcracking. Humid and rainy weather increases russeting. The aim was to determine the ontogeny of moisture-induced russeting in 'Pinova' apple. We recorded the effects of duration of exposure to water and the stage of fruit development at exposure on microcracking, periderm formation and cuticle deposition. Early on (21 or 31 days after full bloom; DAFB) short periods (2 to 12 d) of moisture exposure induced cuticular microcracking-but not later on (66 or 93 DAFB). A periderm was not formed during moisture exposure but 4 d after exposure ended. A periderm was formed in the hypodermis beneath a microcrack. Russeting frequency and severity were low for up to 4 d of moisture exposure but increased after 6 d. Cuticle thickness was not affected by moisture for up to 8 d but decreased for longer exposures. Cuticular ridge thickness decreased around a microcrack. In general, moisture did not affect cuticular strain release. We conclude that a hypodermal periderm forms after termination of moisture exposure and after microcrack formation. Reduced cuticle deposition may cause moisture-induced microcracking and, thus, russeting.
果锈（周皮形成）是苹果（×Borkh.）果实表面的一种关键病害。初期果锈的首个症状是表皮微裂。潮湿多雨的天气会加重果锈。本研究旨在确定水分诱导的‘皮诺娃’苹果果锈的发生过程。我们记录了水分暴露时长以及暴露时果实发育阶段对微裂、周皮形成和角质层沉积的影响。在早期（盛花后21天或31天；DAFB），短时间（2至12天）的水分暴露会诱导表皮微裂，但后期（66或93 DAFB）则不会。在水分暴露期间未形成周皮，但暴露结束后4天形成了周皮。周皮在微裂下方的皮下组织中形成。水分暴露长达4天时，果锈频率和严重程度较低，但6天后增加。角质层厚度在长达8天的时间内不受水分影响，但暴露时间更长时会降低。微裂周围的角质脊厚度减小。总体而言，水分不影响角质层应变释放。我们得出结论，皮下周皮在水分暴露终止后且微裂形成后形成。角质层沉积减少可能会导致水分诱导的微裂，进而导致果锈。
