摘要
【目的】明确‘凯特’杏果实不同发育时期水分运输情况,阐明引发成熟期裂果的主要原因。【方法】跟踪杏发育进程,分别于果实第一次快速生长期、硬核期、第二次快速生长期、成熟期进行采样。品红示踪试验中,将带有杏果和叶片的枝条浸入品红溶液中,每隔30 min观察1次;每次选留3~5颗完好的果实,将果实果柄完整取下并在果实中部切取1 cm3小块,投入预冷的FAA固定液中,4℃冷藏1周后,对切块进行常规石蜡切片处理;采用TUNEL细胞凋亡检测试剂盒（碧云天生物技术有限公司）对不同发育时期果皮细胞活性进行检测;每次采样后切取新鲜的果实表皮,对其进行曲利苯蓝染色,观察果皮细胞死亡程度。【结果】‘凯特’杏发育前期,品红溶液均能较顺畅地运输至果实,进入成熟期后品红溶液运输十分困难。杏果发育过程中,果柄导管均保持较畅通状态。杏果实发育后期,果皮细胞出现较多由表皮毛退化形成的＂缺口＂,有的＂缺口＂直接与皮下层细胞相连。随果实发育进行,‘凯特’杏果皮发生明显的细胞凋亡和死亡现象,且果锈及其周边部位细胞死亡较为严重。【结论】‘凯特’杏发育后期,虽然果柄导管未发生明显的异化,且水分运输功能正常,但内果皮（果核）木质化加剧且与果柄＂对接＂,使根系吸水难以大量进入果实。同时,果实表皮毛退化、表皮细胞出现＂缺口＂,且果皮细胞凋亡、局部死亡,为果实表面水分大量进入果实打开了通道。
【Objective】Fruit cracking happens at the late stage of fruit development, and significantly reduces fruit quality, yield and economic return of apricot fruit. Much attention has been paid upon cracking in fruits such as grape, apple and jujube, but there is a lack of report on fruit cracking in apricot. The authors started the study of fruit cracking in Chinese red date（jujube） in 2009 and obtained some progress in understanding the mechanism of jujube fruit cracking and in developing effective prevention measures,which have been adopted by farmers. The present study was initiated by examining the roles of root-absorbed water and fruit surface water in fruit cracking in order to obtain an understanding of the changes in water transport efficiency in‘Katy’apricot and its association with the occurrence of fruit cracking.【Methods】Changes in water transport efficiency in fruit were studied by magenta tracer. Fruit stalk was sampled, fixed in FAA fixing solution, embedded with conventional method, sectioned, and stained with fast green and safranin for observing changes in vessel structure during fruit development. Pericarp wasevolution was observed by tracing fruit in 30 tagged apricot trees in 2013, and sampling was carried out in the first rapid growth stage（April 20）, the stone hardening stage（May 10）, the second rapid growth stage（May 30） and the maturation stage（June 20）. At each sampling stage, thirty‘Katy’apricot fruit were weighted using an electronic balance to trace fruit weight change. Fifteen bearing twigs were dipped into magenta solution, and the distribution of magenta solution across the transverse and longitudinal sections of fruit was observed and photographed every 30 minutes. Paraffin sections were prepared for observing the structural changes of the vascular and epidermis tissues. For this anatomical study, apricot fruit were cut into pieces about one cubic centimeter, fixed in pre-cooled FAA fixing solution, vacuum de-aired,stored in a freezer for up to one week, dehydrated using graded ethanol solutions, vitrified by dimethylbenzene, embedded in paraffin, sliced into sections up to 8 μm in thickness, stained in safranin and fast green, and observed and photographed under an optical microscope. TUNEL method was used to measure the activity of epidermis cells during fruit development. The extent of cell death of the fleshy fruit skin was tested by trypan blue staining method【.Results】The growth curve of‘Katy’apricot fruit was a＂slowfast-slow-fast＂＂double S＂pattern. The whole development period of apricot fruit can be divided into 4periods, the first fast growth period, stone hardening period, the second fast growth period, and mature stage. The peak of fruit cracking happened during the second fast growth period and the mature period. In the early periods of fruit development, magenta solution could be transported into fruit easily, and it was hardly seen in part-red stage and full-red stage fruit. The paraffin section of the stalks showed that during the development of apricot, the vessels of the stalk kept unobstructed, and there was no obvious degradation or breakage or blockage observed. With the development of apricot,‘gaps’ appeared because of pubescence degeneration, and some of the‘gaps’ developed to the sub-epidermal cells. Trypan blue staining and TUNEL analysis confirmed that apoptosis occurred in the peel apricot developed, especially in the late stage, when skin tissue showed partial death and fruit-rust（the spots produced by external stimuli）caused by cell death appeared.【Conclusion】The results of this study suggested that water transport in the tree was not the main cause of fruit cracking in later developmental stages, and partial death of the epidermal cells, pubescence degeneration and the decrease in the number of epidermal cells were the major causes of apricot cracking. The water staying on the surface of fruit skin might be the major contributor to fruit cracking instead of the water transported from the tree.
出处
《果树学报》
CAS
CSCD
北大核心
2016年第9期1103-1110,共8页
Journal of Fruit Science
基金
山西省科技攻关项目(20140311017-2)
山西省科技重点研发项目(2015-TN-4-5)
关键词
'凯特’杏
裂果
果面积水
细胞凋亡
‘Katy’apricot
Cracking
Fruit surface water
Apoptosis
