不同品系蝴蝶蘭花朵之除雄反應與乙烯敏感性之相關性

Abstract

蝴蝶蘭是國內重要的花卉作物，由於育種者眾多，因此已經產生了許多的雜交群，有關各群之植物學性狀均有詳細的記載，但是相關的生理性狀卻很少研究。蝴蝶蘭是對乙烯的敏感的花卉，花朵對乙烯的敏感性是它的重要生理性狀。本研究是以單朵切花瓶插於水中的方式，觀察花朵於除雄後之生理反應，來探討不同雜交群花朵對乙烯之敏感性。20個蝴蝶蘭雜交群之單朵切花瓶插於水中，大部分的瓶插壽命均在3週以上。所有雜交群的花朵在經授粉之後，花被皆於5日內萎凋。所有雜交群花朵經除雄之後，各雜交群花朵開始老化之時間則表現出很大之差異，依時間之快慢大致可分為3類：(1) 快速老化型：於除雄後5日內開始老化，共有12個雜交群，包括青蘋果、大辣椒、大白花‘V3’、美琪微笑、金星、紅不讓、富樂夕陽、新日本姑娘、第一名、閃電、巨寶紅玫瑰及繽紛櫻桃等；(2) 緩慢老化型：於除雄後15日才開始老化，共有4個雜交群，包括紅天使‘V31’、沙西米、金鑽及立匠火鳥等；(3)中間型：除雄後老化反應介於1和2之間，共有4個雜交群，包括陽光女孩、櫻花公主、巨寶美人及古坑美人等。蝴蝶蘭花朵於除雄後之老化徵狀與正常花朵老化相似。以代表3個類型之9個雜交群進行花朵除雄後之老化生理研究；各雜交群之花朵在除雄後開始老化之時間點，與花朵出現鮮重快速下降及乙烯生成高峰之時間點一致，花朵老化都在乙烯生成高峰的隔日顯現。以0.1 μL•L-1外加乙烯處理9個雜交群的花朵，其花朵開始老化的時間亦不相同，但順序與除雄後花朵出現老化反應的時間一致，二者間之相關係數達r2=0.7682。選擇對除雄後反應快與反應慢之雜交群各一種，對盆花花序上單朵小花做除雄處理，此小花之壽命與單朵切花之反應相同。此結果顯示蝴蝶蘭花朵在除雄後開始出現老化徵狀之早晚與花朵對乙烯之敏感性有關，此一性狀應可以做為該雜交群之生理特性之一。進一步以除雄後快速老化型之巨寶紅玫瑰蝴蝶蘭和除雄後老化緩慢型之紅天使‘V31’蝴蝶蘭為材料，比較花朵於除雄後之乙烯生合成路徑調控上之差異。巨寶紅玫瑰蝴蝶蘭於除雄後6小時，其上蕊柱之乙烯生成速率上升，其他花器部位包括下蕊柱、子房、花被、唇瓣隨後跟著上升，於除雄後36小時達到乙烯生成高峰，花朵於隔日老化。各花器中的ACC含量和ACC oxidase (ACO)活性與乙烯生成速率有類似的變化。紅天使‘V31’蝴蝶蘭於除雄後10小時，其上蕊柱之乙烯生成速率上升，隨後下降，至第3日下降到接近零；花朵其他部位之乙烯生成速率皆維持很低。一直到除雄後16日上蕊柱之乙烯生成再度上升，其他部位亦跟著上升，花朵於第17日出現老化。上蕊柱之ACC與ACO活性在10小時後亦會增加，在3天後降至很低，至第15天後再度快速增加。這些結果顯示，巨寶紅玫瑰蝴蝶蘭為對乙烯很敏感之雜交群，花朵於除雄後6小時乙烯上升，此乙烯可能誘發花朵之乙烯自動催化作用(autocatalysis)，產生大量乙烯而使花朵快速老化。紅天使‘V31’蝴蝶蘭為對乙烯較不敏感之雜交群，花朵於除雄後雖然使上蕊柱產生乙烯，但是無法誘發乙烯自動催化作用，因此花朵不會老化，一直到第17日才發生，應是花朵之自然老化反應。本研究之結果顯示不同的蝴蝶蘭雜交群對乙烯的敏感性是不同的，以單朵帶梗小花做除雄處理，觀察花朵出現老化徵狀的快慢可以做為該雜交群花朵對乙烯敏感性高低之指標。而花朵對乙烯敏感性之差異可能與誘導花朵之自動催化乙烯生成有關。

Phalaenopsis is an important floral crop in Taiwan. Due to its commercial importance and the booming activity of breeders, there are numerous cultivars and greges of Phalaenopsis on the market. The botanical characteristics of each cultivar and grex may have been documented in detail, but there were little information concerning the physiological characteristics of them. Since Phalaenopsisis is sensitive to ethylene, the sensitivity of each grex to ethylene should be an important physiological trait. In this study, a system using single cut flowers held in water was used to observe the response of flower to emasculation, and the result was related to the ethylene sensitivity of the flower. Single cut flowers from 20 Phalaenopsis greges lasted more than 3 weeks when were held in water. When these flowers were pollinated, all of them wilted within 5 days. However, when these flowers were emasculated, there were large variations in the time for the appearance of flower wilting. Based on the length of time to wilting, 3 groups were formed: The Fast Group, all flowers wilted within 5 days of emasculation, these include Phal. Sogo Yukidian and 11 other greges; The Slow Group, all flowers started to wilt 15 days after emasculation, these include Phal. Tai-Lin Red Angel and other 3 greges; The Middle Group, all flowers wilted between 6 to 12 days after emasculation, these include Dtps. Sakura Hime and other 3 greges. The symptoms of flower senescence in emasculated flower were very similar to that of natural senescence. Flowers of 9 Phalaenopsis greges representing the three Groups were used to study the physiology of senescence after emasculation. The timing of appearance of flower wilting after emasculation for each grex matched very well with the timing of starting of fresh weight decline in each grex. It also matched very well with the appearance of ethylene production peak after emasculation in each grex. All flowers wilted on the following day of its ethylene peak. The response of each grex to treatment of 0.1 μL•L-1 ethylene for 24 hrs also showed variation, the hours to the visible sign of wilting were in the same order as the emasculation response. There was a very good correlation between them with r2=0.7682. Emasculation were then performed on a single floret in the inflorescence of two whole orchid plants each representing the Fast or the Slow group; and the results showed similar response of the single cut flower system. These results indicated that the time for the appearance of senescence symptom after emasculation is related to the ethylene sensitivity of the grex, and may be considered as a physiological character of the grex. The difference in the regulation of ethylene biosynthesis between the Fast group and the Slow group were studied. After emasculation, a rise in ethylene production from the upper column of the flower of Dtps. Jiuhbao Red Rose, a member of the Fast group, were detected on the 6th hr. Other parts of the flower also started to produce ethylene, and all of them reached peak after 36 hr of emasculation and the flower wilted on the following day. The ACC content and ACO activity also showed similar pattern as the ethylene production. The ethylene production from the upper column of the flower of Phal. Tai-Lin Red Angel, a member of the Slow group, showed a similar increase 10 hr after emasculation; however, it declined to a basal level after 3 days, and increased again until the 16th day after emasculation and the flower wilted on the 17th day. The ACC content and ACO activity in the upper column increased after 10 hr, it was then declined to a low level on the 3rd day, and started to increase on the 15th day after emasculation. The results indicated that, Dtps. Jiuhbao Red Rose is an ethylene sensitive grex, the ethylene that were produced 6 hr after emasculation may have induced the autocatalytic ethylene system in the flower, which then caused rapid flower wilting. Phal. Tai-Lin Red Angel is an ethylene less sensitive grex; the ethylene that was produced after emasculation failed to induce the autocatalytic ethylene production. The flower remained open until its natural senescence occurred. In conclusion, the results of this study indicated that there are differences in the ethylene sensitivity among Phalaenopsis greges and the time required for the appearance of senescence by emasculated cut single florets may be used as a index of the ethylene sensitivity of the grex. And the differences in ethylene sensitivity may be due to the induction of autocatalytic ethylene production.