
中圖分類號:S662.5 文獻標志碼:A 文章編號:1009-9980(2025)06-1181-09
Abstract: 【Objective】Morphological characteristics of pollen grains of different cherry germplasm resources were observed under a scanning electron microscope.The similarities and differences in pollen among diferent germplasm resources were analyzed,so as to provide a scientific basis for the identification of diffrent cherry germplasm resources. At present, scanning electron microscopy (SEM) technology has opened up a new perspective for the study on pollen structure with its excellent high resolution and the ability to observe three-dimensional morphology. It can observe the microscopic characteristics of the surface of cherry pollen grains in detail,including complex surface decoration,pore structure and microscopic structure of pollen walls.Therefore,this technology is chosen to observe the morphological characteristics of pollen grains in the experiment.【Methods】Polen grains of 17 cherry germplasm resources from the Tongzhou Cherry Breeding Base,F(xiàn)orestry Fruit Research Institute of follows: Summit,Sunburst,Caihong,Rainier,Brooks,MashadBlack,Santina,Russian8,MinieRoyal, Royal Lee, Chelan,Katalin, Tieton,7-2-9,7-5-30,Duiying and Landing 1. During the blooming period of cherries,the pre-bloom flowers were collected,the anthers were completely peeled off with small tweezers,placed in a sulfuric acid paper box,and irradiated with a desk lamp to help loose powder. Then the dried pollen was collected in a bottle of Xilin,stuffed with rubber plugs,labeled and stored in a refrigerator at -20°C for later use. The experiment was conducted in the electron microscope room of the Institute ofFood Science and Technology,CAAS.First,a cottn swab was dipped into asample of dried pollen grains,and they were gently flicked on the sulphate paper,and appropriate amount of pollen was takenwith 1cm×1 cm double-sided conductive tape,and then affixed to the metal platform and gold-plated in the Eiko IB5 Ion Coater ion spater. Finally, the pollen grain morphology of 17 cherry germplasm resources was observed under the Hitachi SU-8010 scanning electron microscope. The population status of pollen grains was photographed and observed under the field of view of 500× ,and20 pollen grains were selected from each cherry germplasm resource to investigate the uniformity of pollen.Image Jwas used to measure the polar axis length (P)and equatorial axis length (E) of selected pollen grains respectively and the polar equatorial ratio (P/E ) was calculated. The polar erythroid ratio indicates the shape of pollen grains, P/Egt;2 indicates that the pollen grains are ultra-elliptic shape, and 1.14
. The polar declination ratio was
.The appearance of pollen grains was mostly elliptic shape or ultra-elliptic shape, of which 12 germplasm resources were ultra-eliptic shape.By observing the morphology of pollen grains under a scanning electron microscope, it was found that most of the pollen grains were elliptical on the equatorial plane,and 3 germination channels were observed in the polar axis direction with circular distribution, belonging to N3P4C5 type pollen. These germination grooves extended to both ends of the pollen, but no joint grooves were formed in the polar region. The outer wall patern was striped,and there were obvious differences in stripe width,spacing,slope,clarity,andouter wallhole densityamong different germplasm resources.【Conclusion】 In the tested cherry germplasm resources, there were 14 pollen uniformity greater than 70% . Concurrently, a significant positive correlation was observed between the pollen viability and the length of the polar axis in 17 cherry germplasm resources. The morphological characteristics of pollen grains can be used as a basis for different cherry germplasm resources. Scanning electron microscopy is crucial for the classification and phylogeny of cherry. Analyzing the morphological characteristics of pollen grains enables the effective distinction of cherry germplasm resources,as wellas the revelation of teir interrelationships.The study of these characteristics provides a basis for genetic research,and also helps to explore the genetic mechanisms that control polln morphology.However,there are stillfew reports on the systematic identification and classification of different cherry germplasm resources based on morphological characteristics of pollen grains,and further studies areneeded.
Key words: Cherry; Germplasm resources; Pollen; Scanning electron microscopy (SEM)
櫻桃(CerasuspseudocerasusLindl.)作為重要的經(jīng)濟果樹,其花粉形態(tài)特征在品種鑒定、親緣關系分析及遺傳多樣性研究中具有重要價值。然而,不同櫻桃品種花粉在大小、形狀及外壁紋飾等方面的差異尚缺乏系統(tǒng)研究[2-3],尤其在高分辨率微觀結構解析方面的研究存在不足。傳統(tǒng)光學顯微鏡技術受分辨率限制,難以清晰揭示花粉表面的精細特征,而掃描電子顯微鏡(ScanningElectron Microscopy,SEM技術以其高分辨率和立體成像優(yōu)勢,為花粉形態(tài)學研究提供了更精確的觀察手段。前人已利用SEM技術對部分果樹品種的花粉形態(tài)進行了觀察,但在櫻桃種質資源的系統(tǒng)性研究及分類鑒定方面仍有待深入[4。筆者利用SEM技術對17份櫻桃種質資源的花粉粒形態(tài)特征進行系統(tǒng)分析,利用相關性分析和聚類分析,全面揭示花粉形態(tài)的變異規(guī)律,以優(yōu)化櫻桃品種鑒定體系,揭示其微觀結構特征,為品種鑒定及遺傳分類提供科學依據(jù)。同時,也為豐富植物分類學與生殖生物學領域關于櫻桃花粉形態(tài)的基礎數(shù)據(jù),以及櫻桃種質資源保護與品種選育提供參考。
1材料和方法
1.1植物材料
試驗所用花粉均取自北京市農林科學院林業(yè)果樹研究所通州櫻桃育種基地,包括薩米特(Sum-mit)、艷陽(Sunburst)、彩虹(Caihong)、雷尼(Raini-er)、布魯克斯(Brooks)、馬什哈德(MashadBlack)、桑緹娜(Santina)、俄八(Russian8)、羅亞明(MinieRoyal)、羅亞李(RoyalLee)、秦林(Chelan)、卡塔琳(Katalin)、美早(Tieton)、7-2-9、7-5-30、對櫻(Duiy-ing)、蘭丁1號(Landing1)。
1.2 采集花粉
在櫻桃盛花期(通常為4月上中旬),在通州櫻桃育種基地采集17份櫻桃種質資源含苞待放的花蕾。采集時間選在清晨至上午的溫度適宜時段(大約08:00—10:00),以避免花粉在高溫或強光下提前脫落。收集后,用小鑷子輕輕地將花藥完全剝取下來,避免破壞花粉粒。將花藥置于干燥的硫酸紙盒中,放置于溫度為 18~22°C 的室內避風環(huán)境中,用臺燈(光源溫度約為 25°C? 照射,促進花粉散發(fā)。花粉完全干燥后,將其小心收集至西林瓶中,塞上橡皮塞,貼好標簽,標明采集時間和種質資源信息。最終,將收集到的花粉存放于 -20°C 冰箱中保存,以保持其活力和形態(tài)特征,為后續(xù)試驗提供可靠的材料。
1.3掃描電子顯微鏡觀察
試驗在中國農業(yè)科學院農產品加工研究所電鏡室進行。先用棉棒蘸取干燥好的花粉粒樣品,輕輕彈在硫酸紙上,再用剪裁好的 1cm×1cm 雙面導電膠帶蘸取適量花粉,貼在金屬載臺上,放入EikoIB5IonCoater離子濺射儀中鍍金,最后置于日本日立公司SU-8010掃描電子顯微鏡下觀察。花粉樣品的觀測:選取有代表性的視野,即在 500× 視野下對花粉粒群體狀態(tài)拍攝,在 1500× 視野下對花粉粒個體形態(tài)拍攝。
1.4相關數(shù)據(jù)分析
首先調查17份櫻桃種質資源的花粉整齊度,該指標用于評估花粉的生長狀態(tài),具體表現(xiàn)為花粉粒是否飽滿、形態(tài)是否正常以及是否存在畸形或褶皺。高整齊度的花粉粒通常較為規(guī)則,而低整齊度的花粉粒則可能表現(xiàn)為不規(guī)則形狀或形態(tài)不佳。利用掃描電子顯微鏡在 500× 視野下拍攝花粉粒群體狀態(tài)照片,并觀察記錄花粉整齊度。利用ImageJ軟件分別測量17份櫻桃種質資源花粉粒的極軸長(P)、赤道軸長(E)和極赤比(P/E)。每份種質資源設置5次生物學重復,每次重復隨機選取20粒花粉。試驗所得數(shù)據(jù)均使用SPSS27.0統(tǒng)計軟件進行分析,采用Duncan新復極差檢驗法進行顯著性檢驗。花粉形狀的分類方法及相關學術用語參照《孢粉學概論》5:極軸長和赤道軸長之比(P/E)表示花粉粒形狀 (P/Egt;2 表示花粉粒為超長球形, 1.14lt; P/E?2 表示花粉粒為長球形)。對17份櫻桃種質資源的花粉粒進行聚類分析,并對其花粉整齊度和極軸長度進行相關性分析。分別調查記錄17份櫻桃種質資源的花粉粒形狀和外壁紋飾的相關性狀,即花粉粒外壁紋飾的條紋寬度、條紋間距、條紋傾斜度、條紋清晰度和花粉粒紋孔密度。
2 結果與分析
2.1花粉整齊度
圖1統(tǒng)計了17份櫻桃種質資源的花粉整齊度。
2.2 花粉粒大小

櫻桃花粉粒通常呈長球形或超長球形,赤道面觀多為橢圓形,三條萌發(fā)溝且呈環(huán)狀分布,屬于N3P4C5 型花粉(圖2)。通過掃描電子顯微鏡觀察17份櫻桃種質資源的花粉,發(fā)現(xiàn)其在極軸方向上具有三條萌發(fā)溝,延伸至花粉兩端,且在極區(qū)未形成合溝。表1統(tǒng)計了17份櫻桃種質資源的花粉粒形態(tài)大小,其極軸長度分布在 41.53~48.57μm ,赤道軸長分布在 21.30~25.29μm ,極赤比分布在 1.67~2.17 。花粉粒極軸長度可分為 40~45μm 和 45~50μm 兩類,第一類包括雷尼、桑緹娜、羅亞李、秦林、卡特琳、美早、7-5-30和蘭丁1號,第二類包括薩米特、艷陽、彩虹、布魯克斯、馬什哈德、俄八、羅亞明、7-2-9、對櫻。其中,7-2-9的極軸長度最大,為 48.57μm ;美早的極軸長度最小,為 41.53μm 。分析結果顯示,17份櫻桃種質資源中部分品種的赤道軸長度存在顯著差異。此外,通過計算17份櫻桃種質資源的極赤比發(fā)現(xiàn),其花粉粒的外觀形態(tài)均呈長球形或超長球形。其中,桑緹娜、羅亞明、卡塔琳、美早和7-5-30為 1.14lt; P/E?2 (長球形),其他櫻桃種質資源均為 P/Egt;2 (超長球形)。

根據(jù)花粉整齊度、極軸長度以及極赤比對17份櫻桃種質資源進行聚類分析(圖3)。根據(jù)花粉整齊度,可將17份櫻桃種質資源分為兩個大類:第一大類為花粉整齊度 gt;70% ,第二大類為花粉整齊度 ? 70% 。根據(jù)花粉整齊度和極赤比將第一大類又分為兩個亞群。第一亞群為花粉整齊度 gt;70%.P/Egt;2 ,包括羅亞李、蘭丁1號、雷尼、7-2-9、對櫻、俄八、馬什哈德、布魯克斯、彩虹、艷陽和薩米特;第二亞群為花粉整齊度 gt;70%.1.14在 40~45μm 。

對17份櫻桃種質資源的花粉整齊度與極軸長度進行相關性分析(表2,圖4)。結果表明,花粉整齊度和極軸長度存在顯著的相關關系, plt;0.05 ,兩者相關系數(shù)是0.271。由此可知,花粉整齊度與極軸


長度之間存在較強的正相關關系。
2.3花粉粒外壁紋飾
對17份櫻桃種質資源花粉粒外壁紋飾的相關性狀進行觀察(圖5)。結果表明,不同櫻桃種質資

源的花粉粒外壁紋飾的相關性狀既有相似性也有差 異性(表3)。薩米特、艷陽、彩虹、桑緹娜、俄八、秦 林、美早、7-2-9、7-5-30和蘭丁1號的條紋寬度較小; 布魯克斯、馬什哈德、羅亞明、卡塔琳和對櫻的條紋 寬度適中;而羅亞李的條紋寬度較大。薩米特、艷 陽、彩虹、雷尼、秦林、美早、7-5-30和蘭丁1號的條 紋間距小;布魯克斯、馬什哈德、桑緹娜、俄八、羅亞 明、羅亞李、卡塔琳、7-2-9和對櫻的條紋間距適中。 彩虹、桑緹娜、羅亞明、羅亞李、秦林、卡塔琳、美早和 蘭丁1號的條紋較平行;薩米特、雷尼、布魯克斯、馬 什哈德、俄八、7-2-9、7-5-30和對櫻的條紋稍有交叉; 艷陽的條紋交叉最為明顯。薩米特、艷陽、彩虹、雷 尼、桑緹娜、俄八、秦林、美早、7-2-9、7-5-30和蘭丁1 號的條紋較為明顯,而布魯克斯、馬什哈德、羅亞明、 羅亞李、卡塔琳和對櫻的條紋卻非常明顯。薩米特、 艷陽、彩虹、雷尼、馬什哈德、桑緹娜、俄八、羅亞明、 羅亞李、秦林、美早、卡塔琳、7-2-9、7-5-30和蘭丁1 號的紋孔密度小;布魯克斯的紋孔密度較為適中;而對櫻的紋孔密度較大。

3討論
近年來,掃描電子顯微鏡技術因能清晰揭示花粉的形態(tài)特征而被廣泛應用于多種植物,包括葫蘆科、核桃[-]、楊梅、蘋果、榛子、枸杞]、弼猴桃、枇杷屬、番荔枝等。覃麗祿等利用普通高真空掃描電鏡在低電壓條件下對不同種類的花粉進行了顯微結構觀察。但當花粉被花粉囊等其他物質覆蓋時,其表面細節(jié)會變模糊,從而影響觀察結果[12]。為解決這一問題,Ermolaev等[13]通過HMDS技術改進了掃描電鏡花粉樣本制備,大幅縮短了研究時間,提高了效率。這些技術不僅可以更清晰地觀察花粉表面紋飾,還可以增強對花粉形態(tài)特征的理解,對植物分類和系統(tǒng)學研究意義重大。
花粉粒的形狀和外壁紋飾由于遺傳上的穩(wěn)定性,對植物分類和演化研究具有極其重要的價值[1]。這些特征不僅有助于鑒定植物的種類,而且對揭示植物間的親緣關系也極為關鍵。Lindau通過綜合分析花粉的形狀、外壁紋飾和開孔數(shù)等性狀,確定了花粉類型的范圍,揭示了這些特征與物種間的聯(lián)系,突出了它們在系統(tǒng)學研究中的重要性[。通過觀察發(fā)現(xiàn),供試17份櫻桃種質資源的花粉整齊度和花粉粒形態(tài)表現(xiàn)出豐富的多樣性。在花粉整齊度方面,大部分櫻桃種質資源的花粉整齊度大于70% 。在花粉粒形態(tài)方面,以花粉粒形狀及外壁紋飾差異最為明顯。有研究表明,較為原始的被子植物花粉體積較大,隨著進化花粉體積趨向減小[],花粉粒形狀由長球形向超長球形演化。本試驗中17份櫻桃種質資源的花粉粒表面紋飾均為條紋狀,除桑緹娜、羅亞明、卡塔琳、美早和7-5-30為長球形之外,其他櫻桃種質資源均為超長球形,說明大多數(shù)櫻桃種質資源較為進化[18]。此外,花粉的形態(tài)特征與其活力之間也具有密切相關性。花粉表面紋飾的完整性及花粉壁的結構會影響花粉的萌發(fā)能力和生理活性,表面光滑、無缺陷的花粉通常具有較高的活力,因此花粉形態(tài)特征可以作為花粉活力的一個參考指標。掃描電子顯微鏡在櫻桃分類和系統(tǒng)發(fā)育研究中發(fā)揮著關鍵作用。通過分析花粉粒的形態(tài)特征,可以有效區(qū)分櫻桃種質資源,揭示它們之間的親緣關系。這些特征的研究也有助于探索控制花粉形態(tài)的遺傳機制,為遺傳學研究提供基礎。
4結論
在供試櫻桃種質資源中, 82.35% 的種質資源花粉整齊度超過 70%,70.59% 的種質資源花粉粒形狀為超長球形。花粉粒整齊度與極軸長呈正相關關系,外壁紋飾多為條紋狀。盡管目前利用花粉粒形態(tài)對櫻桃種質資源進行系統(tǒng)鑒定的研究較少,但本研究表明,花粉粒外壁紋飾的條紋寬度、間距、傾斜度及紋孔密度等特征在不同櫻桃種質資源間存在顯著差異,可作為種質資源鑒定的依據(jù),但仍需深入研究。
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