基于叶片形态及显微特征评价12个猕猴桃栽培品种的抗旱性

Evaluation of drought resistance of 12 kiwifruit cultivars based on leaf morphology and microscopic characteristics

【目的】探讨不同猕猴桃品种的叶片宏观形态和微观结构特征的差异,筛选抗旱性评价关键指标并进行抗旱性综合评价。【方法】采用多功能图像分析法、石蜡切片法和扫描电镜技术,选取12个猕猴桃栽培品种为材料,对叶片形态、气孔器和表皮毛微特征、解剖结构等24项指标进行观测、记录。通过方差分析明确不同品种的叶片形态和解剖结构的差异,以主成分分析筛选综合指标,运用隶属函数法进行抗旱性综合评价。【结果】不同猕猴桃品种的叶片形态、解剖结构、气孔器及表皮毛特征具有显著差异,相关性分析表明不同指标间具有显著或极显著的相关性,运用主成分分析从24个抗旱相关指标中筛选了叶片宽度、叶形指数、气孔长轴、单簇茸毛数、上表皮细胞厚度、下表皮细胞厚度、栅海比、组织结构紧密度共8项关键性指标。通过隶属函数法比较不同品种间的抗旱能力,抗旱性强弱为:徐香>金美>金霞>海沃德>金艳>金魁>金梅>东红>翠玉>金桃>桂海4号>Hort16A。使用聚类分析将12个猕猴桃品种按抗旱能力聚为5类。【结论】通过对叶片形态及显微结构的分析,评价并筛选到抗旱性相对较强的猕猴桃品种,研究结果为猕猴桃品种改良、品种选择及生产管理等提供了基础理论依据。

【Objective】The Actinidia chinensis is the most domesticated species of the genus Actinidia and more than 100 commercially valuable cultivars have been developed.However,few studies have evaluated the drought resistance of different kiwifruit cultivars based on the leaf morphology and microstructure.This research aimed to evaluate the drought resistance of different kiwifruit cultivars by observing and analyzing characteristics,such as leaf morphology,anatomical structure,stomata,epidermis and trichomes.Key indicators for evaluating the drought resistance of kiwifruit cultivars and assessing their drought resistance were identified.【Methods】We selected a total of 12 kiwifruit cultivars(belonging to A.chinensis var.chinensis and A.chinensis var.deliciosa),including Donghong,Guihai No.4,Hort 16A,Jintao,Jinyan,Jinmei,Jinxia,Cuiyu,Jin Mei,Jinkui,Hayward and Xuxiang,as our observation samples.We employed the multifunctional image analysis method,paraffin sectioning method and scanning electron microscopy technique to observe and record the leaf morphology,anatomical structure,stomata and epidermal trichomes of 12 kiwifruit cultivars.A total of 24 traits(designated as X1-X24)were documented.Subsequently,we conducted variance analysis to compare the significant differences in the 24 traits among different cultivars.Then,using principal component analysis,we identified the key traits related to drought resistance from the original set of indicators.Finally,we employed the membership function method to comprehensively evaluate the drought resistance of different kiwifruit cultivars.【Results】There were significant differences in leaf morphology,anatomical structure,stomatal apparatus and the hair of the epidermis among different kiwifruit cultivars.Morphologically,the leaf was heart-shaped or oval-shaped,leaf length(X1)ranged from 10.94 cm to 17.28 cm,leaf width(X2)ranged from 11.39 cm to 16.35 cm,leaf shape index(X3)ranged from 0.93 cm to 1.06 cm,petiole length(X4)ranged from 6.87 cm to 15.91 cm,petiole diameter(X5)and leaf area(X6)ranged from 3.51 mm to 4.58 mm and from 95.03 cm2 to 208.36 cm2.For stomatal apparatus,the length(X7)ranged from 18.77μm to 29.21μm,the width(X8)ranged from 12.64μm to 18.57μm,the macroaxis(X9)ranged from 8.46μm to 16.31μm,and the density(X10)was between 168.70 and 339.63 per square millimeter.In the villi of lower epidermis,all cultivars had fluff,the length(X11)ranged from 249.41μm to 324.10μm,the pedestal density(X12)was between 9.37 and 31.83 pedestals per square millimeter,the villus density(X13)was between 54.93 and 113.95 roots per square millimeter,and the number of villis per pedestal(X14)was between 5.57 and 7.30.For sake of anatomical structures,these cultivars had similar anatomical characteristics.The structure of the leaves from the lower epidermis to the upper epidermis was composed of lower epidermal cells,sponge tissue,palisade tissue and upper epidermal cells.Calcium oxalate crystals were scattered in the mesophyll cells.The leaf veins mainly formed protrusions on the lower epidermis,which were vascular bundles,thin-walled tissues and mechanical tissues from the inside to outside.Lateral vein diameter(X15)ranged from 595.04μm to 860.71μm,leaf thickness(X16)ranged from 177.68μm to 264.53μm,thickness of upper epidermis cell(X17)ranged from 15.36μm to 23.37μm,the first layer of palisade tissue cell density(X18)was between 75.33 and 113.00 per square millimeter,thickness of lower epidermis cell(X19)ranged from 10.03μm to 20.35μm,thickness of palisade tissue(X20)ranged from 75.16μm to 123.60μm,thickness of spongy tissue(X21)ranged from 49.81μm to 85.68μm,the ratio of X20 to X21(X22)ranged from 1.19 to 2.16,tightness of leaf tissue structure(X23)ranged from 0.41 to 0.52,and looseness of leaf tissue structure(X24)ranged from 0.24 to 0.36.The coefficient of variation(CV)of the 24 traits ranged from 8.04%to 35.80%,and the correlation analysis showed that there were significant or extremely significant correlations among the different traits.Principal component analysis showed that the cumulative contribution rate of the first 7 principal components reached 93.046%,effectively retaining most of the information of the 24 indicators.Eight key drought-resistance indicators were selected,including X2(leaf width),X3(leaf shape index),X9(macroaxis),X14(number of villis per pedestal),X17(thickness of upper epidermis cell),X19(thickness of lower epidermis cell),X22(thickness of palisade tissue/thickness of spongy tissue)and X23(tightness of leaf tissue structure).Furthermore,the drought resistance of different cultivars was compared by subordinate function method.The order of drought resistance was as follows:Xuxiang>Jinmei>Jinxia>Hayward>Jinyan>Jinkui>Jin Mei>Donghong>Cuiyu>Jintao>Guihai No.4>Hort 16A.【Conclusion】The differences in leaf morphology,stomata,epidermal hair and anatomical structure of different kiwifruit cultivars were revealed.Leaf width,leaf shape index,stomatal length axis,number of villis per pedestal,thickness of upper epidermis,thickness of lower epidermis cell, thickness of palisade tissue/thickness of spongy tissue, and tightness of leaf tissuestructure were selected to evaluate drought resistance. The drought-resistant cultivars such as Xuxiang,Jinmei and Jinxia were screened by the method of subordinate function analysis, which could providereference for genetic breeding, variety selection and production management in the future.