Morphological Comparison Of Fruits, Seeds And Genetic Diversity Analysis Of Spinacia Oleracea L.

China is the largest spinach grower and consumer in the world.However, the systematic evaluation and identification are lacked to the spinach germplasm resources, so that it has not been utilized effectively in spinach breeding and production. There are two taxonomic varieties of spinach (Spinacia oleracea L.), the spiny variety (5. oleracea var. spinosa Moench) and the spineless variety (S. oleracea var. inermis Peterm). In this study, two taxonomic varieties were compared in terms of macro-morphology of plants, fruits and seeds, AFLP markers, micro-morphology of the fruit surface and seed coat, which were employed to analyze the genetic diversity among 31 spinach germplasms.The main results were as follow:1. 31 spinach germplasm resources showed varying degrees of diversity and the variation coefficient of the quantitative traits was from 25.75%-62.44%, which is quite different. The variation coefficient of each quantitative trait was from big to small: single plant weight, plant height, petiole length, leaf width, plant width, leaf length. Two groups were divided from these 31 spinach germplasms by cluster analysis. Group 1 consisted of 15 materials, mainly European cultivars, including some Asian cultivars, showing the morphological features of western cultivars. Except Zibing Bocai from Korea, all spineless variety wasgathered in this group; Group 2 was consisted of 16 materials, mainly Asian cultivars, showing the morphological features of the Oriental cultivars, all spiny variety was gathered in this group; which indicating that the two varieties of spinach had significant differences in plant morphology.2. Based on AFLP marker2 groups were divided from these 31 spinach germplasms by cluster analysis. Group 1 consisted mainly of Europe cultivars,also included a small amount of Asiagermplasms,with abundant genetic background.Group2consisted mainly of germplasms from southern China. Most of the germplasmscould be grouped according to the geographical source, and the genetic relatives of the same countries were closely related. All 16 stingless cultivars were assigned to group 1, 11 of 15 sting cultivars assigned to group 2, the other 4 assigned to group 1, which illustrated that the differences between the taxonomic varieties of spinach were demonstratedat the molecular level of AFLP markers.3. Between two taxonomic varieties, there were significant differences in the macro-morphology ofspinach fruit, in terms of fruit shapes and the presence of spines.Fruit from the spineless variety was broadly obovate, without any spines on the surface. Fruit from the spiny variety was oblate, with two or three spineson the surface, and the length and angle of spines were different and unstable.Under Scanning Electron Microscope (SEM), we could observe the irregular and unstable sculptures on the fruit surface due to drying and crimpling. There wereno obvious differences in the micro-morphology of thesurface of fruit coat between the spineless and spiny varietiesbased on SEM observation.4. Basedonstereomicroscopy, the seed surface was rough and dull or slightly glossy,and there were no clear and stable differences between the two varieties in seed macro-morphology, thus it is hard to distinguish the two varieties without the fruit coat, which makes seed purity analysis difficult.Under the SEM, the surface reticulation of the seed coat was irregularly quadrilateral, pentagonal,or elliptic,withmultivariable diameters, and significant differences in seed micro-morphology could be observed. Theseed surface reticulation of the spineless varietyhad a regular shape anddeep interspaces;the lateral walls of interspaceswere straight;and the bottoms of the interspaces wereflat or gently rolling, with fingerprint sculptures on the surface of the interspace bottom. On the other hand,reticulation of the spiny varietyhad an irregular shapeand shallow interspaces, the lateral walls of interspaceswere leaning outward and sloping,and there wereobvious irregular fluctuations or rolling,and the interspaces crowded together;in addition,some of the lateral sides of interspaceoverlapped each other so that they were difficult to distinguish.Basedon micro-CT imaging, the internal seed structure was very clear. In the seed center,farinaceous albumen was coiled by the peripheral embryo curving along the inner wall of the seed coat.The whole embryo formed aslightly raised ring on the surface of the seed coat. The radicle tip was slightly elongated, and there was a small notch along the seed edgebetween the radicle tip and the cotyledon tip, with the hilum in the notch. There were no regular and stable differences between the two taxonomic varieties in the internal seed structure.These results provide morphological evidence for distinguishing fruits and seeds between the two spinach taxonomic varieties, and these similarities and differences can be used toclassify spinach cultivars andto analyze seed purity.