| The masson pine(Pinus massoniana Lamb.),a evergreen gymnospermic tree belonging to Pinaceae,Pinus,are widely grown in 17 provinces,autonomous regions,and municipalities of China such as Hunan,Guizhou,and Guangxi.It is the degree of utilization of coniferous species and the dominant tree species with very high economic benefits are the major tree species for product resin.Turpentine is a mixture of terpenoids.It is stored in the resin canal and mainly contains turpentine and resin.It is an important industrial raw material and renewable environmental protection resource in China.In this paper,the masson pine germplasms with different resin yields in March and August were used as materials.To compare the morphological and anatomical structure characteristics between the masson pine germplasms of high-resin yield and low-resin yield.To explore the distribution,initiation,and development characteristics of Pinus massoniana resin canal,and its relationship with resin yield.The structural characteristics of high-resin yield of Pinus massoniana from cytological elucidation,and provide a theoretical reference for early selection and targeted cultivation of excellent germplasm.The results showed that:(1)Resin canals are distributed in the conifer and xylem of the masson pine germplasms,and the structure,initiation and development characteristics of resin canals are basically same.They are developed by the initial cell population of resin canals through the middle layer of cell wall expansion,dissolution and cavity expansion.The resin ducts were formed by Schizolysigeny.The development was divided into four stages: the resin canals initial cell stage,the interstitial formation stage,the expanded interstitial stage,and the resin canal mature stage.(2)There were no significant differences in morphological characteristics such as coniferous length,sheath length,coniferous diameter,cross-sectional area,xylem diameter,and phloem thickness between the masson pine germplasms of high-resin yield and low-resin yield during the March and August.There is no obvious relationship between the resin yield of Pinus massoniana and its morphological characteristics.However,the diameter and cross-sectional area of conifer of Pinus massoniana were significantly different at different periods(P<0.05).(3)Between the high-resin yield and low-resin yield germplasms,there were significant differences in the area of single resin canal in conifer,the total area of resin canal in conifer,the number of resin canal in xylem,the area of single resin canal in xylem and the total area of resin canal in xylem(P<0.01).The numbers of resin canals in xylem and the numbers of resin canals in conifer varied among the different orientations,and those from the East,South and North were significantly higher than that from the West(P<0.05).The area of single resin canal of conifer in March and August was 739.00 ?m2 and 845.50 ?m2,being 1.90 times and 1.73 times of that of low resin yield,respectively.The total area of xylem resin canal was 2.40-and 2.33-fold as much as that of low resin yield,respectively.The number of resin canals in xylem was 1.35-and 1.42-fold of the low resin yield germplasm,respectively.Therefore,the number of resin canal in xylem,the total area of resin canal in xylem and the area of single resin canal in conifer,could be used as an indicator for breeding high resin yield germplasm.(4)In different periods germplasm,there were significant differences in the area of single resin canal in xylem,the number of resin canal in xylem,in the area of single resin canal in conifer,the number of resin canal in conifer and coniferous diameter(P<0.05).In August,the number of resin canal in xylem and the area of single resin canal in conifer,being 1.13 times and 1.18 times of March germplasm.(5)Under scanning electron microscope observations,the resin canal of long stems,the resin canal of short stems,and the number of epithelial cells in xylem and conifer between the masson pine germplasms of high-resin yield and low-resin yield were significantly different(P<0.05),but the long stems and short stems of epithelial cells were no significant differences.Observed by transmission electron microscope,we were found that there are a large number of organelles in the epithelial cells surrounding the mature resin canals.The most obvious is that the epithelial cells have a large number of plastids.The mitochondria and starch granules in the chloroplasts are larger and more abundant in epithelial cells in conifer and xylem of high resin yield germplasms.The chloroplast matrix thylakoids have a tightly packed sheet structure with a small amount of Osmiophilic droplets. |
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