二倍体与四倍体绿玉树乳汁管分布特征的比较

Comparison of the Distribution of Laticifers in Diploid and Tetraploid of Euphorbia tirucalli L

摘要:

采用石蜡切片法、离析法以及徒手切片3种方法研究了绿玉树（Euphorbia tirucalli L.）乳汁管的分布，并对二倍体和四倍体植株茎的乳汁管分布和数量进行了比较研究。结果表明，绿玉树乳汁管为无节型；初级乳汁管主要分布在木质部与韧皮部之间，在两年生茎的髓部也有分布；次级乳汁管以多级分支的形式无规则地散布在韧皮部中；末级乳汁管分布在皮层（或周皮）下部。随着茎成熟度增加，初级乳汁管数量和直径随之增加，直径增加到一定时便停滞，以增加数量的方式来缓解液压。与二倍体相比，相同成熟度的四倍体绿玉树乳汁管数量和直径都显著减少，其中嫩茎的初级乳汁管数量减少了5.5条，直径减少了8.4μｍ；一年生枝条初级乳汁管数量减少了10.7条，直径减少了9.6μｍ。

Abstract:

Laticifer distribution and number were studied in diploid and tetraploid Euphorbia tirucalli L.. The laticifers are non-articulated. Primary laticifers are distributed mainly between the xylem and phloem and in the pith of 2-year-old stems as well. Secondary laticifers are scattered irregularly in the phloem, multi-branched. Terminal laticifers are present beneath the cortex (or periderm). Primary laticifers increase in number and size with stem growth. Then the diameter keeps a certain level and primary laticifers continuously increase in number to relief the sap pressure. Compared with diploid, the number of the primary laticifers decreased by 5.5 and 10.7 in newborn and 1-year-old stems of the tetraploid, respectively, and the diameter decreased by 5.5 and 8.4μｍ, respectively.