Arrangements Of Microtubule Arrays In The Shoot Apex Of Sugarcane (Saccharum Officinarum L.)

Sugarcane is an important crop for sugar in the world. The shoot apexis a center of morphogenesis in vascular plants, microtubules have longbeen known to play a key role in plant differentiation. It is meaningful tostudy microtubule arrays in shoot apex of sugarcane in order to elucidatewhy sugarcane has a wide stem.Two distinct stem diameters sugarcane varieties, Yuetang86/368 andCP80/1827 were investigated in the paper. Improved cryosection methodsand indirect immunofluorescence labeling techniques were used forobserving the cytoskeleton. We discribed the details of the method andreported on the overall in situ arrangements of microtubules in a widerange of shoot apex of sugarcane viewed by this method.1 Improved cryosection method and indirect immunofluorescence labelingtechniques are suitable for examining microtubules in the shoot apex ofsugarcane, four typical microtubule arrays during mitosis such as corticalmicrotubule, preprophase microtubule band, spindle microtubule andphragmoplast microtubule were stained well. Certain concentration DMSOtreatment before cryosection could make plant cell intact. The best antibodies concentration is 1: 200 (first antibody) and 1: 40 (secondaryantibody) in the shoot apex of sugarcane.2 Many transitional microtubule arrays during mitosis were also observed,indicating that sugarcane has some common features to many dicotyis.Transverse cortical microtubules were the main microtubule array in therapidly elongating young leaves, and longitudinal cortical microtubules inthe swelling cells. The mitosis microtubules show anticlinal division in therapidly elongating young leaves. These microtubule arrays have some closerelations with the developing young leaves, but just how they fulfil theirfunctions is still unclear.3 Anticlinal cortical microtubules were the main arrays in tunica inpromeristem in the shoot apex of sugarcane, and the microtubules duringmitosis also show anticlinal division. These microtubules indicating theexpansion of surface were anticlinal to shoot apex, which were closelycorrelated with the tunica. Various cortical microtubule arrays wereobserved in the corpus, and longitudinal microtubules to the surface weredominant. Rib meristem were dominated by transverse corticalmicrotubules and the arrays were spare through the cell, although someother microtubules such as random and oblique were also observed.Different microtubule arrays during mitosis were seen, anticlinal divisionmicrotubules were main microtubules in corpus close to tunica, andpericlinal microtubules during mitosis far from tunica in corpus. Themicrotubules in rib meristem show transverse division.4 There were cortical microtubule,preprophase microtubule bands,spindle microtubule and phragmoplast microtubule in outer layer ofproepidermis, and transverse cortical microtubule were the main corticalarrays, oblique cortical microtubules were seen occasionally. Periclinal and anticlinal division in outer layer of proepidermis were examined, andanticlinal division dominated the cell division. There were significantdifference between the different diameters sugarcane varieties duringmitosis in anticlinal division in the proepidermis, the wider stem sugarcanehas higher rate of anticlinal division than that of smaller sugarcane, andPPBs were the most microtubule arrays among all other microtubuleduring mitosis.5 There were many spindle microtubule arrays in the inner layer ofproepidermis, and periclinal division more than anticlinal division, all kindsof cortical microtubule arrays were also observed, the transverse andoblique cortical microtubule have lower intensity than that of random andlongitudinal arrays.6 There were many mitosis microtubules in the primary thickeningmeristem in the base of the third young leaves, and most of them indicatingpericlinal division, there were significance difference between the twovarieties in periclinal division during mitosis, this was a key ground of whysugarcane become wider. Various cortical microtubules were observed inprimary thickening meristem, transitional arrays in the same cell were alsodiscovered, indicating the cells there were in an actively developing state.7 There were all kinds microtubules in the procambial bundles in the baseof the third young leaves, and many transitional cortical microtubulearrays were also observed in the same cells, and there were differentconcentrations in these cortical microtubules in the developing process.Cortical microtubules were almost transverse to the long axes of vesselwhen procambial bundle cells were developing, there were no microtubulearrays in pitches and perforation. Microtubules during mitosis indicatingpericlinai division were also observed in the region. 8 Various microtubule arrays were observed in ground meristem. Therewere some heterogeneous arrays in cortical microtubules, such as regular inone side and irregular in the side of the nucleus. There were relationsbetween the two varieties, that is longitudinal cortical＞transversearrays＞Oblique arrays＞Random arrays. Wider sugarcane has significantdifference than smaller sugarcane in longitudinal and random corticalmicrotubule arrays. Microtubule arrays during mitosis were also seen, thedirection of them indicating periclinal division, and there were significantdifference between two varieties in microtubule arrays during mitosis, thiswas another causes for sugarcane becoming wider than other plants.9 The results of analysis on correlation indicated that the stem diameter haspositive correlation to the mitosis in the primary thickening meristem,mitosis microtubule and longitudinal cortical microtubule arrays atsignificant level. Periclinal division microtubule array in the primarythickening meristem in the base of the third young leaves play the key rolein stem widening.