The Research Of Cured Tobacco Leaf Development And Regularity For Accumulate Of Cytoderm Expansins

In 2006-2008,through field experiment in KaiYang County and JiYuan Town, and pot experiment in the farm of Henan Agricultural University. Cured tobacco leaf cell development rule and the relationship between cytoderm expansins accumulate and leaf extend were studied. The results were as follows:1 Regularity for change of organization and cell during cured tobacco leafWhen leaf age 1 day, mesophyll cell array closely and regularly. When leaf age 14 day palisade tissue and spongy tissue were differentiation obviously, Palisade tissue cells were portrait elongate paliform, Spongy tissue cells were transverse extension, and out of shape, intercellular space were arisen. When leaf age 28 days, leaf enter vigorous growing stage, palisade tissue and spongy tissue were beginning incrassation, When leaf age 59 days, leaf fixed length, the rate of leaf area extend were reduced to lowest. When leaf age 63 days, leaf matured, nucleolus shrinked, parts of cell were broken down, low electron dense matter inside cell as cotton shap. When leaf age 77 days, most of cell was broken down, the structure of cell was very loosen.Survey the cell ultrastructure, cell gradually largen, cytoderm more and more thick, cytoplasm from dense to thin, inclusion were gradually degradation along with the leaf get long, and it's position were crowded to edge of cell by continuous inflated vacuole. Vacuoles was change from small to big along with the development of leaf, and gradually develop into unbaked center vacuole, crowded cytoplasm and cellular organ to the cell edage. Plastid was change from small to big. The proplastid which unbaked, only have simple, lamellar structure were develop into chloroplast when mature. Thylakoid lamina system, starch grain inside chloroplast change from small to big, high electron dense osmiophilic material change big to small, the quantity from less to more. In addition, the epidermal intra-cellular of spire have nucleolus and cytoplasm, when leaf matured those mass degradation, until overmaturation only cytoderm were left.During the whole developmental phase, the ratio between thickness of palisade tissue spongy tissue were not change obviously, The ratio between thickness of palisade tissue and leaf were indentation changed. When the leaf close to mature, the ratio between thickness of palisade tissue and leaf were reached the largest, and have the active action to the tobacco quality, leaf development from 56 days to 63 days was the best mature period, after 70 days leaf overmaturation, various structures inside cell were begin to degtadation.2 Regularity for change of histochemistry and cytochemistry during curedFrom leaf come out to mature during tobacco growth course, the content of reducing sugar, starch and lipid were continue uplifted. During curing process, the content of starch and lipid were gradually reduced, but the content of reducing sugar had a suddenly rise, analysis the reason maybe carbohydrate such as starch were decompose to reducing sugar, the content of protein was continue reduced, until maturity stage had a large degree reduce, and the lowest content until curing process finished.When tobacco leaves enter vigorous growing stage, the ratio of cell extent reached the maximizing. Cytoderm expansins layer was appeare and colse to the surface of cytoderm. Along with the development, expansins layer began appear and jion together, until after processed 40 days expansins layer began to drop off.3 Regularity for change of cytoderm expansins under adverse circumstancesUnder normal situation, expansins on the cytoderm were gradually increased and flocculation, then gradually dropped off. Compared with cytoderm expansins under normal situation, cytoderm expansins under the situation of flooded were flocculent, while a small quantity of expansins were fall off intercellular space during the early stages of development, finally almost nothing attachment to the diachyma cytoderm. A little of cytoderm expansins attachment to the diachyma cytoderm of drought situation, mostly fallen off intercellular space.