| Amomum villosum Lour, is a species in the genus Amomum which belongs to the family of the Zingiberaceae. Its dry ripe fruit is one of the four famous South China medicines. As a medicine, the dry ripe fruit has the effects of dissipating dampness, promoting appetite, warming the spleen, antidiarrheal, regulating qi, calming fetus and so on. It has high medicinal and economic value.The natural pollination rate of A. villosum is extremely low because of its special’ configuration of floweret. Artificial pollination is helpful for increasing the production, but needs hard labor, which limits the development of planting industry of A. villosum. The natural pollination rate maybe increase by changing the configuration of floweret of A. villosum, which will be benefit to enlarge the production scale.In this paper, the configuration, structure and biological characters growth of A. villosum floweret were studied. The gynandrium-like forming course and forming mechanism were also investigated. The study is benefit to increase the pollination rate of A. villosum.The results of this paper are as follows:1. The division standard of the floweret growth period was established.On the basis of floweret total length, the floweret growth period was divided. Into eight periods were divided from 0.5 mm in length to the day after flowering:0,1st,2nd,3rd, 4th,5th,6th and 7th period. The floweret in the 5th period will flower in the next day. The blossoming floweret was classed in the 6th period, and the floweret in a day after flowering was classed in the 7th period.2. The floweret structure was studied. The configurations or microstructures of the stalk, ovule, nectary, epidermal hairs which growing inside the nectary cavity wall, and abnormal floweret were described first.A short floweret stalk was discovered by anatomy method. Two pieces of nectary locate on the top of ovary, which is near the base of style. PAS reaction was positive, indicating the nectary is starch type. The amount of nectar secreted in a day can be 9μl. Epidermal hairs were found on the nectary cavity wall; they are epidermal cells with split at the top.There are few types of abnormal flowerets. The style in abnormal floweret with double times of stamens is shorter than that in normal floweret. A floweret lacking of stamens tends to lack of lips.3. The growth characters of flowerets in different periods were studied.It takes half a month for a floweret growing from 1 cm in length to blossoming. From the periods of 1st to 3rd, the floweret grows slowly. But from periods of 4th to blossoming, floweret grows fast; it spends only one day in each period. The time more close to blossoming, the faster floweret grows. In 5th period, at the time of one day before blossoming, the floweret elongates for 20 mm in one day.4. The growth characteristics of each structure part in floweret were studied.Before blossoming, floweret grows longitudinally. The length of elongating is contributed by the elongations of nectary cavity and anther chamber. Before flowering, the anther cavity constitutes the main part of total length of floweret, which is 45%. From period 0 to blossoming, the length ratio between nectary cavity and floweret increases significantly, that is from 10% to 39%.As time goes on, the style elongates significantly. It is 0.5 mm in the period 0,20 mm in the period 5th, and 30 mm in the period 6th. In period 0, the style with length of 4.5 mm is at outside of nectary cavity mainly. But in period 6th (blossoming), the style with two-thirds of total length is at inside of nectary cavity mainly.The width of anther is always greater than the thickness. The anther looks flat. From period 0 to blossoming, the width and thickness of anther are increasing. At blossoming, the width and thickness reach maximum. Anther also grows longitudinally. From period 0 to 5th, the length ratio between anther and anther cavity reduces significantly; it reduces from 95%to 68%. At the time of flowering, the stomiums of pollen sacs are gravitated to the middle fast. The angle between left and right stomiums is reducing quickly during flowering; it reduces from 32°to 17°.5. The forming course of Gynandrium-like was depicted.The forming course of Gynandrium-like involves the bending of filaments, bursting of pollen sac and moving of style.Gynandrium-like is a kind of morphological structure in A. villosum floweret that the gynoecium and stamen grow together tightly but not join together. The key time of gynandrium-like formation is one day before blossoming. In period 5th, one day before blossoming, the gap between pollen sacs has expanded to the width of style diameter. The angles of α and β are reducing, which makes anther to bend to style. The style straightens and moves into anther groove along the gap. When flowering, burst pollen sacs blocked the entrance of the gap to prevent the style from escaping. Then gynandrium-like is formed.6. The forming mechanism of the Gynandrium-like was primary studied.They are different in the layer number of cells and cell size between both sides of the filament. The difference maybe is the structure foundation for bending. When flowering, the cells in abaxial side of the filaments become smaller significantly, while the cells in adaxial side have no significant change in size (except to the basic cells). Thus it is able to predict that the bending of filaments is owing to the size of cell in abaxial side reduces.There are close relationships between thickening of endothecium cell wall and bursting of pollen sacs, and reducing of angle between left and right stomiums. In period 2nd, stomium starts to form. At the same time, the cell wall of endothecium thickens in a stripy manner, which is prepared for bursting.It was found that there is asymmetry structure in the morphological upper of style by microstructure observation. There are 1-6 layers of parenchyma cells in adaxial side of style more than that in abaxial side, which provides the structural foundation for moving. Besides, immunofluorescence analysis revealed that the distribution of IAA in both sides of style is unequal. The amount of IAA is greater in adaxial side than that in abaxial side. The results indicated that the growth of both sides of style is uneven, and there is a possibility of asymmetric growth. |
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