Removing the endosperm of ginseng and American ginseng seeds results in embryos developing into normal seedlings

Both ginseng and American ginseng are world-famous traditional medicines with multiple bioactivities. The deep dormancy of their seeds causes serious problems in artificial cultivation. However, little is known about the physiological mechanism of seed dormancy and how to shorten the seed dormancy period for these two plant species. An experiment was conducted to determine whether endosperm removal would promote embryo development in ginseng and American ginseng and if in vitro embryos would suffer nutrient deficiency during seedling establishment. The results show that excised embryos developed radicles longer than 2 mm, using any culture method, whereas no germination was observed for intact seeds. Excised embryos, without the endosperm nutrient-supply have the ability of developing into a normal seedling, but in vitro embryos grown on MS medium have greater fresh weight, seedling height and radicle length than those grown on filter paper and pure agar medium. In summary, removing endosperm can overcome physiological dormancy of ginseng and American ginseng seeds, and nutrient level determines the development and growth rate of the embryo.

CRYOPRESERVATION OF TRUE-SEED AND EMBRYO OF MAIZE AND SOYBEAN FOR LONG-TERM STORAGE

<br />Study on cryopreservation of Indonesian local cultivars and improved varieties of maize and soybean has never been done. This method may be used for long-term preservation of seeds of maize and soybean. In this study, the method was applied to maize and soybean, Arjuna and Wilis respectively, as a model for preserving germplasm of ortodox seeds. Whole seeds and excised embryos of both varieties were subjected to two methods of cryopreservation, i.e., two-stage cooling and rapid freezing with or without 15% dimethyl sulfoxide (DMSO) as cryoprotectant solution prior to immersion in liquid nitrogen (-196oC). Results indicated that there was no significant difference between the use of DMSO for both species in terms of viability, although pretreatment in DMSO was slightly reduced the percentage of viability of both species. Slow freezing to -30oC prior to immersion in the liquid nitrogen could give as high as 76.67% and 51.67% surviving whole seeds of maize and soybean, respectively. Preserving excised embryos of maize in the liquid nitrogen using either slow or rapid freezing significantly reduced the percentage of viability from 20-76.67% to 5-18.33% (four folds) depending on treatments applied. Results also showed that one day or 15 minutes of immersion of samples in the liquid nitrogen gave rise to similar values of viability of maize and soybean, i.e., 20-60% and 20-51.67%, respectively depending on treatments applied. These results implied that for long-term storage of maize and soybean seeds as they could survive at the rate of 76.67% and 51.67% respectively, the seed can be treated by prefreezing to -30oC<br />without the presence of DMSO prior to immersion in liquid nitrogen.<br /><br />

CRYOPRESERVATION OF TRUE-SEED AND EMBRYO OF MAIZE AND SOYBEAN FOR LONG-TERM STORAGE

<br />Study on cryopreservation of Indonesian local cultivars and improved varieties of maize and soybean has never been done. This method may be used for long-term preservation of seeds of maize and soybean. In this study, the method was applied to maize and soybean, Arjuna and Wilis respectively, as a model for preserving germplasm of ortodox seeds. Whole seeds and excised embryos of both varieties were subjected to two methods of cryopreservation, i.e., two-stage cooling and rapid freezing with or without 15% dimethyl sulfoxide (DMSO) as cryoprotectant solution prior to immersion in liquid nitrogen (-196oC). Results indicated that there was no significant difference between the use of DMSO for both species in terms of viability, although pretreatment in DMSO was slightly reduced the percentage of viability of both species. Slow freezing to -30oC prior to immersion in the liquid nitrogen could give as high as 76.67% and 51.67% surviving whole seeds of maize and soybean, respectively. Preserving excised embryos of maize in the liquid nitrogen using either slow or rapid freezing significantly reduced the percentage of viability from 20-76.67% to 5-18.33% (four folds) depending on treatments applied. Results also showed that one day or 15 minutes of immersion of samples in the liquid nitrogen gave rise to similar values of viability of maize and soybean, i.e., 20-60% and 20-51.67%, respectively depending on treatments applied. These results implied that for long-term storage of maize and soybean seeds as they could survive at the rate of 76.67% and 51.67% respectively, the seed can be treated by prefreezing to -30oC<br />without the presence of DMSO prior to immersion in liquid nitrogen.<br /><br />

Causes and Breaking of Seed Dormancy in Flowering Dogwood (Cornus florida L.)

Cornus florida seeds show strong dormancy. In this study, we investigated the causes of the dormancy by assessing the permeability of the stony endocarp, the germination of seeds after mechanical dissection, and the effect of endogenous inhibitors. Water uptake by intact and cracked seeds during imbibition showed that the endocarp formed a strong barrier for water absorption. Meanwhile, extracts from endocarp decreased the germination frequency of chinese cabbage seeds from 99.3% (control) to 2.7%. Therefore, the endocarp was the mechanical barrier and contained endogenous inhibitors for seed germination. However, the germination percentage of decoated seeds and dissected seeds with the exposed radicle were only 13.3% and 28.7%, respectively. It was found that the endosperm also played a role in seed dormancy. Extracts from endosperm decreased the germination frequency of chinese cabbage seeds from 99.3% (control) to 53.0%. By contrast, extracts from embryo did not affect the germination of chinese cabbage seeds. When tested with the excised embryos, germination percentage was up to 85.3% at the 16th day of incubation. Taking these results together, we concluded that the endocarp and endosperm were responsible for seed dormancy in C. florida. To break the seed dormancy of C. florida, stratification and soaking in sulfuric acid are the effective means. The highest germination frequency was achieved by immersing seeds in 98% sulfuric acid for 10 minutes, then soaking the seeds in 500 mg·L−1 gibberellic acid (GA3) for 72 hours before cold stratification at 5 °C for 60 days.

Metabolism of excised embryos of Lupinus luteus L. VI. An electrophoretic analysis of some dehydrogenases in cultured embryos as compared with the normal seedling axes

The electrophoretic patterns (disc electrophoresis) of the studied dehydrogenases: glucose-6-phosphate - (A), malate - (B), glutamate - (C), alcohol - (D) and lactate dehydrogenase (E), in the axial organs of isolated <i>Lupinus luteus</i> embryos and seedlings cultivated over 12 days are characterized by great similarities. With time, after the third day of cultivation the patterns begin to become less deyeloped. Analyses performed during the first 10 hours of imbibition of seed parts indicate that the maximal development of isozyme patterns occurs during the third hour after which the patterns become poorer. The most uniform type of pattern. and the lowest number of isozymes was shown by glutamate dehydrogenase, the richest pattern was shown by malate dehydrogenase. No band common for a 11 the 27 experimental elements was found.