Pollination Methods and Embryo Rescue Techniques of Hybridization between Lilium Oriental Hybrids

The pollination methods and embryo rescue techniques of hybridization between I.ilium Oriental hybrids were studied in this paper. The results showed that ： （ 1 ） in the combination of ＇ Justina＇ x ＇ Shala＇, pollen tubes were observed to grow downward in styles and target to ovules in ovaries when normal sti^na 13o1- lination method was used; pollen tubes were found to grow directionless to a different degree at stylar cuts and in ovaries when cut-style pollination method was used; the longer the styles were left, the more pollen tubes toward to ovules were observed and more plump seeds were produced; the maximum plump seeds were obtained via normal stigma pollination. （2） Hybridization experiments were performed for the 56 combinations of Lilium Oriental hybrids with normal stigma pollina- tion, and one combination generated no plump ovule and three combinations generated fewer than 10 plump ovules while the other 52 combinations generated plenty of plump ovules, which preliminarily indicated that normal stigma pollination method could be used as an universal pollination technique for hybridization between Lilium Oriental hybrids. The experiment results of different embryo rescue techniques showed that using cut-ovule inoculation about 70 d after pollination had a fas- ter germination speed and a higher germination rate of hybrid embryo than normal ovule inoculation, and embryo rescue efficiency of the former method was obviously higher than ＂embryo isolated inoculation＂ on 40 d after pollination. The research suggested that ＂cut-ovule inoculation＂ about 70 d after pollination could be regarded as an universal embryo rescue technique for hybridization between Lilium Oriental hybrids.

Chlorocholine chloride and paclobutrazol treatments promote carbohydrate accumulation in bulbs of Lilium Oriental hybrids 'Sorbonne'

The present study was to test the hypothesis that the plant growth retardants chlorocholine chloride(CCC) and paclobutrazol(PBZ)could improve the carbohydrate accumulation in lily bulbs by enhancing photosynthetic capacity and changing endogenous hormones.Plants of Lilium Oriental hybrids'Sorbonne'were treated with a foliar spray of CCC or PBZ(both at 300 mg/L)solution,at six weeks after planting(6 WAP).The morphological parameters,endogenous hormone contents(gibberellic acid(GA),abscisic acid(ABA),and indole-3-acetic acid(IAA)),and carbohydrate contents were measured from 6 to 18 WAP,at 2-week intervals.The results showed that CCC increased the biomass of leaves and stems which might produce more photoassimilates available for transportation and utilization.However,PBZ treatment suppressed vegetative growth and favored photoassimilate transportation into bulbs.A slight delay of bud and anthesis formation was observed in both treated plants.CCC and PBZ treatments substantially enhanced the sucrose contents in leaves probably due to the increase of chlorophyll contents.Treatment with CCC or PBZ decreased GA but increased IAA contents in lily bulbs which might stimulate starch accumulation and formation of new scales.Our experiment suggested that CCC or PBZ treatment is an effective method to promote carbohydrate accumulation in lily bulbs.

Photosynthetic characteristics of three varieties of Lilium “Oriental Hybrids”in the central areas of Yunnan Province, China

To understand the ecophysiological adapta-tion of Lilium"Oriental Hybrids",which are grown for their commercial bulbs,the gas exchange,leaf N and chlorophyll content of the three varieties were investigated in the central areas of the Yunnan Province.Among the three varieties,light-saturated photosynthetic rate at ambient CO_(2)(Amax)of Tiber was the highest,while that of Siberia was the lowest.The difference in the Amax was related to the carboxylation efficiency(CE),leaf mass per unit area and leaf N content per mass,which indicated that their photosynthetic capacity was influenced by the activity and/or the quantity of Rubisco.The three vari-eties had lower photosynthetic saturation points and pho-tosynthetic compensation points,but the photosynthetic rates were not decreased up to 2000 μmol·m^(-2)·s^(-1) of the light intensity.This indicates that the three varieties had broad adaptability to light intensity.There were signifi-cant differences in the photosyn thetic optimum temper-ature among the three varieties.Siberia had the highest photosynthetic optimum temperature(25.5℃-34.9℃),and is likely to grow well in warm areas.Sorbonne had the lowest photosynthetic optimum temperature(19.3℃-25.6℃),and its growth is favored in cool areas.Tiber can maintain a high photosynthetic rate within a wide range of temperature.Therefore,Tiber is the most suitable variety for the climate in the central areas of the Yunn an Province,China.

The Dynamics of Changes in Starch and Lipid Droplets and Sub-Cellular Localization of β-Amylase During the Growth of Lily Bulbs

The ultra-structure of mother and outer daughter scales of Lilium Oriental hybrid Sorbonne were studied using transmission electron microscope to examine the sub-cellular localization of starch and lipid droplets during growth and development from shoot emergence to senescence.The contents of starch granules and lipid droplets in the cell of the mother scales decreased significantly from shoot emergence to anthesis,indicating that these scales served as a source for growth and development.After flowering,the number of starch granules and lipid droplets increased dramatically,and finally the cells were filled with the above molecules indicating that the bulb becomes a major sink during bulb enlargement.Ultrastructure observation also showed that symplastic pathway is the main pathway in cells in the exchange and transportation of material during bulb development.The activity of β-amylase,one of the key enzymes catalyzing starch breakdown,showed a similar trend.The enzyme sub-cellular localization via immune-gold electron-microscopy showed that βamylase was predominantly located together with starch granules,while the gold particles were scarcely found in other sub-cellular compartments.The result suggested that this enzyme is compartmented together with its functional substrate supporting its function in catalyzing starch breakdown in living plant cells.

MRI can reveal metabolic changes in lily bulbs in vivo during dormancy release

The factors influencing dormancy release in lily bulbs strongly affect commercialization success, but the mechanism of dormancy release is still unclear. Magnetic resonance imaging (MRI) can detect changes in morphology and water status in a living plant bulb and aid in investigating release factors. To evaluate whether MRI could be used to detect intra-bulb metabolic changes during the dormant period in Oriental Lilies (Lilium 'Sorbonne'), a series of MRI and sugar concentration measurements were performed weekly on bulbs stored for 11 weeks at 4°C. The image quality of intra-bulb structure obtained using T 1-weighted imaging was superior to that obtained using T 2 -weighted imaging and had a higher signal-to-noise ratio (0.97±0.01). Magnetization transfer ratio values for the bud and basal plate declined during the first eight weeks of cold storage (P>0.05), and were well correlated with concentration of soluble sugar in the bud (R 2 =0.95) and basal plate (R 2 =0.93). Thus, MRI can serve as a valuable tool for observation and analysis of dynamic morphological and metabolic changes in vivo during dormancy release. This information is potentially useful as a guide in the improvement of horticultural product quality.

Low humic acids promote in vitro lily bulblet enlargement by enhancing roots growth and carbohydrate metabolism

Bulblet development is a problem in global lily bulb production and carbohydrate metabolism is a crucial factor. Micropropagation acts as an efficient substitute for faster propagation and can provide a controllable condition to explore bulb growth. The present study was conducted to investigate the effects of humic acid （HA） on bulblet swelling and the carbohydrate metabolic pathway in Li/ium Oriental Hybrids ＇Sorbonne＇ under in vitro conditions. HA greatly promoted bulblet growth at 0.2, 2.0, and 20.0 mg/L, and pronounced increases in bulblet sucrose, total soluble sugar, and starch content were observed for higher HA concentrations （_〉2.0 mg/L） within 45 d after transplanting （DAT）. The activities of three major starch synthetic enzymes （including adenosine 5＇-diphosphate glucose pyro- phosphorylase, granule-bound starch synthase, and soluble starch synthase） were enhanced dramatically after HA application especially low concentration HA （LHA）, indicating a quick response of starch metabolism. However, higher doses of HA also caused excessive aboveground biomass accumulation and inhibited root growth. Accordingly, an earlier carbon starvation emerged by observing evident starch degradation. Relative bulblet weight gradually decreased with increased HA doses and thereby broke the balance between the source and sink. A low HA concentration at 0.2 mg/L performed best in both root and bulblet growth. The number of roots and root length peaked at 14.5 and 5.75 cm respectively. The fresh bulblet weight and diameter reached 468 mg （2.9 times that under the control treatment） and 11.68 mm, respectively. Further, sucrose/starch utilization and conversion were accelerated and carbon famine was delayed as a result with an average relative bulblet weight of 80.09%. To our knowledge, this is the first HA application and mechanism research into starch metabolism in both in vitro and in vivo condition in bulbous crops.