| Lily(lilium spp.),one of perennial herbs with bulbous,is widely cropped and consumed in Europe and America.Since the breeding research work,which was started from the beginning of 20th Century,lily has become one of the most attractive flowers in the world.In this study,the bulb of lily was employed as materials,the physiological mechanism of bulb during bolting was analyzed.Meanwhile,the bulb activities were determined after the bulb of lily was treated with different physical or chemical strategies.The main results are listed at the following.1.According to the results,the process of lily bolting could be divided into 6 stages:stress response stage,post-ripeness stage,cold induction stage,slow bolting stage,rapid bolting stage and flower feeding stage.The period between the low temperature induction stage and slow bolting stage was the critical time for lily bolting.2.In response to cold stress,the respiratory intensity of bulb decreased rapidly at the stress response stage,maintained the lowest at the post-ripeness stage,increased slowly from the cold induction stage,and reached peak at the rapid bolting stage,while Pro and MDA accumulated rapidly.The activity of POD reached its highest at the cold stress stage,then declined to its lowest at the post-ripeness stage.However,the activity of POD increased to its highest again at the cold induction stage,while that of CAT rose parallelly.Both POD and CAT declined to their lowest at the slow bolting stage,indicating that the activities of POD and CAT might serve as the index of lily bolting.During bolting,the interaction of temperature and stress period showed effect on the content of GA,IAA and ABA in bulb,especially on the GA content,implying that GA might play an important role in the bulb bolting of lily.During bulb bolting,the content of starch in bulb decreased continuously,amylose content declined first.But the ratio of amylopectin/amylose was in a relatively stable state,which was the critical feature for bolting.Meanwhile,the activity of amylase and nitrate decreased at low temperature stress stage,but rise at the end of post-ripeness stage,and then continued to decline at the cold induction stage,stay in the low level at the of slow bolting stage.At the cold induction stage,the content of soluble sugar reached its highest value.The changes of soluble protein content was unstable during bulb bolting,but the content of free amino acid reached and maintained its highest value at the cold induction stage.The content of bound water in the bulb increased at the cold induction period,reached its highest value at the rapid bolting stage,then the ratio of free water:bound water became lower.The ratio of free water:bound water was turned to be lower than 2.57,indicating the completetation of dormancy and post-ripeness process of lily bulb.In conclusion,the response of lily bulb to low temperature included two process,one is cold resistant response,second is cold induction maturation.The symbolic physiological changes of stress response are:total free amino acid and respiration were decreased to the bottom.Pro synthesis was first induced by low temperature,permeable adjustment substance like soluble sugar and soluble protein began synthesis to complement in the post ripeness period,participate in the permeability and gradually replace Pro plays a dominant role in stress tolerance.The synthesis and metabolism of soluble sugar and protein was obviously hysteretic than Pro.3.The study on the differential proteins of bulb during bolting showed that 11 differential expressing proteins were identified by the MALDI-TOF-TOF-MS as 2 chaperone protein,4 involved in the energy metabolism,1 cDNA product by stress induced expression,3 cDNA fragment in lily flower and 1 unknown protein.These differential proteins were involved in energy metabolism,response to abiotic stress,etc.Moreover,the expression of HSP70 in bulb during bolting decreased significantly,which can be used as an index to determine the activity of Vernalization in plants.4.The activity of lily bulb was analyzed after it was treated by different physical and chemical strategies.The result showed that the interaction between temperature and stress period influenced the activity of bulb,which reached its highest at 2 C to-2 C with 135d stress.The bulb activity was improved by 35?-40? heat shock stress.The 37? stress with 3h could achieved the highest activity of bulb.Meanwhile,the activity of lily bulb was promoted under the combination stress of low temperature and hormone.The solution of 100mg/L,100mg/L 6-BA and 50mg/L GA3 was optimization for the activity of bulb.And 30%PEG osmotic agent with 3h treatment also promoted the activity of bulb.The bulb with different radius had different activity under different cold treat period.Bulb with weight of 3-4g showed a high germination rate.With the increase of bulb weight,vigor index increasing.The bulb with different propagating ways had different activity.Bulbils,bulb and the cuttage bulblet showed good maturity,which were better than that of the tube bulb.Meanwhile,the different maturating methods showed different effect on the activity of bulb.The bulb with maturity culture more than 5.5 months had a higher germination rate and vigor index.The germination rate of bulb under different low temperature treatment showed the same increasing trend in "Z" type,which was in "? " shape after a long time of cold treatment.In this study,the physiological mechanism of the bolting of lily bulb was analyzed,and the optimized strategies to improve the activity of bulb were presented.The results implicate a new insight into the regulatory mechanism for the bolting of lily bulb and provide a guild for the practice of lily cultivation. |
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