The Early Development Mechanism Of Macroalgae Gracilaria Sp. And Application In Artificial Breeding

Gracilaria vermiculophylla(Ohmi)Papenfuss is one of the dominant macroalgae inhabiting the intertidal zone,where they are exposed to constant environment factors such as wave action and currents.In the field,Gracilaria vermiculophylla(Ohmi)Papenfuss populations occur in clusters and it is rare to find thalli growing individually.However,the reason for such clustering is not yet known.The early development of tetraspores of Gracilaria vermiculophylla(Ohmi)Papenfuss should be traced and analyzed.Two different patterns of development of tetraspores:in the first pattern,tetraspores developed into discs individually,whereas in the second pattern,adjacent multiple tetraspores coalesced to form a disc during early development.More uprights grew from coalesced discs and the attachment areas of coalesced discs were larger compared with those of individual discs.The retention percentage of coalesced discs after treatment with high water flow is also higher than that of individual discs.The clustering growth form of Gracilaria vermiculophylla(Ohmi)Papenfuss in intertidal zones may be an adaption that enables this macroalga to withstanding the wave action and currents that occur in this zone,and may result from the coalescence of discs during early development.The early stage development of Gracilaria vermiculophylla(Ohmi)Papenfuss is very slow,especially during the stage of the discs develop into uprights.Individual disc merged upright was cultivated for approximately 90 days.The coalesced discs of Gracilaria vermiculophylla(Ohmi)Papenfuss germinated 120 days after initial cultivation.Three erect fronds grew from the coalesced disc,although their growth rates differed.The longest frond was approximately 955.56 μm in length,whereas the others were approximately 322.23μm and 688.89μm,respectively.It is well known that auxin is important in regulation plant growth.To explore whether the auxins IAA promoted the uprights growth or not,we design different concentration gradients of IAA to cultivate the uprights of Gracilaria vermiculophylla(Ohmi)Papenfuss under laboratory conditions.It is showed that low concentrations of IAA(the auxins IAA concentratio1 is 10-6M)had a significant role on the growth of uprights of Gracilaria vermiculophylla(Ohmi)Papenfuss.To further explore the auxins IAA really plays a role in the early development of Gracilaria vermiculophylla(Ohmi)Papenfuss,we also designed two other auxins IAA experiment.First of all,auxins IAA is detected by high performance liquid chromatography method in Gracilaria vermiculophylla(Ohmi)Papenfuss.The results show that the content of IAA were low(a few nanograms per gram fresh weigh).Secondly,it is found auxins IAA is only present in the epidermal cells of Gracilaria vermiculophylla(Ohmi)Papenfuss through the immunohistochemistry technology and medulla cells do not contain IAA.It helps to cultivate Gracilaria vermiculophylla(Ohmi)Papenfuss by taking advantage of sexual reproduction through study the early development of Gracilaria vermiculophylla(Ohmi)Papenfuss.To obtain high quantities seeds by adding IAA in the early development has a very important role on large-scale artificial breeding Gracilaria vermiculophylla(Ohmi)Papenfuss,and combined with chlorophyll fluorescence technique in the early development of Gracilaria vermiculophylla(Ohmi)Papenfuss,proteomics technology on study on the function of different tissues of Gracilaria vermiculophylla(Ohmi)Papenfuss.