Research On Specific Traits Of A New Tea Variety "Dongbeikang"

Tea plant（Camellia sinensis（L.）O.Ktze.）is one of the major woody cash crops in China,and germplasm resources of tea is the basis of tea industry development.The exploration of germplasm specificity is the key procedure of germplasm innovation and also the indispensable work to meet the need of diversified breeding.Thus,identification,exploitation and utilization of germplasm resources have important significance for tea innovation.Based on previous character identification work,we selected a new strain named“Dongbeikang”,which has Strong growth potential and high-temperature resistance.In this paper,comparative studies on the growth of new shoot,photosynthesis index,the change of chlorophyll fluorescence parameters under high temperature between Dongbeikang and other varieties certified the specificity in growth and resistance of Dongbeikang from both physiology and biochemistry.Besides,from the perspective of molecular biology,Based on transcriptome data,2 CsSPLs transcription factors CsSPL6and CsSPL9 were cloned and 5 CsSPLs transcription factors—CsSPL6,CsSPL7,CsSPL9,CsSPL13a,CsSPL18 were identified.And the mechanism in the expression of Csn-miR156a and CsSPLs in different positions of leaves and different varieties with high-temperature stress was analyzed via the technology of q RT-PCR.Main results were as follows:1.The new strain“Dongbeikang”was selected from Qimen tea population.The tree is bush and semiappress type,the leave is middle class,long oval with green and luster color,the leaf blade is slightly upheavaled and inflexed,the leaf edge is undulated and serrated,the leaf tip is acuminate,tea shoot keep fertile and tenderness.The stream tea sample contains 19%tea polyphenols,4.4%amino acids,caffeine 3.3%,water extracts 51.5%.The manufactured tea have a fresh taste,lasting aroma,good quality.In addition,it has a Strong resistance to stress and good growth potential.2.To vertify whether Dongbeikang has a good growth potential or not,we compared new shoot growth and photosynthesis on Dongbeikang and some other different varieties（strains）.In the 3-year-old varieties（strains）like Dongbeikang,Fushezao,C.sinensis cv.Shidacha and C.sinensis cv.Texiangzao,Dongbeikang is more superior to others on new shoot growth and photosynthesis.Besides,in the 1-year-old cutting varieties（strains）like Dongbeikang,C.sinensis cv.Huangshanbaicha 1,C.sinensis cv.Shuchazao and C.sinensis cv.Texiangzao,Dongbeikang also shown good photosynthetic and productive capacity.3.Measurement on chlorophyll fluorescence parameters of different varieties of tea under high temperature stress indicated that after 4 days the values of Fv/Fm,Y（II）,q P,ETR and PI_ABS from 4 varieties gained a significant decline,but the value of NPQ increased first and then declined.Above all,the ranking of ability to tolerate high temperature stress from high to low was Dongbeikang,C.sinensis cv.Shuchazao,C.sinensis cv.Huangshanbaicha 1 and C.sinensis cv.Texiangzao.4.Csn-miR156a target genes CsSPL6 and CsSPL9 both were cloned in tea plants.CsSPL6 had a full-length of 2318 bp,which contained a full 1668-bp-long ORF（Gen Bank accession number:KX808499）encoding a protein consisted of 555 Amino acids.For CsSPL9,the full-length is 1954 bp,which contained a full 1116-bp-long ORF（Gen Bank accession number:KY569510）encoding a protein consisted of 371 Amino acids.5.Expression analysis indicated that,from different leaf positions in Dongbeikang,Csn-miR156a gained its the highest expression in buds,and the higher the position of leaf was the lower its expression was.Besides,the expression of Csn-miR156a had negative correlations with the regulation of CsSPL6 and CsSPL9 but had positive correlation with CsSPL7.The correlations between Csn-miR156a and CsSPL13a was not certified clearly,and so was it with CsSPL18.Results showed that Csn-miR156a participated in the growth and played a key role in the conversion from vegetative growth to reproductive growth.In the expression among different varieties（strains）,Csn-miR156a had the same expression trend with the growth of new shoots and the value of Photosynthesis index,furthermore,that trend had negative correlation with the regulation of CsSPLs,by which Csn-miR156a and CsSPLs was certified a molecular method to measure the growth of varieties.The expression of Csn-miR156a and CsSPLs showed significant different in 4 varieties（strains）underheat stress.Besides,the expression trends went separately with no correlation except the fact that CsSPL9 had negative correlation with Csn-miR156a.It may means that Csn-miR156a could regulate CsSPL9 to gain a better tolerance when tea plants were under high temperature,furthermore,complicated relationships of regulation between other members of CsSPLs could be shown.It can be seen that Csn-miR156a regulates different CsSPLs members in different situations to participate in tea plant growth and stress resistance.