Research On Larix Olgensis Families’ Variation Under Drought Stress

Larix olgensis Henry is one of the most important conifer species in China. It is a fast-growing timber species and shares the largest afforestation area in northeast China. The study take22L. olgensis control pollinated families of4-years-old as the materials and the experiment materials were divided into control group and drought stress treatment group, then studied on the growth, photosynthesis, physiology and drought stress-responsive protein expression, finally made a comprehensive evaluation of height, photosynthesis, transpiration, MDA, POD, soluble protein and chlorophyll. And the conifer of day-30and control were also used for research of differentially expressed proteins.The results showed that there were rich variations among the families and family’s variation was significant difference in height, photosynthesis and physiology indicator, it was helpful for the excellent family selection. Each family had a different performance under the drought stress for its self-protection mechanism is different.There were rich variations within the families, too. The most variation coefficient was the one of stomatal conductance and it was103.79%, the range of families were from28.72%to76.64%; the least variation coefficient was the one of chlorophyll and it was12.86%, the range of families were from4.8%to27.5%which was the smallest difference of families. The POD variation coefficient range of families was from40.3%to130.8which was the most difference among families. The variation coefficient range of family2×1was the most, it was from10.8%(height) to130.8%(POD).Among all families, family34×1’s growth was significantly higher than the control and other families; it was57.8%more than the slowest growth family2×2and18.5%more than the average. The height of family14×3,34×1,1×14,14×34was all more than the control during the whole drought period, the height average of these4families were17.5%more than the average of all families.3.7%more than the control.50.09%more than the one of4worst families. On day0. the height of the best family was132.06%more than the worst one,35.49%more than the control, while on day45. the height of best family was135.91%more than the worst one, only0.25%more than the control. It indicated that even the better families’ height was decrease under drought stress.Compared with the control, photosynthesis rate, stomatal conductance, transpiration rate, POD, chlorophyll were downward trend under drought stress while height increased slowly, MDA increased significant, soluble protein first increased and then decreased. The performance of families was different during the different drought period. Height, photosynthesis rate, stomatal conductance, POD was significant difference between families of different female or male parent; MDA, transpiration rate and soluble protein was significant difference between families of male parent, while chlorophyll was significant difference between families of female parent.Proteins were extraction from the control and drought stress samples,23differentially expressed proteins were found and18were indentified after analysis. According to biological function, these drought stress-responsive protein were classified into6groups:protein related to transduction, enzyme related to ATP synthesis, protein related to photosynthetic regulation, protein related to metabolism, enzyme to degradation hazardous substance, others.Height has no significant correlation with other index. Photosynthesis was positive correlation with height but no significant, significant positive correlation with POD and transpiration rate. MDA was significant positive correlation with soluble protein while negative correlation with other index, of which POD, photosynthesis rate and transpiration rate was significant.22L. olgensis families had different drought resistance capacity according to the membership function.34×2,2×land34×34are the best3families to drought stress,2×2,3×1and3×14were the worst3ones. Height was the most reliable index of all. The first one34×2was32.49%than the worst one2×2. and10.99%more than the average. Height had the most proportion (18.37%) among all index of membership function. so it was the most reliable indicator to identification of drought resistance.