Study On Morphological And Physiological-Biochemical Characteristics And Senescence Associated Gene In Miscanthus Lutarioriparius During Senescence

Miscanthus lutarioriparius is an endemic Miscanthus species in China which is planted on a large scale and adapted to the humid and flooded environment, and have the high yield, high fiber content, and the best quality of fiber.With the above-ground stem of M. lutarioriparius getting senescence every year, the carbohydrate and mineral substance in stem and leaf were transported to the under ground to improve the biomass quality and maintain the mineral nutrition for the growth of next years. The plantation is more than 2 million acres in south Dongting lake, and M.lutarioriparius were always harvested before mature, that lead to the growth degradation, yield decreased evry year.Therefore to study the molecular mechanism in leaf senescence, the senescence trait was observed in M.lutarioriparius, physiological and biochemical indexes during aging determined, and the senescence -associated gene researched.The results were as follows:(1)By measuring the senescence score of 57 M.lutarioriparius samples.56 samples reached the second senescence score in October 21st,19 materials reached the third senescence score in October 28th, but 37 M.lutarioriparius reached the third degree in November 5th.26 samples reached the forth score in November 12th,51 samples reached the fifth score in December 3rd with the leaves losing water and drying. B0129 and C0121 got senescent more early than others.The senescence speed were different among genotypes.(2)The chlorophyll content,the superoxide dismutase (SOD) activity and the malondialdehyde (MDA) content were measured in three different parts of 5 M. lutarioriparius.The results shows:the leaves chlorophyll content of M. lutarioriparius were decreased from booting stage to ripening stage, MDA content were increased from booting stage to ripening stage gradually, the activities of SOD activity were increased from booting stage to heading stage and showed a downward trend from heading to maturing stage. M.lutarioriparius senescence show no law in space, but the rates of senescence were different in the different genetype.(3) The total water content on stems of 5 M.lutarioriparius genotype were determined in 2 different years. B0129 and C0121 had the lowest moisture content in 2013 and 2014, the water content of B0129 were 46.6% and 45.8% respectively in 2013 and in2014,the water content of C0121 were 50.1% and 46.1% in 2013 and 2014. Moisture was correlated with genotypes.(4)The moisture were determined in the 5 upper nodes, the middle sections and the 3 basal nodes of stem from 10 different samples in different times.The moisture were decreased gradually over harvest times in the 5 upper nodes and the middle sections of M.lutarioriparius The moisture in the 3 basal nodes were stable in different harvest times. So the moisture of the stems show the significant difference among different parts and harvest times.(5)The correlation of the stem miostures and the stem diameters were analyzed in 10 M.lutarioriparius. The coefficient of correlation were R2=0.8519、0.676、0.4833、 0.7236、0.7467 respectively between the first basal node external, internal diameter, the forth basal node external diameter, innernal diameter, the fifth basal node,external diameter and the middle stem moistures.The coefficient of correlation were R2=0.8432.0.9619、0.912、0.9395、0.3481 respectively between the first basal node external, internal diameter, the forth basal node,external diameter, innernal diameter, the fifth basal node external diameter and the basal stem moistures.(6) A 1438bp gene was cloned, a complete open reading frame was detected and the 340AA sequence was got.