Analysis On Cold-Resistant Physiological Characteristics And Cloning Genes Of Winter Wheat Dongnongdongmai1

Winter wheat Dongnongdongmai1 is a sup-cold resistant variety which used different varieties hybridizing under the cold condition in the winter of Heilongjiang. Dongnongdongmai1 is the first and the only winter wheat which could pass the winter securely in Heilongjiang province, and now it was popularized in Heilongjiang province. Dongnongdongmai1 not only increased the exponent of refarming and the utilization of the land, realized the third times ripes in two years, but also solved the problem of continuous cropping of the bean. It has great significance to the increases in grain production of our country. We researched into the cold-resistance and the regulatory mechanism had practical value to solve the practical production problem and theory significance to enriching the plant cold-resistance theory and the practical production.We took samples under the condition of a nature drop in temperature in field, we studied the differences between Dongnongdongmai1 and Jimai22 from two aspacts by physiological characteristics and Sq RT-PCR, one was cold-resistance physiological characteristics, the other is the expression of cold-genes in different varieties and part. We explored the physiological and biochemical mechanism or the differences of different part. We provided the basis for scientific cultivating of new varieties for winter wheat and popularizing. The conclusions are as follows:(1)Analysis on physiological and biochemicalWith the dropping of temperature, Relative electrical conductivity rised slowly in Dongnongdongmai1 overwintering and its tillering node had the minimal damage.we calculated LT50(-20.67℃)with Logistic. First the content of MDA showed increasing, then constanting,the change of MDA content in tillering node was the least. First the Proline content of Dongnongdongmai1 increased at first and than declined, it presented better protective effect at the low-temperature. The soluble sugar and protein appeared a clear upward trend and accumulated the largest number of them in tillering node. Chlorophyll content in Dongnongdongmai1 was higher than Jimai22's, increased an first and than tended to be steady. The changes of CAT, POD, SOD,are about the same. They all appeared appeared a upward trend Especially from -15℃to -20℃, they were very hyperactive, and helped to resist low-temperature.In general, the winter hardiness of Dongnongdongmai1 was better than Jimai22's, its tillering node accumulated large numbers of substances during the overwintering time.(2)Analysis on cold-resistance genes by Sq RT-PCRWrab17and wcor80 expressed both in the leaves and roots of Dongnongdongmai1 and Jimai22. These two genes in the leaves accumulated gradually with the decrease of temperature. When the temperature dropped to -15℃, wrab17and wcor80 had the largest expression and its expression in Dongnongdongmai1 was apparently higher than Jimai22's. Wrab17and wcor80 in the roots both expressed and accumulated obviously in Jimai22 and Dongnongdongmai1 with the decrease of temperature. Especially when the temperature fallen to -30℃, these genes reached to the maximizing. We also could see that the expressions of wrab17 and wcor80 in Dongnongdongmai1 was higher than Jimai22. The mRNA of wrab17, wcor80 and wcor413-like accumulated in various degree in tillering node of these wheats. wrab17 in Dongnongdongmai1 increased gradually with dropping of temperature and the expression reached to the maximizing when the temperature fallen to -25℃～-30℃. But when the temperature dropped to -25℃, wrab17 had a transient expression and then disappeared.Wcor80 and wcor413-like only expressed in Dongnongdongmai1 and when the temperature dropped to -25℃, it had the largest accumulation, the expression was decreased when the temperature reached to -30℃.The expression are discrepant in different genes which in differet two wheats that had different winter hardiness. Wrab17, wcor80 and wcor413-like had both expressions in tillering node of Dongnongdongmai1, and wrab17 only appeared in tillering node of Jimai22. The leaves and roots of Dongnongdongmai1 and Jimai22 only had wrab17 and wcor80. These showed the same conclusion with physiological and biochemical indexes that a lot of cold-resistant substances were stored in tillering node of Dongnongdongmai1, it had the strongest cold-resistant ability and was the main organ through the winter.The full length of wrab17 was 928 bp, it generated five ribonucleotides mutant sites and led to the mutation of five amino acids. The full length of wcor80 was 999bp, caused six ribonucleotides mutant sites. The full length of wcor413-like was 931bp, it generated ten ribonucleotides mutant sites, mainly base transversion. May be the mutations of ribonucleotides related to that Dongnongdongmai1 was a new cold-resistant variety. We found that wrab17, wcor80, wcor413-like and the cold-resistant of wheats on Genebank had high homology by comparing, 99%, 98% and 96% respectively. These conclusions will support molecule base for the further research of Dongnongdongmai1.