Molecular Cytogenetical Identification And Physiolog Drought Tolerance Of 6u Addition Line Of T. Aestivum-ae. Biuncialis

Drought is one of key agrometeorological disasters that restrict agriculture development in North China. Common wheat (Triticum aestivum L.), the biggest commissariat crop in the world and the second leading crop in China, has been strictly limited by water deficiency. Wheat breeding for drought tolerance is becoming increasingly important in this area and exotic drought resistant germplasm is urgently needed.Wild relatives of common wheat in Triticeae are of a great number of potentially valuable genes. Development of alien genetic germplasm from related species has been an important method for improving genetic basis of wheat. Aegilops biuncialis, for example, is an important source of alien genes because of its considerable tolerance to a series of biotic and abiotic stresses and widely used in wheat improvement.In order to introduce the potential drought resistance of Aegilops, cross was made between Chinese Spring and Aegilops biuncialis, and wheat-Ae.biuncialis hybrids obtained in 2004. Through backcrossing and selfishing, individual plant was selected on the basis of seed setting rate and drought tolerance. A set of wheat- Ae.biuncialis germplasm with high drought resistances were screened out according to their field performance.In this experiment, one wheat-Ae.biuncialis line, 131-1, was used to analysize the chromosome composition and identify its alien chromosome by the sequential C-banding–FISH. Artificial drought treatment by PEG-6000 was used to test its physiological and biochemical responses to drought stress. The results were as follows:1. Chromosome numbers of Wheat-Ae.biuncialis derivative 131-1 and its offsprings were 2n=43 in somatic cells. It is proved by sequential C-banding–FISH analysis that 6U chromosome was added to wheat genome.2. Under 15% PEG treatment, the superoxide dismutase (SOD) activity of wheat- Ae.biuncialis derivative 131-1 increased 6.4%, the peroxidase (POD) activity increased 6.3%; in contrast, the activities of the two enzymes of Chinese Spring were added 5.9% and 5% respectively. In photosynthesis facet, the decrease of transpiration rate and photosynthetic rate of wheat-Ae.biuncialis derivative 131-1 were 33% and 46%, stomatic degree reduce 12.5%, but Chinese Spring were 64%, 49% and 17.6% respectively. Changes of relative water content increased 6.3%; in contrast, the activities of the two enzymes of Chinese Spring were added 5.9% and 5% respectively. In photosynthesis facet, the decrease of transpiration rate and photosynthetic rate of wheat-Ae.biuncialis derivative 131-1 were 33% and 46%, stomatic degree reduce 12.5%, but Chinese Spring were 64%, 49% and 17.6% respectively. Changes of relative water content (RWC) of 131 and Chinese Spring were significantly different during PEG treatment. These results indicate that 131-1 has better drought tolerance than Chinese Spring.3. 131-1 offsprings were tested for their drought tolerance with Chinese Spring as control. According to the results of relative water content (RWC), peroxidase (POD) activity, superoxide dismutase (SOD) activity, and malondialdehyde (MDA) content, it is reasonable to postulate that the offsprings of wheat-Ae.biuncialis derivative 131-1 are of better drought resistance.These addition lines showed normal fertility, desirable agronomic traits and strong drought resistance.