Study On Different Traits And Related Mechanism Of Different Ploidy Rice

In china, the planting area of rice take up about 30% of the total arable land. In the progress of species and the formation of new species, genome polyploidization play an important role that can enhance adaptability to the stress and increase the yield especially in rice. The dose effect induced by chromosome doubling in rice can advance the yielding, quality and the ability to adapt the environment. Therefore, the comparative study was conducted. This dissertation mainly research the feature of different traits in the different ploidy rice, which can provide theoretical guidance for the better utilization of autotetraploid rice.In this paper, 5 types of Autotetraploid Rice and the corresponding diploid rice were selectted as the study object. After the harvest, 7 kinds of grain traits was studied, including chalkiness, gel consistency, alkali spreading value, gelatinization temperature, the content of soluble protein and amylose. At the same time, the difference of seed setting rate was analysed. Besides this, the development of tetraploid rice pollen and dynamic growth pollen tube was observed and studied by laser scanning confocal microscopy. Meanwhile, pollen diameter and normal development of pollen was measured for the probability statistics. In the end, tetraploid rice salt tolerance mechanism were researched through the physiology study, including the accumulation of endogenous substance such as lipid membrane peroxidation products(MDA), and the condition of antioxidant enzyme activity such as superoxide dismutase(SOD), catalase(CAT) and peroxidase(POD). The results of the study are as follows:1, Compared the grain traits of tetraploid rice with that of corresponding diploid rice, most of the 5 types reached significant difference level. The plant stem thickness of autotetraploid rice is increased than that of diploid in the most cases. Tetraploid single grain weight is higher, the highest is Guyana630(4), up to 0.57 g. for the gel consistency, the variety of red rice basically reached a Gel Consistency level, which belong to the favourite level of consumers. In the gelatinization temperature, Autotetraploid Rice reached the level of middle that is accepted by consumers. In the aspect of soluble protein, amylose and protein, the content were increased in the tetraploid rice. But the shortage is that the chalkiness is larger. In the research of the rate of seed setting, although the tetraploid rice is lower than its corresponding diploid varieties, there is still a higher seed setting rate in some varieties. In short, although different tetraploid varieties exist differences, some of these varieties can increase the yield and quality of rice by the dose effect of doubling, which lays a foundation for the use of potential value.2, After the four points body, the process of pollen development is divided into seven stages. The pollen diameter statistics research found that tetraploid rice was higher than that of its corresponding diploid rice, and most of them reached extremely significant level, the largest increasing is purple rice(4) 62.426μm. The increase of pollen has a certain relation with the doubled chromosome of tetraploid rice. Pollen development is consistent with diploid, but there are many abnormal development phenomenon. the probability of tetraploid rice normal growth is obviously lower than the corresponding diploid rice, among which purple rice(4) was the lowest 57.40%. It is worth to be mentioned that double germination aperture is found in tetraploid rice. The phenomenon of abnormal development of pollen in autotetraploid rice include some cytoplasm disappeared, cell cytoplasm folds, cytoplasmic aggregation, the formed of cavity in cell etc. In the research of pollen development, the process of autotetraploid rice is consistent with the diploid but the growth rate of autotetraploid rice pollen tube is slightly lower than the corresponding diploid. At the same time, the study found when the pollen grain with two germination hole fall on the stigma, there are two kinds of results. One situation is that some can only puts out one pollen tube; another result is two germination hole extend pollen tube at the same time, In addition to this, It is also found that some abnormal development of pollen grains can also further develop and put out the pollen tube.3, In the study of stress environment, the higher concentration of salt stress reduced the germination rate in the different ploidy rice seedlings, but tetraploid rice germination rate and germination potential will be higher than their corresponding varieties at different extent. For the study of proline content, we found that the content showed an upward trend and the increase was higher in tetraploid rice after treated. The content of soluble protein decreased significantly. But also the content of tetraploid rice is higher than that of the diploid rice after the treatment.4, After salt stress, the content of MDA were significantly increased in all the varieties of rice, but the increase of tetraploid rice is lower compared to the diploid rice. This demonstrated that the damage of membrane systemin the Tetraploid rice is less under salt stress, Under salt stress, three kinds of protective enzyme(CAT SOD, POD)activity in tetraploid rice was higher than that of diploid rice. This show that the active oxygen scavenging capacity in tetraploid rice is higher than that of diploid rice in the stress of salt. In a ward,this study found that autotetraploid rice showed better adaptability and antistress ability under the salt stress.This article investigated and studied the rice quality among different varieties and different ploidy rice and physiological changes in the salt stress. In addition,we use the laser scanning confocal microscopy to observe the dynamic process of pollen development and pollen tube growth. The results showed that the tetraploid rice quality showed advantages in most aspect, the abnormal pollen development may be the main reasons for low seed setting rate. At the end, the study of the salt tolerance mechanism can provide a theoretical basis for the application of tetraploid rice.