The Mechanism Of The Endosperm Weight Enhancement Of The Normal Oil Corn Pollinated By High Oil Corn

A method of producing high oil corn (HOC), the TEU system (three effect utilization system) has been developed in China rencently,which involves a blend of a cytoplasmic male-sterile version of an elite single cross normal oil corn (NOC)hybrid (account for above 90%) and a male fertile version of HOC pollinator (-8 %).The oil content of NOC will increase because of xenia, and the grain yield maybe increased because of heterosis, which can minimize the yield disadvantage associated with HOC hybrids. This HOC production system has been licensed by DuPont Specialty Grains, which has been regarded as the preferred method of producing HOC in the United States. Three NOC hybrids, ND108, LY20,SCF03-62, and three HOC hybrids, HOC202, HOC115, HOC4515 have been selected for planting in the field. The NOC hybrids were pollinated by HOC hybrids respectively at anthesis stage and NOC hybrids were self-pollinated as the control. Yields, oil content, characters of grain filling, endosperm cell proliferation and the programmed cell death were determined. The relationship among them was studied and the theory basis of TEU system was provided The main results and conclusions are as follows:1. The yield change of normal corn pollinatated by high oil cornFor the grain yields of NOC in F0 generation two of the nine combinations were higher than those of NOC self pollination treatments and one combination (ND108 HOC115) had significant difference compared with NOC self pollination treatments.Among the yield reduction combinations six combinations (ND108×HOC4515, LY20×HOC115, LY20×HOC202, LY20×HOC4515, SCF03-62×HOC115, and SCF03-62×HOC4515) were significant different with NOC self pollination treatments. The yield of the increasing combination (ND108 HOC115) increased by 12.81% compared with ND108 self pollination. While the yield of reduction combination (LY20 HOC115) decreased by 18.10% compared with LY20 self pollination. The differences were significant.In this experiment the plant which grow uniformly were selected to carry on the amply pollination so that the impact of ear rows and grain rumber per spike on grain weight could be effectively avoided.The experiment shows that the change of grain weight is the main reason of the yield change. The grain weight of increasing combination (ND108 HOC115) was higher than ND108 and the grain weight of reduction combination (LY20 HOC115) was lower than LY20. Their differences were significant. So the change of weight mainly contributed to the yield changes.The xenia includes embryo xenia and endosperm xenia. The experiment shows that among the yield increasing combination of ND108×HOC115, the endosperm contribution ratio of the grain weight increasing was 70.51% and among the yield reduction combination of LY20×HOC115 the endosperm contribution ratio of the grain weight decreasing was -85.46%. So the primary reason for change of grain weight was the increasing or decreasing of the endosperm weight.2. The kernel quality change of normal corn pollinatated by high oil cornCompared with NOC self pollination, the kernel quality of the combinations improved. Starch content, protein content and oil content of NOC kernels significantly increased when pollinated by high oil corn. The mean oil content of combinations increased by 35.41 % and the maximum oil content was 50.41% compared with NOC self pollination. The dry weight and volume of embryo in the crossed-pollination treatments increased compared with NOC self pollination treatments. This might be the main reason for the oil content enchancement in the combination treatments.3. The kernel endosperm cells change of normal oil corn pollinated by high oil cornThe Ro,Gmax,Wmax and Gaverage of the endosperm cell proliferation of the yield increasing combination (ND108×HOC115) were higher than the self pollination of ND108 and D was shorter. The Ro,Gmax,Wmax and Gaverage of the endosperm cell proliferation the yield reduction combination (LY20×HOC115) were lower than the self pollination of LY20 and D was longer. It showed the opposite trend compared with the yield increasing combination.The endosperm cells of increasing combination (ND108 HOC115) increased compared with self pollination (ND108). Against to it, the endosperm cells of reduction combination (LY20 HOC115) decreased compared with LY20. The results showed that the increasing number of endosperm cell was the main reason for weight increase. The endosperm cell number of ND108 HOC115 increased by 26.65% compared with ND108, while the weight of the single cell of ND108 HOC115 was lower than that of ND108. The endosperm cell number of LY20 HOC115 decreased by 20.96% compared with LY20 while the weight of single cell of LY20 HOC115 was higher than LY20. So increasing the number of endosperm cell and improving endosperm weight were a viable way to further improve the grain weight of the normal corn pollinated by high oil corn pollen.4. The change of grain filling rate of normal corn after being pollinated by high oil cornThe Ro,Gmax,Wmax and Gaverage of the grain filling parmeter of the yield increasing combination (ND108×HOC115) were higher than the self pollination of ND108 and D was shorter. The Ro,Gmax,Wmax and Gaverage of the grain filling parmeter of the yield reduction combination (LY20×HOC115) were lower than the self pollination of LY20 and D was longer. It showed the opposite trend compared with the yield increasing combination.Before 14 DAF the grain filling rate of the yield increasing group(ND108×HOC115) was lower than the combination of self pollination after being pollinated by high oil corn compared with normal corn. While the rate was higher after DAF and the maximal filling rate was 15.68% higher than the combination of self pollination. In the grain filling period the grain filling rate of the yield reduction combination of LY20×HOC115 was almost lower than the combination of self pollination and the maximal grain filling rate was 17.04% lower than self pollination combination. Therefore, the impact of high oil corn pollen on graining filling was another reason of the grain weight change.5. The relationship between grain weight and programmed cell death (PCD) of the normal corn pollinated by high oil cornCompared with normal corn self pollination the grain weight of hybrid vigor group (ND108×HOC115) was higher. While the apoptosis process of the endosperm cell was faster than ND108 self pollination. Apoptotic bodies of the hybrid vigor combination (ND108×HOC115) appeared and some apoptosis totally in the 20 DAF. The cell nucleolus disappeared and only the remnant of the cell nucleolus remained. At 20 DAF ,ND108 self pollination have noe been found Apoptotic bodies. It was probably because that hybrid vigor group had higher filling rate.6. The changes of the grain endogenous hormones content of the normal corn after being pollinated by high oil cornThe IAA , CTK contents in the grain filling period and the ABA content in the starting grain filling period of the yield increasing combination (ND108×HOC115) were higher compared with normal corn self pollination. While the IAA , CTK contents in the grain filling period and the ABA content in the starting grain filling period of the yield reduction combination (LY20×HOC115) were lower.The higher CTK content of grain filling period promotes the endosperm proliferation and the higher IAA conten of grain filling period and ABA content in the starting grain filling period improved grain filiing. So they improved the grain weight.