Morphologic And Physiologic Characterizations Of An Ovule Abortion Mutant In Brassica Napus

Rapeseed is one of major oilseed crops in China, It is not only an important source of edible vegetable oil, but also an important bio-energy feedstock crop. Therefore, genetic improvement of rapeseed plays an important role in economic development and social stability of China. The components of rapeseed yields, number of siliques per plant, number of seeds per silique, and seed weight are mutually cooperative and restricted between each other. The ovule abortion seriously affects per pods of grains and leaded to significant economic losses in rapeseed. In this study, a mutant line of ovule developmental disorders from the DH population derived from’Express’(Winter B. napus from Germany) and ’SWU07’(semi-winter B. napus from China), named OVA047, was investigated for morphologic and physiologic characterizations. Meanwhile, the factors that might affect abortion of OVA047were analyzed, such as boron nutrition and the changes of temperature during development. The main results were as follows:1) The mutant possesses normal sexual organisms and high pollen fertility, the pollen dye ability rate of95.90%. Pollen tube could germinate and reach the ovary. The development of ovule was well7days and14days after pollination, while most of ovules stopped growth after20days after pollination in OVA047, especially at the top of inflorescence, where the seed-set was0.8seeds per pod35days after pollination, equal to4%of the control.2) The content of Boron in leaf increased with the content of foliar-applied boron treatment in both normal material and OVA047. No significant differences were detected between OVA047and control for the content of Boron in leaf in the same treatment of Boron fertilization. However, in the different treatments of Boron fertilization, all the OVA047still exhibited low seed-set (3.2seeds per pod) and around60%of ovule abortion ratio in the whole of inflorescence, and the control still exhibited normal seed-set (29seeds per pod).3) Two years field observation showed that large-scale ovule abortion of OVA047at the top, middle and basal of the inflorescence occurred at the period of significant temperature increase in Chongqing, the ovule abortion was increased with the daily temperature. A strong positive association was found between ovule abortive rate of OVA047and daily maximum temperature. The ovule abortion of OVA047does not possible relate with Boron fertilization, but associates with temperature.