Preliminary Investigation On Male Sterility Inducing Effect And Mechanism Of Several New Chemicals In Rapeseed

There exsits significant heterosis for Rapeseed. Chemical aided hybridization is becoming one of the most important ways to utilize heterosis in rapeseed. In this investigation, three kinds of sulfonamide compounds, found by Rapeseed Biotech-Breeding Group of Northwest A & F University were investigated for their male sterility-inducing ability, and effects on the main agronomical traits. Cytological changes of male organs, changes of physiological and biochemical characters, and changes of the target enzyme activity, acetolactate synthase(ALS) , were studied after treated with one of the three chamicals ,CHA1.The main results obtained are as follows:1. The effect of three new CHAs on male sterility-inducing ability in rapeseedThe result indicated that all the three CHAs have some effects on male sterility-inducing ability on rapeseed. When they were sprayed onto leaves of rapeseed plants twice,CHA1 and CHA2 can induce 100% sterile plant rate, and the sterilizing duration can last for more than 20 days. For the semi-winter varieties, the optimal concentration of CHA1 for inducing male sterility was 0.05-0.1μg/ml, however, for the winter varieties, 0.1-0.2μg/ml. In combination of the effects of agronomic traits, CHA1 and CHA2 were suggested as chemical hybridizing agent for rapeseed, moreover, CHA1 is better than CHA2.The effect of CHA1 on inducing male sterility ability depends on the types of different rapeseed varieties. According to the changes of full sterile plant rate, the 50 tested cultivars can be divided into three categories (sensitive cultivars, semi-sensitive cultivars, and none sensitive cultivars). Full sterile plants rate of sensitive cultivars was over 95 percent, the sterile period lasted for more than 15 days, plant height reduced significantly. Full sterile plant rate of none sensitive cultivars was below 30 percent, the sterile period lasted for less than 15 days, plant height reduced significantly. Semi-sensitive cultivar, the plants were induced to semi-sterile plants, the sterile period lasted for about 15 days, have some effect on plant height and yield. Among the four main agromical traits investigated, plant height and siliques per plant showed negative relationship with the rate of male sterile plant, seed number per silique and seed number per plant showed positive relationship with the rate of male sterile plant, however, these four correlation efficiencies with the rate of male sterile plant did not reach signicant level.2. Cytological study on male sterility in rapeseed induced by CHA1Cytology results revealed that CHA1 has effect on rapeseed anther development in each period. CHA1 treatment made pollen mother cell gap increased, cytoplasm vacuolated, the contents of pollen mother cell degraded, nucleus shrunk and gradually disintegrated; made tapetal cells arranged loosely, the contents of tapetal cells decreased, shrunk, adhesive and partially necrosed. The abnormal development of the tapetum is likely to be the main reason that CHA1 can induce male sterility in rapeseed.3. The impact of CHA1 on the change of active oxygen metabolism of leaves and bud in rapeseedCHA1 have impact on the activity of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT), and on the content of MDA: after the treatment of CHA1, the activity of SOD, POD and CAT all increased, and the content of MDA reduced in leaves of sensitive cultivar 638 and not sensitive cultivar 82089; in buds of sensitive cultivar 638 and not sensitive cultivar 82089, the activity of SOD increased, the activity of POD and CAT decreased, and the content of MDA increased, and the change of sensitive cultivar 638 is larger than not sensitive cultivar 82089. The decrease of activity of POD and CAT made the process of free radical scavenging blocked, and membrane lipid peroxidation, so lead to male sterility in rapeseed.4. The impact of CHA1 on the activity of ALS of different rapeseed cultivarsThe experimental results revealed that after the treatment of CHA1, the activity of ALS of 50 rapeseed cultivars were all suppressed, but the degrees of be suppressed differed in different rapeseed cultivars, The sensitive cultivar was higher than the none sensitive cultivars. But, the degree of activity change of ALS was not large in different rapeseed cultivars, decrease degree of activity of ALS is small in both sensitive cultivar and none sensitive cultivars. Correlation analysis showed that, the persentage of sterile plant was negatively correlated with ALS activity, and the difference was not significant.