Investigation On Effect And Mechanism Of Chemical Hybridization Agents Inducing Male Sterility In Chinese Cabbage

Chinese cabbage,a cruciferous crop native to China,has a significant hybrid generation advantage.At present,the main way to produce hybrid seeds is to use self-incompatible lines for seed production.However,seed production of self-incompatible lines has many defects,such as increased cost of artificial pollination and weakened plant growth after multiple generations of self-incompatibility.Therefore,it is particularly important to screen out the chemical hybridization agents for C hinese cabbage seed production,find out the anti-chemical hybridization agents material of C hinese cabbage,use the resistant material as the male parent,and the sensitive material as the female parent for the hybrid generation.At present,there are no reports on the application of chemical hybridization agents in Chinese cabbage.In this experiment,four common herbicides were used for chemical emasculation screening test,followed by screening of suitable chemical pesticides for Chinese cabbage to screen germplasm resources.The enzyme activity of ALS,GSTs was determined for different resistant tribenuron-methyl materials,and the acetolactate synthase related gene was cloned and analyzed.The specific results are as follows:1.Screening out the chemical hybridization agents and their dosages suitable for male sterility in C hinese cabbage.The effects of seven Chinese cabbage materials on the different concentrations of four different chemical hybridization agents showed that tribenuron-methyl is a suitable chemical hybridization agents for Chinese cabbage,and the optimum spraying concentration is 0.075μg/m L,and the optimum dosage is 10 m L per plant,which will notcause damage to plants.2.Screening out Chinese cabbage materials with different sensitivity to tribenuron-methyl.According to the male sterility effect of tribenuron-methyl on Chinese cabbage,15 self-compatible C hinese cabbage were divided into two sensitive materials（male sterility rate≥95%,14S23 and 14S530）,seven semi-sensitive materials（30%～95%formale sterility rate,12S771,13S93,15S951,15S964,15S929,12S858,15S957）,two low-sensitivity materials（male sterility rate≤30%,15S1023 and 15S948）and four resistant materials（0%male sterility rate,92S24,14S291,14S463 and 14S176）.3.The mechanism of chemical hybridization agents of tribenuron-methyl was preliminarily studied.By measuring the ALS and GSTs activities of the selected cabbage materials with different tolerance to tribenuron-methyl,it was found that the ALS enzyme activity was inhibited to a certain extent,and the time of maximum inhibition of ALS was consistent with the time when the earliest sterility appeared in the material,indicating that tribenuron-methylcould inhibit the activity of ALS enzyme.The GSTs enzyme activity of different drug-resistant materials showed an increasing trend after spraying tribenuron-methyl.The maximum activity of GSTs was the time when tribenuron-methyl induced complete male sterility occurred.To some extent,these results indicate that the mechanism of chemical emasculation is related to the activity of ALS and GSTs enzymes.4.The relationship between the anti-tribenuron-methyl Chinese cabbage material and acetolactate synthase gene mutation was preliminarily investigated.The base 717 of Br ALS2 of the anti-tribenuron-methyl 14S176 was mutated from C to A,resulting in the amino acid at position P239 being changed from proline（P）to threonine（T）.This finding may indicate that the reason for the resistance of C hinese cabbage material 14S176 to tribenuron-methyl was a single base mutation in Br ALS2⁷¹⁷.