| Popis: |
This study aimed to investigate the effects of physical mutagenesis on the development and adaptive traits of early-stage shrimp larvae and to explore the feasibility of increasing genetic diversity and utilizing genetic variation in breeding populations through mutation technology. Atmospheric and room-temperature plasma (ARTP) mutagenesis technology was used to perform batch mutagenesis on fertilized eggs (gastrula stage) of four different families (A, B, C, and D) of Penaeus vannamei at the same power (360 W) and different times (2, 4, 8, and 12 min). Hatching rates, limb bud stage hatching deformity rates, survival rates, metamorphosis rates, and indicators of juvenile shrimp hypoxia tolerance and ammonia nitrogen stress were analyzed.The experimental results showed that all groups except for the 2 min mutation group showed hatching deformity rates significantly higher than those of the control group for the A and D families (P < 0.05). The deformity rate of each treatment group showed no significant differences from that of the control group in Family B. The malformation rate for Family C in the 8 min mutation treatment group was significantly higher than that in the control group. However, there was no significant difference between the 2 and 4 min treatment groups. In all four families, the hatching rate of fertilized eggs decreased with an increase in mutation time, and when the mutation time was greater than or equal to 4 min, the hatching rates of all four families were less than 15%. Compared with that of the control group, all treatment groups of the families except for the 2 min mutation group from Family A showed a significant decrease in hatching rate (P < 0.05). The hatching rate of the 2 min group for families A, B, C, and D was significantly higher than that of the 4, 8, and 12 min mutation groups, and the hatching rate of the 4 min mutation group from Family B was significantly higher than that of the 8 min mutation group (P < 0.05). The hatching and limb bud stage hatching deformity rates were moderately and highly correlated with mutagenic time, respectively.Compared with the control group, the survival rates of families A, B, C, and D in the same treatment group at the same stage showed no significant differences. The survival rate of the 8 min mutation group from Family A was significantly reduced (P < 0.05), that of the 4 and 8 min mutation groups from Family C was significantly increased, and that of the 2 and 4 min mutation groups from Family D was significantly reduced relative to the control value, whereas that of the 8 min group from Family D was significantly increased. Considering Family A as an example, metamorphosis rates in each stage were analyzed. The metamorphosis rates of the control group and the 2 min mutation group showed a significant decreasing trend during the three stages of larval development (P < 0.05); however, the metamorphosis rate in the M–P stage was significantly lower than that in the N–Z and Z–M stages. The metamorphosis rate in the Z–M stage of the 4 min and 12 min groups was significantly lower than that during the N–Z and M–P stages, whereas the metamorphosis rate during the N–Z stage of the 8 min group was significantly lower than that of the Z–M stage. After low-dose (0 and 2 min) mutagenesis of fertilized eggs of P. vannamei, the peak period of death mainly occurred in the late stage of larval development. The peak period of larval death after relatively high doses of mutagenesis (4, 8, and 12 min) mainly occurred in the middle or early stages of larval development. The peak period of death varied among different treatment groups. The results caused by radiation treatment showed directionality, and this trend of peak mortality was similar between all families.Hypoxia tolerance and ammonia-nitrogen stress testing in Family A of juvenile shrimp revealed that almost all shrimp in the 4, 8, and 12 min groups died after 5.5 h of hypoxia stress. In contrast, the control group died after 9 h of stress, and the 2 min group died after 10 h of stress. The results indicate that low doses of radiation (2 min) may improve hypoxia tolerance to some extent. The survival rates of the 2 min and 8 min groups were highest on the fourth and seventh days of the ammonia nitrogen stress experiment, respectively. Mutation had a certain impact on the ability of larvae in Family A to resist ammonia-nitrogen stress.The experimental results suggest that ARTP induced the mutation of fertilized P. vannamei eggs with non-directional changes in adaptive traits. These findings suggest the feasibility of novel methods for creating new germplasms and preparing functional research materials for P. vannamei and provide basic data and a scientific basis for the mutagenic breeding of P. vannamei. |
