团头鲂(♀)×翘嘴鲌(♂)杂交三倍体的生长性能及形态分析

Growth Performance and Morphological Analysis of Triploids of Megalobrama amblycephala(♀)×Culter alburnus(♂)

鲂鲌(Megalobrama amblycephala♀×Culter alburnus♂)三倍体因性腺不发育或败育而将更多能量用于生长,因为不育可以保持F1代的杂种优势而避免继续繁殖造成的种质衰退,同时具备生态安全性,因此,鲂鲌三倍体具有优越的“生长优势”或“经济性状”。为了解鲂鲌三倍体的生长情况与形态特征,本研究运用静水压技术对团头鲂(♀)×翘嘴鲌(♂)杂交受精卵进行三倍体化诱导,获得了诱导成功的鲂鲌三倍体群体(hybrid-3n)与未诱导成功的鲂鲌二倍体群体(hybrid-2n),并构建团头鲂(MA)和翘嘴鲌(CA)2个自交群体,通过生长对比实验比较分析了4个群体鱼的生长性能及形态差异。结果显示,在210 d生长周期内,鲂鲌三倍体绝对增重率[(0.88±0.11)g/d]比二倍体提高8.64%,较MA提高20.55%,较CA提高120.00%。可数性状上,鲂鲌三倍体和二倍体杂种指数平均值分别为41.05和36.07,都略偏向于母本团头鲂。可量性状上,鲂鲌三倍体杂种指数平均值为36.73,略偏向于母本团头鲂;鲂鲌二倍体杂种指数平均值为57.57,略偏向于父本翘嘴鲌。聚类分析显示,鲂鲌三倍体首先和二倍体聚在一起归为一类,然后再与母本团头鲂聚为一支,最后再与父本翘嘴鲌聚在一起。判别分析显示,对鲂鲌三倍体的判别准确率为90%,对4个群体的综合判别率达95%。主成分分析共得到累计贡献率达75.10%的4个主成分,主要体现了鱼体高和躯干的形态变异。综合分析表明,鲂鲌三倍体具有较快的生长速度,具备在生产上推广应用的基础条件;鲂鲌三倍体与二倍体体型均介于双亲之间,都略偏向于母本,主要体现了鱼体高和躯干的形态变异。研究结果对鲂鲌杂交后代种群鉴定、倍性育种具有重要意义。

Megalobrama amblycephala,which belongs to the genus Megalobrama of the subfamily Culterinae in the family Cyprinidae,is an important freshwater cultured species in China because of its low culture cost and high growth rate.Culter alburnus,belonging to the subfamily Culter,is another slender carnivorous species,whose meat is more delicate and delicious than that of M.amblycephala;however,the scales of C.alburnus are small and thin and are easily injured and fall off,and these fish are slow-growing and expensive to feed.Although both the fish are quite different in terms of diet,growth,and stress resistance,they are highly complementary to each other.Crossbreeding can combine the desired characteristics of both parents;however,this advantage is usually limited to the F1 generation.Theoretically,because the gonads are almost undeveloped during triploid growth and development,F1 heterosis can be maintained to avoid germplasm decline caused by continuous reproduction,and energy can be saved to accelerate growth and improve muscle quality.This will greatly expand the breeding space of new hybrid varieties and ensure high economic,social,and ecological value.Therefore,the triploids of M.amblycephala♀×C.alburnus♂have superior growth and economic value.To understand the growth and morphological characteristics of the triploids of M.amblycephala♀×C.alburnus♂,the triploid population of M.amblycephala♀×C.alburnu♂was induced by hydrostatic pressure,and successfully induced triploid(hybrid-3n)and uninduced diploid(hybrid-2n)populations were obtained.At the same time,two self-breeding populations of Megalobrama(MA)and Culter(CA)were established.The growth performance and morphological characteristics of the four kinds of fish were compared and analyzed in growth contrast experiments.The results showed that during the 210-day growth cycle,the absolute weight gain(0.88±0.11 g/day)of hybrid-3n was 8.64%higher than that of hybrid-2n,20.55%higher than that of MA,and 120.00%higher than that of CA.In terms of countable traits,the hybrid index of hybrid-3n and hybrid-2n was 41.05 and 36.07,respectively.In terms of measurable traits,the hybrid index of hybrid-3n and hybrid-2n was 36.73 and 57.57,respectively.Cluster analysis showed that hybrid-3n was first grouped with hybrid-2n,then grouped with maternal MA,and finally grouped with paternal CA.The results showed that hybrid-3n and hybrid-2n were closer to their mothers in quantifiable traits and frame structure,showing a maternal effect.Discriminant analysis showed that the discriminant accuracy of hybrid-3n was 90%,and the comprehensive discriminant rate of the four populations was 95%.A scatterplot of the discriminant analysis showed that the distribution centers of hybrid-3n and hybrid-2n were located between the parents and closer to the mothers.Hybrid-3n and hybrid-2n occupied partially overlapping areas,which indicates that the two are similar in proportion and frame structure,making it difficult to distinguish between them.These results are basically consistent with those obtained by cluster analysis.Most of the 11 biological traits used to construct the discriminant function were related to the longitudinal axis of the body,especially the ratio of the height of the body to the trunk,which is similar to the results obtained by principal component analysis.During principal component analysis,four principal components with a cumulative contribution rate of 75.10%were obtained,which mainly reflect morphological variations of body height and trunk length.In this study,the experimental fish were cultured in still water ponds with abundant bait.The morphological differences may be attributed to the adaptation of the fish to this ecological environment.Comprehensive analysis showed that:Hybrid-3n has a fast growth rate and has the basic conditions for promotion and application in production;The body size of hybrid-3n and hybrid-2n is between the parents,and both are slightly biased towards the mother,which mainly reflect the morphological variations of body height and trunk length;In this study,three multivariate analyses were used to effectively reflect the morphological differences among the four populations of hybrid-3n,hybrid-2n,MA,and CA from different perspectives,which has made them irreplaceable.In conclusion,this study confirmed the superior breeding potential of triploids of M.amblycephala♀×C.alburnu♂,and provided basic data for the morphological comparison of hybrid offspring of M.amblycephala and C.alburnu,which is significant for the identification and protection of fish resources,and is expected to provide a theoretical basis for the establishment of new strains of M.amblycephala and C.alburnu.The results are of great significance for population identification and ploidy breeding of hybrid offspring of M.amblycephala and C.alburnu.