二化螟寄主种群分化及其交配节律差异产生的内源机制

发布时间：2018-10-17 18:23

【摘要】：同域物种形成是物种形成的基本方式之一,同域物种形成过程中的生殖隔离机制一直是进化生物学领域的研究热点。二化螟Chilo suppressalis严重危害水稻和茭白等禾本科植物,有学者认为二化螟已经分化为水稻和茭白寄主种群,处于同域物种形成的早期阶段。交配节律差异可能是导致二化螟寄主种群间交配前生殖隔离的重要因素之一。然而,目前仍然缺乏证据证实交配节律差异在二化螟水稻和茭白种群间生殖隔离中的作用,不清楚种群间交配节律差异产生的内源机制。本研究以二化螟水稻和茭白种群为材料,研究了寄主植物对二化螟寄主种群生物学特征及交配节律的影响,验证了二化螟水稻和茭白种群交配节律的遗传模式,明确了二化螟水稻和茭白种群交配节律差异在种群间生殖隔离中的作用,探索了二化螟水稻和茭白种群交配节律差异的内源机制。主要结果及结论如下:1.寄主植物对二化螟寄主种群生物学特征及交配节律的影响通过转换寄主实验研究了寄主植物对二化螟幼虫存活率、幼虫发育历期、3日龄蛹重、成虫前翅长、交配节律等表型的影响。结果显示,寄主植物显著影响二化螟水稻和茭白种群的幼虫存活率、幼虫发育历期、3日龄蛹重、成虫前翅长等生物学指标,但不影响二化螟成虫的交配节律。研究结果证实二化螟已经分化为水稻和茭白寄主种群,水稻和茭白种群特有交配节律是长期适应进化形成的可稳定遗传的表型。2.二化螟水稻和茭白种群交配节律的遗传模式通过二化螟水稻和茭白种群的种群间杂交、杂交代与亲本种群的回交实验,验证了二化螟交配节律的遗传模式,分析了两种群控制交配节律的等位基因的显隐性关系。结果显示,二化螟水稻和茭白种群正交及反交获得的F1代与水稻种群进行回交时,交配节律与两亲本种群交配节律的存在显著差异;与茭白种群进行回交时,交配节律与茭白种群的交配节律一致。F1代的母本及父本的种群来源均显著影响F1代成虫的交配节律。研究结果支持二化螟交配节律受到常染色体上的多基因控制,表明茭白种群控制交配节律的常染色体上的等位基因对水稻种群的等位基因具有显性作用。3.二化螟水稻和茭白种群交配节律差异在种群间生殖隔离中的作用在不同光周期条件下,进行种群间的成虫交配选择实验,研究了交配节律差异在种群间生殖隔离中的作用。结果显示,两种群交配节律存在差异时,二化螟水稻和茭白种群间无选择实验、雌虫选择实验、雄虫选择实验及多选择实验中,种群间的隔离指数IPSI均显著大于随机交配条件下隔离指数值(IPSI=0);交配高峰时,不同交配选择实验中,种群间的隔离指数IPSI分别为与随机交配条件下隔离指数值(IPSI=0)相比均无显著差异,即种群间的生殖隔离水平降低,种群间接近随机交配。研究结果明确了二化螟水稻和茭白种群成虫交配节律差异是导致种群间部分生殖隔离的重要因素。4.二化螟水稻和茭白种群交配节律差异产生的内源机制研究通过观察二化螟雌虫的求偶行为,检测了雌虫求偶时性腺中的性信息素滴度及性信息素生物合成基因表达量,分析了种群间交配节律产生的内源机制。结果显示,二化螟水稻和茭白种群雌虫性信息素组分Z11-16Ald滴度及暗期变化节律存在明显差异,而Z9-16Ald及Z13-18Ald的含量很低,暗期没有明显的滴度变化节律。基于二化螟两种群雌虫性腺转录组测序结果,鉴定了可能参与性信息素合成的基因,包括2个脂酶(Lipase1、Lipase2)、2个脂肪酸转运蛋白(FATP1、FATP2)、2个去饱和酶(DES1、DES7)、1个乙酰辅酶A脱氢酶(ACD1)、3个长链脂肪酸延长酶(ELO1、ELO6、ELO7)、2个醛酮还原酶(ALR1、ALR2)。两种群雌虫性腺中上述基因的表达量存在显著差异。qRT-PCR验证了Lipase2、FATP2、ACD1、ELO1在性腺中的表达,结果显示,水稻种群这4个基因的表达量均比茭白种群高。研究结果表明二化螟水稻和茭白种群雌虫性信息素滴度变化节律及性信息素合成相关基因表达节律均存在差异,暗示了种群间交配节律差异的内源生理及分子机制。本研究表明,二化螟已经分化为水稻和茭白寄主种群,两种群成虫特有交配节律是长期适应不同寄主植物后形成的可稳定遗传表型,两种群控制交配节律的遗传因子存在差异,种群间交配节律差异是导致种群间生殖隔离的重要因子,种群间雌虫的性信息素生物合成节律差异是种群间交配节律差异产生的内源机制。研究结果不仅为深入研究二化螟水稻和茭白种群交配节律差异产生的分子调控机制提供了数据平台,也为揭示同域物种形成过程中交配前生殖隔离机制提供了新证据,还为应用灯光诱杀及性信息素诱捕技术综合防治二化螟提供了科学依据。
[Abstract]:The formation of the same domain species is one of the basic forms of species formation, and the isolation mechanism in the process of formation of the same domain species has been a hot topic in the field of evolutionary biology. In the early stage of the formation of the same domain species, the dicotyledonous plants have been divided into rice and white-white host populations. The difference of mating rhythm may be one of the important factors leading to the isolation between the two host populations before mating. However, there is still a lack of evidence to demonstrate the role of mating rhythm differences in the isolation between two species of rice and white-white populations, and there is no clear understanding of the endogenous mechanism of the difference in mating rhythm among populations. The effects of plant species on the biological characteristics and mating rhythm of the host population were studied. The genetic patterns of the mating rhythm of the two species of rice and dicotyledonous species were verified. In this paper, the difference of mating rhythm between two species of rice and the white-white population is defined, and the endogenous mechanism of the difference of mating rhythm between the two species of rice and the white-white population is explored. The main results and conclusions are as follows: 1. The effects of dicotyledonous plants on the biological characteristics and mating rhythm of two species of host population were studied by means of transformation host experiment. The effects of dicotyledonous plants on the survival rate, larval development calendar period, 3rd day pupal weight, adult prefin length, mating rhythm, etc. were studied. The results showed that the larval survival rate, larval development calendar period, 3rd day pupal weight, adult prefin length and other biological indexes were significantly affected by dicotyledonous plants, but it did not affect the mating rhythm of adult imago. The results of the study confirmed that the unique mating rhythm of two species of rice and white-white host population, rice and white-white population was a stable genetic phenotype of long-term adaptation to evolution. The genetic model of the mating rhythm of the two-year-old rice and the two-year-old white population was tested by the backcross experiment between the two hybrid rice and the wild-white population, and the genetic pattern of the mating rhythm of the two-year-old rice was verified. The recessive relationship between the alleles of two groups of control mating rhythm was analyzed. The results showed that the mating rhythm and the mating rhythm of the two parent populations were significantly different when the F1 generation and the rice population obtained by orthogonal and anti-crossing were crossed with the rice population, and the mating rhythm was consistent with the mating rhythm of the wild white population in the backcross between the two parents. The population source of F1 generation female parent and male parent significantly affected the mating rhythm of F1 generation adult. The results of the study show that the mating rhythm is controlled by multiple genes on the normal chromosome, indicating that the allele of the normal chromosome in the control of mating rhythm has a dominant effect on the allele of the rice population. The difference of mating rhythm among the two species of rice and the white population in the interpopulation was studied under different conditions under different conditions, and the effect of the difference of mating rhythm among populations was studied. The results showed that there was no difference in the mating rhythm of the two populations, there was no choice experiment between the two populations, the selection of female insects, the selection of males and the multi-selection experiment, the isolation index IPSI among the populations was significantly greater than the isolation index value (IPSI = 0) under the random mating conditions. During mating peak, the isolation index IPSI among populations showed no significant difference compared with the isolation index value (IPSI = 0) under the random mating condition. The results showed that the difference of mating rhythm between the two species of rice and the adult white population was an important factor contributing to the isolation of the interpopulations. The endogenous mechanism of the difference of mating rhythm of the two-year-old rice and the white-white population was studied by observing the courtship behavior of the female and female worm, detecting the sex pheromone droplet degree and the expression amount of the sex pheromone biosynthesis gene in the gonad of the female worm, The endogenous mechanism of interspecies mating rhythm was analyzed. The results showed that Z11-16Ald and Z13-18Ald had a very low content of Z9-16Ald and Z13-18Ald, while Z9-16Ald and Z13-18Ald had a very low content. Based on the sequencing results of the gonadal transcription group of the two groups of females, the genes which might be involved in the synthesis of the participatory pheromone were identified, including 2 lipases (caspase 1, caspase 2), 2 fatty acid transporter (CDP1, KPP2), 2 desaturation enzymes (DES1, DES7), 1 coenzyme A dehydrogenase (ACD1), 3 long-chain fatty acid elongases (ELO1, ELO6, ELO7), and 2 aldehyde ketoreductases (ALR1, ALR2). There was a significant difference in the expression of the above genes in the gonads of the two groups. qRT-PCR verified the expression of caspase-2, cyclin P2, ACD1 and ELO1 in gonad. The results showed that the expression of these four genes in rice populations was higher than that of the wild-white population. The results showed that there was a difference in the circadian rhythm and the expression rhythm of the sex pheromone in both the male and female populations, suggesting the endogenous physiological and molecular mechanism of the difference in the mating rhythm among the populations. The results showed that the mating rhythm of the two groups was a stable genetic phenotype after long-term adaptation to different plant species, and the two groups had different genetic factors to control the mating rhythm. The difference of mating rhythm among populations is an important factor which leads to the isolation between populations, and the difference of sex pheromone biosynthesis rhythm among populations is the endogenous mechanism of the difference of mating rhythm among populations. The results of the study provide a data platform not only for the further study of the molecular regulation mechanism of the difference of mating rhythm of the two-year-old rice and the white-white population, but also provides new evidence for revealing the pre-mating isolation mechanism during the formation of the same domain species. It also provides scientific basis for the application of light trapping and sex pheromone trapping technology.
【学位授予单位】：华中农业大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：S433.4

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