【作者】 余昊；

【导师】 万方浩；

【作者基本信息】 中国农业科学院 ， 生物安全， 2009， 博士

【摘要】 超级害虫烟粉虱的全球广泛入侵,引起了人们对粉虱入侵机制的理论探讨。目前的研究发现,B型烟粉虱和土著烟粉虱之间存在的“非对称交配互作”,是B型烟粉虱广泛入侵并取代土著烟粉虱的一个重要行为机制; B型烟粉虱的寄主范围远比土著烟粉虱广泛也被认为是B型烟粉虱入侵及取代的机制之一;B型烟粉虱与植物的双生病毒互利共生加剧入侵。浙江1型(ZHJ1)等本地生物型,是本地长期存在的物种,但在B型、Q型烟粉虱入侵本地之前,并没有本地生物型烟粉虱严重危害和广泛分布的报道,在B型、Q型烟粉虱入侵之后,又发现本地型正被入侵生物型取代。那么,在没有B型、Q型入侵之间,为什么本地生物型并没有大量扩张危害?入侵型和本地型存在哪些差异?本文从温度胁迫适应性差异的生态学现象出发,研究了不同生物型烟粉虱(B型、Q型、ZHJ1型和ZHJ2型)和温室白粉虱的3种hsp基因表达和温度胁迫耐受性的关系,并采用RNAi技术分别验证了温室白粉虱和B型烟粉虱3种hsp基因的功能,探讨从hsp表达和功能的差异来解释粉虱入侵粉虱温度的生态适应性差异,从温度适应性方面来揭示粉虱生物入侵扩展能力的差异。温室白粉虱和B型烟粉虱的hsp表达存在差异,温室白粉虱hsp基因开始诱导表达的温度Ton和表达量最高时的温度Tmax分别比B型烟粉虱低2~6℃。这与温室白粉虱低温耐受性强于B型烟粉虱,而B型烟粉虱有脚温室白粉虱耐高温胁迫的生态学现象相一致。全球广泛入侵的烟粉虱B型和Q型烟粉虱较土著种ZHJ1型烟粉虱具有较强的高低温胁迫耐受性,B型和Q型烟粉虱从高温胁迫存活率显著下降的温度到低温胁迫存活率显著下降的温度区间显著宽于ZHJ1型烟粉虱。B型和Q烟粉虱3中hsp基因开始诱导表达的温度Ton和表达量最高时的温度Tmax分别比ZHJ1型烟粉虱高2~4℃。另一本地烟粉虱生物型ZHJ2型,它的高温胁迫耐受性和ZHJ1没有显著差异,它的高温胁迫耐受性和hsp诱导表达的Ton和Tmax都比入侵生物型B型和Q型低2℃左右。温室白粉虱和B型烟粉虱的3中hsp的诱导表达机制和功能存在很大差异。B型烟粉虱的hsp70和hsp20低温不被诱导,hsp90的诱导量也非常低。但温室白粉虱低温诱导下3中hsp都能极显著的诱导表达。两种粉虱hsp90基因在高低温胁迫耐受性的作用不显著,hsp70和hsp20在两种粉虱的高温胁迫耐受性和温室白粉虱低温胁迫耐受性中起到关键作用,hsp70和hsp20对B型烟粉虱低温耐受性作用不显著。本研究试图构建这样的一个生物入侵机制的理论:烟粉虱的高温耐受性与其体内hsp表达相关;hsp表达差异可能促使入侵生物型有很强的高温逆境适应能力;hsp的表达较低可能是限制本地生物型高温增长的重要原因,从而限制其种群数量的扩增与分布的扩展。更多还原

【Abstract】 Bemisia tabaci (Gennadius), called a“superbug”, has been reported to distribute over 90 countries in the world, the study of invasive mechanism has been aroused widely. Asymmetric mating interactions promote widespread invasion and displacement of indigenous B. tabaci population by the invasive biotype B. Mutualism between B. tabaci biotype B and begomoviruses via its host plants speed up widespread invasion. B. tabaci biotype B has a wide range of host plants make its invasion into new environmental location successful. Bemisia tabaci was found in China in 1949 and was not considered an important pest until the recent invasion of B. tabaci biotype B and biotype Q, which has been found in most provinces of China and become a severe pest of numerous field and ornamental crops. Why the indigenous B. tabaci biotype ZHJ1 and ZHJ2 were not widespread in China? What different between the invasive biotype and indigenous biotype?Temperature is an important factor that determines the distribution and expansion of a species. Our work to study the relation between hsp espression level and differential thermotolerent abilities in invasive biotype (biotype B and biotype Q) and indigenous biotype (biotype ZHJ1 and biotype ZHJ2), RNAi study proved that hsp play key roles for thermotolerence in whiteflies.The hsp expression profile results showed that temperatures for onset (Ton) or maximal (Tmax) induction of hsp expression in T. vaporariorum were generally 2~6℃lower than those in B. tabaci biotype B. These results suggest that the Ton (or Tmax) of hsps can represent the differences in temperature tolerance of these two whitefly species, and may be used to determine their natural geographical distribution and natural population seasonal dynamics. Our work found that B. tabaci biotype B and biotype Q were more heat and cold resistant than biotype ZHJ1, the hsp expression inductively Ton or Tmax in B. tabaci invasive biotype (biotype B and biotype Q) were generally 2~4℃higher than those in indigenous biotype ZHJ1. Another indigenous B. tabaci biotype ZHJ2, Its thermotolerent abilities has not different with biotype ZHJ1, the hsp expression inductively Ton or Tmax in indigenous biotype ZHJ2 were generally 2℃lower than those in B. tabaci invasive biotype (biotype B and biotype Q). hsp23, hsp70 and hsp90 mRNA levels were significantly decreased in both T. vaporariorum and B. tabaci biotype B after injection of dsRNA for 24h.RNAi study proved that hsp23 and hsp70 play key roles for thermotolerence in T. vaporariorum but not in B. tabaci biotype B cold tolerence, and hsp90 showed no significant roles for thermotolerence in both whiteflies species.Our work try to establish a theory of invasive mechanism in B. tabaci, the higher hsp expression Ton or Tmax promote the invasive biotype thermotolerence, conduces to B. tabaci biotype B and biotype Q have a strong ability to stress environment, accelerated the population broadly distributed and amount increased.更多还原