Data from: Asymmetric adaptation to indolic- and aliphatic-glucosinolates in the B and Q sibling species of Bemisia tabaci (Hemiptera: Aleyrodidae)

The role glucosinolates play in defending plants against delicate phloem feeders such as aphids and whiteflies is currently not clear as these herbivores may avoid bringing glucosinolates from the phloem sap into contact with myrosinase enzymes. Here, we investigated the effects of high levels of aliphatic- and indolic-glucosinolates on life history traits and detoxification gene expression in two sibling species, B and Q, of the whitefly Bemisia tabaci. High levels of aliphatic-glucosinolates decreased the average oviposition rate of both species, and reduced the survival and developmental rate of Q nymphs. High levels of indolic-glucosinolates decreased the oviposition rate and survival of nymphal stages of the B species and the developmental rate of both species. Molecular analyses revealed two major asymmetries between the B and Q species. First, specific GST genes (BtGST1 and BtGST2) were significantly induced during exposure to indolic-glucosinolates only in Q. This may reflect the genes putative involvement in indolic-glucosinolates detoxification and explain the species' good performance on plants accumulating indolic-glucosinolates. Second, the constitutive expression of eight of the ten detoxification genes analyzed was higher in the Q species than in the B species. Interestingly, four of these genes were induced in B in response to high levels of glucosinolates. It seems, therefore, that the B and Q species differ in their "optimal defense strategy". B utilizes inducible defenses which are profitable if the probability of experiencing the stress is small and its severity is low, while Q invests significant resources in being always "ready" for a challenge.

硫代葡萄糖苷（glucosinolates）在植物抵御蚜虫、粉虱等脆弱韧皮部取食昆虫的防御过程中所扮演的角色目前尚未明确，原因在于这类植食性昆虫可避免将韧皮部汁液中的硫代葡萄糖苷与黑芥子酶（myrosinase）接触。本研究针对烟粉虱（Bemisia tabaci）的两个姊妹种B型与Q型，探究了高浓度脂肪族硫代葡萄糖苷与吲哚族硫代葡萄糖苷对其生活史特征及解毒基因表达的影响。高浓度脂肪族硫代葡萄糖苷会降低两个烟粉虱姊妹种的平均产卵率，并降低Q型若虫的存活率与发育速率。高浓度吲哚族硫代葡萄糖苷则会降低B型若虫的产卵率与存活率，并降低两个姊妹种的发育速率。分子分析揭示了B型与Q型烟粉虱之间存在两处显著的不对称差异：其一，仅在Q型烟粉虱中，特定谷胱甘肽S-转移酶（GST）基因（BtGST1与BtGST2）在暴露于吲哚族硫代葡萄糖苷时会被显著诱导表达。这一现象可能反映了这些基因参与吲哚族硫代葡萄糖苷的解毒过程，并可解释Q型烟粉虱在积累吲哚族硫代葡萄糖苷的植物上表现良好的原因；其二，在本次分析的10个解毒基因中，有8个在Q型烟粉虱中的组成型表达水平高于B型。值得注意的是，其中4个基因在B型烟粉虱中会因高浓度硫代葡萄糖苷的胁迫而被诱导表达。由此可见，B型与Q型烟粉虱的"optimal defense strategy"存在差异：B型采用诱导型防御策略，仅在遭遇胁迫概率较低且胁迫强度较小时具备优势；而Q型则投入大量资源，始终处于应对胁迫的"备战状态"。