Melo C G, Tomaz A C, Soares B O, Kuki K N, Peternelli L A, Barbosa M H Pereira
Department of Plant Sciences,Universidade Federal de Viçosa,Avenue pH Rolphs,s/n,Viçosa- MG,36570-000,Brazil.
Department of Statistics,Universidade Federal de Viçosa,Av. pH Rolphs,s/n,Viçosa- MG,36570-000,Brazil.
Bull Entomol Res. 2018 Aug;108(4):556-564. doi: 10.1017/S0007485317001110. Epub 2017 Nov 23.
The purpose of this study was to investigate and compare root morpho-anatomical traits and physiological responses of susceptible (SP81-3250) and resistant (H. Kawandang) sugarcane genotypes exposed to the attack by nymphs of spittlebug Mahanarva fimbriolata (Stål) (Hemiptera: Cercopidae). Two experiments were conducted to compare the damage caused by spittlebug nymphs on fresh and dry biomass weight; lignin content in stalks; root anatomy; chlorophyll content; photosynthetic rate (A); carboxylation efficiency (A/Ci); stomatal conductance (gS) and transpiration rate (E) of these genotypes. SP81-3250 consistently obtained significantly higher damage scores than H. Kawandang in both experiments, confirming the previously observed level of resistance in each genotype. Attack by spittlebug nymphs had a much higher effect on both fresh and dry biomass weight, chlorophyll content, A, A/Ci, gs and E of SP81-3250, than that on H. Kawandang. Anatomical studies indicated the presence of aerenchyma tissue in the root cortex of SP81-3250, a feature which may facilitate penetration of the nymph's stylet into the vascular cylinder. In contrast, roots of H. Kawandang are characterized by having more dense and compact parenchyma cells. In addition, infested plants of this genotype contained an unidentified mucilaginous compound in the vascular cylinder of the roots. We conclude that resistance of H. Kawandang to spittlebug is related to the ability of this genotype to maintain normal chlorophyll content, as well as stomatal conductance and photosynthesis, thus, allowing for biomass accumulation under spittlebug attack, in contrast to SP81-3250. In addition, the presence of more compact and denser parenchymal cells, as well as that of an induced mucilaginous compound in the root's vascular cylinder, are likely to hinder host-feeding activity in nymphs, causing higher nymph mortality and therefore, reduced damage in plants of this genotype.
本研究旨在调查和比较易感甘蔗品种（SP81 - 3250）和抗性甘蔗品种（H. Kawandang）在遭受吹沫虫若虫（Mahanarva fimbriolata (Stål)，半翅目：沫蝉科）攻击时的根系形态解剖特征和生理反应。进行了两项实验，以比较吹沫虫若虫对这些品种的鲜重和干重生物量、茎中木质素含量、根系解剖结构、叶绿素含量、光合速率（A）、羧化效率（A/Ci）、气孔导度（gS）和蒸腾速率（E）造成的损害。在两项实验中，SP81 - 3250的损害评分始终显著高于H. Kawandang，证实了之前观察到的每个品种的抗性水平。吹沫虫若虫的攻击对SP81 - 3250的鲜重和干重生物量、叶绿素含量、A、A/Ci、gS和E的影响，远高于对H. Kawandang的影响。解剖学研究表明，SP81 - 3250的根皮层中存在通气组织，这一特征可能便于若虫的口针穿透到维管束中。相比之下，H. Kawandang的根具有更致密紧实的薄壁细胞。此外，该品种受侵染植株的根维管束中含有一种未鉴定的黏液状化合物。我们得出结论，H. Kawandang对吹沫虫的抗性与其维持正常叶绿素含量、气孔导度和光合作用的能力有关，因此，与SP81 - 3250相比，在吹沫虫攻击下能够积累生物量。此外，更紧实致密的薄壁细胞的存在，以及根维管束中诱导产生的黏液状化合物，可能会阻碍若虫的取食活动，导致若虫死亡率更高，从而减少该品种植株的损害。
