Tropical Research and Education Center, University of Florida, 18905 S.W. 280th Street, Homestead, FL 33031, USA.
USDA, ARS, Subtropical Horticulture Research Station, 13601 Old Cutler Road, Miami, FL 33158, USA.
Tree Physiol. 2021 Jun 7;41(6):1004-1018. doi: 10.1093/treephys/tpaa137.
Laurel wilt, a lethal vascular wilt disease caused by the fungus Raffaelea lauricola, affects several tree species in the Lauraceae, including three Persea species. The susceptibility to laurel wilt of two forest tree species native to the southern USA, Persea borbonia and Persea palustris, [(Raf.) Sarg.] and avocado, Persea americana (Mill.) cv Waldin, was examined and related to tree physiology and xylem anatomy. Net CO2 assimilation (A), stomatal conductance (gs), leaf chlorophyll index (LCI), leaf chlorophyll fluorescence (Fv/Fm), xylem sap flow, theoretical stem hydraulic conductivity (Kh) and xylem vessel anatomy were assessed in trees of each species that were inoculated with R. lauricola and in control trees. Laurel wilt caused a reduction in A, gs, LCI, Fv/Fm and blockage of xylem vessels by tyloses formation that negatively impacted Kh and sap flow in all Persea species. However, disease susceptibility as indicated by canopy wilting and sapwood discoloration was less pronounced in P. americana cv Waldin than in the two forest species. Xylem vessel diameter was significantly smaller in P. borbonia and P. palustris than in P. americana cv Waldin. Differences in laurel wilt susceptibility among species appear to be influenced by physiological and anatomical tree responses.
Laurel 萎蔫病，一种由 Raffaelea lauricola 真菌引起的致命维管束萎蔫病，影响樟科的几种树种，包括三种鳄梨属树种。本研究检测了原产于美国南部的两种森林树种，薄壳山矾（ Persea borbonia ）和沼地山矾（ Persea palustris ） [(Raf.) Sarg.] 和鳄梨（ Persea americana （Mill.） cv Waldin ）对 Laurel 萎蔫病的敏感性，并与树木生理学和木质部解剖结构相关联。在接种了 Raffaelea lauricola 的和对照的每一种树木中，评估了净 CO2 同化（A）、气孔导度（gs）、叶片叶绿素指数（LCI）、叶片叶绿素荧光（Fv/Fm）、木质部液流、理论茎水力传导度（Kh）和木质部导管解剖结构。 Laurel 萎蔫病导致 A、gs、LCI、Fv/Fm 降低，木质部导管被木质素形成的胼胝质堵塞，从而降低 Kh 和液流，这对所有鳄梨属树种都有负面影响。然而，与两种森林树种相比，Waldin 鳄梨品种的树冠萎蔫和边材变色表明其对 Laurel 萎蔫病的敏感性较低。薄壳山矾和沼地山矾的木质部导管直径明显小于 Waldin 鳄梨品种。物种间 Laurel 萎蔫病易感性的差异似乎受到生理和解剖学树木响应的影响。
