青杨脊虎天牛的危害与杨树氨基酸组成和含量的相关性

Association between the damage of Xylotrechus rusticus (Coleoptera: Cerambycidae) and the compositions and contents of amino acids in different poplar strains

为了研究不同品种杨树上青杨脊虎天牛XylotrechusrusticusL.的危害与树木氨基酸组成和含量之间的相关性,利用HPLC柱前AccQ·Tag衍生法,分析35a小青杨、24a小青×黑杨、24a小黑杨、16a香杨、27a和40a小叶杨的韧皮部和木质部中氨基酸的组成及相对含量。在各杨树品系主干2.5m高处,韧皮部共检测出15种氨基酸:丙氨酸、精氨酸、天冬氨酸、半胱氨酸、胱氨酸、谷氨酸、甘氨酸、异亮氨酸、亮氨酸、赖氨酸、苯丙氨酸、脯氨酸、丝氨酸、苏氨酸和组氨酸;木质部氨基酸种类与韧皮部的相近,区别在于木质部缺少组氨酸,多了缬氨酸。各杨树品系韧皮部同种氨基酸的相对含量差异显著,但与青杨脊虎天牛危害株率无紧密相关性;木质部中同种氨基酸相对含量差异显著,且与青杨脊虎天牛危害株率呈显著正相关。结果提示杨树木质部氨基酸相对含量越高,越利于天牛幼虫的生长发育。小青杨中氨基酸种类齐全、含量均衡,其株被害率高达84%;小黑杨木质部氨基酸种类和相对含量都较贫乏,香杨的氨基酸种类不全,且相对含量不均衡,二者均不受青杨脊虎天牛危害。不同部位株被害率的差异与氨基酸的相对含量无关,可能与青杨脊虎天牛只在老树皮裂缝处产卵的习性有关。

The amino acid compositions and relative contents of phloem and xylem in different poplar Strains, including 35-yr-old Populus pseud-simonii, 24-yr-old P. pseudo-simonii ×P. nigra, 24-yr-old P. simonii × P. nigra, 16-yr-old P. koreana, 27-yr-old P. simonii and 40-yr-old P. simonii, were detected by high performance liquid chromatography method with AccQ＇Tag precolumn derivatization. The relationship between amino acid and the damage of Xylotrechus rusticus to poplars was also evaluated. The results showed that fifteen amino acids including Ala, Arg, Asp, Cys, Cyss, Glu, Gly, Ile, Leu, Lys, Phe, Pro, Ser, Thr and His were detected in the phloem at 2.5 m height of stem of tested poplar strains; the kinds of amino acids in the xylem were similar to that in the phloem, except that Val instead of His was present in the xylem. In the phloem, the relative contents of the same amino acids in different poplar strains were remarkably different, but there was no significant correlation between amino acid relative contents and the ratio of damaged trees. In xylem, the relative contents of the same amino acids in different poplar strains were also remarkably different, but there was significant positive correlation between amino acid relative contents and the ratio of damaged trees. The results suggested that the higher the amino acid relative contents in xylem, the better for the growth and development of Xylotrechus rusticus larvae. In P. with their contents in rather balanced level in the pseud-simonii, the 15 kinds of amino acids were all present xylem, and the rate of damaged trees was as high as 84 % In P. simonii ×P. nigra, only 4 kinds of amino acids were present with their contents in relatively lower level, and in P. koreana, 13 kinds of amino acids were present with their relative contents not balanced; the both strains showed high resistance to Xylotrechus rusticus. The rate of damaged trees showed no correlation with the relative contents of amino acids in different heights of trees examined, and this may be related to the oviposition habit of Xylotrechus rusticus L , which only lays eggs in cracks of old bark.