蓝莓根毛缺失的机制及内生菌根真菌的促生作用

Mechanism of root hair deficiency and growth-promoting effect of endophytic mycorrhizal fungi in blueberry

为探究蓝莓根毛缺失机制,以‘布里吉塔’蓝莓根系为材料,对6个根毛发生关键基因进行分离鉴定;同时,为筛选蓝莓促生内生菌根真菌并研究其促生机制,从地栽‘夏普蓝’和‘奥尼尔’蓝莓根系中分离并纯化了12株蓝莓内生菌根真菌,并回接到‘海岸’蓝莓苗进行接种试验。结果表明:根毛发生负调控基因GL2、WER、TTG均有表达,而正调控基因TRY、CPC、ETC1未见表达,这可能是蓝莓根毛缺失的主要原因。分离得到的菌根真菌主要来自于镰刀菌属(Fusarium)、踝节菌属(Talaromyces)、赤霉属(Gibberella)、青霉属(Penicillium)和曲霉属(Aspergillus),其中:A1、A4、X2及X22真菌接种显著促进了蓝莓株高增长;同时,A1、A4和X22接种显著提高了蓝莓的根系活力;A4、X2和X22接种对根际的酸化效果显著。对根际栽培基质及叶片中磷素含量分析表明,A4、X22处理组叶片总磷含量显著提高,而根际栽培基质中速效磷含量并未见降低,推断A4、X22形成的菌根可促进磷元素有效化。此外,在X22分泌物中检测到维生素B2的存在,而维生素B2与植物生长及抗逆性有关,暗示维生素B2的分泌或是杜鹃花类菌根的另一促生机制。

In order to elucidate the mechanism of root hair deficiency in blueberry,six key genes involved in root hair development were isolated and identified using‘Brigitta’blueberry seedlings as materials;meanwhile,to screen probiotic endophytic mycorrhizal fungi and study their mechanism of promoting seedling growth,12 strains of endophytic mycorrhizal fungi were isolated and purified from the roots of mature blueberry bushes of‘Sharpblue’and‘O’Neal’.Then these isolated fungi were separately inoculated on‘Gulfcoast’blueberry seedlings.The results showed that the negative regulators in root hair development,GL2,WER and TTG were expressed in root hairs,while the positive regulators TRY,CPC and ETC1 were not expressed,which may be the main mechanism resulted in root hair deficiency in blueberry.The isolated mycorrhizal fungi mainly belonged to the genera of Fusarium,Talaromyces,Gibberella,Penicillium and Aspergillus.Inoculation experiments showed the strains A1,A4,X2 and X22 significantly promoted the growth of blueberry;meanwhile,A1,A4 and X22 significantly increased root activity;A4,X2 and X22 significantly acidified the rhizospheric soil.In the A4 and X22 treatment groups,the total phosphorus contents of leaves increased significantly,but no obvious decrease was observed in the available phosphorus content in rhizosphere.Therefore,it can be inferred that the mycorrhiza formed by the strains of A4 and X22 can enhance the phosphorus availability.Vitamin B2,related to plant growth and resistance,was detected in the secretion of X22,which suggests that biosynthesis of vitamin B2 may be another plant growth-promoting mechanism of ericoid mycorrhizae.