C1L細菌處理與葉枯病菌感染改變玉米根圈之細菌族群

Abstract

植物根圈存在大量的微生物，整體根圈的微生物相組成與植物健康有高度的關聯性。臘狀芽孢桿菌C1L為臺灣百合根圈篩選出的生物防治潛力菌株，目前已被研究證實具有誘導玉米系統性抗葉枯病的能力。本研究中探討施用C1L菌株於玉米根圈，對根圈細菌族群之影響，並分析葉枯病菌感染玉米葉片後，所引發的根圈細菌族群變化，及從中找出新的具生物防治潛力菌株。研究結果顯示玉米根圈在施用C1L菌株後3天，Proteobacteria門假單胞菌屬根圈細菌之豐度大幅增加；而玉米根圈在施用C1L菌株後6天，假單胞菌屬根圈細菌之豐度則回復至原始狀態。當玉米根圈在施用C1L菌株後3天，接種葉枯病菌3天後的假單胞菌屬根圈細菌之豐度比未施用C1L菌株但接種葉枯病菌者高。這些結果指出，假單胞菌屬根圈細菌族群的增加與植物抗病狀態有相當的關聯性。此外接種葉枯病菌後3天，腸桿菌屬、假單胞菌屬、類芽孢桿菌屬與芽孢桿菌屬根圈細菌的豐度，相對於對照組有增加的情形。另一方面，從施用C1L菌株後3天，再接種葉枯病菌後3天的玉米根圈中，分離到對葉枯病可降低至少30%罹病度的假單胞菌屬細菌12株以及芽孢桿菌屬細菌14株，推測這些分離株之施用能加強玉米植株之抗病性，有進一步應用發展的潛力。

A large number and wide variety of microorganisms are associated with plant roots and the genetic elements of rhizosphere microbiome determine the plant health. Bacillus cereus C1L screened from the rhizosphere of Lilium formosanum could reduce severe symptom development of southern corn leaf blight (SCLB) caused by Cochliobolus heterostrophus. In this research, the changes of maize rhizobacterial community post C1L application and C. heterostrophus infection were analyzed by metagenomic mining. The abundance of Pseudomonas rhizobaceria remarkably increased at 3 days post C1L application, then decreased to the original state at 6 days after C1L application. Moreover, the abundance of Pseudomonas rhizobacteria was higher at 3 days post inoculation with C. heterostrophus on maize plants 3 days post C1L application as compared with that without C1L pretreatment. These results indicated a high relatedness between Pseudomonas and disease resistance state of maize. Besides, the relative abundance of Enterobacter, Pseudomonas, Paenibacillus and Bacillus rhizobacteria increased in maize rhizosphere 3 days post inoculation with C. heterostrophus as compared with that in the control. On the other hand, 12 isolates of Pseudomonas and 14 isolates of Bacillus, reducing at least 30% disease severity of leaf blight in corn seedlings, were screened from maize rhizobacterial community. These bacterial isolates capable of enhancing plant disease resistance were presumed and have potential for further development of application.