Loline alkaloids (LA), which are 1-aminopyrrolizidines with an oxygen bridge, are produced by Epichloë (anamorph=Neotyphodium) species, endophytes of grasses. LA are insecticidal, thus helping protect host plants from insect herbivory. Suppression subtractive hybridization PCR was used to isolate transcripts up-regulated during loline alkaloid production in cultures of
Neotyphodium uncinatum
. Subtracted cDNAs were cloned, and a &lgr;-phage cDNA library from an LA-expressing
N. uncinatum
culture was screened with subtracted cDNA. In BLAST searches, several cDNAs identified had sequence similarities to aspartate kinases, and another with O-acetylhomoserine-(thiol)lyase. Differential expression of these two genes in LA-producing cultures of
N. uncinatum
was confirmed, and in a survey of 23 isolates from 21 Neotyphodium and Epichloë species these two genes strictly correlated with LA production. Two nucleic acid molecules encoding two loline alkaloid gene clusters have been identified.
洛林
生物碱(Loline alkaloids,
LA)是一种带有氧桥的 1-aminopyrrolizidines,由禾本科植物的内生菌 Epichloë (anamorph=Neotyphodium)物种产生。
LA 具有杀虫作用,因此有助于保护寄主植物免受昆虫的草食性侵害。利用抑制减弱杂交聚合酶链式反应(PCR)分离了在禾本科内生菌 Neotyphodium uncinatum 的培养物中产生洛林
生物碱过程中上调的转录本。
Neotyphodium uncinatum
.克隆了减去的 cDNA,并从表达
LA 的 Neotyphodium uncinatum 中获得了一个 &lgr;-phage cDNA 文库。
N. uncinatum
培养物的噬菌体 cDNA 文库进行筛选。在 B
LAST 搜索中,发现几个 cDNA 与
天冬氨酸激酶序列相似,另一个与 O-乙酰高
丝氨酸(
硫醇)裂解酶序列相似。在 N. uncinatum 的
LA 生产培养物中,这两个
基因的表达存在差异。
N. uncinatum
这两个
基因与
LA 的产生密切相关。已经确定了两个核酸分子编码两个洛林
生物碱基因簇。