DON, as a virulence factor, plays an important role in the infection of Fusarium graminearum in wheat. The infection ability of F. graminearum depends on its capacity of producing DON. The production of DON by F. graminearum is significantly decreased in the wheat varieties with scab resistance. In this study, GeneChip analysis indicated that an EST encoding an ATP-binding cassette (ABC) transporter was up-regulated by 45 times in a wheat landrace Wangshuibai, which is resistant to DON accumulation. A pair of EST-derived primers were designed based on the EST sequence, and a clone was then isolated from a wheat genomic DNA TAC library. The TAC clone was sequenced using chromosome walking and gene prediction was conducted using Softberry. A cDNA clone of this gene was subsequently isolated from Wangshuibai induced by DON using gene-specific primers designed according to the untranslated sequence of the gene. The genome size of the gene is 7377 bp, consisting of 19 exons with coding sequences of 4308 bp. It encodes a protein with 1435 amino acid residues and the calculated molecular weight is about 161 kD. BLAST analysis indicated that the gene may belong to pleiotropic drug resistance (PDR) sub-family, and hence designated as TaPDR1 (Triticum aestivum pleiotropic drug resistance). TaPDR1 was located on chromosome 5A of wheat using nullisomic-tetrasomic lines of Chinese Spring. TaPDR1 was up-regulated by induction of both DON and F. graminearum. Expression patterns of TaPDR1 were different in wild-type Wangshuibai and the fast-neutron induced Wangshuibai mutant lacking FHB1, a major QTL of FHB resistance and DON resistance in chromosome arm 3BS. These results suggested that TaPDR1 might be a candidate gene responsible for DON ac-cumulation resistance. The expression profile showed that TaPDR1 expression was neither induced by hormones typically involved in biotic stress, such as JA and SA, nor by abiotic stresses, such as heat, cold, wounding and NaCl. However, TaPDR1 expression was regulated by Al3+ and [Ca2+], in
脱氧血腐镰刀菌烯醇(deoxynivalenol,DON)在小麦赤霉病发病过程中起重要作用,是一种毒性因子.禾谷镰刀菌的侵染能力依赖于其产生DON的能力,抗病品种能显著降低病穗组织中DON的含量.本研究利用Affymetrix小麦基因组芯片,对抗赤霉病小麦品种望水白经DON诱导后的穗组织基因表达特点进行了分析,结果发现,一个编码PDR型转运蛋白的EST受DON诱导后上调表达45倍.根据该EST设计引物筛选小麦基因组TAC文库,得到一个包含该基因的TAC单克隆.利用染色体walking对该单克隆测序,用Softberry软件进行基因预测,根据预测基因的5′和3′非翻译区设计引物,从DON诱导的小麦望水白穗组织cDNA中克隆出该转运蛋白基因.该基因组全长7377bp,包含19个外显子,CDS长度为4308bp,编码长1435aa且分子量161kD的蛋白.蛋白序列比对表明,该基因属于PDR蛋白家族,命名为TaPDR1(Triticum asetivum Pleiotropic Drug Resistance).利用一套中国春缺体-四体系将TaPDR1基因定位在小麦5A染色体上.半定量RT-PCR表明,TaPDR1在望水白穗中受DON和禾谷镰刀菌诱导表达,表明其参与了植物抗病防御反应.该基因在望水白感病突变体中低水平表达,进一步证明TaPDR1与赤霉病抗性有关.TaPDR1的表达不受与生物胁迫相关的激素(JA和SA)和非生物胁迫因子(热、冷、伤害和NaCl)的诱导,但受到Al3+和游离Ca2+的诱导表达,推测[Ca2+]i介导了TaPDR1的表达信号.
