DIFFERENTIAL INDUCTION AND SUPPRESSION OF POTATO 3-HYDROXY-3-METHYLGLUTARYL COENZYME-A REDUCTASE GENES IN RESPONSE TO PHYTOPHTHORA-INFESTANS AND TO ITS ELICITOR ARACHIDONIC-ACID
DIFFERENTIAL INDUCTION AND SUPPRESSION OF POTATO 3-HYDROXY-3-METHYLGLUTARYL COENZYME-A REDUCTASE GENES IN RESPONSE TO PHYTOPHTHORA-INFESTANS AND TO ITS ELICITOR ARACHIDONIC-ACID
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DOI：
10.1105/tpc.4.10.1333
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发表时间：
1992-10-01
期刊：
影响因子：
11.6
通讯作者：
BOSTOCK, RM
中科院分区：
文献类型：
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作者：
CHOI, D;WARD, BL;BOSTOCK, RM
3-羟基-3-甲基戊二酰辅酶A还原酶（HMGR）的诱导是茄科植物在受到伤害和病原体感染胁迫后合成倍半萜类植物抗毒素和类固醇衍生物所必需的。为了更好地理解应激响应类异戊二烯合成的这一复杂步骤，我们使用来自拟南芥HMGR cDNA的探针从马铃薯块茎文库中分离出编码HMGR的三类cDNA （hmg1， hmg2和hmg3）。马铃薯cdna在部分蛋白质编码区具有广泛的同源性，但在3'非翻译区同源性较低。利用基因特异性探针进行的RNA凝胶印迹分析表明，hmgl在块茎组织中受到损伤的强烈诱导，但用真菌激发子花生四烯酸或接种不相容或相容的真菌病原菌疫霉对块茎组织的损伤诱导强烈抑制。hmg2和hmg3 mrna也在损伤反应中积累，但与hmgl不同的是，花生四烯酸或接种后，这些mrna被强烈增强。接种亲和小种R侵染菌，hmg2和hmg3的HMGR基因表达模式相似，只是mRNA水平的变化幅度和速率相对于不亲和互作有所降低。HMGR基因家族成员的差异调控可能部分解释了先前报道的HMGR酶活性在损伤和激发剂处理后的变化。在诱导子处理或接种不相容种后，hmg1的抑制和hmg2和hmg3转录水平的增强与早期研究中观察到的类固醇的抑制和倍半萜类积累的刺激相似。这些结果与马铃薯和其他茄属植物中甾醇和倍半萜的生物合成存在离散组织通道的假设有关。
Induction of 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR) is essential for the biosynthesis of sesquiterpenoid phytoalexins and steroid derivatives in Solanaceous plants following stresses imposed by wounding and pathogen infection. To better understand this complex step in stress-responsive isoprenoid synthesis, we isolated three classes of cDNAs encoding HMGR (hmg1, hmg2, and hmg3) from a potato tuber library using a probe derived from an Arabidopsis HMGR cDNA. The potato cDNAs had extensive homology in portions of the protein coding regions but had low homology in the 3' untranslated regions. RNA gel blot analyses using gene-specific probes showed that hmgl was strongly induced in tuber tissue by wounding, but the wound induction was strongly suppressed by treatment of the tissue with the fungal elicitor arachidonic acid or by inoculation with an incompatible or compatible race of the fungal pathogen Phytophthora infestans. The hmg2 and hmg3 mRNAs also accumulated in response to wounding, but in contrast to hmgl, these mRNAs were strongly enhanced by arachidonic acid or inoculation. Inoculation with a compatible race of R infestans resulted in similar patterns in HMGR gene expression of hmg2 and hmg3 except that the magnitude and rate of the changes in mRNA levels were reduced relative to the incompatible interaction. The differential regulation of members of the HMGR gene family may explain in part the previously reported changes in HMGR enzyme activities following wounding and elicitor treatment. The suppression of hmg1 and the enhancement of hmg2 and hmg3 transcript levels following elicitor treatment or inoculation with the incompatible race parallel the suppression in steroid and stimulation of sesquiterpenoid accumulations observed in earlier investigations. The results are discussed in relation to the hypothesis that there are discrete organizational channels for sterol and sesquiterpene biosynthesis in potato and other Solanaceous species.