DIFFERENTIAL GENE-EXPRESSION IN CHILLING-ACCLIMATED MAIZE SEEDLINGS AND EVIDENCE FOR THE INVOLVEMENT OF ABSCISIC-ACID IN CHILLING TOLERANCE
DIFFERENTIAL GENE-EXPRESSION IN CHILLING-ACCLIMATED MAIZE SEEDLINGS AND EVIDENCE FOR THE INVOLVEMENT OF ABSCISIC-ACID IN CHILLING TOLERANCE
复制标题
DOI：
10.1104/pp.105.1.331
复制
发表时间：
1994-05-01
期刊：
影响因子：
7.4
通讯作者：
STEWART, CR
中科院分区：
文献类型：
--
作者：
ANDERSON, MD;PRASAD, TK;STEWART, CR
低温敏感玉米（Zea mays L.）近交系C50（Pioneer）。将幼苗在27 ℃下发芽3 d，然后在黑暗中暴露于4、5或6 ℃的低温处理2、4、7或10 d。在更严重的治疗中，损伤症状包括积水外观和组织变色。症状在中胚轴最为明显。经过10天的生长期，在温室中，中度受损的幼苗表现出褪绿的领域，偶尔中断叶片扩张，和收缩的中胚轴。生长和存活的改善，首先暴露于14摄氏度的驯化处理3天，然后再施加冷却处理。在5 ℃低温处理7d后，79%的驯化苗存活，而只有22%的非驯化苗存活。利用差减和差异筛选技术研究了驯化苗和对照苗之间基因表达的差异。对应于三个基因，car333，car30，和car757（冷驯化响应），转录本，在驯化后的幼苗中存在较高的水平。序列分析表明car333为cat3，编码玉米线粒体过氧化氢酶同工酶3。这三个克隆的表征表明，所有相应的成绩单升高，在驯化幼苗的方式，依赖于器官，即胚芽鞘，中胚轴，或根。虽然成绩单升高，在所有三个器官的适应，car30是最丰富的胚芽鞘和根，而cat3和car757是最丰富的胚芽鞘和中胚轴。过氧化氢酶活性遵循与cat3转录水平相同的总体趋势。外源处理脱落酸（ABA）导致非驯化，冷苗的生长和存活的改善。抑制ABA的生物合成与氟草酮废除驯化诱导的耐冷性，和外源ABA的氟草酮处理的幼苗恢复耐冷性。外源ABA处理也导致在猫3，汽车30，和汽车757转录水平和过氧化氢酶活性的增加，在相同的器官特异性的方式在驯化的幼苗。这些结果表明ABA的合成是抗寒性所必需的。然而，ABA水平的测量中胚轴在驯化和冷却过程中发现，只有一个边际增加在驯化和冷却过程中急剧增加，无论是否幼苗驯化。因此，虽然ABA可能需要耐冷性，我们没有确凿的证据表明，驯化过程是由ABA介导的。
An acclimation phenomenon was characterized in seedlings of chilling-sensitive maize (Zea mays L.) inbred C50 (Pioneer). Seedlings were germinated at 27 degrees C for 3 d and then exposed to chilling treatments of 4, 5, or 6 degrees C for 2, 4, 7, or 10 d in darkness. Damage symptoms in the more severe treatments included a waterlogged appearance and a discoloration of the tissue. The symptoms were most obvious in the mesocotyl. After a 10-d grow-out period in the greenhouse, moderately damaged seedlings exhibited chlorotic areas, an occasional disruption in leaf expansion, and a constriction of the mesocotyl. Growth and survival were improved by first exposing seedlings to a 14 degrees C acclimation treatment for 3 d before applying the chilling treatment. After chilling at 5 degrees C for 7 d, 79% of the acclimated seedlings survived, whereas only 22% of the nonacclimated seedlings survived. Differences in gene expression between acclimated and control seedlings were investigated using subtraction and differential screening techniques. Transcripts corresponding to three genes, car333, car30, and car757 (chilling acclimation responsive), were present in higher levels in seedlings after acclimation. Sequence analysis identified car333 as cat3, which encodes maize mitochondrial catalase isozyme 3. Characterization of these three clones revealed that all corresponding transcripts were elevated in acclimated seedlings in a manner that depended on the organ, i.e. coleoptile, mesocotyl, or root. Although transcripts were elevated in all three organs in response to acclimation, car30 was most abundant in the coleoptile and root, whereas cat3 and car757 were most abundant in the coleoptile and mesocotyl. Catalase activity followed the same general trend as cat3 transcript levels. Exogenous treatment with abscisic acid (ABA) resulted in an improvement in growth and survival of nonacclimated, chilled seedlings. Inhibition of ABA biosynthesis with fluridone abolished acclimation-induced chilling tolerance, and exogenous application of ABA to fluridone-treated seedlings restored chilling tolerance. Exogenous ABA treatment also resulted in increases in cat3, car30, and car757 transcript levels and catalase activity in the same organ-specific manner as in acclimated seedlings. These resorts indicate that ABA synthesis is essential for chilling tolerance. However, measurement of ABA levels in mesecotyls during acclimation and chilling revealed only a marginal increase during acclimation and a dramatic increase during chilling, regardless of whether or not seedlings were acclimated. Thus, although ABA may be required for chilling tolerance, we have no conclusive evidence that the acclimation process is mediated by ABA.