Characterization and genetic analysis of a low-temperature-sensitive mutant, sy-2, in Capsicum chinense
Characterization and genetic analysis of a low-temperature-sensitive mutant, sy-2, in Capsicum chinense
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DOI：
10.1007/s00122-010-1460-0
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发表时间：
2011-02-01
影响因子：
5.4
通讯作者：
Kang, Byoung-Cheorl
中科院分区：
文献类型：
--
作者：
An, Song-Ji;Pandeya, Devendra;Kang, Byoung-Cheorl
辣椒（Capsicum chinense）的温度敏感突变体sy-2在24℃以上生长时表现为正常发育表型，但在20℃生长时，sy-2表现出叶绿素缺乏和叶片萎缩等发育缺陷。为了了解这种温度依赖性反应的潜在机制，进行了表型表征和遗传分析。结果表明，在20℃条件下生长的sy-2植株叶片叶绿体结构异常，细胞崩溃，并且在叶片叶绿素缺乏的部分检测到活性氧（ROS）的过度积累导致细胞死亡。然而，在20℃下生长的sy2植株中，清除ROS基因的表达谱没有改变。进一步分析叶片中脂肪酸含量发现亚油酸（18:2）到亚麻酸（18:3）的通路受损。此外，在sy-2植物中，Cafad7基因表达下调。这种变化可能会导致sy-2植物的生理紊乱和叶片形态的改变，使其失去耐低温能力。对中国c.c’s -2’与野生型中国c.c’No. 3341’杂交的F-2群体的遗传分析表明，sy2表型由一个单隐性基因控制。分子定位结果表明，sy-2基因位于辣椒连锁组1的基因组区域，与番茄1号染色体Ch1_scaffold 00106的300 kb区域相对应。该区域的候选基因将揭示sy-2的身份和温度依赖性植物反应的潜在机制。
A temperature-sensitive mutant of Capsicum chinense, sy-2, shows a normal developmental phenotype when grown above 24A degrees C. However, when grown at 20A degrees C, sy-2 exhibits developmental defects, such as chlorophyll deficiency and shrunken leaves. To understand the underlying mechanism of this temperature-dependent response, phenotypic characterization and genetic analysis were performed. The results revealed abnormal chloroplast structures and cell collapse in leaves of the sy-2 plants grown at 20A degrees C. Moreover, an excessive accumulation of reactive oxygen species (ROS) resulting in cell death was detected in the chlorophyll-deficient sectors of the leaves. However, the expression profile of the ROS scavenging genes did not alter in sy-2 plants grown at 20A degrees C. A further analysis of fatty acid content in the leaves showed the impaired pathway of linoleic acid (18:2) to linolenic acid (18:3). Additionally, the Cafad7 gene was downregulated in sy-2 plants. This change may lead to dramatic physiological disorder and alteration of leaf morphology in sy-2 plants by losing low-temperature tolerance. Genetic analysis of an F-2 population from a cross between C. chinense 'sy-2' and wild-type C. chinense 'No. 3341' showed that the sy-2 phenotype is controlled by a single recessive gene. Molecular mapping revealed that the sy-2 gene is located at a genomic region of the pepper linkage group 1, corresponding to the 300 kb region of the Ch1_scaffold 00106 in tomato chromosome 1. Candidate genes in this region will reveal the identity of sy-2 and the underlying mechanism of the temperature-dependent plant response.