Samarina L S, Matskiv A O, Koninskaya N G, Simonyan T A, Malyarovskaya V I, Malyukova L S
Federal Research Centre the Subtropical Scientific Centre of the Russian Academy of Sciences, Sochi, Russia.
Vavilovskii Zhurnal Genet Selektsii. 2020 Oct;24(6):598-604. doi: 10.18699/VJ20.653.
Low-temperature stress is one of the main factors limiting the distribution and reducing the yield of many subtropical crops, including the tea crop. Efficient breeding to develop frost-tolerant cultivars requires a reliable set of genetic markers for identifying resistance donors, and that is why it is necessary to reveal the specific genetic response in frost-tolerant genotypes in comparison with frost- susceptible ones. In this work, we performed a comparative analysis of the expression of 18 tea genes (ICE1, CBF1, DHN1, DHN2, DHN3, NAC17, NAC26, NAC30, bHLH7, bHLH43, P5CS, WRKY2, LOX1, LOX6, LOX7, SnRK1.1, SnRK1.2, SnRK1.3) under cold and frost conditions in two tea genotypes, tolerant and susceptible. Low-temperature stress was induced by placing the potted plants in cold chambers and lowering the temperature to 0…+2 °С for 7 days (cold stress), followed by a decrease in temperature to -4…-6 °С for 5 days (frost stress). Relative electrical conductivity of leaf was measured in response to the stress treatments, and a significant difference in the frost tolerance of the two tea genotypes was confirmed. Cold exposure did not lead to a change in the electrical conductivity of leaf tissue. On the other hand, frost treatment resulted in increased REC in both genotypes and to a greater extent in the susceptible genotype. Increased expression of all the genes was shown during cold and frost. The genes that were strongly expressed in the tolerant tea genotype were revealed: ICE1, CBF1, DHN2, NAC17, NAC26, bHLH43, WRKY2, P5CS, LOX6, SnRK1.1, SnRK1.3. These genes can be proposed as markers for the selection of frost-tolerance donors in tea germplasm collections. Additionally, it was shown that the tolerant genotype is characterized by an earlier response to stress at the stage of cold acclimation. The study of the expression of the identified genes in different organs of tea plants and in different exposures to low temperature is relevant for further investigations.
低温胁迫是限制包括茶树在内的许多亚热带作物分布和降低其产量的主要因素之一。通过高效育种培育抗冻品种需要一套可靠的遗传标记来鉴定抗性供体，这就是为什么有必要揭示抗冻基因型与感冻基因型相比的特定遗传反应。在这项工作中，我们对两种茶树基因型（抗冻型和感冻型）在低温和霜冻条件下18个茶树基因（ICE1、CBF1、DHN1、DHN2、DHN3、NAC17、NAC26、NAC30、bHLH7、bHLH43、P5CS、WRKY2、LOX1、LOX6、LOX7、SnRK1.1、SnRK1.2、SnRK1.3）的表达进行了比较分析。通过将盆栽植物置于低温室中，将温度降至0…+2℃持续7天（冷胁迫），然后将温度降至-4…-6℃持续5天（霜冻胁迫）来诱导低温胁迫。测量叶片的相对电导率以响应胁迫处理，证实了两种茶树基因型在抗冻性上存在显著差异。冷暴露并未导致叶片组织电导率的变化。另一方面，霜冻处理导致两种基因型的相对电导率均增加，且感冻基因型增加的程度更大。在低温和霜冻期间，所有基因的表达均增加。揭示了在抗冻茶树基因型中强烈表达的基因：ICE1、CBF1、DHN2、NAC17、NAC26、bHLH43、WRKY2、P5CS、LOX6、SnRK1.1、SnRK1.3。这些基因可被提议作为茶树种质资源库中抗冻性供体选择的标记。此外，研究表明抗冻基因型的特征是在冷驯化阶段对胁迫的反应更早。研究已鉴定基因在茶树不同器官以及不同低温暴露条件下的表达，对于进一步的研究具有重要意义。
