Liu Linya, Song Shuyi, Yang Na, He Bin, Xin Lusheng, Huang Yacheng
School of Biological Science and Technology, Liupanshui Normal University, Liupanshui, China.
School of Public Health, Jining Medical University, Jining, China.
Front Plant Sci. 2024 Oct 18;15:1425072. doi: 10.3389/fpls.2024.1425072. eCollection 2024.
Kiwifruit growth and development are severely affected by various biotic and abiotic stresses, especially cold stress and the bacterial disease caused by pv. (Psa). Metallothioneins (MTs) are a group of cysteine-rich proteins that play crucial roles in stress response, metal detoxification, and homeostasis in plants. However, the protective role of these MTs in kiwifruit remains to be elucidated. In the present study, four genes were identified in the Hongyang kiwifruit genome, namely, two Type 2 isoforms ( and ) and two Type 3 isoforms ( and ) located separately on four different chromosomes. The hormones and stress response -elements within the promoter regions of these were characterized. It was revealed that the four genes exhibited different expression patterns in different tissues: and were expressed at much higher levels in the fruit, male flower, female flower, root, and bark, while was expressed mainly in the fruit and was expressed highly in the bark. The expression patterns of these genes after exposure to Psa infection and different phytohormones, including gibberellic acid A3(GA), ethylene (ET), and abscisic acid (ABA), were evaluated. It was revealed that in response to Psa infection, the main in each tissue (those with expression levels higher compared to the other in that tissue) were downregulated during the early stage in kiwifruits, followed by a recovery phase. In addition, most were downregulated after exposure to ET and GA, while type 2 ( and ) were upregulated after treatment with ABA. The overexpression of in presented a higher tolerance to HO, heavy metals, low temperature, and high temperature. Collectively, these findings demonstrated the protective roles of in terms of stress resistance conferred through plant hormone-related signal pathways.
猕猴桃的生长发育受到各种生物和非生物胁迫的严重影响，尤其是低温胁迫和由丁香假单胞菌猕猴桃致病变种（Psa）引起的细菌性疾病。金属硫蛋白（MTs）是一类富含半胱氨酸的蛋白质，在植物的胁迫响应、金属解毒和体内平衡中发挥着关键作用。然而，这些MTs在猕猴桃中的保护作用仍有待阐明。在本研究中，在红阳猕猴桃基因组中鉴定出四个MT基因，即两个2型异构体（MT2a和MT2b）和两个3型异构体（MT3a和MT3b），它们分别位于四条不同的染色体上。对这些MT基因启动子区域内的激素和胁迫响应元件进行了表征。结果表明，这四个MT基因在不同组织中表现出不同的表达模式：MT2a和MT2b在果实、雄花、雌花、根和树皮中的表达水平要高得多，而MT3a主要在果实中表达，MT3b在树皮中高表达。评估了这些MT基因在受到Psa感染以及不同植物激素（包括赤霉素A3（GA）、乙烯（ET）和脱落酸（ABA））处理后的表达模式。结果表明，在猕猴桃中，响应Psa感染时，各组织中的主要MT基因（那些在该组织中表达水平高于其他MT基因的）在早期阶段被下调，随后是恢复期。此外，大多数MT基因在暴露于ET和GA后被下调，而2型MT基因（MT2a和MT2b）在用ABA处理后被上调。在拟南芥中过表达MT3b对过氧化氢、重金属、低温和高温表现出更高的耐受性。总的来说，这些发现证明了MT基因在通过植物激素相关信号通路赋予的抗逆性方面的保护作用。
