Silencing threonine deaminase and JAR4 in Nicotiana attenuata impairs jasmonic acid-isoleucine-mediated defenses against Manduca sexta
Silencing threonine deaminase and JAR4 in Nicotiana attenuata impairs jasmonic acid-isoleucine-mediated defenses against Manduca sexta
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DOI：
10.1105/tpc.106.041103
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发表时间：
2006-11-01
期刊：
影响因子：
11.6
通讯作者：
Baldwin, Ian T.
中科院分区：
文献类型：
--
作者：
Kang, Jin-Ho;Wang, Lei;Baldwin, Ian T.
苏氨酸脱氨酶（TD）催化转化的Thr α-酮丁酸在Ile的生物合成，然而，其戏剧性的上调后，在叶片中的植食动物的攻击表明在防御中的作用。在烟草中，强烈沉默的TD转基因植物发育不良，而轻度沉默的TD转基因植物生长正常，但对烟草的攻击高度敏感。草食动物的敏感性与茉莉酸异亮氨酸（JA-Ile），胰蛋白酶蛋白酶抑制剂和尼古丁的水平降低。将[C-13（4）] Thr加入到用口腔分泌物处理的伤口中显示TD为JA-Ile合成提供Ile。将Ile或JA-Ile应用于TD沉默植物的伤口恢复了草食动物抗性。沉默JASMONATE-RESISTANT 4（JAR 4），N.通过病毒诱导的基因沉默，证实了JA-Ile在激活植物防御中起重要作用。TD也可能在昆虫肠道中作为抗营养防御蛋白发挥作用，降低Thr的可用性，因为连续补充TD沉默的植物大量（2 mmol）Thr，而不是Ile，增加M。六倍增长然而，TD和JAR沉默的植物的草食动物抗性完全恢复信号量（0.6 mmol）的JA-Ile治疗的事实表明，TD的防御作用可以更多地归因于信号比抗营养防御。
Threonine deaminase (TD) catalyzes the conversion of Thr to alpha-keto butyrate in Ile biosynthesis; however, its dramatic upregulation in leaves after herbivore attack suggests a role in defense. In Nicotiana attenuata, strongly silenced TD transgenic plants were stunted, whereas mildly silenced TD transgenic plants had normal growth but were highly susceptible to Manduca sexta attack. The herbivore susceptibility was associated with the reduced levels of jasmonic acid isoleucine (JA-Ile), trypsin proteinase inhibitors, and nicotine. Adding [C-13(4)] Thr to wounds treated with oral secretions revealed that TD supplies Ile for JA-Ile synthesis. Applying Ile or JA-Ile to the wounds of TD-silenced plants restored herbivore resistance. Silencing JASMONATE-RESISTANT4 (JAR4), the N. attenuata homolog of the JA-Ile-conjugating enzyme JAR1, by virus-induced gene silencing confirmed that JA-Ile plays important roles in activating plant defenses. TD may also function in the insect gut as an antinutritive defense protein, decreasing the availability of Thr, because continuous supplementation of TD-silenced plants with large amounts (2 mmol) of Thr, but not Ile, increased M. sexta growth. However, the fact that the herbivore resistance of both TD- and JAR-silenced plants was completely restored by signal quantities (0.6 mmol) of JA-Ile treatment suggests that TD's defensive role can be attributed more to signaling than to antinutritive defense.