Chilling and Ammonium Absorption in Wild and Cultivated Tomatoes

9306521在一个冷敏番茄品种(番茄)中开花。CV。T5)，短时间暴露于5℃下，迅速且不可逆地抑制了根的铵离子内流。相比之下，该分类群中的铵外流和硝酸盐吸收，以及耐寒同类种(番茄属多毛番茄LA1778)中的铵和硝酸盐吸收，都立即和完全地从这种暴露中恢复。本研究将对这一现象的生理和遗传学进行研究，以阐明铵运输的调节以及铵运输在番茄冷害反应中的重要性。生理学实验将使用选择铵的微电极来定位根中的铵吸收，并确定在冷期后恢复铵的内流是否需要蛋白质合成、转录或新的生长。这些特性有助于鉴定与铵离子内流相关的根膜蛋白。基因研究将包括使用自动化的NH4+分析系统，每天筛选30种植物，以确定是否有冷敏的铵离子流入。对冷敏感型、耐冷型和杂交型杂交F1群体的分离分析应确定该性状的遗传规律。最后，我们将测试已被选为耐冷铵流入的F1与L.esculentum的回交，以了解它们的整体耐冷性。更好地了解植物对氨的吸收对于研究植物特定的氮素关系和一般的植物运输过程是至关重要的。此外，在将特定的耐冷性状转移到番茄中时，我们应该阐明地下过程在植物低温反应中的作用。***

9306521 Bloom In a chilling-sensitive tomato cultivar (Lycopersicon esculentum Mill. cv. T5), short exposures to 5 degree centigrade rapidly and irreversibly inhibited root ammonium influx. By contrast, ammonium efflux and nitrate absorption in this taxon, as well as ammonium and nitrate absorption in a chilling-tolerant congener (Lycopersicon hirsutum LA1778), recovered immediately and fully from such exposures. The research would examine the physiology and genetics of this phenomenon to elucidate the regulation of ammonium transport and the importance of ammonium transport in the chilling response of tomato. The physiological experiments would employ ammonium-selective microelectrodes to localize ammonium absorption in the root and to determine whether resumption of ammonium influx after a chilling episode requires protein synthesis, transcription, or new growth. These characteristics should assist in the identification of root membrane proteins associated with ammonium influx. The genetic studies would involve the screening of 30 plants a day for chilling-sensitive ammonium influx using an automated NH4+ analysis system. Segregation analysis of the chilling-sensitive L. esculentum, the tolerant L. hirsutum, and L. esculentum x L. hirsutum F1 populations should determine the inheritance of this trait. Lastly, we would test backcrosses of the F1 hybrids to L. esculentum that have been selected for chilling-tolerant ammonium influx for their overall chilling tolerance. A better understanding of plant ammonium absorption is critical to the study of plant nitrogen relations in specific, and plant transport processes in general. Moreover, in transferring a specific chilling-tolerant trait to tomato, we should elucidate the role of below-ground processes in the chilling response of plants. ***