Chilling and Ammonium Absorption in Wild and Cultivated Tomatoes

9306521在对低温敏感的番茄栽培品种（Lycopersicon esculentum Mill. CV. 5 ℃短时间暴露可迅速且不可逆地抑制根系铵离子内流。 相比之下，铵流出和硝酸盐的吸收在这个类群，以及铵和硝酸盐的吸收在耐冷同源（Lycopersicon hirsutum LA 1778），立即完全恢复，从这样的曝光。 本研究将从生理和遗传学角度探讨这一现象，阐明铵离子转运的调控机制及其在番茄低温反应中的重要性。 生理学实验将采用铵选择性微电极定位根中的铵吸收，并确定在寒冷事件后恢复铵流入是否需要蛋白质合成，转录或新的生长。 这些特点应有助于确定根膜蛋白与铵流入。 遗传研究将涉及使用自动NH4+分析系统每天筛选30株植物，以了解对低温敏感的铵流入。 冷敏感型L. esculentum、耐盐L. hirsutum和L.香芋 hirsutum F1群体应决定这一性状的遗传。 最后，我们将测试F_1杂种与L的回交。 已被选择为耐冷铵流入其整体耐冷性。 更好地了解植物对铵离子的吸收对于研究植物氮素的具体关系和植物氮素的运输过程具有重要意义。 此外，在将一个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冷反应中的作用。 ***

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. ***