A shift from drought avoidance to drought tolerance in wheat with increase in ploidy level
Drought resistance of dryland wheats mainly comprises two critical characteristics, drought avoidance and drought tolerance.To clarify differential implications of these two mechanisms in drought adaptability of the wheat crop, a meta-analysis was made using the results presented in about 800 papers dealing with drought, previously published in international journals over last many decades.Three different experiments were conducted to verify the information gained from meta-analysis on mechanism of drought resistance in wheats differing in ploidy levels.The results of the meta-analysis illustrated that dryland wheats tend to adopt selective drought-resistace strategies under natural and artificial selection pressures.Wheat genotypes with a large root system, including wild relatives and old hexaploid cultivars, displayed mainly drought avoidance characteristics, including greater root biomass, more compact canopy and stronger water-uptake ability to improve population fitness under harsh environmental conditions.However, modern hexaploid cultivars generally had a small root system and showed stronger drought tolerance characteristics such as considerable osmotic adjustment, lower lethal leaf water potential and non-hydraulic stomatal sensitivity.Artificial selection through modem breeding aimed to improve wheat germplasm had led to higher harvest index and population yield as a result of enhanced expression of drought tolerance trait, whereas historical natural selection appeared to be in favor of drought avoidance.Given current understanding of dryland wheat improvement as examined in the present investigation, drought avoidance and drought tolerance traits could be tailored for better trade-off in future breeding programs aiming at improvement of drought resistance in wheat.
Dryland wheats drought avoidance drought tolerance artificial selection trade-off
Zheng-Guo Cheng Guijun Yan Bao-Luo Ma Jian-Yong Wang Guang-Chao Lv You-Cai Xiong
State Key Laboratory of Grassland Agro-ecosystems, Institute of Arid Agroecology, School of Life Sci School of Plant Biology, Faculty of Science and The UWA Institute of Agriculture, The University of Eastern Cereal and Oilseed Research Centre (ECORC), Agriculture and Agri-Food Canada,Ottawa K1A0C6,
国际会议
兰州
英文
66-84
2013-10-14（万方平台首次上网日期，不代表论文的发表时间）