调节物候发育和驯化速率的因素之间的相互作用决定了小麦的低温耐受性。
Interactions among factors regulating phenological development and acclimation rate determine low-temperature tolerance in wheat.
作者信息
Fowler D B, Limin A E
机构信息
Department of Plant Sciences, University of Saskatchewan, 51 Campus Drive, Saskatoon, Saskatchewan, Canada S7N 5A8.
出版信息
Ann Bot. 2004 Nov;94(5):717-24. doi: 10.1093/aob/mch196. Epub 2004 Sep 16.
BACKGROUND AND AIMS
Exposure to low temperatures (LT) produces innumerable changes in morphological, biochemical and physiological characteristics of plants, with the result that it has been difficult to separate cause and effect adjustments to LT. Phenotypic studies have shown that the LT-induced protective mechanisms in cereals are developmentally regulated and involve an acclimation process that can be stopped, reversed and restarted. The present study was initiated to separate the developmental factors determining duration from those responsible for rate of acclimation, to provide the opportunity for a more in depth analysis of the critical mechanisms that regulate LT tolerance in wheat (Triticum aestivum).
METHODS
The non-hardy spring wheat cultivar 'Manitou' and the very cold-hardy winter wheat cultivar 'Norstar' were used to produce reciprocal near-isogenic lines (NILs) in which the vrn-A1 (winter) alleles of 'Norstar' were inserted into the non-hardy 'Manitou' genetic background and the Vrn-A1 (spring) alleles of 'Manitou' were inserted in the hardy 'Norstar' genetic background so that the effects of duration and rate of LT acclimation could be quantified.
KEY RESULTS
Comparison of the acclimation curves of the NILs and their parents grown at 2, 6 and 10 degrees C established that the full expression of LT-induced genetic systems was revealed only under genotypically dependent optimum combinations of time and temperature. Both duration and rate of acclimation were found to contribute significantly to the 13.8 degrees C difference in lowest survival temperature between 'Norstar' and 'Manitou'.
CONCLUSIONS
Duration of LT acclimation was dependent upon the rate of phenological development, which, in turn, was determined by acclimation temperatures and vernalization requirements. Rate of acclimation was faster for genotypes with the 'Norstar' genetic background but the ability to sustain a high rate of acclimation was dependent upon the length of the vegetative stage. Complex time/temperature relationships and unexplained genetic interactions indicated that detailed functional genomic or phenomic analyses of natural allelic variation will be required to identify the critical genetic components of a highly integrated system, which is regulated by environmentally responsive, complex pathways.
背景与目的
暴露于低温环境会使植物的形态、生化和生理特征发生无数变化，因此很难区分对低温的因果调节。表型研究表明，谷物中低温诱导的保护机制受到发育调控，涉及一个可停止、逆转和重启的驯化过程。开展本研究的目的是将决定持续时间的发育因素与负责驯化速率的因素区分开来，以便有机会更深入地分析调节小麦（普通小麦）耐低温性的关键机制。
方法
利用不耐寒的春小麦品种“马尼图”和极耐寒的冬小麦品种“诺斯塔”构建了相互近等基因系（NILs），即将“诺斯塔”的vrn-A1（冬性）等位基因插入不耐寒的“马尼图”遗传背景中，将“马尼图”的Vrn-A1（春性）等位基因插入耐寒的“诺斯塔”遗传背景中，从而能够量化低温驯化的持续时间和速率的影响。
主要结果
对在2℃、6℃和10℃下生长的近等基因系及其亲本的驯化曲线进行比较，结果表明，只有在基因型依赖的时间和温度最佳组合下，低温诱导的遗传系统才能充分表达。发现驯化的持续时间和速率对“诺斯塔”和“马尼图”最低存活温度之间13.8℃的差异都有显著贡献。
结论
低温驯化的持续时间取决于物候发育速率，而物候发育速率又由驯化温度和春化要求决定。具有“诺斯塔”遗传背景的基因型驯化速率更快，但维持高驯化速率的能力取决于营养生长期的长度。复杂的时间/温度关系和无法解释的基因相互作用表明，需要对自然等位变异进行详细的功能基因组或表型组分析，以确定一个高度整合系统的关键遗传成分，该系统由环境响应的复杂途径调控。
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