Pinto R Suzuky, Lopes Marta S, Collins Nicholas C, Reynolds Matthew P
International Maize and Wheat Improvement Center (CIMMYT,Int.), Apdo. Postal 6-641, 06600, México, D.F., Mexico.
Australian Centre for Plant and Functional Genomics (ACPFG), School of Agriculture Food and Wine, University of Adelaide, Glen Osmond, Adelaide, SA, 5064, Australia.
Theor Appl Genet. 2016 Nov;129(11):2055-2074. doi: 10.1007/s00122-016-2757-4. Epub 2016 Aug 22.
Staygreen traits are associated with heat tolerance in bread wheat. QTL for staygreen and related traits were identified across the genome co-located with agronomic and physiological traits associated to plant performance under heat stress. Plant chlorophyll retention-staygreen-is considered a valuable trait under heat stress. Five experiments with the Seri/Babax wheat mapping population were sown in Mexico under hot-irrigated environments. Normalized difference vegetation index (NDVI) during plant growth was measured regularly and modelled to capture the dynamics of plant greenness decay, including staygreen (Stg) at physiological maturity which was estimated by regression of NDVI during grainfilling. The rate of senescence, the percentage of plant greenness decay, and the area under the curve were also estimated based on NDVI measurements. While Stg and the best fitted curve were highly environment dependent, both traits showed strong (positive for Stg) correlations with yield, grainfilling rates, and extended grainfilling periods, while associations with kernel number and kernel weight were weak. Stg expression was largely dependent on rate of senescence which was related to the pattern of the greenness decay curve and the initial NDVI. QTL analyses revealed a total of 44 loci across environments linked to Stg and related traits, distributed across the genome, with the strongest and most repeatable effects detected on chromosomes 1B, 2A, 2B, 4A, 4B and 7D. Of these, some were common with regions controlling phenology but independent regions were also identified. The co-location of QTL for Stg and performance traits in this study confirms that the staygreen phenotype is a useful trait for productivity enhancement in hot-irrigated environments.
持绿性状与面包小麦的耐热性相关。在全基因组中鉴定出了与持绿及相关性状相关的数量性状基因座（QTL），这些基因座与热胁迫下植物表现相关的农艺和生理性状共定位。植物叶绿素保留——持绿——被认为是热胁迫下的一个重要性状。利用Seri/Babax小麦作图群体在墨西哥炎热灌溉环境下进行了五项试验。在植物生长期间定期测量归一化植被指数（NDVI）并进行建模，以捕捉植物绿度衰减的动态变化，包括生理成熟期的持绿（Stg），通过灌浆期NDVI的回归来估计。还根据NDVI测量值估算了衰老速率、植物绿度衰减百分比和曲线下面积。虽然Stg和最佳拟合曲线高度依赖环境，但这两个性状与产量、灌浆速率和延长的灌浆期均表现出强相关性（Stg为正相关），而与粒数和粒重的相关性较弱。Stg表达在很大程度上取决于衰老速率，衰老速率与绿度衰减曲线模式和初始NDVI有关。QTL分析揭示了在不同环境中共有44个与Stg及相关性状相关的基因座，分布在整个基因组中，在1B、2A、2B、4A、4B和7D染色体上检测到的效应最强且最具重复性。其中，一些与控制物候的区域相同，但也鉴定出了独立区域。本研究中Stg和性能性状QTL的共定位证实，持绿表型是在炎热灌溉环境下提高生产力的一个有用性状。
