Biswas Dilip K, Coulman Bruce, Biligetu Bill, Fu Yong-Bi
Department of Plant Sciences, University of Saskatchewan, Saskatoon, SK, Canada.
Plant Gene Resources of Canada, Saskatoon Research and Development Centre, Agriculture and Agri-Food Canada, Saskatoon, SK, Canada.
Front Plant Sci. 2020 Jan 15;10:1673. doi: 10.3389/fpls.2019.01673. eCollection 2019.
Breeding forage crops for high yields of digestible biomass along with improved resource-use efficiency and wide adaptation is essential to meet future challenges in forage production imposed by growing demand, declining resources, and changing climate. Bromegrasses ( spp.) are economically important forage species in the temperate regions of world, but genetic gain in forage yield of bromegrass is relatively low. In particular, limited breeding efforts have been made in improving abiotic stress tolerance and resource-use efficiency. We conducted a literature review on bromegrass breeding achievements and challenges, global climate change impacts on bromegrass species, and explored the feasibility of applying high-throughput imaging phenotyping techniques and genomic selection for further advances in forage yield and quality selection. Overall genetic gain in forage yield of bromegrass has been low, but genetic improvement in forage yield of smooth bromegrass ( Leyss) is somewhat higher than that of meadow bromegrass ( Rehm). This low genetic gain in bromegrass yield is due to a few factors such as its genetic complexity, lack of long-term breeding effort, and inadequate plant adaptation to changing climate. Studies examining the impacts of global climate change on bromegrass species show that global warming, heat stress, and drought have negative effects on forage yield. A number of useful physiological traits have been identified for genetic improvement to minimize yield loss. Available reports suggest that high-throughput imaging phenotyping techniques, including visual and infrared thermal imaging, imaging hyperspectral spectroscopy, and imaging chlorophyll fluorescence, are capable of capturing images of morphological, physiological, and biochemical traits related to plant growth, yield, and adaptation to abiotic stresses at different scales of organization. The more complex traits such as photosynthetic radiation-use efficiency, water-use efficiency, and nitrogen-use efficiency can be effectively assessed by utilizing combinations of imaging hyperspectral spectroscopy, infrared thermal imaging, and imaging chlorophyll fluorescence techniques in a breeding program. Genomic selection has been applied in the breeding of forage species and the applications show its potential in high ploidy, outcrossing species like bromegrass to improve the accuracy of parental selection and improve genetic gain. Together, these new technologies hold promise for improved genetic gain and wide adaptation in future bromegrass breeding.
培育高产可消化生物量、提高资源利用效率并具有广泛适应性的饲料作物，对于应对未来饲料生产面临的增长需求、资源减少和气候变化等挑战至关重要。雀麦属植物是世界温带地区重要的经济饲料作物，但雀麦属植物的饲料产量遗传增益相对较低。特别是，在提高非生物胁迫耐受性和资源利用效率方面的育种工作有限。我们对雀麦属植物的育种成就和挑战、全球气候变化对雀麦属植物的影响进行了文献综述，并探讨了应用高通量成像表型技术和基因组选择在饲料产量和品质选择方面取得进一步进展的可行性。总体而言，雀麦属植物饲料产量的遗传增益较低，但无芒雀麦（Bromus inermis Leyss）的饲料产量遗传改良略高于草地雀麦（Bromus riparius Rehm）。雀麦属植物产量的这种低遗传增益归因于一些因素，如遗传复杂性、缺乏长期育种工作以及植物对气候变化的适应性不足。研究全球气候变化对雀麦属植物影响的结果表明，全球变暖、热胁迫和干旱对饲料产量有负面影响。已确定了一些有用的生理性状用于遗传改良，以尽量减少产量损失。现有报告表明，高通量成像表型技术，包括视觉和红外热成像、成像高光谱光谱学和成像叶绿素荧光，能够在不同组织尺度上捕捉与植物生长、产量和对非生物胁迫适应性相关的形态、生理和生化性状的图像。通过在育种计划中结合使用成像高光谱光谱学、红外热成像和成像叶绿素荧光技术，可以有效评估光合辐射利用效率、水分利用效率和氮利用效率等更复杂的性状。基因组选择已应用于饲料作物育种，其应用显示出在高倍体、异交物种如雀麦属植物中提高亲本选择准确性和提高遗传增益的潜力。总之，这些新技术有望在未来的雀麦属植物育种中提高遗传增益并实现广泛适应性。
