Xu Yunbi, Li Ping, Zou Cheng, Lu Yanli, Xie Chuanxiao, Zhang Xuecai, Prasanna Boddupalli M, Olsen Michael S
Institute of Crop Science, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
International Maize and Wheat Improvement Center (CIMMYT), El Batan, Texcoco, CP 56130, México.
J Exp Bot. 2017 May 17;68(11):2641-2666. doi: 10.1093/jxb/erx135.
As one of the important concepts in conventional quantitative genetics and breeding, genetic gain can be defined as the amount of increase in performance that is achieved annually through artificial selection. To develop pro ducts that meet the increasing demand of mankind, especially for food and feed, in addition to various industrial uses, breeders are challenged to enhance the potential of genetic gain continuously, at ever higher rates, while they close the gaps that remain between the yield potential in breeders' demonstration trials and the actual yield in farmers' fields. Factors affecting genetic gain include genetic variation available in breeding materials, heritability for traits of interest, selection intensity, and the time required to complete a breeding cycle. Genetic gain can be improved through enhancing the potential and closing the gaps, which has been evolving and complemented with modern breeding techniques and platforms, mainly driven by molecular and genomic tools, combined with improved agronomic practice. Several key strategies are reviewed in this article. Favorable genetic variation can be unlocked and created through molecular and genomic approaches including mutation, gene mapping and discovery, and transgene and genome editing. Estimation of heritability can be improved by refining field experiments through well-controlled and precisely assayed environmental factors or envirotyping, particularly for understanding and controlling spatial heterogeneity at the field level. Selection intensity can be significantly heightened through improvements in the scale and precision of genotyping and phenotyping. The breeding cycle time can be shortened by accelerating breeding procedures through integrated breeding approaches such as marker-assisted selection and doubled haploid development. All the strategies can be integrated with other widely used conventional approaches in breeding programs to enhance genetic gain. More transdisciplinary approaches, team breeding, will be required to address the challenge of maintaining a plentiful and safe food supply for future generations. New opportunities for enhancing genetic gain, a high efficiency breeding pipeline, and broad-sense genetic gain are also discussed prospectively.
作为传统数量遗传学和育种中的重要概念之一，遗传增益可定义为通过人工选择每年实现的性能提升量。为了开发满足人类日益增长需求的产品，特别是在食品、饲料以及各种工业用途方面，育种者面临着不断以更高速度提升遗传增益潜力的挑战，同时缩小育种者示范试验中的产量潜力与农民田间实际产量之间仍存在的差距。影响遗传增益的因素包括育种材料中可用的遗传变异、目标性状的遗传力、选择强度以及完成一个育种周期所需的时间。通过提升潜力和缩小差距可以提高遗传增益，这一过程随着现代育种技术和平台的发展而不断演变和完善，主要由分子和基因组工具驱动，并结合改进的农艺实践。本文综述了几种关键策略。通过分子和基因组方法，包括突变、基因定位与发现、转基因和基因组编辑，可以解锁和创造有利的遗传变异。通过控制良好且精确测定环境因素或环境分型来优化田间试验，特别是为了理解和控制田间水平的空间异质性，可以提高遗传力估计。通过提高基因分型和表型分析的规模和精度，可以显著提高选择强度。通过标记辅助选择和双单倍体发育等综合育种方法加速育种程序，可以缩短育种周期时间。所有这些策略都可以与育种计划中其他广泛使用的传统方法相结合，以提高遗传增益。需要更多跨学科方法，即团队育种，来应对为子孙后代维持充足且安全的粮食供应这一挑战。还前瞻性地讨论了提高遗传增益的新机会、高效育种流程以及广义遗传增益。
