Chakradhar Thammineni, Hindu Vemuri, Reddy Palakolanu Sudhakar
Sehgal Foundation, C/o International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru, Hyderabad, 502 324, Telangana, India.
Department of Biotechnology, Sri Padmavati Mahila Visvavidyalayam, Tirupati, Andhra Pradesh, India.
Genetica. 2017 Dec;145(6):525-539. doi: 10.1007/s10709-017-9981-y. Epub 2017 Sep 5.
Maize has traditionally been the main staple diet in the Southern Asia and Sub-Saharan Africa and widely grown by millions of resource poor small scale farmers. Approximately, 35.4 million hectares are sown to tropical maize, constituting around 59% of the developing worlds. Tropical maize encounters tremendous challenges besides poor agro-climatic situations with average yields recorded <3 tones/hectare that is far less than the average of developed countries. On the contrary to poor yields, the demand for maize as food, feed, and fuel is continuously increasing in these regions. Heterosis breeding introduced in early 90 s improved maize yields significantly, but genetic gains is still a mirage, particularly for crop growing under marginal environments. Application of molecular markers has accelerated the pace of maize breeding to some extent. The availability of array of sequencing and genotyping technologies offers unrivalled service to improve precision in maize-breeding programs through modern approaches such as genomic selection, genome-wide association studies, bulk segregant analysis-based sequencing approaches, etc. Superior alleles underlying complex traits can easily be identified and introgressed efficiently using these sequence-based approaches. Integration of genomic tools and techniques with advanced genetic resources such as nested association mapping and backcross nested association mapping could certainly address the genetic issues in maize improvement programs in developing countries. Huge diversity in tropical maize and its inherent capacity for doubled haploid technology offers advantage to apply the next generation genomic tools for accelerating production in marginal environments of tropical and subtropical world. Precision in phenotyping is the key for success of any molecular-breeding approach. This article reviews genomic technologies and their application to improve agronomic traits in tropical maize breeding has been reviewed in detail.
玉米一直是南亚和撒哈拉以南非洲的主要主食，数百万资源匮乏的小规模农民广泛种植。大约3540万公顷土地种植热带玉米，约占发展中世界的59%。热带玉米除了面临恶劣的农业气候条件外，还面临巨大挑战，其平均产量低于3吨/公顷，远低于发达国家的平均水平。与低产量相反，这些地区对玉米作为食物、饲料和燃料的需求却在不断增加。20世纪90年代初引入的杂种优势育种显著提高了玉米产量，但遗传增益仍然遥不可及，尤其是对于在边缘环境下种植的作物。分子标记的应用在一定程度上加快了玉米育种的步伐。一系列测序和基因分型技术的出现，通过基因组选择、全基因组关联研究、基于群体分离分析的测序方法等现代方法，为提高玉米育种计划的精度提供了无与伦比的服务。利用这些基于序列的方法，可以轻松识别复杂性状背后的优良等位基因并有效地导入。将基因组工具和技术与先进的遗传资源（如巢式关联作图和回交巢式关联作图）相结合，肯定能够解决发展中国家玉米改良计划中的遗传问题。热带玉米的巨大多样性及其在双单倍体技术方面的内在能力，为应用下一代基因组工具以加速热带和亚热带世界边缘环境下的产量提供了优势。表型分析的精确性是任何分子育种方法成功的关键。本文详细综述了基因组技术及其在改善热带玉米育种农艺性状方面的应用。
