Chakraborty Animikha, Viswanath Aswini, Malipatil Renuka, Rathore Abhishek, Thirunavukkarasu Nepolean
Genomics and Molecular Breeding Lab, Indian Council of Agricultural Research-Indian Institute of Millets Research, Hyderabad, India.
Statistics, Bioinformatics and Data Management, International Crops Research Institute for the Semi-Arid Tropics, Hyderabad, India.
Front Genet. 2020 Dec 8;11:608421. doi: 10.3389/fgene.2020.608421. eCollection 2020.
Millets are the strategic food crops in arid and drought-prone ecologies. Millets, by virtue of nature, are very well-adapted to drought conditions and able to produce sustainable yield. Millets have important nutrients that can help prevent micro-nutrient malnutrition. As a result of the adverse effect of climate change and widespread malnutrition, millets have attained a strategic position to sustain food and nutritional security. Although millets can adapt well to the drought ecologies where other cereals fail completely, the yield level is very low under stress. There is a tremendous opportunity to increase the genetic potential of millet crops in dry lands when the genetics of the drought-tolerance mechanism is fully explained. MicroRNAs (miRNAs) are the class of small RNAs that control trait expression. They are part of the gene regulation but little studied in millets. In the present study, novel miRNAs and gene targets were identified from the genomic resources of pearl millet, sorghum, foxtail millet, finger millet, and proso millet through approaches. A total of 1,002 miRNAs from 280 families regulating 23,158 targets were identified using different filtration criteria in five millet species. The unique as well as conserved structural features and functional characteristics of miRNA across millets were explained. About 84 miRNAs were conserved across millets in different species combinations, which explained the evolutionary relationship of the millets. Further, 215 miRNAs controlling 155 unique major drought-responsive genes, transcription factors, and protein families revealed the genetics of drought tolerance that are accumulated in the millet genomes. The miRNAs regulating the drought stress through specific targets or multiple targets showed through a network analysis. The identified genes regulated by miRNA genes could be useful in developing functional markers and used for yield improvement under drought in millets as well as in other crops.
粟类作物是干旱和易干旱生态环境中的战略粮食作物。粟类作物天生非常适应干旱条件，能够实现可持续产量。粟类作物含有重要营养成分，有助于预防微量营养素营养不良。由于气候变化的不利影响和普遍存在的营养不良现象，粟类作物在维持粮食和营养安全方面已占据战略地位。尽管粟类作物能很好地适应其他谷类作物完全无法生长的干旱生态环境，但在胁迫条件下产量水平很低。当耐旱机制的遗传学得到充分解释时，提高旱地粟类作物遗传潜力的机会巨大。微小RNA（miRNA）是一类控制性状表达的小RNA。它们是基因调控的一部分，但在粟类作物中的研究很少。在本研究中，通过多种方法从珍珠粟、高粱、谷子、黍稷和黍的基因组资源中鉴定出了新的miRNA和基因靶点。使用不同的筛选标准在5种粟类作物中总共鉴定出了来自280个家族的1002个miRNA，它们调控着23158个靶点。解释了粟类作物中miRNA独特以及保守结构特征和功能特性。在不同物种组合的粟类作物中约有84个miRNA是保守的，这解释了粟类作物的进化关系。此外，215个调控155个独特的主要干旱响应基因、转录因子和蛋白质家族的miRNA揭示了粟类作物基因组中积累的耐旱遗传学。通过网络分析展示了通过特定靶点或多个靶点调控干旱胁迫的miRNA。鉴定出的受miRNA基因调控的基因可用于开发功能标记，并用于提高粟类作物以及其他作物在干旱条件下的产量。
