The research progress of indica adaptation to low-temperature adversity mechanism.

Low temperature seriously affects the geographical distribution, growth and production of rice.
in recent years, the number of extreme weather has increased frequently, and the number of low-temperature disasters such as cold spring and cold wind has increased year by year.
annual food losses caused by low temperatures in China amount to 3-500 million tons, seriously affecting food supply.
Asian cultivated rice (commonly known as rice) is divided into two subspecies: indica and indica.
generally speaking, indica is grown mainly in tropical and subtropical regions, while indica is grown in temperate regions because it has greater low temperature tolerance than indica.
with the continuous northward migration of rice-growing areas, it is of great theoretical and practical significance to reveal the molecular mechanism of adapting to the low temperature environment in the process of indica domestication, which is of great theoretical and practical significance for cultivating low-temperature tolerable rice varieties in high-latitude high altitude areas.
plants to respond to external adverse environments such as low temperature and mainly through two major types of genes.
the first category is functional genes, such as osmosis protector synthase, molecular companion class and antioxidant enzymes and other genes, its products in plants encounter low temperature and other adversity can directly protect the biological macromolecules and biofilms in plant cells;
that is, a regulatory gene can regulate many functional genes of correlation, so that plants can cope more effectively with adverse environments.
many of the key genes or quantitative traits (QTLs) that control the importance of the character is mostly regulatory genes of the code transcription factor class.
Therefore, starting with the regulation of genes, mining resources to control the excellent ethnostle variation of important agronomic traits in the resource group is of great significance in crop breeding improvement, and is also the focus of scientists and breeding companies for a long time.
Over the past 100 years, the U.S. Department of Agriculture (USDA) has collected more than 18,000 diverse rice resources from 116 countries and territories around the world, and compiled 203 mini-core seed samples based on phetype and genotype data.
genetic analysis shows that these 203 micro-core seed can be a good representative of the genetic diversity of cultivated rice in the world, therefore, micro-core seed is the mining of important functional genes of genetic resources.
2016, Wang Hongru, Ph.D., of the Institute of Genetics and Developmental Biology of the Chinese Academy of Sciences, and HuaDa Gene, in collaboration, completed the genome resequencing of rice micro-core seed materials, and systematically studied the group structure of Asian rice, successfully conducting the whole genome association analysis of important agronomic traits (GWAS Plant, 2016) through this diverse small group.
In view of the key role of transcription factors in regulating important agronomic traits, especially the role of bZIP transcription factors in low temperature tolerance, the project group Liu Tsitao, etc. through the rice micro-core seed group to identify low temperature tolerance, and low temperature tolerance with 91 bZIP The amino acid sequence of transcription factors was analyzed, the correlation analysis was carried out in combination with the methods of population genetics and evolutionary biology, and a low-temperature gene of indica resistance , bZIP73, which was associated with the low temperature tolerance of the seedling period and was strongly selected in evolution, was analyzed.
bZIP73 gene coding region, location 511 single nucleotide polymorphism (SNP) (SPs), (511 bp, G. A; 171 aa, Glu?gt; Lys) determines the difference in tolerance between differentiation and low temperature.
genetically modified and near-ethogenic gene lines have proved that the indica type bZIP73Ind is sensitive to low temperature. Further studies
show editing that bZIP73Jap increases rice resistance to low temperatures by interimposing with another bZIP protein (bZIP71) to regulate the levels of plant hormone shedding acid (ABA) and reactive oxygen (ROS) in rice (Figure 1). Further analysis of the genome sequence of wild rice population by Shujun in
area found that bZIP73 may have been artificially selected as early as the rice ancestors, and the frequency of cold-resistant alleles (bZIP73Jap) increased rapidly in indica, indicating that the cold-resistant alleles were favored in indica domestication (Figure 1).
combined with these wild rice distribution areas, the team found only indica-type bZIP73Jap (G) in wild rice resources in southern China, while in-wild rice in India, Bangladesh and the western part of the Central and Southern Peninsula spour spent both indica and indica-type bZIP73.
most interestingly, combined with the analysis of average surface temperature data over the period 1960-1990, it was found that the main distribution area of individual sutone-containing bZIP73Ind (A) in the wild rice population was significantly related to surface temperature, indicating that the indica type bZIP73Jap had a significant correlation with the northward shift of indica (Figure 2).
Figure 2. Geographical distribution of two different types of bZIP73 in ordinary wild rice (O. rufipogon).
blue and green dots represent wild rice distribution areas containing indica type bZIP73Jap (G) and indica-containing bZIP73Ind (A) respectively.
heat map shows the average surface temperature from 1960 to 1990 for 30 years.
it can be found that the main distribution area of wild rice containing indica type bZIP73Ind (A) is separated by dotted lines and related to surface temperature, indicating that the indica type bZIP73Jap has a significant correlation with the northward shift of indica.
Copyright ESRI.
at the same time, the study found that the non-cold-resistant indica allele gene bZIP73Ind (A) was also significantly artificially selected during the domestication of indica, but the cause was not yet clear (Figure 1).
the results of this study show that bZIP73Jap and bZIP71 are important for the improvement of low temperature tolerance of southern indica varieties and the northward migration of rice growing areas. On August 17,
, Nature Communications published its findings online (DOI: 10.1038/s41467-018-05753-w).
Liu Tsitao and District Shujun are the co-authors of the paper, Wang Xiping, a professor at Beijing Normal University, and A. Tsu-cheng, a researcher at the Institute of Genetic Development, are co-authors of the paper.
the research was funded by the NSFC project.
.