Genetic architecture of inducible and constitutive metabolic profile related to drought resistance in qingke (Tibetan hulless barley)

Abstract

Qingke (Tibetan hulless barley, Hordeum vulgare L. var. nudum) is the primary food crop on the Tibet Plateau, the long-term drought and other harsh environments makes qingke an important resource for the study of abiotic resistance. Here, we evaluated the drought sensitivity of 246 qingke varieties. Genome-wide association studies (GWAS) found that root-specific expressed gene CYP84 may be involved in the regulation of drought resistance. Based on widely targeted metabolic profiling, we identified 2,769 metabolites in qingke leaves, of which 302 were significantly changed in response to drought stress, including 4-aminobutyric acid (GABA), proline, sucrose and raffinose. Unexpectedly, these drought-induced metabolites changed more violently in drought-sensitive qingkes, while the constitutive metabolites that had little response to drought stress, such as C-glycosylflavonoids and some amino acids, accumulated excessively in drought-resistant qingkes. Combined with metabolite-based genome-wide association study (mGWAS), a total of 1,006 metabolites under optimal condition and 1,031 metabolites under mild drought stress had significant associated loci. As a marker metabolite induced by drought stress, raffinose was significantly associated with two conservatively adjacent α-galactosidase genes, qRT-PCR suggests that these two genes may jointly regulate the raffinose content in qingke. Besides, as constituent metabolites with stable differences between drought-sensitive and drought-resistant qingkes, a class of C-glycosylflavonoids are simultaneously regulated by a UDP-glucosyltransferase gene. Overall, we performed GWAS for sensitivity and widely targeted metabolites during drought stress in qingke for the first time, which provides new insights into the response mechanism of plant drought stress and drought resistance breeding.

Advances in Crop Genetic Improvement to Overcome Drought Stress: Bibliometric and Meta-Analysis

“…These plant response mechanisms are the basis of breeding research that seeks resistance/tolerance to drought stress in crops, providing plants with changes in physiological, biochemical, and adaptive parameters [1,5].…”

“…Among the studies dealing with gene expression, ref. [1] reported finding five genes related to resistance to water stress, being directly associated with proteins responsible for oxidizing a large number of substances CYP450; HORVU2Hr1G092360; HORVU2Hr1G092370; HORVU2Hr1G092390; HORVU2Hr1G092380; HORVU2Hr1G092400.…”

“…In addition, genome resequencing and SNP calling were detected in the CYP450 gene promoter. The genes of the CYP450 family contribute to improving resistance to water stress in plants since they actively participate in the production of various natural compounds produced by plants to protect them from abiotic and biotic stresses [1,53].…”

“…Drought-tolerant crops are of paramount importance in a worldwide scenario of increased food demand caused by the growth of the human population [1]. Drought is one of the most frequent stresses in several parts of the world, affecting many agricultural species, reducing photosynthesis, and favoring the accumulation of reactive oxygen species (ROS) and the occurrence of cell membrane damage, significantly reducing the yield and quality of agricultural products [2,3].…”

“…From this perspective, the search for advances in breeding programs aimed at resistance to drought stress in agricultural crops is a path that should be pursued with greater emphasis. Breeding programs have been working with different crops and mechanisms to investigate resistance to drought stress, including gene expression, genetically modified organisms, plant hormones, biostimulants, and the identification of genes that confer resistance in crops such as corn, soybean, cotton, rice, wheat, common bean, sugarcane, and tomato, among others [1,4,[7][8][9][10][11][12][13][14][15][16][17].…”