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Biology and Biotechnology of Environmental Stress Tolerance in Plants, Volume 3

Oladzad and coworkers (2019) conducted a single and multiple-trait

GWAS in which four genes associated with production traits have been

identified common bean in relation to abiotic stress (heat and drought).

Nucleotide polymorphism found within or in the nearby candidate genes

which were related to the signaling and detoxification of ROS were identified

which can further be used in the breeding of common bean. Brassica juncea

has been studied for terminal heat stress (THS) using GWAS as to improve

productivity in the changing climatic conditions. A total of 491 genotypes

were accessed for the study to understand the variations under natural heat

stress conditions. 18,258 SNPs were identified from 71 genotypes after the

filtration process. Later, 24 SNPs under THS were identified which were

associated with traits related to seed yield. This was the first reported study

in which 24 marker traits were recognized under terminal heat stress condi­

tion (Sandhu et al., 2019).

GWAS was employed in the identification of two new loci responsible for

photosynthetic traits which is associated with the efficiency of phosphorus

(P) in soybean. As P is important for plant’s growth and development, it plays

a vital role in acquiring energy, enzyme regulation and yield. Therefore, soil

with Pdeficiency inhibits the production and yield of any crop. To evaluate the

efficiency of P, 219 soybean accessions from three environments were taken.

As a result, 30 notable SNPs found in 14 different regions of the genome

were observed which were associated with traits related to photosynthesis.

The observation was done under different phosphorous levels (Yang et al.,

2020). Similarly, deficiency of sulfur is one of the main causes in reduc­

tion of grain quality and yield in rice. Therefore, the genotypic variation

against resistance to sulfur deficiency has been assessed using GWAS and

loci associated with tolerance has been identified. The genes identified near

the loci associated were found in the coding of enzymes (sulfotransferases)

related to metabolic pathways, and also the role of sulfated compounds was

recognized against abiotic stress responses. Further, the haplotypes obtained

could make use in marker assisted breeding to develop cultivars that can

tolerate S-deficiency (Pariasca-Tanaka et al., 2020).

A transcriptome based GWAS analysis has been performed to understand

the traits involved in seminal root length under drought condition in the maize

seedlings. In this study, 209 maize accessions were taken under different

water conditions and as a result four traits associated with root and shoot

were evaluated. To identify the genes for drought response, the comparison

of transcriptome results of seminal roots for n four drought-sensitive and

drought-tolerant lines has been done under different water conditions. After