“Genetic Basis for Resistance to Abiotic Stress and Their Application in Plant Breeding”

UNIVERSITY OF AGRICULTURAL SCIENCES, BANGALORE

DEPARTMENT OF GENETICS AND PLANT BREEDING

SEMINAR – GPB 682 (0+1)

“Genetic Basis for Resistance to Abiotic Stress and Their Application in Plant Breeding”

The major challenges that agriculture is facing in the twenty-first century are increasing droughts, water scarcity, flooding, poorer soils, and extreme temperatures due to climate change. The aim in the near future, in a world with hunger and an increasing population, is to breed and/or engineer crops to tolerate abiotic stress with higher yield. Some crop varieties display a certain degree of tolerance, which has been exploited by plant breeders to develop varieties that thrive under stress conditions. Moreover, a long list of genes involved in abiotic stress tolerance has been identified and characterized by molecular techniques and overexpressed individually in plant transformation experiments. Stress tolerance phenotypes are being dissected by modern genomic technologies to accelerate genetic introgression utilizing molecular markers or site-directed mutagenesis, such as CRISPR-Cas9³.

Developing a rice variety with inherent tolerance against these major abiotic stresses will help achieve a sustained increase in rice production under unfavorable conditions. A marker-assisted backcross breeding method was used to introgress major effect quantitative trait loci (QTLs) conferring tolerance against drought (qDTY1.1, qDTY2.1), salinity (Salttol), and submergence (Sub1) into the genetic background of the well-known rice variety Improved White Ponni (IWP)². The complex nature of abiotic stresses and variability in plants’ sensitivity to different stresses during their life cycle further complicate the selection criteria for increased stress tolerance in conventional breeding. Genetic engineering is an alternative strategy that could be employed to improve abiotic stress tolerance and enhance crop yield and quality.

The discovery of ZmSNAC13 gene in drought-tolerant maize lines and its overexpression in Arabidopsis led to enhanced tolerance to salt and drought stresses, as evidenced by a reduction in the water loss rate and increased cell membrane stability in leaves. It also promoted the expression of stress-responsive genes such as PYL9 and DREB3, thereby enhancing tolerance to adverse environments¹.

It is essential to increase agricultural plants’ resilience to stresses, as well as their yield and survival. Hence, it is crucial to understand and identify the factors that affect abiotic stress tolerance in cereals. The emergence of functional tools like marker-assisted selection (MAS) and gene editing tools such as CRISPR/Cas9 have assisted researchers in unraveling the underlying mechanisms of stress tolerance in plants. The application of genes and QTLs in cereals that impart abiotic stress resistance helps increase yield under stress.

REFERENCES

1. Luo, P., Chen, Y., Rong, K., Lu, Y., Wang, N., Xu, Z., Pang, B., Zhou, D., Weng, J., Li, M. and Zhang, D., 2022. ZmSNAC13, a maize NAC transcription factor conferring enhanced resistance to multiple abiotic stresses in transgenic Arabidopsis. Plant Physiol. Biochem., 170: 160–170.

2. Muthu, V., Abbai, R., Nallathambi, J., Rahman, H., Ramasamy, S., Kambale, R., Thulasinathan, T., Ayyenar, B. and Muthurajan, R., 2020. Pyramiding QTLs controlling tolerance against drought, salinity, and submergence in rice through marker-assisted breeding. PLoS One, 15(1): 0227421.

3. Villalobos-Lopez, M.A., Arroyo-Becerra, A., Quintero-Jimenez, A. and Iturriaga, G., 2022. Biotechnological advances to improve abiotic stress tolerance in crops. Int. J. Mol. Sci., 23: 12053.