Diversity & Stress Response in Aromatic Short-Grain Rice Landraces

Megha Saha, Amity University Kolkata

Brief

Highlighted in this writeup is a paper that discusses the physiological responses and genetic diversity found among various aromatic short-grain rice varieties in the Northern Eastern Ghats region of India (Behera et al., 2023). The ever-expanding population’s consumption demands necessitated a substantial increase in rice production. However, adverse changes in climate and pollution have significantly heightened the incidence of abiotic stresses, such as drought, salt, and flooding. As a result, the loss of over 50% in rice volume has greatly affected rice production, particularly in rainfed lands.

Rice has now become the target crop for various stress enhancement programs, aiming to increase productivity through the environmentally effective and economically efficient broad-spectrum genetic resistance to multiple stresses. Recent studies have reported the successful pyramiding of QTLs for multiple traits within the genetic backgrounds of widely cultivated rice varieties. However, researchers have noticeably lacked dedication to investigating the genetic variants associated with tolerance to multiple abiotic stresses in landraces of aromatic rice. The aim of this study, conducted by Behera et al. (2023), was to address this research gap.

Pre-requisite research available on aromatic short-grain rice vs. non-scented rice

Aromatic short-grain rice features natural chemical compounds which give it a distinctive aroma. It can be used just like conventional rice for cooking but adds a new dimension of flavour and flamboyance to meals. Aromatic rice has significantly higher demand because of its unique characteristics like smell, taste and quality. Yet, scented rice cultivators are comparatively low yielders and exposure to abiotic stresses such as salinity, flooding, and drought further leads to an impact that is much worse in comparison as well.

For the past few decades, advancements in the identification of tolerant lines to single abiotic stresses, for example N22 for drought resistance, flood tolerance contributed by FR13A, Pokkali as parental for salt stress resistance, etc., has shown promising results against such adversities. However, despite the economic and cultural significance of these rice genotypes, there is a lack of sufficient data on molecular characterizations related to their genetic improvement, particularly in terms of stress tolerance. The lack of well-defined knowledge regarding this aspect necessitated the design of this study by the respective authors. The study aims to determine the physiological response profile and genetic diversity among short grain aromatic rice varieties. The acquired knowledge will be indispensable for further research involving genetic engineering, such as the creation of transgenics and the utilization of other novel methods, to develop rice varieties with multiple resistances.

Outcomes of analyses

After examining the results of the various plant profiles, the scientists reported that drought, salt, flooding stress, etc., caused a significant reduction in plant biomass, relative growth index (RGI), relative water content (RWC), leaf photosynthesis, PSII activity, and SPAD relative index. The susceptible IR64 variety exhibited a more pronounced effect. The scientists utilized 32 SSR primers to help them utilize molecular markers associated with abiotic stress QTLs for the characterization of 21 rice genotypes. The photosynthetic rate was much better for the stress tolerant varieties (N22, Pokkali and FR 13A) in comparison to other genotypes. The scientists conducted cluster analysis to analyze the profiles of the aromatic landraces regarding their multiple stress tolerances, using N22, Pokkali, and FR 13A as references for their respective stress tolerances.

The scientists performed statistical analysis to determine the variation among growth and physiological variables. The analysis revealed a high genetic dissimilarity score, indicating an increased genetic diversity among the population. Additionally, structure analysis demonstrated a broad genetic base (K). It is widely recognized that a more diverse population leads to a higher k value. The rice landraces exhibiting various abiotic stress tolerances can be utilized as parental materials, contributing to the management of rice production in diverse climates. The encountered genetic forms in these genotypes hold potential for germplasm preservation and have an overall impact.

Also read: Bioinformatics for Beginners: A Beginner’s Guide to Analyzing Biological Data

Reference:

Behera, P. K., Kumar, V., Sharma, S. S., Lenka, S. K., & Panda, D. (2023). Genotypic diversity and abiotic stress response profiling of short-grain aromatic landraces of rice (Oryza sativa l. Indica). Current Plant Biology, 33, 100269. https://doi.org/10.1016/j.cpb.2022.100269

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