Generation of High-Value Genomic Resource in Rice: A “Subgenomic Library” of Low-Light Tolerant Rice Cultivar Swarnaprabha

SIMPLE SUMMARY: The present investigation into the “Generation of high-value genomic resource in rice cultivar Swarnaprabha” was carried out to isolate the phytochrome photoreceptors from low-light tolerant cultivar of rice. Two contrasting cultivars of rice (IR-64 and Swarnaprabha) were grown under low-light conditions to note the morphological differences in their responses to low-light. Based on the growth of the plants, they were confirmed to be tolerant (Swarnaprabha) and susceptible (IR-64) to light intensity. To investigate the molecular basis of low-light tolerance, the tolerant cultivar was used to construct a subgenomic library. Sixty-six clones from the library were randomly screened for the presence of genomic fragments and were found to be recombinant. Further, the constructed Swarnaprabha library is a valuable genomic resource for Gramineae community users, and it can be used as an important resource for understanding the molecular basis of the variation in the response to low-light among the photosensitive cultivars of rice. All the clones of the generated library were stored long-term to isolate and characterize the phytochromes and other intrinsic yield genes involved in the shade-avoidance response (SAR) in rice. ABSTRACT: Rice is the major staple food crop for more than 50% of the world’s total population, and its production is of immense importance for global food security. As a photophilic plant, its yield is governed by the quality and duration of light. Like all photosynthesizing plants, rice perceives the changes in the intensity of environmental light using phytochromes as photoreceptors, and it initiates a morphological response that is termed as the shade-avoidance response (SAR). Phytochromes (PHYs) are the most important photoreceptor family, and they are primarily responsible for the absorption of the red (R) and far-red (FR) spectra of light. In our endeavor, we identified the morphological differences between two contrasting cultivars of rice: IR-64 (low-light susceptible) and Swarnaprabha (low-light tolerant), and we observed the phenological differences in their growth in response to the reduced light conditions. In order to create genomic resources for low-light tolerant rice, we constructed a subgenomic library of Swarnaprabha that expedited our efforts to isolate light-responsive photoreceptors. The titer of the library was found to be 3.22 × 10(5) cfu/mL, and the constructed library comprised clones of 4–9 kb in length. The library was found to be highly efficient as per the number of recombinant clones. The subgenomic library will serve as a genomic resource for the Gramineae community to isolate photoreceptors and other genes from rice.