Impact of Pre-Anthesis Drought Stress on Physiology, Yield-Related Traits, and Drought-Responsive Genes in Green Super Rice

Abstract

Optimum soil water availability is vital for maximum yield production in rice which is challenged by increasing spells of drought. The reproductive stage drought is among the main limiting factors leading to the drastic reduction in grain yield. The objective of this study was to investigate the molecular and morphophysiological responses of pre-anthesis stage drought stress in green super rice. The study assessed the performance of 26 rice lines under irrigated and drought conditions. Irrigated treatment was allowed to grow normally, while drought stress was imposed for 30 days at the pre-anthesis stage. Three important physiological traits including pollen fertility percentage (PFP), cell membrane stability (CMS), and normalized difference vegetative index (NDVI) were recorded at anthesis stage during the last week of drought stress. Agronomic traits of economic importance including grain yield were recorded at maturity stage. The analysis of variance demonstrated significant variation among the genotypes for most of the studied traits. Correlation and principal component analyses demonstrated highly significant associations of particular agronomic traits with grain yield, and genetic diversity among genotypes, respectively. Our study demonstrated a higher drought tolerance potential of GSR lines compared with local cultivars, mainly by higher pollen viability, plant biomass, CMS, and harvest index under drought. In addition, the molecular basis of drought tolerance in GSR lines was related to upregulation of certain drought-responsive genes including OsSADRI, OsDSM1, OsDT11, but not the DREB genes. Our study identified novel drought-responsive genes (LOC_Os11g36190, LOC_Os12g04500, LOC_Os12g26290, and LOC_Os02g11960) that could be further characterized using reverse genetics to be utilized in molecular breeding for drought tolerance.

Evaluation of Green Super Rice Lines for Agronomic and Physiological Traits under Salinity Stress

“…Crops are frequently faced with different biotic and abiotic stresses that limit their development, causing impressive decreases in farming production all over the world [ 25 , 39 , 40 ]. Plants are immobile and take essential nutrients, and water from the soil.…”

“…SSI was also used previously to calculate the stress susceptible index [ 69 , 70 ]. Previously it is reported that S3 is a drought-sensitive genotype [ 25 ]. In this study, we also found that S3 and S24 are salt-susceptible genotypes.…”

“…Twenty-two GSR lines reported previously [ 25 ] along with two local varieties (“IRRI 6 and Kissan Basmati”) were selected and screened for salinity tolerance under different conditions ( Supplementary Table S1 ). For this purpose, three experiments i.e., glasshouse screening, field evaluation, and molecular evaluation were performed to identify the salt-tolerant and salt-susceptible GSR lines and understand the genetic mechanism underlying the salt tolerance in rice.…”

“…SSI for grain yield was calculated by using the following equation. Y s and Y p is the yield under stress and control field conditions, respectively, while D is a stress intensity as described previously [ 25 ].…”

Physiological and molecular implications of multiple abiotic stresses on yield and quality of rice

“…Drought stress during grain filling stage increases the proportion of chalky grains ( Yang et al., 2018 ). The imposition of drought stress at the onset of anthesis for 30 days reduced the grain yield and harvest index of 25 rice genotypes, with reduced pollen fertility and test weight of grains for most genotypes, compared to irrigated conditions ( Ahmad et al., 2022 ). While leaf rolling is considered a defense mechanism against drought stress, its promptness correlated with anatomical traits rather than water deficit ( Nithya et al., 2021 .…”