Plants respond to various stresses during their lifecycle among which abiotic stress is the most severe one comprising heat, cold, drought, salinity, flooding, etc. which take a heavy toll on crop yield worldwide in every corresponding year. ROS has a dual role in abiotic stress mechanisms where, at high levels, they are toxic to cells while at the same time, the same molecule can function as a signal transducer that activates a local as well as a systemic plant defense response against stress. The most common ROS species are Hydrogen peroxide (H2O2), Superoxide anions (O2-), Hydroxyl radicals (OH-), and Singlet oxygen (1O2) which are results of physiological metabolism often controlled by enzymatic and non-enzymatic antioxidant defense systems. ROS generally accumulate in plants during abiotic and biotic stress conditions resulting in oxidative damage which ultimately leads to programmed cell death. Many ROS scavenging pathways have been well studied against stress responses. Through careful manipulation of ROS levels in plants, we can enhance stress tolerance in plants under unfavorable environmental conditions. This chapter presents an overview of ROS regulation in plants and the essential enzymes involved in the abiotic stress tolerance mechanisms which are thoroughly discussed below.
Seventy five crosses of Indian mustard [Brassica juncea (L.) Czern & Coss] generated by crossing of fifty lines with five testers in a line x tester mating design, which were used to estimate the standard heterosis potentiality for seed yield, its component traits and oil content. These parents, crosses and checks were sown in randomized complete block design under four environments each replicated thrice at two different locations. Observations were recorded on thirteen different characters. Standard heterosis was estimated on the basis of best check PUSA BOLD for these characters based on the pooled data over environments. The maximum values of standard heterosis recorded were 47.87% for seed yield per plant. The highest value of standard heterosis in case of yield components was 41.43% for harvest index; 34.01% for number of primary branches per plant; 31.59% for number of siliqua per plant; 27.03% for biological yield; 25.92% for 1000-seed weight; 18.12% for number of seeds per siliqua; 17.21% for siliqua length; 13.79% for number of secondary branches per plant; 6.95% for plant height; -17.00% for days to 50% flowering and -8.85% for days to maturity. Standard heterosis results revealed that few hybrids viz., RH-30 x RGN-298, RL-1359 x RGN-298 and PBR-378 x Bio-902 were shown significant standard heterosis results for 10 or more characters towards desirable direction. The best three hybrids for seed yield per plant were Kranti x RGN-298 (47.87%), RL-1359 x RGN-298 (47.53%) and Kranti x RH-749 (43.98%).
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.