Plant Defense Responses to Biotic Stress and Its Interplay With Fluctuating Dark/Light Conditions

Abstract

Plants are subjected to a plethora of environmental cues that cause extreme losses to crop productivity. Due to fluctuating environmental conditions, plants encounter difficulties in attaining full genetic potential for growth and reproduction. One such environmental condition is the recurrent attack on plants by herbivores and microbial pathogens. To surmount such attacks, plants have developed a complex array of defense mechanisms. The defense mechanism can be either preformed, where toxic secondary metabolites are stored; or can be inducible, where defense is activated upon detection of an attack. Plants sense biotic stress conditions, activate the regulatory or transcriptional machinery, and eventually generate an appropriate response. Plant defense against pathogen attack is well understood, but the interplay and impact of different signals to generate defense responses against biotic stress still remain elusive. The impact of light and dark signals on biotic stress response is one such area to comprehend. Light and dark alterations not only regulate defense mechanisms impacting plant development and biochemistry but also bestow resistance against invading pathogens. The interaction between plant defense and dark/light environment activates a signaling cascade. This signaling cascade acts as a connecting link between perception of biotic stress, dark/light environment, and generation of an appropriate physiological or biochemical response. The present review highlights molecular responses arising from dark/light fluctuations vis-à-vis elicitation of defense mechanisms in plants.

The Effect of Photoperiod on Necrosis Development, Photosynthetic Efficiency and ‘Green Islands’ Formation in Brassica juncea Infected with Alternaria brassicicola

“…However, a peak of jasmonic acid (JA), a hormone that is required in plant defence against necrotrophic fungi such as A. brassicicola, is observed in the middle of a light period in Arabidopsis [38]. Lack of a dark period may enhance plant resistance against A. brassicicola and also through extensive production of metabolites with antifungal properties, e.g., phenolic compounds or, characteristic for Brassicas, glucosinolates [39,40]. Glucosinolate biosynthesis is also regulated by light and it has been demonstrated that dark exposure decreases its content in Chinese cabbage seedlings [40,41].…”

“…Lack of a dark period may enhance plant resistance against A. brassicicola and also through extensive production of metabolites with antifungal properties, e.g., phenolic compounds or, characteristic for Brassicas, glucosinolates [39,40]. Glucosinolate biosynthesis is also regulated by light and it has been demonstrated that dark exposure decreases its content in Chinese cabbage seedlings [40,41]. Moreover, several phytopathogenic fungi, e.g., the necrotroph Botrytis cinerea, display a circadian rhythm, and light influences their development and stress responses [42,43].…”

Comparative Transcriptome Analysis Reveals Genetic Mechanisms of Sugarcane Aphid Resistance in Grain Sorghum

“…The seeds of both genotypes were planted in plastic cones (25 × 5 cm) in a greenhouse and transferred to a climate-controlled growth chamber at the two-leaf stage at Agricultural Research Center-Hays, Kansas State University. The climate-controlled growth chamber was set to 23 ± 1 • C and a 14:10 h (light:dark) daylength, conditions known to facilitate both plant growth and SCA survival and reproduction [20] and plant defense mechanisms [67]. Seedlings of both the R and S genotypes were each infested at the three-leaf stage with fivefourth instar SCA nymphs.…”

Novel Approach and Biological Techniques to Improve the Crop Yields under Stress Conditions

“…High temperature also damages the roots of plant cells by altering the cellular and molecular mechanisms. Visible symptoms appear on the roots as well as the damage leaves that ultimately suppress the seedling [9,10]. Elevated temperatures can reduce the germination potential of the seeds and, thus, results in poor germination and stand establishment.…”