Role of He-Ne laser pre-treatment in protecting Zea mays against the deleterious effects of ultraviolet radiations

Abstract

The current st udy aims to r ec ord the rol e of the pretreatment of Z ea m ays grains with a He-Ne las er in d amage rep air of ultr aviolet (UVA+B) radiati on eff ect. Plants wer e divided into f our groups; c ontrol group, group expos ed to t he He -Ne l aser onl y f or 1-300 sec onds, group expos ed t o U V A+ B only and protect ed group. In t he prot ect ed group the grains were tr eated with diff erent H e -Ne las er irradiation dur ation f or two w eeks t hen expos ed to 3. 6 and 7. 2 KJ m − 2 d −1 UVA+B radiation.Irradiation with H e-Ne las er significantl y (p ≤ 0.05) increas ed shoot length, number of l eav es, s hoot biomas s (week 1), root dr y w eight, c hl orophyll -a, chl orophyll -b, and t ot al c hlor ophyll . Sup eroxide free r adical, hydrogen peroxide and lipid peroxidation wer e decreas ed at l ow dos es and increas ed with higher dos es of las er. V arious d elet erious eff ects of ultravi olet r adiations w ere recorded in Zea m ays i ncluding decr eased phot os ynt hetic pigments, s hoot and root biomass, and root and shoot length. The pretreatm ent with a l aser bef ore expos ure t o UVA+B radiation c auses a slight i ncrease i n plant l engt h and t he number of leav es, an increase of r oot length, whil e a decreas e of shoot /root length and an i ncreas e i n l eaf paramet ers at s ome las er tr eatments wer e observed . T he res ults rev eal ed t hat the pretreatm ent of m aize grai ns wit h H e -N e laser dos es f or 10s to 300s allevi at ed the damaging eff ect s of U V-B radiati on in the range of 7.2 KJ m −2 d −1 UVA+B radiation. KEY WORDS:He-Ne las er, Ultravi olet r adiation, prot ectiv e role, pigments, oxidative stress, antioxidants, U V-B abs orbing compounds, flav onoids. I NTRODUCTI ON :Ultraviolet radiati ons (UV) ar e a nonionizing el ectrom agnetic spectr um t hat embraces about 8-9% of s ol ar energ y (Gill et al., 2015). O zone depleti on in the strat osphere has r esult ed in an increm ent i n ultravi olet-B irradiati on (UV-B ; 280-320 nm), which has pot entiall y destr uctiv e consequences for crop yield and production and aff ect nat ural environm ents (J ulkunenTiitto et al., 2005;Siipola et al ., 2015).Enhanc ed levels of ultravi olet r adiations trigger different str uct ural, p hysiol ogical and molec ular resp ons es i n plant s (Cas ati, 2003; Kum ari et al. , 2009; Sal ama et al. , 2011;Gill et al. , 2015). A higher d ose of UV-B prov ok es impairment and modific ation of macrom olec ules like DNA , RN A, and prot eins , decreas e net phot os ynthesis and adjust the activities of sev eral antioxidant enz ym es (Gill and T ut eja, 2010;Sharma et al., 2012). Nevert heless , plants hav e d evel oped v arious protectiv e strategies to m anage and withst and, agai nst high UV-B irradiation. The act ual accum ulation of U V -absorbing materi als c an cert ainl y help in the prev ention of U V penetrati on to vul ner able layers of the leaf . T his kind of c ompounds build -up withi n the upper epidermal l ayers of the leav es of sev eral higher plants purs uin...

Quantitative Determination of the Effects of He–Ne Laser Irradiation on Seed Thermodynamics, Germination Attributes and Metabolites of Safflower (Carthamus tinctorius L.) in Relation with the Activities of Germination Enzymes

“…During the germination process the newly developed seedling uses the stored reserves in seeds for the purpose of energy and building blocks. These include sugars and amino acids that fulfill the cellular energy demand, building blocks for structural purposes as well as the biosynthesis of secondary metabolites [23,24]. These all processes are dependent on the activities of specific enzymes.…”

“…Moreover, as the literature depicts, both the positive and negative influences of different types of lasers, including the He-Ne lasers, on seed treatment for seed germination and seedling emergence are due to laser type, dose of applied laser and specific plant species. However, these laser-energy induced processes are laser-energy dose dependent [23,24].…”

Effect of Laser Biostimulation on Germination of Sub-Optimally Stored Flaxseeds (Linum usitatissimum)

“…That could mainly be attributed to the synergistic effect of various simultaneous bio-physico-chemical actions by the cotyledon and endosperm cells inside the seeds upon the absorption of laser light [8,9]. The previous studies evidenced that laser light may increase cells' mitochondria membrane potential, cyclic adenosine monophosphate (cAMP), and adenosine triphosphate (ATP), modify cells' reactive oxygen, affect cell divisions, and induce transcription factors [30]. It is speculated that the aforementioned actions could result in enhanced chlorophyll, carotenoid, and mineral contents [8,9], modifications of genes/activity of various enzymatic/non-enzymatic antioxidants, including, but not limited to, superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), ascorbate peroxidase (APX), ascorbate acid (AsA), glutathione (GSH), and phenylalanine ammonia-lyase (PAL) [8,9,24,25,28,32].…”

“…The effect of laser biostimulation on enhancing the growth characteristics of various seeds has already been demonstrated, such as wheat [10][11][12], pea [13], eggplant [14][15][16], radish seeds [17], sunflower [18], soybean [19,20], white lupine, faba bean [21], tomato [22], alfalfa [23], etc. In addition, plant tolerance to biotic and abiotic stresses has also been shown to be enhanced through laser treatment [24][25][26][27][28][29][30][31][32]. In the majority of reported studies, a He-Ne gas laser has been used as the laser source [8,9,33].…”