Drought mediated physiological and molecular changes in muskmelon (Cucumis melo L.)

Abstract

Water deficiency up to a certain level and duration leads to a stress condition called drought. It is a multi-dimensional stress causing alteration in the physiological, morphological, biochemical, and molecular traits in plants resulting in improper plant growth and development. Drought is one of the major abiotic stresses responsible for loss of crops including muskmelon (Cucumis melo. L). Muskmelon genotype SC-15, which exhibits high drought resistance as reported in our earlier reports, was exposed to deficient water condition and studied for alteration in physiological, molecular and proteomic profile changes in the leaves. Drought stress results in reduced net photosynthetic rate (Pn), stomatal conductance (Gs) and transpiration (E) rate. With expanded severity of drought, declination recorded in content of total chlorophyll and carotenoid while enhancement observed in phenol content indicating generation of oxidative stress. In contrary, activities of catalase (CAT), superoxide dismutase (SOD), ascorbate peroxidase (APX), and guaiacol (POD) were increased under drought stress. Peptide mass fingerprinting (PMF) showed that drought increased the relative abundance of 38 spots while decreases10 spots of protein. The identified proteins belong to protein synthesis, photosynthesis, nucleotide biosynthesis, stress response, transcription regulation, metabolism, energy and DNA binding. A drought-induced MADS-box transcription factor was identified. The present findings indicate that under drought muskmelon elevates the abundance of defense proteins and suppresses catabolic proteins. The data obtained exhibits possible mechanisms adopted by muskmelon to counter the impacts of drought induced stress.

In Vitro Screening of Cucmis Melo L. Against Drought Mediated By PEG and Sorbitol

“…One reason for pigment reduction during drought can br increasing abscisic acid and ethylene, chlorophyllase and peroxidase enzymes 14 . A decline of chlorophyll content was reported in melon 3,2,11 , and cucumber 15 . The GIR had the greatest decrease in photosynthetic pigments in most treatments, which probably is related to leaves being pale green in color during the dry season.…”

“…Increased simulated drought resulted in reduction in total protein content of plants 11 . Total protein content of plants under PEG and sorbitol treatments decreased compared to control genotypes.…”

“…Increase drought effects reduce cytokines and increase ABA that affect cell division, reduce fresh weight and restrict plant growth 12,13 Reduction of fresh weight was reported in cucumber 13 , melon 3 under drought. Dry weight of drought tolerant plants increase under water de cit 17 as does dry matter partitioning and biomass disposition which is strongly related to plant e ciency under water shortage Enhancement of dry mass is probably due to dehydration and new substance synthesis required for protection of higher osmotic level to continue water uptake 11 .…”

“…Studies on effects of drought in melons have been done under eld and greenhouse conditions 2,3,11 , and none study has been conducted using in vitro screening selection in cucurbitaceae family and especially in C. melo by means of seed culture. Some studies were conducted in association with effects of osmotic materials by creation of in vitro and in vivo drought in other crops, but it has not been done on C. melo seedlings in tissue culture 6,7,9 . This study was undertaken to assess drought-tolerant melons using PEG or sorbitol in vitro with objectives of: 1) rapid and accurate identi cation of tolerant genotypes at 7 days after application of osmolytes; 2) use of one, or some, traits as indicators for identi cation of drought tolerant melons in tissue culture 3) to extend invitro screening for drought tolerance using landraces of melons with different water use e ciency; and 4) nally, comparison of sorbitol with PEG as drought simulators, while they are completely different structurally and chemically, and selection of better osmolyte.…”

Overexpression of AtDREB1 and BcZAT12 Genes Confers Drought Tolerance by Reducing Oxidative Stress in Double Transgenic Tomato (Solanum Lycopersicum Mill.)

“…Under stress condition SOD mediates the removal of superoxide radicals; it evacuates O 2 by catalyzing its dismutation. Earlier under drought stress critical increment in SOD activity has been seen in a number of muskmelon genotypes with better drought tolerance capability (Ansari et al 2017;Ansari et al 2018;Ansari et al 2019), and ST tomato plants over-expressing BcZAT12 (Rai et al 2012a) and AtDREB1A (Rai et al 2013a), additionally drought tolerant transgenic peanut (Bhatnagar et al 2009), chrysanthemum (Hong et al 2006), and Lolium perenne plants (Li et al 2011) over-expressing AtDREB1A. In cherry tomato enhanced activity of CAT was reported particularly drought exposed tolerant varieties (Bhatnagar et al 2009), and ST plants over-expressing AtDREB1A and BcZAT12, individually.…”