Brassinosteroid analogue affects the senescence in two papaya genotypes submitted to drought stress

Abstract

Brassinosteroids (BS) application is associated with the increase of tolerance to some kinds of stresses, such as those induced by the infection of pathogens, temperature, salt and water deficiency. In this work, the influence of a spirostanic analogue of brassinosteroid (SAB) in the leaves of papaya Golden and UENF/CALIMAN 01 (UC 01) was tested to evaluate alterations in the content of chlorophyll in plants submitted to drought stress (DS). When plants were 70 d old, SAB was applied (0,1 mg L-1) for five consecutive days in half of the plants meant for the experiment. The treatments were: control irrigated (I), I with SAB (IB), DS and DS with SAB (DSB). The evaluated leaves were marked in accordance to the age: LEAF 1 (youngest expanded leaf), LEAF 2 (insertion immediately below LEAF 1) and LEAF 3 (insertion immediately below LEAF 2). The same leaves were used throughtout the experimental period. After the thirteenth day, the chlorophyll contents of DSB (Golden and UC 01) were always lesser than the treatment DS in LEAF 2. The irrigation was restarted in stressed plants on the fifteenth day, followed by new application of SAB (IB and DSB treatments). In Golden plants, DSB showed the lowest values of chlorophyll contents after re-watering, while in UC 01, differences in chlorophyll contents between treatments DS and DSB had not occurred. Alterations in F v /F m relation did not occur among the treatments during stress. In genotype UC 01, the irrigated plants showed minor values of F v /F m at the end of the experiment, whereas the plants submitted to DS presented increments in this relation in this same time. These results indicate that SAB might have contributed to accelerate the rate of leaf senescence of the oldest leaves of stressed plants, redistributing photoassimilates and other compounds for the youngest leaves.

Transcriptomic analysis reveals key transcription factors associated to drought tolerance in a wild papaya (Carica papaya) genotype

“…Several authors agree that Fv/Fm is a very sensitive physiological parameter that can be used as an effective quantitative measurement to characterize the magnitude of stress to which a plant is exposed [ 54 ]. Similar Fv/Fm values to those measured in our experiment were reported earlier in other genotypes exposed to WDS [ 55 ] and again the wild tolerant genotype was able to maintain higher efficiency of PSII than the commercial one, after the same WDS period. On the other hand, it is well known that an increase in Electrolyte Leakage (EL) normally indicates the degree of damage to the membrane by heat, salinity or WDS [ 33 ].…”

Brassinosteroids make plant life easier under abiotic stresses mainly by modulating major components of antioxidant defense system

“…EpiBL-induced tolerance to heat shock (HS) in tomato seedlings (BR-deficient mutant, extreme dwarf d(x)), a partially BR-insensitive mutant curl 3 (-abs) allele (curl 3 altered brassinolide sensitivity; and a line overexpressing the dwarf, BR-biosynthesis gene, 35SD) was argued as a result of reduced ion leakage, lipid peroxidation through enhanced activities of antioxidative enzymes (Mazorra et al, 2011). Anuradha and Rao, 2007b Brassica juncea Hayat et al, 2007 Lycopersicon esculentum Hayat et al, 2010a Lycopersicon esculentum Hasan et al, 2011 Triticum aestivum Kroutil et al, 2010 Solanum lycopersicum Hayat et al, 2012 Helianthus annuus Filova et al, 2013 Helianthus tuberosus Gao et al, 2013 Solatium nigrum Zhao et al, 2013 Al Vigna radiata Ali et al, 2008b Glycine max Dong et al, 2008 Ni Brassica juncea Kanwar et al, 2012 24-epiBL Cd Brassica napus Janeczko et al, 2005 Raphanus sativus Anuradha and Rao, 2009 Phaseolus Upreti and Murti, 2004 Sorghum vulgare Vardhini and Rao, 2005 Lycopersicon esculentum Behnamnia et al, 2009 Solanum lycopersicum Yuan et al, 2010 Carica papaya Gomes et al, 2013 Raphanus sativus Mahesh et al, 2013 Flooding Brassica napus Liang and Liang, 2009 BL Drought Robinia pseudoacacia Li et al, 2008 Glycine max Zhang et al, 2008 Xanthoceras sorbifolia Li and Feng, 2011 Arachis hypogaea Savaliya et al, 2013 Flooding Cucumis sativus…”

Physiological Responses of Oil Palm Seedlings to the Drought Stress Using Boron and Silicon Applications

“…In the period after drought stress, the ratio of chlorophyll a/b tends to increase. The increase in the ratio of chlorophyll a/b associated with degradation rate of chlorophyll a and b, where the degradation rate of chlorophyll a much slower than the one of chlorophyll b. Chlorophyll b damaged more severely due to direct interaction with high energy of sunlight during the drought period (Legros et al, 2009;Cha-um et al, 2010;Biglary et al, 2011;Cao et al, 2011;Dastan et al, 2011;Sun et al, 2011;Chutia and Borah, 2012;Khayatnezzhad and Gholamin, 2012;Rahimi et al, 2012;Zlatev and Lindon, 2012;Ashraf and Harris, 2013;Bharwana et al, 2013;Gomes et al, 2013). Oil palm seedlings allegedly degrade leaf chlorophyll and amino acids resulted from the degradation of the chlorophyll used as the base material to synthesize some important osmoregulator in osmotic adjustment (Legros et al, 2009;Cha-um et al, 2010;Cao et al, 2011;Sun et al, 2011;Chutia and Borah, 2012;Khayatnezzhad and Gholamin, 2012;Zlatev and Lindon, 2012;Ashraf and Harris, 2013).…”