Functional Characterization of Tomato Phytochrome A and B1B2 Mutants in Response to Heat Stress

Abstract

Heat stress (HS) is a prevalent negative factor affecting plant growth and development, as it is predominant worldwide and threatens agriculture on a large scale. PHYTOCHROMES (PHYs) are photoreceptors that control plant growth and development, and the stress signaling response partially interferes with their activity. PHYA, B1, and B2 are the most well-known PHY types in tomatoes. Our study aimed to identify the role of tomato ‘Money Maker’ phyA and phyB1B2 mutants in stable and fluctuating high temperatures at different growth stages. In the seed germination and vegetative growth stages, the phy mutants were HS tolerant, while during the flowering stage the phy mutants revealed two opposing roles depending on the HS exposure period. The response of the phy mutants to HS during the fruiting stage showed similarity to WT. The most obvious stage that demonstrated phy mutants’ tolerance was the vegetative growth stage, in which a high degree of membrane stability and enhanced water preservation were achieved by the regulation of stomatal closure. In addition, both mutants upregulated the expression of heat-responsive genes related to heat tolerance. In addition to lower malondialdehyde accumulation, the phyA mutant enhanced proline levels. These results clarified the response of tomato phyA and phyB1B2 mutants to HS.

SlIAA9 Mutation Maintains Photosynthetic Capabilities under Heat-Stress Conditions

“…Stomata facilitate gas and water exchange between plants and the surrounding environment [ 44 ], and lower stomatal conductance was often linked with a lower net photosynthetic rate [ 45 ]. CO 2 used for photosynthesis was acquired through the stomata opening [ 46 ].…”

“…In contrast, both iaa9-3 and iaa9-5 mutants have higher chlorophyll fluorescence under normal and heat stress conditions ( Figure 6 ). Higher chlorophyll fluorescence of both iaa9-3 and iaa9-5 can be attributed to lower MDA content ( Figure 5 ), which indicates less leaf oxidative damages [ 44 ], higher leaf chlorophyll and carotenoid contents, which helps prevent photo-oxidative stress [ 55 ], and higher stomatal conductance which prevents Fq/Fm reduction [ 46 ].…”

CRISPR/Cas9 Technique for Temperature, Drought, and Salinity Stress Responses

“…One of the targets could be PHTOCHROME (PHY). PHYB has been identified as a thermosensor [ 84 , 85 ], and the phy mutant exhibited high tolerance to heat stress in Arabidopsis [ 86 ] and tomato [ 87 ]. This mutant information is important for the definition of targets of genome editing.…”

Engineering Abiotic Stress Tolerance in Crop Plants through CRISPR Genome Editing

“…Phytochrome (PHY) could be an important target in this respect as PHYB has been identified as a thermo-sensor [ 160 , 161 ]. The PHY mutants expressed improved tolerance to high temperatures in Arabidopsis [ 162 ] and tomato plants [ 163 ]. This mutant information is important for the definition of targets of genome editing.…”