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The use of coinoculations of indole-3-acetic acid-synthesizing bacteria has become increasingly common in agriculture. Different bacterial isolates are capable of synthesizing IAA. Depending on the amount, IAA can promote, inhibit, or modify the growth and development of plants. However, little is known about the effect of auxins on plants under coinoculation conditions. The present study aimed to verify whether coinoculation with indole-3-acetic acid (IAA)-synthesizing bacteria may or may not harm plant development in three tomato genotypes with different sensitivities to auxins: Micro-Tom (MT), diageotropica (dgt) (low auxin sensitivity) and Entire (high auxin biosynthesis). The experiment was conducted in a completely randomized design with six replicates and eight treatments: control; Bacillus velezensis (BV); B. pumilus (BP); Azospirillum brasilense (AZ); B. velezensis + Bacillus pumilus (BV + BP); B. velezensis + A brasilense (BV + AZ); B. pumilus + A brasilense (BP + AZ); B. velezensis + Bacillus pumilus + A. brasilense (BV + BP + AZ), for each tomato genotype. The parameters analyzed were dry shoot and root weight, plant height, and leaf area. The results showed an increase in root dry weight with BV + BP + AZ treatment in the MT genotype, an increase in shoot dry weight in the dgt genotype with BV and no increase in any parameter in the Entire genotype for the analyzed parameters. The results also showed that coinoculation with BP + AZ decreased the shoot dry weight, dry root weight, and leaf area values of the dgt and Entire genotypes. Coinoculations with BP + AZ reduced the parameters analyzed in the dgt genotype, which is insensitive to the IAA and Entire genotypes and is sensitive. In addition, coinoculation with BV + BP + AZ, which provided the highest IAA concentration, increased the dry root weight in the MT genotype. These results suggest that the reduction in plant development caused by coinoculation is not related to IAA synthesis produced by bacteria but is probably due to negative interference in the interaction mechanisms between plants and bacteria and might also be due to negative bacteria–bacteria interactions. [ABSTRACT FROM AUTHOR]

Plant growth-promoting bacteria have several abilities to promote plant growth and development. One of these skills is the synthesis of indole-3-acetic acid (IAA), which mainly promotes root and shoot development. The bacteria Bacillus subtilis and Azospirillum brasilense have been widely used in agriculture with this function. However, little is known about whether the joint inoculation of these bacteria can reduce plant development by the excess of IAA produced as a result of the joint inoculation. The objective of the present study was to verify the effect of IAA on the inoculation of B. subtilis and A. brasilense in three tomato genotypes. The Micro-Tom genotype without mutation for IAA synthesis, Entire, has high sensitivity to IAA, and the diageotropic genotype (dgt) has low sensitivity to IAA. The results show that the plant parameter most sensitive to microbial inoculation is the number of roots. No treatment increased the shoot dry mass parameters for the Micro-Tom genotype and dgt, root dry mass for the Micro-Tom genotype, plant height for the Micro-Tom and Entire genotypes, root area and root volume for the genotype dgt. The Azm treatment reduced plant height compared to the control in the dgt, the BS + Azw and BS + Azm treatments in the Micro-Tom genotype and the Azw + Azm treatment in the dgt genotype reduced the plant diameter compared to the control. BS and BS + Azw reduced the number of roots in the Micro-Tom. The results strongly support that the mixture of B. subtilis and A. brasilense can reduce some parameters of plant development; however, this effect is possibly an interference in the mode of action of growth promotion of each isolate and is not related to an excess of IAA produced by the bacteria. [ABSTRACT FROM AUTHOR]

Photoreceptors are primarily known as key photomorphogenic modulators of various physiological events during plant development. Although there are different groups of photoreceptors, the phytochrome B (phyB) family mediates developmental responses in a wide range of plant species, from seed germination to flowering. In addition, these molecules also regulate abiotic stress acclimation responses, such as salinity, drought, low/high temperature, high light and heavy metals. The signalling pathways mediated by phyB could enhance plant resistance to environmental stresses, as phyB photoreceptors reduce leaf transpiration, increase the antioxidant system, enhance protective pigments and increase the expression of genes related to plant stress acclimation. Thus, the elucidation of positive or negative roles for phyB in these stress tolerance characteristics would provide essential knowledge for genetic engineering, improving plant growth and development in critical environments. In this review, we cover the main findings on how the phyB family works to modulate abiotic stress by discussing biochemical and molecular aspects of the underlying mechanisms operated by these photoreceptors. [ABSTRACT FROM AUTHOR]

It is well-documented that phytochromes can control plant growth and development from germination to flowering. Additionally, these photoreceptors have been shown to modulate both biotic and abiotic stress. This has led to a series of studies exploring the molecular and biochemical basis by which phytochromes modulate stresses, such as salinity, drought, high light or herbivory. Evidence for a role of phytrochromes in plant stress tolerance is explored and reviewed. [ABSTRACT FROM AUTHOR]

• Cryptochrome 1a (cry1a) of tomato induces roots nutrient accumulation under P, K, and S deficiencies. • cry1a maintained leaf pigmentation and plant growth during nutrient deficiency treatments. • Non-functional CRY1a alleviates lipid peroxidation in the leaves during K and S omissions. The blue light photoreceptor cryptochromes are involved in nutritional response pathways in plants. Evidence shows that cryptochromes mediate the control of genes related to nutrients accumulation in plants. However, nothing is known about the role of cryptochrome 1a (cry1a) in tomato (Solanum lycopersicum L.) nutritional stress responses. Thus, this study aims to evaluate the importance of cry1a photoreceptors in plant responses to nutrient deficiency. To this end, we proposed the use of a tomato mutant carrying a lesion in a gene encoding the blue light photoreceptor cry1a (cry1a) and its wild type (WT; cv. Moneymaker). Both genotypes (20-day-old plants) were grown under treatments consisting of a complete nutrient solution and the individual omission of each nutrient (–N, –P, –K, –Ca, or –S) from a balanced nutrient solution. Subsequently, we measured the growth, pigmentation, oxidative stress, and nutrient accumulation, as well as uptake efficiency, transport efficiency, and use efficiency of nutrients in all treated plants. The cry1a plants had greater shoot extension growth than WT plants in all tested growth conditions, although the shoot biomass accumulation with cry1a was greater than in the WT only under Ca omission. Except in the –N and –Ca conditions, the cry1a plants accumulated less root biomass than WT plants. In addition, leaf pigments (chlorophyll a+b and carotenoids) were reduced in the mutant plants compared to WT plants grown under CS, –P, and –S conditions. Thus, considering that WT plants have the full functions of cry1a photoreceptor, here we showed that cry1a plays an important role in the nutrient deficiency responses in tomato, particularly, mediating growth and development of stressed plants through changes in plant growth and oxidative stress, as well as the nutrient contents and efficiencies of transport use. [ABSTRACT FROM AUTHOR]