Proline accumulation in two different bean (Phaseolus vulgaris L.) cultivars, one drought-sensitive (Canario 60) and one drought-resistant (Pinto Villa) was investigated. Both tolerated salt concentrations up to 150 mM NaCl, but the sensitive Canario 60 did not survive at 400 mM NaCl. In response to salt stress, both cvs. accumulated proline in all the analyzed tissues, the lowest contents were detected in roots. Pinto Villa accumulated higher proline concentrations than Canario 60 only at 400 mM NaCl. The addition of polyamines or ornithine increased proline content in plant tissues without stress, while they decreased it under salt stress.

The Myrtillocactus geometrizans (Mart. ex. Pfeiff.) fruit, locally called garambullo, is an important source of bioactive compounds, mainly betalains, polyphenols, and ascorbic acid. However, information on the application of post-harvest technologies that prolong the shelf life of the fruits is still insufficient. The objective of the present research was to evaluate the effect of a gelatin coating incorporating 0%, 1%, or 3% tomato oily extract (TOE), compared to a control (without coating), on the physicochemical and antioxidant properties of garambullo fruits stored for 15 days at 5 °C. The gelatin coatings with TOE significantly (p ≤ 0.05) delayed changes in weight loss, brix degrees, titratable acidity and pH, compared to the control during storage. Fruits coated with TOE-gelatin had a higher content of betalains, ascorbic acid, total phenols, and flavonoids. The results showed that a higher concentration of phytochemicals increased antioxidant activity in vitro; the maximum values found for Trolox equivalents per kg of fresh weight were 10.46 and 17.65 mM for the 2,2′-diphenyl-1-picrylhydrazyl (DPPH) and Trolox Equivalent Antioxidant Capacity Method (TEAC) tests, respectively. The gelatin coating with TOE-3% (COTE-3%) reduced water loss by 1.66 times, compared to the control. In addition, the fruits covered with COTE-3% showed the highest concentration of bioactive compounds during storage.

Opuntia spp. is easily adaptable to arid and semiarid climates, and represents a valuable alternative for the agricultural development in dry regions. Twelve accessions of Opuntia spp. fruits were characterized to know the evolution of their bioactive compounds concentration such as phenolics, flavonoids and pigments (Isobetanins, betanins, indicaxanthins and total betalains) during their ripening process. DPPH and ABTS radical scavenging capacity were determined and correlated with pigments and bioactive compounds concentration. Bioactive compounds and pigments concentration increased along ripening. Higher concentration of total betalains were found in ripe ꞌBondaꞌ (O. guerrana Griffiths) and ꞌRojo Tolucaꞌ (Opuntia robusta var. Larreyi) accessions, being of 78.96 ± 0.54 mg 100 g-1 DW and 69.87 ± 0.29 mg 100 g-1 DW respectively. Findings in this work can help to select Opuntia spp. accessions with high potential to be established as a valuable crop in the arid zones of Mexico.

In seed technology, the use of biocompatible materials, such as chitosan, has been demonstrated to improve the germination process and establishment of seedlings. This research is focused on the effect of a chitosan coating on the germination and development of sesame and bean plantlets. The seeds were treated with different coating techniques and combinations of chitosan: chitosan solutions at 0.1, 0.5 and 1% were used in film coating, chitosan flakes with particle sizes of 1.19 mm and 0.71 mm were used as a crusted coating, and chitosan flakes with a size of 1.19 mm were used for coating with acrylic resin. Images of the coatings were obtained by means of scanning electron microscopy; the effect on germination, germination speed, vigor index, length and root area of plantlets were also determined. Chitosan treatments increased germination by 26% in bean and 16% in sesame compared with the control; the germination speed index showed an increase of 61% in bean and 58% in sesame. The treatments with chitosan increased the length of the root in bean by 77%, and in sesame four times more, compared with the control treatments. Different forms of chitosan coatings improve germination and seedling establishment; however, the response to the type of coating at a given stage of seedling development will depend on the crop species.

Late embryogenesis abundant (LEA) proteins are a large protein family that mainly function in protecting cells from abiotic stress, but these proteins are also involved in regulating plant growth and development. In this study, we performed a functional analysis of LEA13 and LEA30 from Arabidopsis thaliana. The results showed that the expression of both genes increased when plants were subjected to drought-stressed conditions. The insertional lines lea13 and lea30 were identified for each gene, and both had a T-DNA element in the regulatory region, which caused the genes to be downregulated. Moreover, lea13 and lea30 were more sensitive to drought stress due to their higher transpiration and stomatal spacing. Microarray analysis of the lea13 background showed that genes involved in hormone signaling, stomatal development, and abiotic stress responses were misregulated. Our results showed that LEA proteins are involved in drought tolerance and participate in stomatal density.

Soil salinity is a condition that limits crop growth and productivity, and soil-dwelling bacteria from halophytic plant roots may be a viable strategy to cope with low productivity due to salt stress. Halophilic and halotolerant bacteria of the root soil of Sesuvium verrucosum were analyzed in this study as there is little evidence regarding its associated microbiology. Soil was sampled from the roots of Sesuvium verrucosum to obtain the cultivable bacteria. Their morphological characteristics were identified and they were molecularly identified by the 16S sequence. The growth capacity of the bacteria was determined at different levels of pH and salinity, and several growth promotion characteristics were identified, such as phosphorus solubilization, indole acetic acid production by the tryptophan-dependent (AIAt) and tryptophan-independent (IAA) pathways, ammonium production from organic sources, solubilization of carbonates, and zinc and sodium capture capacity. In addition, the bacteria that presented the best characteristics for germination variables of Solanum lycopersicum were evaluated. A total of 20 bacteria from root soil of Sesuvium verrucosum Raf. belonging to the phyla Proteobacteria (50%), Firmicutes (45%) and Actinobacteria (5%) were identified, with each one having different morphological characteristics. Among the bacterial isolates, 45% had the ability to resist different levels of salinity and pH, ranging from 0 to 20% of NaCl, and pH between 5 and 11. Moreover, these bacteria had the capacity to solubilize carbonates, phosphorus and zinc, capture sodium, produce ammonium from organic substrates and IAA (indole acetic acid), and promote enzymatic activity of amylases, proteases, lipases and cellulases. The bacteria evaluated on the germination of Solanum lycopersicum had an influence on germination at different salinity levels, with greater influence at 100 mM NaCl. This demonstrated that halophilic bacteria belonging to the rhizosphere of Sesuvium verrucosum have the ability to promote growth in extreme salinity conditions, making them candidates for the recovery of productivity in saline soils.