Wheat Transformation with <i>ScTPS1-TPS2</i> Bifunctional Enzyme for Trehalose Biosynthesis Protects Photosynthesis during Drought Stress

Wheat cultivation makes an important contribution to human nutrition. Trehalose synthesis plays a role in the tolerance to drought stress. A bifunctional TPS-TPP enzyme gene from yeast was used to obtain transgenic wheat plants to increase trehalose synthesis. Mature wheat embryos were transformed using pGreen rd29A::TPS1-TPS2 or pGreen 35S::TPS1-TPS2 constructs. The transgene presence in mature leaves of T3 plants was confirmed by sequencing a PCR fragment of the inserted transgene. Transgenic and NT plants were submitted to drought stress for eight days. Transformed wheat lines retained a higher relative water content than NT plants during drought stress, and the Rubisco activity was unaffected. Plants transformed with the 35S construct showed a lower photosynthetic rate and lower fructose 1–6-bisphosphatase (FBPase) activity during drought, suggesting that constitutive trehalose and sucrose synthesis caused a reduced ribulose 1,5-bisphosphate (RuBP) regeneration. Lines transformed with the rd29A promoter showed a higher photosynthetic rate after eight days of drought, as the RuBP regeneration was unaffected. Transgenic wheat plants had higher biomass and grain weight than NT plants after drought. These results suggest that trehalose synthesis improves photosynthesis during stress and induces changes in the activity of some Calvin-cycle enzymes, reflected in plant metabolism and growth

The Effects of Brief Heat During Early Booting on Reproductive, Developmental, and Chlorophyll Physiological Performance in Common Wheat (Triticum aestivum L.)

Rising temperatures due to climate change threaten agricultural crop productivity. As a cool-season crop, wheat is heat-sensitive, but often exposed to high temperatures during the cultivation period. In the current study, a bread wheat panel of spring wheat genotypes, including putatively heat-tolerant Australian and CIMMYT genotypes, was exposed to a 5-day mild (34°C/28°C, day/night) or extreme (37°C/27°C) heat stress during the sensitive pollen developmental stage. Worsening effects on anther morphology were observed, as heat stress increased from mild to extreme. Even under mild heat, a significant decrease in pollen viability and number of grains per spike from primary spike was observed compared with the control (21°C/15°C), with Sunstar and two CIMMYT breeding lines performing well. A heat-specific positive correlation between the two traits indicates the important role of pollen fertility for grain setting. Interestingly, both mild and extreme heat induced development of new tillers after the heat stress, providing an alternative sink for accumulated photosynthates and significantly contributing to the final yield. Measurements of flag leaf maximum potential quantum efficiency of photosystem II (Fv/Fm) showed an initial inhibition after the heat treatment, followed by a full recovery within a few days. Despite this, model fitting using chlorophyll soil plant analysis development (SPAD) measurements showed an earlier onset or faster senescence rate under heat stress. The data presented here provide interesting entry points for further research into pollen fertility, tillering dynamics, and leaf senescence under heat. The identified heat-tolerant wheat genotypes can be used to dissect the underlying mechanisms and breed climate-resilient wheat

Assessing the relationship between autonomy support and student group cohesion across Ibero-American countries

Teacher-endorsed supporting behaviors present themselves as key influencers of student adaptive academic and social functions. The objective of this paper was twofold. First, this study sought to test a model in which student-perceived autonomy support was associated with group cohesion, considering the mediating role of basic psychological needs satisfaction and intrinsic motivation. Second, the current study examined the dimensionality of the model across five Western countries, namely Spain, Portugal, Brazil, Chile, and Mexico. A convenience sample of 3033 college students (Mage = 21.51 ± SD = 3.71) were recruited for the analysis. The results revealed that perceived autonomy support was positively associated with needs satisfaction, being consequently associated with intrinsic motivation and, ultimately, with group cohesion. Additionally, a multigroup analysis revealed that the model was invariant across college students from the different countries. The current results are discussed around the promotion of teacher uses of autonomy-supportive behaviors fostering adaptive outcomes in students regarding positive social relations and that the cultures of Ibero-American countries are equivalent in this process.info:eu-repo/semantics/publishedVersio