Elevated carbon dioxide offers promise for wheat adaptation to heat stress by adjusting carbohydrate metabolism.

Carbohydrate metabolism in plants is influenced by thermodynamics. The amount of carbon dioxide (CO2) in the atmosphere is expected to rise in the future. As a result, understanding the effects of higher CO2 on carbohydrate metabolism and heat stress tolerance is necessary for anticipating plant responses to global warming and elevated CO2. In this study, five wheat cultivars were exposed to heat stress (40 °C) at the onset of anthesis for three continuous days. These cultivars were grown at two levels of CO2 i.e. ambient CO2 level (a[CO2], 380 mmol L-1) and elevated CO2 level (e[CO2], 780 mmol L-1), to determine the interactive effect of elevated CO2 and heat stress on carbohydrate metabolism and antioxidant enzyme activity in wheat. Heat stress reduced the photosynthetic rate (Pn) and grain yield in all five cultivars, but cultivars grown in e[CO2] sustained Pn and grain yield in contrast to cultivars grown in a[CO2]. Heat stress reduced the activity of ADP-glucose pyrophosphorylase, UDP-glucose pyrophosphorylase, invertases, Glutathione reductase (GR), Peroxidase (POX), and Superoxide dismutase (SOD) at a[CO2] but increased at e[CO2]. The concentration of sucrose, glucose, and fructose mainly increased in tolerant cultivars under heat stress at e[CO2]. This study confirms the interaction between the heat stress and e[CO2] to mitigate the effect of heat stress on wheat and suggests to have in-depth knowledge and precise understanding of carbohydrate metabolism in heat stressed plants in order to prevent the negative effects of high temperatures on productivity and other physiological attributes. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s12298-021-01080-5.

Transgenerational Seed Exposure to Elevated CO2 Involves Stress Memory Regulation at Metabolic Levels to Confer Drought Resistance in Wheat.

Drought is the worst environmental stress constraint that inflicts heavy losses to global food production, such as wheat. The metabolic responses of seeds produced overtransgenerational exposure to e[CO2] to recover drought's effects on wheat are still unexplored. Seeds were produced constantly for four generations (F1 to F4) under ambient CO2 (a[CO2], 400 µmol L-1) and elevated CO2 (e[CO2], 800 µmol L-1) concentrations, and then further regrown under natural CO2 conditions to investigate their effects on the stress memory metabolic processes liable for increasing drought resistance in the next generation (F5). At the anthesis stage, plants were subjected to normal (100% FC, field capacity) and drought stress (60% FC) conditions. Under drought stress, plants of transgenerational e[CO2] exposed seeds showed markedly increased superoxide dismutase (16%), catalase (24%), peroxidase (9%), total antioxidants (14%), and proline (35%) levels that helped the plants to sustain normal growth through scavenging of hydrogen peroxide (11%) and malondialdehyde (26%). The carbohydrate metabolic enzymes such as aldolase (36%), phosphoglucomutase (12%), UDP-glucose pyrophosphorylase (25%), vacuolar invertase (33%), glucose-6-phosphate-dehydrogenase (68%), and cell wall invertase (17%) were decreased significantly; however, transgenerational seeds produced under e[CO2] showed a considerable increase in their activities in drought-stressed wheat plants. Moreover, transgenerational e[CO2] exposed seeds under drought stress caused a marked increase in leaf Ψw (15%), chlorophyll a (19%), chlorophyll b (8%), carotenoids (12%), grain spike (16%), hundred grain weight (19%), and grain yield (10%). Hence, transgenerational seeds exposed to e[CO2] upregulate the drought recovery metabolic processes to improve the grain yield of wheat under drought stress conditions.

Morphological diversity of Morus spp. (Mulberry accessions) grown in Muzaffarabad, Azad Jammu & Kashmir, Pakistan / La diversidad morfológica de Morus spp. (accesiones de mora) cultivados en Muzaffarabad, Azad Jammu y Cachemira, Pakistán

Genetic diversity of thirty mulberry accessions was determined by using the eleven different phenotypic characters. The study was conducted in field areas of Azad Jammu and Kashmir. The main objective of this study was to find out the diversity in morphological characters of Mulberry accessions found in Azad Jammu and Kashmir and Pakistan. The results showed that there is a significant difference in quantitative parameters among the thirty accessions (p≤0.001). The cluster analysis showed that the data is divided into two main groups at near 80 dissimilarity level. This study suggests that the Morus germplasm is quite diverse.

Se determinó la diversidad genética de treinta accesiones de mora utilizando once caracteres fenotípicos diferentes. El estudio se realizó en áreas de campo de Azad Jammu y Cachemira. El objetivo principal de este estudio fue conocer la diversidad en los caracteres morfológicos de lss accesiones de mora encontrados en Azad Jammu, Cachemira y Pakistán. Los resultados mostraron que hay una diferencia significativa en los parámetros cuantitativos entre las treinta accesiones de mora (p≤0.001). El análisis de conglomerados mostró que los datos se dividen en dos grupos principales a un nivel de disimilitud cercano a 80. Este estudio sugiere que el germoplasma de Morus es muy diverso.