Oduor, R. O. | bioRxiv Science

bioRxiv2023

Overexpressing the IPT gene improves drought tolerance and nutritional value of tropical maize (Zea mays L.)

Drought stress poses a significant threat to crop productivity, making the development of drought-tolerant crops a priority. The impact of drought on grain yield loss varies significantly, ranging from 10% to 76%, depending on the specific stage of occurrence and the severity of the drought. In this study, we investigated the effects of introducing the pSARK::IPT transgene on the drought tolerance and nutritional composition of successive generations of tropical maize. Towards this goal, we screened different generations of maize plants by genotyping PCR, exposed them to long term drought stress and analysed several drought stress markers and nutritional profiles of the plants. Our results demonstrated that the pSARK::IPT transgene was present in 4 successive generations of maize plants. Under drought conditions, transgenic maize exhibited higher relative water content, and delayed senescence compared to wild-type plants. Additionally, transgenic plants showed increased levels of total chlorophyll, chlorophyll a, and chlorophyll b, indicating improved photosynthetic activity under water deficit. Our study also showed that IPT-transgenic plants produced substantially higher yields and demonstrated enhanced nutritional value compared to wildtype plants when grown under well-watered conditions. Further research is warranted to investigate the underlying molecular mechanisms involved in these improvements and assess the performance of pSARK::IPT maize under field conditions.

bioengineering↗

bioRxiv2019

Varietal differences in physiological and biochemical responses to salinity stress in six finger millet plants

Finger millet is one of the most important cereals that are often grown in semiarid and arid regions of East-Africa. Salinity is known to be a major impediment for the crop growth and production. This study was aimed to understand the mechanisms of physiological and biochemical responses to salinity stress of Kenyan finger millet varieties (GBK043137, GBK043128, GBK043124, GBK043122, GBK043094, GBK043050) grown across different agroecological zones under NaCl-induced salinity stress. Seeds were germinated on the sterile soil and treated using various concentrations of NaCl (100, 200 and 300 mM) for two weeks. Again, the early-seedling stage of germinated plants was irrigated with the same salt concentrations for 60 days. Results indicated depression in germination percentage, shoot and root growth rate, leaf relative water content, chlorophyll content contents, leaf K+ concentration, and leaf K+/Na+ ratios increased salt levels. Contrary, proline and malonaldehyde (MDA) contents reduced sugar content and leaf total proteins. At the same time, the leaf Na+ and Cl- amounts of all plants increased substantially with rising stress levels. Clustering analysis revealed that GBK043094 and GBK043137 were placed together and identified as salt-tolerant varieties based on their performance under salt stress. Overall, our findings indicated a significant varietal variability for most of the parameters analysed. These superior varieties identified could be potentially used as promising genetic resources in future breeding programmes development directed towards salt-tolerant finger millet hybrids. Further analysis at genomic level need to be undertaken to better understand the genetic factors that promote salinity tolerance in finger millet.

plant biology↗