Goad, D. M. | bioRxiv Science

bioRxiv2021

Intraspecific variation in elemental accumulation and its association with salt tolerance in Paspalum vaginatum

Most plant species, including most crops, perform poorly in salt-affected soils because high sodium levels are cytotoxic and can disrupt uptake of water and important nutrients. Halophytes are species that have evolved adaptations to overcome these challenges and may be a useful source of knowledge for salt tolerance mechanisms and genes that may be transferable to crop species. The salt content of saline habitats can vary dramatically by location, providing ample opportunity for different populations of halophytic species to adapt to their local salt concentrations; however, the extent of this variation, and the physiology and polymorphisms that drive it, remain poorly understood. Differential accumulation of inorganic elements between genotypes or populations may play an important role in local salinity adaptation. To test this, we investigated the relationships between population structure, tissue ion concentrations (i.e., ionomic profiles) and salt tolerance in 17 "fine-textured" genotypes of the halophytic turfgrass seashore paspalum (Paspalum vaginatum Swartz). A high-throughput ionomics pipeline was used to quantify the shoot concentration of 18 inorganic elements across three salinity treatments. We found a significant relationship between population structure and ion accumulation, with strong correlations between principal components derived from genetic and ionomic data. Additionally, genotypes with higher salt tolerance accumulated more K and Fe and less Ca than less tolerant genotypes. Together these results indicate that differences in ion accumulation between P. vaginatum populations may reflect locally adapted salt stress responses.

plant biology↗

bioRxiv2018

Function of the Pedicellate Spikelet and Awn in Sorghum and Related Grasses

Sorghum and its relatives in the grass tribe Andropogoneae bear their flowers in pairs of spikelets, in which one spikelet (seed-bearing, or SS) of the pair produces a seed and the other is sterile or male (staminate). This division of function does not occur in other major cereals such as wheat or rice. Additionally, one bract of the seed-bearing spikelet often produces a long extension, the awn, which is in the same position as but independently derived from that of wheat and rice. The function of the sterile spikelet is unknown and that of the awn has not been tested in Andropogoneae. We used radioactive and stable isotopes of carbon, as well as RNA-seq of metabolically important enzymes to show that the sterile spikelet assimilates carbon, which is translocated to the largely heterotrophic SS, thereby functioning as a nurse tissue. The awn shows no evidence of photosynthesis. These results apply to distantly related species of Andropogoneae. Thus, the sterile spikelet, but not the awn, could affect yield in the cultivated species and fitness in the wild ones.

plant biology↗