Global environmental temperature changes threaten innumerable plant species. Although various signaling networks regulate plant responses to temperature fluctuations, the mechanisms unifying these diverse processes are largely unknown. Here, we demonstrate that an Arabidopsis monothiol glutaredoxin, AtGRXS17 (At4g04950), plays a critical role in redox homeostasis and hormone perception to mediate temperature-dependent postembryonic growth. AtGRXS17 expression was induced by elevated temperatures. Lines altered in AtGRXS17 expression were hypersensitive to elevated temperatures and phenocopied mutants altered in the perception of the phytohormone auxin. We show that auxin sensitivity and polar auxin transport were perturbed in these mutants, whereas auxin biosynthesis was not altered. In addition, atgrxs17 plants displayed phenotypes consistent with defects in proliferation and/or cell cycle control while accumulating higher levels of reactive oxygen species and cellular membrane damage under high temperature. Together, our findings provide a nexus between reactive oxygen species homeostasis, auxin signaling, and temperature responses.

Legumes' sensitivity to salt is exacerbated under growth conditions requiring nitrogen fixation by the plant. Phosphorus (P) deficiency is widespread in legumes, especially common bean (Phaseolus vulgaris L). To examine the performance of P. vulgaris under salt stress conditions, a field experiment was conducted using two recombinants inbred lines (RILs) 115 (P‐deficiency tolerant) and 147 (P‐deficiency susceptible), grown under different salinity levels (L) (1.56, 4.78, and 8.83 dS m−1 as LI, L2, and L3, respectively) and supplied with four P rates (0, 30, 60, and 90 kg ha−1 P as P0, P30, P60, and P90, respectively) in order to assess the impact of P on salt tolerance. Results indicate that growing both RILs at P60 or P90 under all salinity levels (especially L1) significantly increased total chlorophyll, carotenoids, total soluble sugars, total free amino acids, and proline. Increasing P supply up to P60 under all salinity levels significantly induced higher accumulation of P, K+, Ca2+ and Mg2+ leaves in both RILs. Based on quadratic response over all locations, the maximum seed yield of 1.465 t ha−1 could be obtained at application of P 81.0 kg ha‐1 in RIL115, while seed yield of 1.275 t ha−1 could be obtained with P rate of 78.3 kg ha−1 in RIL147. RIL115 exhibited more salt‐tolerance with positive consequence on plant biomass and grain yield stability. Improved salt tolerance through adequate P fertilization is likely a promising strategy to improve P. vulgaris salinity tolerance and thus productivity, a response that seems to be P‐rate dependent.

Accurate and efficient phenotyping has become the biggest hurdle for evaluating large populations in plant breeding and genetics. Contrary to genotyping, high‐throughput approaches to field‐based phenotyping have not been realized and fully implemented. To address this bottleneck, a novel, low‐cost, flexible phenotyping platform, named Phenocart, was developed and tested on a field trial consisting of 10 historical and current elite wheat (Triticum aestivium L.) breeding lines at the International Maize and Wheat Improvement Center (CIMMYT). The lines were cultivated during the 2013 and 2014 growing cycle in Ciudad Obregon, Mexico, and evaluated multiple times throughout the growing season. The phenotyping platform was developed by integrating several sensors: a GreenSeeker for spectral reflectance, an infrared thermometer (IRT), and a global navigation satellite system (GNSS) receiver into one functional unit. The Phenocart enabled simultaneous collection of normalized difference vegetation index (NDVI) and canopy temperature (CT) with precise assignment of all measurements to plot location by georeferenced data points. Across the set of varieties, the Phenocart temperature measurements were highly correlated to a handheld IRT. In addition, CT and NDVI were both significantly correlated to yield throughout the growing season. The Phenocart is a flexible, low‐cost, and easily deployable platform to increase the amount of phenotypic data that crop breeders obtain as well as provide high‐resolution phenotypic data for genetic discovery.

Iron (Fe) is an essential mineral nutrient and a metal cofactor required for many proteins and enzymes involved in the processes of DNA synthesis, respiration, and photosynthesis. Iron limitation can have detrimental effects on plant growth and development. Such effects are mediated, at least in part, through the generation of reactive oxygen species (ROS). Thus, plants have evolved a complex regulatory network to respond to conditions of iron limitations. However, the mechanisms that couple iron deficiency and oxidative stress responses are not fully understood. Here, we report the discovery that an Arabidopsis thaliana monothiol glutaredoxin S17 (AtGRXS17) plays a critical role in the plants ability to respond to iron deficiency stress and maintain redox homeostasis. In a yeast expression assay, AtGRXS17 was able to suppress the iron accumulation in yeast ScGrx3/ScGrx4 mutant cells. Genetic analysis indicated that plants with reduced AtGRXS17 expression were hypersensitive to iron deficiency and showed increased iron concentrations in mature seeds. Disruption of AtGRXS17 caused plant sensitivity to exogenous oxidants and increased ROS production under iron deficiency. Addition of reduced glutathione rescued the growth and alleviates the sensitivity of atgrxs17 mutants to iron deficiency. These findings suggest AtGRXS17 helps integrate redox homeostasis and iron deficiency responses.

Biological responses to photothermal effects of gold nanoparticles (GNPs) have been demonstrated and employed for various applications in diverse systems except for one important class - plants. Here, the uptake of GNPs through Arabidopsis thaliana roots and translocation to leaves are reported. Successful plasmonic nanobubble generation and acoustic signal detection in planta is demonstrated. Furthermore, Arabidopsis leaves harboring GNPs and exposed to continuous laser or noncoherent light show elevated temperatures across the leaf surface and induced expression of heat-shock regulated genes. Overall, these results demonstrate that Arabidopsis can readily take up GNPs through the roots and translocate the particles to leaf tissues. Once within leaves, GNPs can act as photothermal agents for on-demand remote activation of localized biological processes in plants.