Chao, S. | Search bioRxiv

bioRxiv2018

Potassium nutrition recover impacts on stomatal, mesophyll and biochemical limitations to photosynthesis in Carya cathayensis and Hickory illinoensis

Potassium (K) influences the photosynthesis process in a number of ways; However, the mechanism of photosynthetic response to the long-term supply of potassium is not yet clear. Concurrent measurements of gas exchange and chlorophyll fluorescence were made to investigate the effect of potassium nutrition on photosynthetic efficiency and stomatal conductance (gs), mesophyll conductance (gm) in Pecan (Carya illinoensis K.Kock) and Hickory (Carya cathayensis Sarg.) seedlings in a greenhouse. The results show that the photosynthetic capacity of Pecan and Hickory plants was not limited when the leaves had potassium concentrations >1.4% and 1.42% of dry weight. Most of limitation under potassium deficiency were dominated by MCL for Pecan and Hickory. Both cultivars showed remarkable improvement in SL, MCL, J and Vc,max with additional K supplies. However, effect from potassium deficiency on photosynthesis in plant leaves was irreversible. All of SL, MCL, and BL nearly half down with recovery K supply in both species. These results emphasize the important role of potassium on regulation of photosynthesis by three limitations.

physiology↗

bioRxiv2017

Genome-wide homology analysis reveals new insights into the origin of the wheat B genome

Wheat is a typical allopolyploid with three homoeologous subgenomes (A, B, and D). The ancestors of the subgenomes A and D had been identified, but not for the subgenome B. The goatgrass Aegilops speltoides (genome SS) has been controversially considered a candidate for the ancestor of the wheat B genome. However, the relationship of the Ae. speltoides S genome with the wheat B genome remains largely obscure, which has puzzled the wheat research community for nearly a century. In the present study, the genome-wide homology analysis identified perceptible homology between wheat chromosome 1B and Ae. speltoides chromosome 1S, but not between other chromosomes in the B and S genomes. An Ae. speltoides-originated segment spanning a genomic region of approximately 10.46 Mb was identified on the long arm of wheat chromosome 1B (1BL). The Ae. speltoides-originated segment on 1BL was found to co-evolve with the rest of the B genome in wheat species. Thereby, we conclude that Ae. speltoides had been involved in the origin of the wheat B genome, but should not be considered an exclusive ancestor of this genome. The wheat B genome might have a polyphyletic origin with multiple ancestors involved, including Ae. speltoides. These novel findings provide significant insights into the origin and evolution of the wheat B genome, and will facilitate polyploid genome studies in wheat and other plants as well.

genetics↗