Optimizing plant architecture to increase yield, stress tolerance, and water use efficiency (WUE) is a major challenge for modern agricultural biotechnology. Gibberellins are growth hormones known to be directly related to plant height and tillering, which in turn are directly related to grain yield in cereals. GA 2-oxidase is a key enzyme that regulates the level of endogenous gibberellins and their precursors. A team of scientists from the National Chung Hsing University and Academia Sinica in Taiwan, with leading author Shuen-Fang Lo, has recently published an article describing the effect of expression of various mutant forms of the GA 2-oxidase enzyme (including amino acid substitutions in conserved regions of the enzyme) in transgenic rice plants over the plant architecture, seed yield, stress tolerance and WUE. In some plants with moderate level of gibberellin decrease, along with the observed reduced height, more productive tillers, expanded root system, increased WUE and photosynthesis were also observed as well as increased tolerance to abiotic and biotic stress. There was also a 10-30% increase in yield in field conditions. The study demonstrates an effective way to modify commercially significant traits by modeling gibberellin levels, which could also be applied to other crop plants.
Source: Crop Biotech Update
Lo, S.-F., Ho, T.-H.D., Liu, Y.-L., Jiang, M.-J., Hsieh, K.-T., Chen, K.-T., Yu, L.-C., Lee, M.-H., Chen, C.-y., Huang, T.-P., Kojima, M., Sakakibara, H., Chen, L.-J. and Yu, S.-M. (2016) Ectopic expression of specific GA2 oxidase mutants promotes yield and stress tolerance in rice. Plant Biotechnol. J., doi: 10.1111/pbi.12681