Abstract
Gibberellins (GAs) are a very important group of phytohormones involved in seed germination, vegetative growth, flowering, and fruit development, being only 4 of the 136 known bioactives: GA1, GA3, GA4, and GA7. It has been evidenced that mutations in the OsGA20ox-2 gene produce rice (Oryza sativa) dwarf varieties, which were one of the main pillars of the green revolution. In this work two main objectives were proposed: (i) develop a rapid and broad phytohormone profiling method and (ii) to study the effects on the GA content of the GA20ox-2 mutation in several rice developmental stages using three varieties (tall variety, elite variety, mutated variety). A phytohormone extraction using an SPE step and HPLC-MS/MS detection using a QqQ instrument was determined which resulted in limits of detection (LOD) and limits of quantification (LOQ) for GAs that varied between 0.1–0.7 and 0.3–2.3 pg ⋅ g-1 (f.w.) of rice sample, respectively, allowing highly sensitive phytohormones detection in samples. Moreover, a good reproducibility was obtained for the GAs as relative standard deviations (RSD) for a 40 ng ⋅ mL-1 pattern varied between 0.3 and 0.9%. Notoriously, GA1 was absent in the coleoptile and GA4 was the GA with higher content in the majority of developmental stages. We also observed a large content increase of the four bioactive GAs in the internode of the flag leaf of the mutated variety allowing to reach same height as the elite variety. Therefore, we provide a rapid and broad phytohormonal profiling method and evidence that the GA20ox-2 mutation is not the only factor generating dwarf varieties. To our knowledge, this is the first study that it has been reported such a high number of simultaneously analyzed gibberellins in rice samples (Oryza sativa ssp. japonica) in different tissues of different growth stages.
Highlights
Plants rely on plant hormones, called phytohormones, for several processes throughout their life including growth, development and responses to stress
We report, for the first time, the application of a rapid and broad phytohormone profiling method, with high specific and accuracy, that can detect in one single run a total of 16 phytohormones on rice samples from different tissues and reproductive stages (Oryza sativa), using an solid phase extraction (SPE) step and HPLC-MS/MS detection
It can be seen that Bomba is significantly taller than dwarf -Bomba and NRVC980385 starting from week three and seven, respectively
Summary
Plants rely on plant hormones, called phytohormones, for several processes throughout their life including growth, development and responses to stress. These small molecules are naturally occurring substances that act at very low concentrations and have signaling functions (Davies, 2010; Kudo et al, 2013). More than 136 different gibberellin structures have been found, but four of them are highly bioactive: GA1, GA3, GA4, and GA7 (Hedden and Phillips, 2000; Yamaguchi, 2008; Macías et al, 2014) These four bioactive GAs have been detected in different rice developmental stages (Ma et al, 2011; Wu et al, 2012)
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