1. Field‐work reveals a novel function for MAX2 in a native tobacco's high‐light adaptions.
- Author
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Li, Suhua, Baldwin, Gundega, Yang, Caiqiong, Lu, Ruirui, Meng, Shuaishuai, Huang, Jianbei, Wang, Ming, and Baldwin, Ian T.
- Subjects
REACTIVE oxygen species ,CROP yields ,TOBACCO ,CELLULAR signal transduction ,HYDROGEN peroxide ,NICOTIANA benthamiana ,NICOTIANA - Abstract
Laboratory studies have revealed that strigolatone (SL) and karrikin (KAR) signalling mediate responses to abiotic and biotic stresses, and reshape branching architecture that could increase reproductive performance and crop yields. To understand the ecological function of SL and KAR signalling, transgenic lines of wild tobacco Nicotiana attenuata, silenced in SL/KAR biosynthesis/signalling were grown in the glasshouse and in two field plots in the Great Basin Desert in Utah over four field seasons. Of the lines silenced in SL and KAR signalling components (irMAX2, irD14, irKAI2 and irD14 × irKAI2 plants), which exhibited the expected increases in shoot branching, only irMAX2 plants showed a strong leaf‐bleaching phenotype when grown in the field. In the field, irMAX2 plants had lower sugar and higher leaf amino acid contents, lower lifetime fitness and were more susceptible to herbivore attack compared to wild‐type plants. These irMAX2 phenotypes were not observed in glasshouse‐grown plants. Transcriptomic analysis revealed dramatic responses to high‐light intensity in irMAX2 leaves in the field: lutein contents decreased, and transcriptional responses to high‐intensity light, singlet oxygen and hydrogen peroxide increased. PAR and UV‐B manipulations in the field revealed that the irMAX2 bleaching phenotype is reversed by decreasing PAR, but not UV‐B fluence. We propose that NaMAX2 functions in high‐light adaptation and fitness optimisation by regulating high‐light responses independently of its roles in the SL and KAR signalling pathways. The work provides another example of the value of studying the function of genes in the complex environments in which plants evolved, namely nature. Summary statement: Strigolatone (SL) and karrikin (KAR) signalling are known reshape branching architecture. Transgenic lines of wild tobacco Nicotiana attenuata, silenced in SL/KAR biosynthesis/signalling were grown in the glasshouse and in field plots in the Great Basin Desert during four field seasons. Of the lines silenced in SL and KAR signalling components (irMAX2, irD14, irKAI2 and irD14 × irKAI2 plants), which exhibited increases in shoot branching, only irMAX2 plants showed a strong leaf‐bleaching phenotype when grown in the field, but not in the glasshouse. Experimentation revealed that NaMAX2 functions in high‐light adaptations independently of its roles in SL and KAR signalling. The work provides another example of the value of studying gene function in the environments in which plants evolved, namely nature. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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