The Genetic Complexity of Type-IV Trichome Development Reveals the Steps towards an Insect-Resistant Tomato

Area of Science:

• Plant genetics
• Entomology
• Agricultural science

Background:

• Wild tomato (S. galapagense) leaves have type-IV glandular trichomes (GT) producing acylsugars (AS) for insect resistance.
• Domesticated tomatoes (S. lycopersicum) lack leaf GTs, making them susceptible to insect pests.

Purpose of the Study:

• To engineer cultivated tomatoes with type-IV GTs for enhanced insect resistance.
• To investigate the genetic basis of type-IV GT development and AS production.

Main Methods:

• Introgressing genetic determinants for type-IV GTs from S. galapagense into Micro-Tom (MT) to create MT-Get.
• Utilizing mapping-by-sequencing and genetic mapping to identify responsible S. galapagense alleles.
• Conducting metabolic and gene expression analyses to assess AS production and exudation.

Main Results:

• MT-Get plants developed type-IV GTs on adult organs, though at lower densities.
• Type-IV GT presence did not correlate with increased AS production or exudation.
• Engineered tomatoes showed some AS production but lacked whitefly resistance.

Conclusions:

• Type-IV glandular trichome development alone is insufficient for high acylsugar accumulation.
• Breeding insect-resistant tomatoes requires understanding additional steps beyond GT development.
• Further research is needed to achieve effective insect resistance in cultivated tomatoes.