Mi-1.2 Transcripts Accumulate Ubiquitously in Resistant Lycopersicon esculentum

Area of Science:

• Plant genetics
• Molecular biology
• Crop protection

Background:

• The tomato Mi-1.2 gene is known to confer resistance against pests like root-knot nematodes and potato aphids.
• Differential resistance timing exists, with plants resistant to nematodes early but susceptible to aphids later.

Purpose of the Study:

• To investigate the transcriptional expression of the Mi-1.2 gene in tomato plants.
• To correlate Mi-1.2 gene expression patterns with observed resistance phenotypes against nematodes and aphids.

Main Methods:

• Reverse transcription polymerase chain reaction (RT-PCR) was employed to monitor Mi-1.2 gene expression.
• Expression levels were analyzed in both resistant (Mi/Mi) and susceptible (mi/mi) tomato cultivars.
• Gene expression was assessed across various plant tissues and developmental stages, with and without pest infestation.

Main Results:

• Mi-1.2 transcripts were found to accumulate in seeds, roots, stems, leaves, flowers, and green fruits of resistant tomato plants.
• No Mi-1.2 expression was detected in the corresponding organs of susceptible tomato plants.
• Mi-1.2 RNA was detectable early in root and leaf development and remained consistent regardless of nematode or aphid attack.

Conclusions:

• The Mi-1.2 gene is transcriptionally active in resistant tomato plants across multiple tissues and developmental stages.
• The presence of Mi-1.2 transcripts correlates with the plant's resistance to both root-knot nematodes and potato aphids.
• Expression of the Mi-1.2 gene appears constitutive and is not induced by pest infestation.