“Chihuahua teeth”!!! I am dead. 
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The patents for “Smooth” varieties that I find at a quick glance all indicate that the rachises are free of prickles. Some do indicate that a few prickles might be produced at the base of vigorous canes (which is similar to the ‘Austin Thornless’-derived gene found in blackberries), but are otherwise completely smooth:
For me, too, the absence of prickles on the rachis is a very desirable trait.
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Convergent evolution of plant prickles by repeated gene co-option over deep time
https://www.science.org/doi/10.1126/science.ado1663
This article might give some help, although it didn’t answer the question directly.
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