The systemic acquired resistance (SAR) demonstrated in the experiment with the tobacco mosaic virus is possible due to signals sent: Question 2 options: through the air through the xylem along the leaf surface through the phloem through the air through the xylem along the leaf surface through the phloem Solution Answer: through the phloem Explanation: Several studies have shown that the establishment of SAR involves the generation and transport of signals via phloem to the uninfected distal tissues.