A model-guided alternating high-temperature thermotherapy achieves complete eradication of sugarcane mosaic virus and preserves physiological integrity in Saccharum officinarum cv. Xuezhe.

INTRODUCTION

Sugarcane mosaic virus (SCMV) undermines both yield and eating quality of the chewing-cane cultivar Saccharum officinarum cv. Xuezhe. Although constant high-temperature thermotherapy can eliminate SCMV, it frequently causes serious heat injury in heat-sensitive genotypes. This study developed an alternating high-temperature thermotherapy (AHTT) scheme to eradicate SCMV while maintaining axillary-bud vigor on rooted cuttings.

METHODS

A uniform-design experiment combined with quadratic regression analysis was used to optimize three factors: maximum treatment temperature (42-48 °C), duration of the high-temperature pulse (2-6 h in darkness), and the subsequent recovery phase at 38 °C (3-6 h under light). These cycles were applied daily over a 12-day regimen. Outcomes included sprouting, rooted-cutting performance, and virus elimination.

RESULTS

The model predicted an optimal schedule of 47 °C for 5 h (dark) followed by a 7-h recovery at 38 °C, repeated daily for 12 days; this schedule was experimentally validated. Under the optimized regime, axillary buds on 12-day-rooted cuttings were completely SCMV-free by RT-PCR, with 97% sprouting and acceptable vigor. AHTT was also associated with increased catalase (CAT) activity and reduced peroxidase (POD) activity.

DISCUSSION: The model-guided AHTT protocol reconciles effective SCMV eradication with acceptable plant stress and performs better than constant-temperature thermotherapy. It provides a practical, scalable, and environmentally friendly approach to generate virus-free sugarcane planting material, with potential relevance to other vegetatively propagated, heat-sensitive crops.