Switching between Heat Shock Proteins and Cold Inducible Proteins under Temperature Fluctuation in Solanum tuberosum L. Cultivars in In Vivo Condition

Abstract

Cross-talking between heat shock proteins (HSPs) and cold inducible proteins (CIPs) subsequent to combinational mild heat (35°C) and cold (8°C) stress was investigated in vivo for four cultivars of Solanum tuberosum L. viz. Kufri Pukhraj (PO), Kufri Jyoti (GS), Kufri Ashoka (KF) and Kufri Chandramukhi (CM) in the order of their decreasing thermotolerance, to understand how this economic crop adapts to extreme temperature fluctuation. We showed a time-course differential genotypic expression pattern for HSPs at 35°C for 10h and CIPs at 8°C for 12h time-lapse. Remarkably, we noted the disappearance of a housekeeping protein (HKP) of about 19.8KD at 2h, 35°C in GS absent in CM, KF and PO; but strongly expressed as CIPs at 8°C for all the cultivars. Furthermore, heat-stress led to an outstanding transient induction of HSP95.9, HSP83.6, HSP78.7, HSP70.7, HSP66.0, HSP54.1, HSP48.6, HSP43, sHSP38.3, sHSP35.3, sHSP29, sHSP22.5, sHSP17.8 and sHSP9.5 in GS at 6h, while HKP58.7, HKP55.5 and HKP43.7 were stably overexpressed in CM, KF and PO. Temperature switching from 35°C to 8°C upregulated HKP43.4, HKP54.6, CIP14.1 and HKP19.9 for all the cultivars. The recovery process 24h subsequent to this archetype switching was governed by overexpression of small(s)HSPs of about 25.4KD-14.1KD, HKP58.7 and HKP43.5 for all cultivars. Results suggest cross-talk protection for this paradigm-shift in temperature is chiefly conferred by isoforms of constitutively expressed HKPs, CIP19.9 and CIP14.1 in S. tuberosum L. Explicitly, this differential proteome change within 22h signify HKPs may not participate in thermotolerance as HSPs, but participate in cold acclimation as CIPs, recovery as sHSPs and even switch-off during heat-stress in some cultivars as depicted in GS.