Int. J. Mol. Sci. 2013, 14, 9643-9684; doi:10.3390/ijms14059643 OPEN ACCESS International Journal of Molecular Sciences ISSN 1422-0067 www.mdpi.com/journal/ijms Review Physiological, Biochemical, and Molecular Mechanisms of Heat Stress Tolerance in Plants Mirza Hasanuzzaman 1,*, Kamrun Nahar 2,3, Md. Mahabub Alam 2, Rajib Roychowdhury 4 and Masayuki Fujita 2,* 1 Department of Agronomy, Faculty of Agriculture, Sher-e-Bangla Agricultural University, Dhaka 1207, Bangladesh 2 Laboratory of Plant Stress Responses, Department of Applied Biological Science, Faculty of Agriculture, Kagawa University, Miki-cho, Kita-gun, Kagawa 761-0795, Japan; E-Mails:
[email protected] (K.N.);
[email protected] (M.M.A.) 3 Department of Agricultural Botany, Faculty of Agriculture, Sher-e-Bangla Agricultural University, Sher-e-Bangla Nagar, Dhaka 1207, Bangladesh 4 Department of Biotechnology, Visva-Bharati University, Santiniketan 731235, West Bengal, India; E-Mail:
[email protected] * Authors to whom correspondence should be addressed; E-Mails:
[email protected] (M.H.);
[email protected] (M.F.); Tel.: +8187-891-3133 (M.F.); Fax: +8187-891-3021 (M.F.). Received: 1 February 2013; in revised form: 16 April 2013 / Accepted: 19 April 2013 / Published: 3 May 2013 Abstract: High temperature (HT) stress is a major environmental stress that limits plant growth, metabolism, and productivity worldwide. Plant growth and development involve numerous biochemical reactions that are sensitive to temperature. Plant responses to HT vary with the degree and duration of HT and the plant type. HT is now a major concern for crop production and approaches for sustaining high yields of crop plants under HT stress are important agricultural goals.