The invention relates to methods of producing a desired phenotype in a plant by manipulation of gene expression within the plant. The method relates to means which increase the level of expression of a MYB-subgroup14 polynucleotide or a MYB68 polypeptide. The method also relates to expression of a nucleic acid sequence encoding a MYB-subgroup14 or a MYB68 transcriptional factor. The methods are directed to elevating the levels of a MYB-subgroup14 or a MYB68 expression, wherein a desired phenotype such as reduced flower abortion and increased yield during heat stress is observed. The invention also relates to nucleic acid sequences useful in such methods.