A transgenic crop plant transformed by a Hookless-Like Stress-Related Polypeptide (HSRP) coding nucleic acid, wherein expression of the nucleic acid sequence in the crop plant results in the plant's increased root growth, and/or increased yield, and/or increased tolerance to environmental stress as compared to a wild type variety of the plant. Also provided are agricultural products, including seeds, produced by the transgenic crop plants. Also provided are isolated novel HSRPs and isolated novel nucleic acid coding HSRPs, and vectors and transgenic plant containing the same.