<P> Main function: initiate mobilization of storage materials in seeds during germination, cause elongation of stems, stimulate bolting in biennials, stimulate pollen tube growth . </P> <P> Gibberellins, or GAs, include a large range of chemicals that are produced naturally within plants and by fungi . They were first discovered when Japanese researchers, including Eiichi Kurosawa, noticed a chemical produced by a fungus called Gibberella fujikuroi that produced abnormal growth in rice plants . Gibberellins are important in seed germination, affecting enzyme production that mobilizes food production used for growth of new cells . This is done by modulating chromosomal transcription . In grain (rice, wheat, corn, etc .) seeds, a layer of cells called the aleurone layer wraps around the endosperm tissue . Absorption of water by the seed causes production of GA . The GA is transported to the aleurone layer, which responds by producing enzymes that break down stored food reserves within the endosperm, which are utilized by the growing seedling . GAs produce bolting of rosette - forming plants, increasing internodal length . They promote flowering, cellular division, and in seeds growth after germination . Gibberellins also reverse the inhibition of shoot growth and dormancy induced by ABA . </P> <P> Other identified plant growth regulators include: </P> <Ul> <Li> Brassinosteroids--are a class of polyhydroxysteroids, a group of plant growth regulators . Brassinosteroids have been recognized as a sixth class of plant hormones, which stimulate cell elongation and division, gravitropism, resistance to stress, and xylem differentiation . They inhibit root growth and leaf abscission . Brassinolide was the first identified brassinosteroid and was isolated from extracts of rapeseed (Brassica napus) pollen in 1979 . </Li> <Li> Salicylic acid--activates genes in some plants that produce chemicals that aid in the defense against pathogenic invaders . </Li> <Li> Jasmonates--are produced from fatty acids and seem to promote the production of defense proteins that are used to fend off invading organisms . They are believed to also have a role in seed germination, and affect the storage of protein in seeds, and seem to affect root growth . </Li> <Li> Plant peptide hormones--encompasses all small secreted peptides that are involved in cell - to - cell signaling . These small peptide hormones play crucial roles in plant growth and development, including defense mechanisms, the control of cell division and expansion, and pollen self - incompatibility . </Li> <Li> Polyamines--are strongly basic molecules with low molecular weight that have been found in all organisms studied thus far . They are essential for plant growth and development and affect the process of mitosis and meiosis . </Li> <Li> Nitric oxide (NO)--serves as signal in hormonal and defense responses (e.g. stomatal closure, root development, germination, nitrogen fixation, cell death, stress response). NO can be produced by a yet undefined NO synthase, a special type of nitrite reductase, nitrate reductase, mitochondrial cytochrome c oxidase or non enzymatic processes and regulate plant cell organelle functions (e.g. ATP synthesis in chloroplasts and mitochondria). </Li> <Li> Strigolactones--implicated in the inhibition of shoot branching . </Li> <Li> Karrikins--not plant hormones because they are not made by plants, but are a group of plant growth regulators found in the smoke of burning plant material that have the ability to stimulate the germination of seeds </Li> <Li> Triacontanol--a fatty alcohol that acts as a growth stimulant, especially initiating new basal breaks in the rose family . It is found in alfalfa (lucerne), bee's wax, and some waxy leaf cuticles . </Li> </Ul>

Name the plant growth regulator which is synthesized by ripening fruits